Rate Constants for Reactions of Phenoxyl Radicals in Solution

Pedatsur Netaa… National Institute of Standards and Technology, Gaithersburg, Maryland 20899

Jan Grodkowski Institute of Nuclear Chemistry and Technology, 03195 Warsaw, Poland

Received 12 January 2004; revised manuscript received 17 May 2004; accepted 1 June 2004; published online 7 April 2005

Absolute rate constants for reactions of phenoxyl radicals in solution have been com- piled and evaluated from the literature ͑172 citations͒. Rate constants are included for phenoxyl radicals bearing various substituents, including semiquinone radicals and radical ions, as well as aroxyl radicals derived from polycyclic aromatic compounds. The reactions tabulated include self-reactions of the radicals, reactions with other radicals, reactions with inorganic compounds, and reactions with organic compounds. A subset of the latter group includes electron transfer reactions for which the rate constants of both the forward and the reverse reaction have been measured. The radicals were generated by radiolysis, photolysis, thermolysis, or chemical reactions, and their rate constants were determined generally by kinetic spectrophotometry or electron spin resonance. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1797812͔ Key words: phenoxyl radicals; rate constants; reaction kinetics; semiquinone radicals

Contents 1. Introduction

1. Introduction...... 109 Phenols and quinones are found among hormones, vita- 2. Arrangement of the Tables...... 110 mins, antibiotics, antioxidants, and other natural and com- 3. List of Abbreviations and Symbols...... 111 mercial products. Phenoxyl and semiquinone radicals are 4. References for the Introductory Material...... 112 formed in thermochemical, photochemical, radiation chemi- 5. References for Tables 1–9...... 197 cal, and biochemical processes which involve the oxidation of phenols or the reduction of quinones. Phenoxyl type radicals are involved in biological redox processes and in the biosynthesis of natural products. For these reasons, there has List of Tables 1–7 1 Self-reactions of phenoxyl radicals...... 113 been much interest in the chemistry of phenoxyl radicals. 2 Reactions of phenoxyl radicals with other The rate constants for reactions of various radicals with phe- radicals...... 134 nols and quinones, which lead to the formation of phenoxyl 3 Reactions of phenoxyl radicals with inorganic and semiquinone radicals, were reported in previous 8–11 compounds...... 142 compilations and are available in the NDRL-NIST Solu- ͑ 4 Reactions of phenoxyl radicals with tion Kinetics Database http://kinetics.nist.gov/solution/ hydrocarbons, alcohols, oleﬁns, fatty acid esters.. 152 index.php͒. 5 Reactions of phenoxyl radicals with amines, In this compilation we tabulate the absolute rate constants other nitrogen compounds, sulfur compounds. . . . 156 for reactions of phenoxyl radicals. The methods of produc- 6 Reactions of phenoxyl radicals with phenols..... 160 tion and monitoring of these radicals have been summarized 7 Reactions of phenoxyl radicals with ascorbic in a recent chapter7 and earlier reviews1–6 and will not be acid and derivatives...... 173 repeated here. That chapter also discussed the chemical prop- 8 Reactions of phenoxyl radicals with erties and reactions of phenoxyl radicals and presented se- hydroperoxides and peroxides...... 178 lected rate constants. In this compilation we attempt to sum- 9 Electron transfer equilibrium reactions of marize all published absolute rate constants but do not phenoxyl and semiquinone radicals include relative rate constants that have not been converted Phenoxyl and semiquinone radicals as oxidants... 184 into absolute values by the original authors. The relative rate Semiquinone radicals as reductants ...... 193 constants, as well as the absolute values reported through 1994 were summarized in the Landolt-Boernstein series.12,13 a͒Electronic mail: [email protected] The present compilation, which covers the literature through © 2005 American Institute of Physics. 2003, is presented in a more concise format and is also avail-

Õ Õ Õ Õ Õ 0047-2689 2005 34„1… 109 91 $39.00109 J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 110 P. NETA AND J. GRODKOWSKI able in a searchable form as part of the NDRL-NIST Solu- complex; the reported rate constants are not given in the tion Kinetics Database. present tables. Most of the rate constants tabulated in this compilation One-electron oxidation of phenols is known to take place have been reported in only one study. In those cases where much more slowly with neutral phenols than with the corre- multiple determinations have been reported in the literature, sponding phenolate ions. Therefore, most electron transfer the values are listed together, with no attempt to choose a equilibrium reactions involving phenols were studied in al- preferred value or to average the listed values. In all of these kaline solutions, where the phenols are ionized. Certain equi- cases, the different values appeared to have the same degree librium studies, however, were carried out in neutral solu- of validity since they were generally measured by the same tions and report very low rate constants for forward or Ϫ Ϫ approach. The standard uncertainties in the listed rate con- reverse reactions with phenols (Ͻ105 L mol 1 s 1͒. Such re- stants is generally between Ϯ10% and Ϯ20%. When the sults are included in Table 9, but the reader is advised to take uncertainty is larger the values are reported with an approxi- into account that the rapid reaction in one direction is likely mate sign (ϳ). Some rate constants were reported with three to have a correct rate constant but the rate constant for the significant figures, which is beyond the expected uncertainty slow reaction in the opposite direction may be in doubt. In in such measurements; those values are rounded to two sig- such cases, the equilibrium constant is also in doubt. This nificant figures. depends on the lifetime of the radicals involved in the elec- Rate constants were not reported when the approach taken tron transfer equilibrium and whether equilibrium is reached for their measurement was clearly incorrect. This was the before the radicals decay to any significant extent. case in several studies where second-order radical–radical rate constants were reported from measurements in which the 2. Arrangement of the Tables solution contained more than one radical. For example, the decay of semiquinone radicals was followed by pulse radi- Table 1 summarizes the rate constants for the self- olysis in aqueous solutions containing the quinone and reactions of phenoxyl and semiquinone radicals. Self- 14 t-BuOH. In this case, the semiquinone radicals can decay reactions of radicals ͑R͒ are characterized by the formalism: by self-reaction and also by cross-reaction with the radicals Ϫd͓R͔/dtϭ2k͓R͔2 and values of 2k are tabulated. The radi- derived from t-BuOH and thus the values reported for the cals are presented in the following order: self-reactions are in doubt. A similar situation existed in the phenoxyl measurement of semiquinone decay in the presence of monosubstituted phenoxyl 15 EtOH because the radical derived from EtOH does not re- substituents bound through C duce the quinone rapidly; these results also are not reported. C–H and C–C only, ordered by increasing number In general, when 2-PrOH or formate ions were used as scav- of carbons engers in pulse radiolysis experiments, it was assumed that C–N ͑CN͒ the radicals produced from the reactions of these solutes with C–O ͑C–OH, C–OR, COOH, CONH , COOR, " " 2 H atoms and OH radicals transfer an electron to the quinone COR, CHO͒ and thus all the primary radicals of water radiolysis are con- C–S verted into the semiquinone radical and the observed second- C–Halogen ͑F, Cl, Br, I͒ order decay can be ascribed to the self-reaction of the semi- substituents bound through N (NH2 , NHR, NR2 , ͒ quinone radical. In this approach one neglects the small NHCOR, NO2 amount of beta-hydroxyalkyl radicals formed from 2-PrOH, substituents bound through O ͑OR, OOR, not OH͒ which do not reduce the quinone rapidly. Similarly, when halogens ͑F, Cl, Br, I͒ phenoxyl radicals are produced by oxidation of phenols in disubstituted phenoxyl aqueous solutions containing bromide or azide ions and satu- trisubstituted phenoxyl rated with N2O, one assumes complete conversion of pri- tetrasubstituted phenoxyl mary radicals into phenoxyl radicals, although the small pentasubstituted phenoxyl " amount of H atoms formed by the radiolysis do not always polycyclic aroxyl lead to production of phenoxyl. heterocyclic aroxyl There are other cases of literature data not included in this chromanoxyl and tocopheroxyl compilation. For example, in one case,16 the rate constants other heterocyclic oxyl were given only in a graph on a logarithmic scale and it is semiquinones ͑and hydroxyphenols͒. not possible to tabulate the rate constants with a reasonable In each of the above groups the same order of substitution degree of uncertainty. In another case,17 the rate constant of a and complexity is followed. reversible reaction in the reverse direction was reported Table 2 summarizes the rate constants for reactions of phe- along with the reduction potential difference between the two noxyl radicals with other radicals. Reactions between two redox pairs; derivation of the rate constant for the forward radicals, R1 and R2 , are characterized by the formalism: Ϫ ͓ ͔ ϭϪ ͓ ͔ ϭ ͓ ͔͓ ͔ reaction from such data will introduce a large uncertainty d R1 /dt d R2 /dt k R1 R2 and values of k are tabu- and thus was not reported. In two cases,18,19 the experimental lated. The table is organized by the type of the other reacting " "Ϫ conditions were not specified and the approach taken was radical. First, the inorganic: I ,O2 , then the organic: carbon

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 111

" " centered radicals (R ), peroxyl radicals (RO2 ), phenoxyl AQS anthraquinonesulfonate radicals, ascorbate radical, nitroxides, diphenylpicrylhydra- AscH2 ascorbic acid zyl ͑DPPH͒, other nitrogen and sulfur containing radicals. BQ benzoquinone Within each type of the other radical, the phenoxyl radicals Bu butyl are ordered as in Table 1. BuOH butanol Table 3 summarizes the rate constants for reactions of phe- t-BuOH tert-butyl alcohol noxyl radicals with inorganic compounds. It is arranged by t-Bu2O2 di-tert-butyl peroxide ϩ the inorganic reactant in alphabetic order of the main ele- BV2 benzyl viologen (1,1Ј-dibenzyl- ment of this reactant ͑following the order used in previous 4,4Ј-bipyridinium dication͒ compilations͒.8–11 The inorganic reactants include, in this or- chem. chemical Ϫ Ϫ 2ϩ der: SCN , ClO2 , Co(acac)2 ,Cu , Fe ions, Fe com- contg. containing Ϫ Ϫ 2Ϫ plexes, ferrocenes, I ,N3 ,O2 , Rh ions, Ru ions, SO3 , CTAB hexadecyltrimethylammonium bromide and VO. Within each inorganic reactant, the phenoxyl radi- CTAC hexadecyltrimethylammonium chloride cals are ordered as in Table 1. detd. determined The other tables summarize the rate constants for reaction d.k. decay kinetics of phenoxyl radicals with organic compounds. They are ar- DMSO dimethylsulfoxide ranged by groups of reactants, except for reversible electron dopa 3,4-dihydroxyphenylalanine transfer reactions, which are presented in the last table. The dopamine 3,4-dihydroxyphenethylamine arrangement is somewhat arbitrary and sometimes is gov- DQ duroquinone ͑tetramethyl-1,4-benzoquinone͒ erned by the type of information available for each group of Ea activation energy compounds and an attempt to tabulate the available informa- EDTA ethylenediaminetetraacetate tion in a space-saving manner. ESR electron spin resonance Table 4 lists reactions of phenoxyl radicals with hydrocar- estd. estimated bons, alcohols, olefins, fatty acid esters, in that order, with Et ethyl increasing complexity within each group. Table 5 lists reac- EtOH ethanol tions with amines, other nitrogen compounds, sulfur com- f.p. flash photolysis pounds. Table 6 lists reactions of phenoxyl radicals with phe- formn. formation nols; it is arranged by increasing complexity of the reacting ⌬H activation enthalpy phenol: monohydroxybenzenes, dihydroxybenzenes, polyhy- I ionic strength droxybenzenes, polycyclic phenols, heterocyclic phenols, Ind indole within each group—by increasing complexity and for each J joule (4.184 Jϭ1 cal) reacting phenol the phenoxyl radicals are arranged by in- K equilibrium constant creasing complexity as in Table 1. Table 7 lists reactions with k rate constant ascorbic acid and derivatives. Table 8 lists reactions with kf rate constant of the forward reaction hydroperoxides and peroxides. Table 9 lists electron transfer kr rate constant of the reverse reaction equilibrium reactions where both the forward and the reverse Me methyl reaction rate constants were reported. The first part of this MeCN acetonitrile table lists reactions in which phenoxyl or semiquinone radi- MeOH methanol cals react as oxidants and the second part lists reactions in MV2ϩ methyl viologen (1,1Ј-dimethyl- which semiquinone radicals react as reductants. This table is 4,4Ј-bipyridinium dication͒ also arranged by increasing complexity of the molecular re- NADϩ nicotinamide adenine dinucleotide actant and for each reactant by increasing complexity of the NADH nicotinamide adenine dinucleotide, reduced phenoxyl radical. Np naphthalene, substituted naphthalene, naphthyl NQ naphthoquinone 3. List of Abbreviations and Symbols p.b.k. product buildup kinetics A frequency factor p.r. pulse radiolysis abs. absorption Ph phenyl abstr. abstraction PhCl chlorobenzene ABTS 2,2Ј-azinobis PhOH phenol ͑3-ethylbenzothiazoline-6-sulfonate͒ phot. photolysis Ac acetyl pKa negative logarithm of the acid dissociation ϩ Ϫϩ ϩ acac acetylacetonate constant (AH H2OvA H3O ) AcOH acetic acid p.r. pulse radiolysis alk. alkaline Pr propyl An anthracene, substituted anthracene, anthryl PrOH propanol AQ anthraquinone Pz promethazine

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 112 P. NETA AND J. GRODKOWSKI

Q quinone 8 G. V. Buxton, C. L. Greenstock, W. P. Helman, and A. B. Ross, J. Phys. redn. reduction Chem. Ref. Data 17, 513 ͑1988͒. rel. relative 9 P. Neta, R. E. Huie, and A. B. Ross, J. Phys. Chem. Ref. Data 17, 1027 ⌬S activation entropy ͑1988͒. satd. saturated 10 P. Neta, R. E. Huie, and A. B. Ross, J. Phys. Chem. Ref. Data 19,413 SDS sodium dodecylsulfate ͑1990͒. s.f. stopped-ﬂow 11 P. Neta, J. Grodkowski, and A. B. Ross, J. Phys. Chem. Ref. Data 25,709 soln. solution ͑1996͒. TEOA triethanolamine 12 J. A. Howard and J. C. Scaiano, in Landolt-Bornstein. Numerical Data THF tetrahydrofuran and Functional Relationships in Science and Technology. New Series, TMPD N,N,NЈ,NЈ-tetramethyl-p-phenylenediamine Group II; Atomic and Molecular Physics, edited by K.-H. Hellwege and ͑ ͒ Toc-OH tocol, tocopherol O. Madelung Springer, Berlin, 1984 , Vol. 13, Part d, p. 1. 13 Trp tryptophan J. A. Howard, in Landolt-Bornstein. Numerical Data and Functional Re- ͑ lationships in Science and Technology. New Series, Group II; Molecules Tx-OH Trolox C 6-hydroxy-2,5,7,8- ͑ ͒ ͒ and Radicals, edited by H. Fischer Springer, Berlin, 1997 , Vol. 18, sub- tetramethylchroman-2-carboxylic acid vol. D1, Ch. 8, p. 231. Tyr tyrosine 14 K. E. O’Shea and M. A. Fox, J. Am. Chem. Soc. 113,611͑1991͒. 15 4. References for the Introductory Material L. Fackir, D. Jore, M. Gardes-Albert, F. Acher, R. Azerad, and B. Hickel, Radiat. Res. 141,86͑1995͒. 16 M. V. Voevodskaya and I. V. Khudyakov, Russ. J. Phys. Chem. 57,362 1 K. U. Ingold, Adv. Chem. Series 75,296͑1968͒. ͑1983͒. 2 L. R. Mahoney, Angew. Chem. Int. Ed. Engl. 8, 547 ͑1969͒. 17 M. Faraggi, R. Chandrasekar, R. B. McWhirter, and K. H. Klapper, Bio- 3 J. A. Howard, Adv. Free Radical Chem. 4,49͑1972͒. chem. Biophys. Res. Commun. 139, 955 ͑1986͒. 4 E. B. Burlakova, Russ. Chem. Rev. 44, 871 ͑1975͒. 18 W. Bors and C. Michel, Free Radical Biol. Med. 27, 1413 ͑1999͒. 5 I. V. Khudyakov and V. A. Kuzmin, Russ. Chem. Rev. 44,801͑1975͒. 19 V. A. Kuz’min, A. K. Chibisov, and A. V. Karyakin, Int. J. Chem. Kinet. 4, 6 G. W. Burton and K. Ingold, Acc. Chem. Res. 19, 194 ͑1986͒. 639 ͑1972͒. 7 S. Steenken and P. Neta, In The Chemistry of Phenols, edited by Z. Rap- poport ͑Wiley, New York, 2003͒, p. 1107.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

1 Phenoxyl C H O ϫ 9 Ϸ1 water RT p.r. D.k. at 400 nm in deoxygenated aq. soln. contg. 82TRI/SCH 6 5 • 2.3 10 Ϫ1 Ϫ1 0.1 mol L H2SO4 and 0.01 mol L phenol. ϫ 9 2.6 10 11 water RT p.r. D.k. of the Raman peak nm in N2O-satd. aq. soln. contg. 84TRI/SCHa 0.002 mol LϪ1 phenol. ϩ → Ј Ј Јϭ C6H5O• C6H5O• 7.3–11.4 water RT p.r. Product ratio 4,4 /2,4 /2,2 1.0/1.7/0.7 in N2O-satd. soln. 89YE/SCH 4,4Ј-dihydroxybiphenyl, contg. 0.01 mol LϪ1 phenol, w/wo 0.1 mol LϪ1 azide. 2,4Ј-dihydroxybiphenyl, Slight variations with conditions. 2,2Ј-dihydroxybiphenyl 5.6ϫ108 8 water 285 f.p. D.k. at 400 nm in deoxygenated soln. 73KHU/KUZ

2 2-Methylphenoxyl SOLUTION IN RADICALS PHENOXYL ϫ 8 2-CH3C6H4O• 3.2 10 8 water 285 f.p. D.k. at 405 nm in deoxygenated soln. 73KHU/KUZ 1.9ϫ108 1.1 water RT f.p. D.k. at 405 nm in deoxygenated soln. 78KHU/KUZ 3 3-Methylphenoxyl ϫ 9 Ϫ1 3-CH3C6H4O• 2.8 10 alk. water 290 13.9 25.1 p.r. D.k. at 400 nm in N2O-satd. soln. contg. 0.1 mol L 93ALF/SHO azide. 1.5ϫ108 8 water 285 f.p. D.k. at 420 nm in deoxygenated soln. 73KHU/KUZ 4 4-Methylphenoxyl ϫ 9 Ϫ1 4-CH3C6H4O• 2.0 10 alk. water 290 13.2 21.9 p.r. D.k. at 400 nm in N2O-satd. soln. contg. 0.1 mol L 93ALF/SHO azide. 2.2ϫ108 8 water 285 f.p. D.k. at 400 nm in deoxygenated soln. 73KHU/KUZ 54-͑tert-Butyl͒phenoxyl ϫ 9 Ϫ1 4-(CH3)3CC6H4O• 1.4 10 alk. water 290 12.6 19.5 p.r. D.k. at 400 nm in N2O-satd. soln. contg. 0.1 mol L 93ALF/SHO azide. 64-͑2-Aminoethyl͒phenoxyl ͑Tyramine phenoxyl͒ ϫ 8 4-(H2NCH2CH2)C6H4O• 4.7 10 11 water RT p.r. D.k. at 400–410 nm in N2O-satd. soln. contg. azide. 00DAL/BIA 7 Tyrosyl ϫ 8 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. TyrO• 8 10 7 water RT p.r. D.k. at 405 nm in N2O-satd. soln. contg. 1 89HUN/DES Ϫ1 Ϫ1 mmol L Tl2SO4 and 0.4 mmol L tyrosine. ϫ 8 4.5 10 9 water RT p.r. D.k. at 405 nm in N2O-satd. soln. contg. azide. 93JIN/LEI 84-͑2-Hydroxyethyl͒phenoxyl ͑Tyrosol phenoxyl͒ ϫ 9 4-(HOCH2CH2)C6H4O• 1.0 10 11 water RT p.r. D.k. at 400–410 nm in N2O-satd. soln. contg. azide. 00DAL/BIA 9 4-Cyanophenoxyl ϫ 9 4-NCC6H4O• 2.3 10 11 water RT p.r. D.k. at 436 nm in N2O-satd. soln. contg. azide. 00DAL/BIA 10 4-Aminophenoxyl ϫ 9 4-H2NC6H4O• 1.9 10 10.5 water p.r. D.k. at 440 nm in N2O-satd. soln. 84TRI/SCHb 11 4-͑Acetylamino͒phenoxyl ϫ 9 4-CH3CONHC6H4O• 2.2 10 8.3 water RT p.r. D.k. at 462 nm in N2O-satd. soln.; k independent of ionic 88BIS/TAB strength; k is the same at pH 7–10.5 but decreases at higher pH; at pH 12 k increases with ionic strength; radical

has pKa 11.1. 12 3-Nitrophenoxyl ϫ 7 3-O2NC6H4O• 2.6 10 8 water 285 f.p. D.k. at 450 nm in deoxygenated soln. 73KHU/KUZ 113 1 .NT N .GRODKOWSKI J. AND NETA P. 114 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

13 3-Methoxyphenoxyl ϫ 9 3-CH3OC6H4O• 3.2 10 alk. water 290 12.8 23.1 p.r. D.k. at 400 nm in N2O-satd. soln. 93ALF/SHO contg. 0.1 mol LϪ1 azide. 14 4-Methoxyphenoxyl ϫ 9 4-CH3OC6H4O• 1.0 10 alk. water 290 12.9 21.9 p.r. D.k. at 420 nm in N2O-satd. soln. 93ALF/SHO contg. 0.1 mol LϪ1 azide. 15 4-Fluorophenoxyl ϫ 9 4-FC6H4O• 2.5 10 alk. water 290 12.1 14.9 p.r. D.k. at 400 nm in N2O-satd. soln. 93ALF/SHO contg. 0.1 mol LϪ1 azide. 16 4-Chlorophenoxyl ϫ 9 4-ClC6H4O• 1.7 10 alk. water 290 12.4 17.6 p.r. D.k. at 400 nm in N2O-satd. soln. 93ALF/SHO contg. 0.1 mol LϪ1 azide. 17 4-Bromophenoxyl ϫ 9 4-BrC6H4O• 1.3 10 alk. water 290 12.3 16.2 p.r. D.k. at 400 nm in N2O-satd. soln. 93ALF/SHO contg. 0.1 mol LϪ1 azide. 18 4-Iodophenoxyl ϫ 9 4-IC6H4O• 1.1 10 9 water RT f.p. D.k. at 420 nm in aerated soln. 74KHU/KUZ contg. 4-iodophenol and anthraquinone-2,6-disulfonate. 19 2,6-Dimethylphenoxyl ϫ 9 2,6-(CH3)2C6H3O• 4.2 10 5.8 water RT p.r. D.k. at 375 and 390 nm in 95TER/SER N2O-satd. soln. contg. azide. 20 3,4-Dimethylphenoxyl ϫ 9 3,4-(CH3)2C6H3O• 1.5 10 5.8 water RT p.r. D.k. at 400 and 415 nm in 95TER/SER N2O-satd. soln. contg. azide. 21 2,6-Di͑tert-Butyl͒phenoxyl ϫ 8 ͑ ͒ 2,6-(t-Bu)2C6H3O• 3.8 10 1,2-epoxybutane 294 10.1 8.5 photo. Kinetic ESR rotating sector in 88RUE/FIS soln. contg. di-t-butyl peroxide. 4.6ϫ108 n-heptane 293 10.2 8.8 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. 9.6ϫ108 MeCN 295 9.9 4.9 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. 2.7ϫ108 t-Bu-benzene 294 10.7 12.5 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. 2.0ϫ108 3-Me-3-pentanol 296 11.2 16.2 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. 3.0ϫ108 2-PrOH 275 10.5 10.5 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. 2.9ϫ108 benzene RT photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. Addition of p-toluene sulfonic acid did not affect k. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

22 3,4-Dimethoxyphenoxyl ϫ 9 3,4-(CH3O)2C6H3O• 1.3 10 3–14 water 293 p.r. D.k. at 430 nm in N2O-satd. soln. 91JOV/TOS 23 3,5-Dimethoxyphenoxyl ϫ 9 3,5-(CH3O)2C6H3O• 1.3 10 3–14 water 293 p.r. D.k. at 505 nm in N2O-satd. soln. 91JOV/TOS 24 3,4-Methylenedioxyphenoxyl ͑Sesamoxyl͒ ϫ 8 sesamol-O• 5.0 10 3–14 water 293 p.r. D.k. at 435 nm in N2O-satd. soln. 91JOV/TOS 25 2,4-Dibromophenoxyl ϫ 8 2,4-Br2C6H3O• 2.0 10 8 water 285 f.p. D.k. at 420 nm in deoxygenated 73KHU/KUZ soln. 26 2,4,6-Trimethylphenoxyl ϫ 7 2,4,6-Me3C6H2O• 4 10 benzene 343 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. SOLUTION IN RADICALS PHENOXYL 27 2-tert-Butyl-4,6-diethylphenoxyl ϫ 5 2-t-Bu-4,6-Et2C6H2O• 2.8 10 benzene 323 8.56 19 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 28 2,6-Di-tert-butyl-4-methylphenoxyl ϫ 3 2,6-(t-Bu)2-4-MeC6H2O• 8.7 10 benzene 323 7.17 20 therm. Steady-state ESR signal in 85ROG ϩ 2,6-(t-Bu)2-4-MeC6H2 deoxygenated soln. contg. the → O• dimer phenol and dicyclohexylperoxy dicarbonate. 1.8ϫ108 n-heptane 254 10.1 8.9 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. For ϭ Ϫ1 reverse reaction kr 2.4 s ,logA ϭ ϭ 15.1, Ea 72 1.3ϫ108 3-Me-3-pentanol 265 13.0 25.1 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. For ϭ Ϫ1 reverse reaction kr 3.9 s ,logA .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. ϭ ϭ 19, Ea 93 8.7ϫ107 t-Bu-benzene 260 11.3 16.6 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS soln. contg. di-t-butyl peroxide. For ϭ Ϫ1 reverse reaction kr 5.1 s ,logA ϭ ϭ 16.8, Ea 80 3.1ϫ107 di-n-butyl 275 11.3 20 photo. Kinetic ESR ͑rotating sector͒ in 88RUE/FIS phthalate soln. contg. di-t-butyl peroxide. For ϭ Ϫ1 reverse reaction kr 9.8 s ,logA ϭ ϭ 25, Ea 126 2.6ϫ108 MeCN 263 8.9 2.7 photo. Kinetic ESR ͑rotating sector͒ in 199RUE/FIS soln. contg. di-t-butyl peroxide. For ϭ Ϫ1 reverse reaction kr 8.4 s , ϭ ϭ logA 16.8, Ea 80 1.1ϫ108 1,2-epoxybutane 255 9.6 7.8 photoKinetic ESR ͑rotating sector 88RUE/FIS in soln. contg. di-t-butyl peroxide. ϭ Ϫ

For reverse reaction kr 2.8 s 1, 115 ϭ ϭ logA 17.0, Ea 81 1 .NT N .GRODKOWSKI J. AND NETA P. 116 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

1.7ϫ108 1,2-epoxybutane 298 photo. Kinetic ESR ͑rotating sector in 89RUE/FIS soln. contg. di-t-butyl peroxide. Ϸ1ϫ108 n-heptane 298 photo. Kinetic ESR ͑rotating sector͒ in 89RUE/FIS soln. contg. di-t-butyl peroxide. ͑ ͒ → ϫ 4 Ϫ1 4-CH3-2,6- t-Bu 2C6H2O• CH2- 4 10 s cyclohexane RT p.r. D.k. at 305 nm in deoxygenated 91BRE/WOJ 2,6-(t-Bu)2C6H2OH soln. 29 2,6-Di-tert-butyl-4- ethylphenoxyl ϫ 3 2,6-(t-Bu)2-4-EtC6H2O• 2.4 10 benzene 323 7.58 26 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 30 2,6-Di-tert-butyl-4-isopropylphenoxyl 2,6-(t-Bu)2-4-(i-Pr)C6H2O• 1.8 benzene 293 chem. Kinetic ESR in deaerated soln. 67AYS/RUS contg. DPPH radicals and the phenol. 7.7 benzene 323 6.23 33 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 31 4-Methyl-2,6-di-tert-pentylphenoxyl ϫ 3 4-Me-2,6-(CMe2Et)C6H2O• 2.4 10 benzene 323 6.95 23 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 32 2,6-Di-tert-butyl- 4-(2Ј-hydroxyethyl)phenoxyl ϫ 3 benzene 323 7.27 26.3 therm. Steady-state ESR signal in 85ROG 2,6-(t-Bu)2-4-(HOCH2CH2)C6H2O• 1.1 10 deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 33 2,6-Di-tert-butyl-4-͑methoxymethyl͒phenoxyl ϫ 2 2,6-(t-Bu)2-4-(MeOCH2)C6H2O• 1.1 10 benzene 323 7.18 32 34 2,4,6-tri-tert-butylphenoxyl Ͻ ϫ Ϫ5 2,4,6-(t-Bu)3C6H2O• 1 10 benzene 323 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 35 2,6-Di-tert-butyl-4-cyclohexylphenoxyl ϫ 1 2,6-(t-Bu)2-4-(c-Hx)C6H2O• 1.1 10 benzene 323 5.24 26 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 36 2,6-Dicyclohexyl-4-phenylphenoxyl → ϫ 7 ϭ ϫ 3 Ϫ1 2 2,6-(c-C6H11)2-4-Ph-C6H2O• dimer 2.7 10 n-PrOH 293 f.p. D.k. at 510 nm. kr 1 10 s . 79KUZ/KHU Kϭ(4Ϯ2)ϫ10Ϫ5. 37 2,4,6-Triphenylphenoxyl → ϫ 7 ϭ 2 2,4,6-Ph3-C6H2O• dimer 8 10 n-PrOH 293 f.p. D.k. at 550 or 750 nm. kr 3 79KUZ/KHU ϫ103 sϪ1. Kϭ(4Ϯ2)ϫ10Ϫ5. 38 2,6-Di-tert-butyl-4-͑methoxycarbonylethyl͒phenoxyl 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

ϫ 2 2,6-(t-Bu)2-4-(CH3OCOCH2CH2)C6H2O• 7.4 10 benzene 323 7.27 27 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 39 2,6-Di-tert-butyl-4-͑octadecyloxycarbonylethyl͒phenoxyl ͑ ͒ ͑ ͒ ϫ 2 2,6- t-Bu 2-4- C18H37OCOCH2CH2 C6H2O• 4.2 10 benzene 299 7.66 29 chem. Decay of ESR signal in 85YAR/ROG deoxygenated soln. contg. d i-tert-butyl peroxide. Phenoxyl radical formed by photolysis in the ESR cavity and the kinetics followed after termination of photolysis. 1.5ϫ103 benzene 323 6.48 20.5 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. SOLUTION IN RADICALS PHENOXYL dicyclohexylperoxy dicarbonate. 40 2,6-Di-tert-butyl-4-(3Ј,5Ј-di-tert-butyl-4Ј-hydroxyphenyl)phenoxyl 9 2,6-(t-Bu)2-4-(3Ј,5Ј-(t-Bu)2- 1.4ϫ10 AcOH 296 f.p. D.k. at 650 nm. 78KHU/BUR Ј 4 -HOC6H2)-C6H2O• 7ϫ108 formic acid 296 f.p. D.k. at 650 nm. 78KHU/BUR 1.3ϫ106 toluene 193–233 Ϸ0 f.p. D.k. of UV-vis abs. in 83TUM/PRO deoxygenated soln. 41 2,4-Di-tert-butyl-6-(3Ј,5Ј-di-tert-butyl-2Ј-hydroxyphenyl)phenoxyl 1 2,4-(t-Bu)2-6-(3Ј,5Ј-(t-Bu)2- 1.4ϫ10 benzene 299 8.91 39 chem. Decay of ESR signal in 85YAR/ROG Ј 2 -HOC6H2)C6H2O• deoxygenated soln. contg. di-tert-butyl peroxide. Phenoxyl radical formed by photolysis in the ESR cavity and the kinetics followed after termination of photolysis. 42 2,6-Di-tert-butyl-4-(3Ј,5Ј-di-tert-butyl-4Ј-hydroxyphenyl)methylphenoxyl .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 2,6-(t-Bu)2-4-(3Ј,5Ј-(t-Bu)2- 3.5ϫ10 benzene 299 7.13 26 chem. Decay of ESR signal in 85YAR/ROG Ј 4 -HOC6H2CH2)C6H2O• deoxygenated soln. contg. di-tert-butyl peroxide. Phenoxyl radical formed by photolysis in the ESR cavity and the kinetics followed after termination of photolysis. 43 2,4-Di-tert-butyl-6-(3Ј,5Ј-di-tert-butyl-2Ј-hydroxyphenyl)methylphenoxyl 1 2,4-(t-Bu)2-6-(3Ј,5Ј-(t-Bu)2-2Ј- 4.6ϫ10 benzene 299 7.87 36 chem. Decay of ESR signal in 85YAR/ROG HOC6H2CH2)C6H2O• deoxygenated soln. contg. di-tert-butyl peroxide. Phenoxyl radical formed by photolysis in the ESR cavity and the kinetics followed after termination of photolysis. 117 1 .NT N .GRODKOWSKI J. AND NETA P. 118 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

2.4ϫ102 benzene 323 8.64 38.8 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 44 2-tert-Butyl-4-methyl-6-(3Ј-tert-butyl-5Ј-methyl-2Ј-hydroxyphenyl)methylphenoxyl 2-(t-Bu)-4-Me-6-(3Ј-(t-Bu)-5Ј- 5ϫ106 benzene 343 therm. Steady-state ESR signal in 85ROG Me-2Ј-HOC6H2CH2) deoxygenated soln. contg. C6H2O• dicyclohexylperoxy dicarbonate. 45 2,6-Di-tert-butyl-4-(4Ј-hydroxy-3Ј,5Ј-di-tert-butylphenylmethyl)phenoxyl ϫ 3 HOC6H2(t-Bu)2CH2C6H2(t-Bu)2-O• 3.1 10 benzene 323 6.48 18.5 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 46 2-tert-Butyl-4-methyl-6-(2Ј-methoxy-3Ј-tert-butyl-5Ј-methylphenylmethyl)phenoxyl 6 MeOC6H2(t-Bu)(Me)CH2C6H2(t-Bu) 5ϫ10 benzene 343 therm. Steady-state ESR signal in 85ROG ϫ (Me)–O• deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 47 4,6-Di-tert-butyl-2-(2Ј-methoxy-3Ј,5Ј-di-tert-butylphenylethyl)phenoxyl ϫ 3 MeOC6H2(t-Bu)2CH2CH2C6H2(t-Bu)2 –O• 3.0 10 benzene 323 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 48 2,6-Di-tert-butyl-4-(tris(3Ј,5Ј-di-tert-butyl-4Ј-hydroxyphenylpropanoyloxy-methyl)ethyloxycarbonylethyl)phenoxyl 2 (HOC6H2(t-Bu)2CH2CH2COOCH2)3 5.5ϫ10 benzene 299 6.98 24 chem. Decay of ESR signal in 85YAR/ROG CCH2OCOCH2CH2C6H2(t-Bu)2 –O• deoxygenated soln. contg. di-tert-butyl peroxide. Phenoxyl radical formed by photolysis in the ESR cavity and the kinetics followed after termination of photolysis. 2.4ϫ103 benzene 323 5.89 15.5 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 49 2,6-Di-tert-butyl-4-(2Ј,4Ј,6Ј-trimethyl-3Ј,5Ј-di(4Љ-hydroxy-3Љ,5Љ-di-tert-butylphenylmethyl))methylphenoxyl 2 (HOC6H2(t-Bu)2CH2)2 –Me3 – 1ϫ10 benzene 323 7.16 33 therm. Steady-state ESR signal in 85ROG C6H2CH2C6H2(t-Bu)2 –O• deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 50 2-tert-Butyl-6-methyl-4-(4Ј-hydroxy-3Ј-methyl-5Ј-tert-butylphenylpropanoylethyloxyethyloxycarbonylethyl)phenoxyl ͑ ͒͑ ͒ 5 HOC6H2 t-Bu Me CH2CH2COOCH2CH2OCH2 2.4ϫ10 benzene 323 7.63 14 therm. Steady-state ESR signal in 85ROG deoxygenated soln. contg. CH2OCOCH2CH2C6H2(Me)(t-Bu)-O• . dicyclohexylperoxy dicarbonate 51 2,6-Di-tert-butyl-4-(4Ј-hydroxy-3Ј,5Ј-di-tert-butylphenylpropanoylethyloxyethyloxycarbonylethyl)phenoxyl 3 HOC6H2(t-Bu)2CH2CH2COOCH2CH2OCH2 1.8ϫ10 benzene 323 7.06 24 therm. Steady-state ESR signal in 85ROG CH2OCOCH2CH2C6H2(t-Bu)2-O• deoxygenated soln. contg. dicyclohexylperoxy dicarbonate. 52 2,6-Diphenyl-4-(3Ј,5Ј-diphenyl-4Ј-hydroxyphenyl)phenoxyl 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

Ј Ј Ј ϫ 5 2,6-Ph2-4-(3 ,5 -Ph2-4 -HOC6H2)C6H2O• 1.3 10 toluene 296 f.p. D.k. of the ESR signal. Radical 78KHU/BUR formed by photolysis of soln. contg. the phenol and the corresponding quinone. 53 4-Methoxy-2,6-diphenylphenoxyl → ϫ 8 ϭ ϫ 2 Ϫ1 2 4-MeO-2,6-Ph2-C6H2O• dimer 7 10 n-PrOH 293 f.p. D.k. at 650 nm. kr 3 10 s . 79KUZ/KHU Kϭ(4Ϯ1)ϫ10Ϫ7. ⌬H‡ϭ(21 Ϯ4) kJ molϪ1, ⌬S‡ϭ(0 Ϯ12) J molϪ1 KϪ1. 54 4-Ethoxy-2,6-diphenylphenoxyl → ϫ 8 ϭ ϫ 3 Ϫ1 2 4-EtO-2,6-Ph2-C6H2O• dimer 3.5 10 n-PrOH 293 f.p. D.k. at 650 nm. kr 1 10 s . 79KUZ/KHU Kϭ(3Ϯ1)ϫ10Ϫ6. ⌬H‡ϭ(17 Ϯ4) kJ molϪ1, ⌬S‡ϭϪ(21 SOLUTION IN RADICALS PHENOXYL Ϯ12) J molϪ1 KϪ1. 55 4-Octadecyloxy-2,6-diphenylphenoxyl ϫ 8 ϭ ϫ 3 Ϫ1 2 4-n-C18H37O-2,6-Ph2-C6H2O• 1.9 10 n-PrOH 293 f.p. D.k. at 650 nm. kr 1 10 s . 79KUZ/KHU → dimer Kϭ(5Ϯ1)ϫ10Ϫ6. ⌬H‡ϭ(17 Ϯ4) kJ molϪ1, ⌬S‡ϭϪ(25 Ϯ12) J molϪ1 KϪ1. 56 3,4,5-Trimethoxyphenoxyl ϫ 9 3,4,5-(CH3O)3C6H2O• 1.3 10 3–14 water 293 p.r. D.k. at 495 nm in N2O-satd. soln. 91JOV/TOS 57 2,4,5-Trichlorophenoxyl ϫ 9 2,4,5-Cl3C6H2O• 1.5 10 10 water RT p.r. D.k. at 430 nm in N2O-satd. soln. 89DRA/FOX contg. azide. 58 4-Methoxy-2,3,5,6-tetramethylphenoxyl ϫ 4 4-(CH3O)C6(CH3)4O• 6 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. No effect of

O2 . .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 59 Pentachlorophenoxyl ϫ 9 C6Cl5O• 1.8 10 8 water RT p.r. D.k. at 440 nm in N2O-satd. soln. 91TER/SER contg. azide. 60 Pentabromophenoxyl ϫ 9 C6Br5O• 5.6 10 8 water RT p.r. D.k. at 350 and 470 nm in 91TER/SER N2O-satd. soln. contg. azide. 61 2,2,5,7,8-Pentamethylchroman-6-oxyl ϫ 3 PMC–O• 3 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. No effect of

O2 . 2.2ϫ103 benzene 323 8.12 29.7 therm. Steady-state ESR signal in 87ROG/KRA deoxygenated soln. contg. the phenol and di-tert-butyl hyponitrite. 119 2 .NT N .GRODKOWSKI J. AND NETA P. 120 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

8.9ϫ102 PhCl 310 therm. Radicals generated by reaction 95BOW/ING with di-tert-butylhyponitrite or 2,2Ј- azobis(2,4-dimethylvaleronitrile). Monitored absorbance at 424 nm vs 440 nm. Detd. also from decay of PMC-O• after fast reaction of PMCO with DPPH•. 1.1ϫ103 EtOH 310 Chem. D.k. of ESR signal in deaerated 00WAT/NOG soln. contg. galvinoxyl. 62 2-Carboxy-2,5,7,8-tetramethylchromane-6-oxyl ͑Trolox phenoxyl radical͒ ϫ 7 TxO 1.6 10 4.5 water RT p.r. D.k. at 440 nm in N2O-satd. soln. 86CAB/BIE • 6 Ϫ1 4.2ϫ10 5.1 contg. 0.1 mol L Na2SO4 , 2.1ϫ106 5.3 0.01 mol LϪ1 BrϪ, and Ϫ 1.9ϫ106 5.4 0.16 mmol L 1 Trolox. 3.6ϫ105 5.7 63 5,7-Dimethyltocoxyl ϫ 3 DMToc-O• 4.5 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. 64 ␣-Tocopheroxyl ␣ ϫ 3 -Toc-O• 3 10 benzene 296 f.p. Kinetic ESR in soln. contg. 9% 84DOB/BUR di-t-butyl peroxide. No effect of 85BUR/DOB

O2 . 1.0ϫ104 benzene 299 7.73 21 chem. Decay of ESR signal in 85YAR/ROG deoxygenated soln. contg. di-tert-butyl peroxide. Phenoxyl radical formed by photolysis in the ESR cavity and the kinetics followed after termination of photolysis. 1.4ϫ103 EtOH 293 8.2 27.6 chem. Kinetic ESR. Radical produced by 88ROU/RIC reaction of tocopherol with DPPH. 5.6ϫ102 heptanol 293 6.1 18.0 chem. Kinetic ESR. Radical produced by 88ROU/RIC reaction of tocopherol with DPPH. Paper quotes 2kϭ1.9ϫ102 in chloroform and various values in benzene. 3ϫ103 n-BuOH chem. Decay of ESR signal, radical 93OND/MIS produced by reaction of ␣-tocopherol with DPPH.

␣ ϩ␣ → ϫ 2 -Toc-O• -Toc-O• dimer 1.1 10 benzene 298 f.p. Kinetic ESR in soln. contg. 94LUC/PED ϭ di-t-butyl peroxide. kr 2 ϫ10Ϫ2 sϪ1. ␣ ϩ␣ → ϫ 3 -Toc-O• -Toc-O• disproportionation 6 10 benzene 298 f.p. Kinetic ESR in soln. contg. 94LUC/PED di-t-butyl peroxide. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

8.6ϫ102 PhCl 298 7.4 25.5 therm. Radicals generated by reaction of 95BOW/ING di-tert-butylhyponitrite or 2,2Ј- azobis(2,4-dimethylvaleronitrile). Monitored absorbance at 424 nm vs 440 nm. Cor. for reaction with impurity. Detd. also from the decay ␣ of Toc-O• after fast reaction of ␣ -tocopherol with DPPH•. Deuteration of ␣-tocopherol

(5-CD3 or 5,7-(CD3)2) reduces 2k by a factor of 3.7. 1.0ϫ103 EtOH 310 chem. D.k. of ESR signal in deaerated 00WAT/NOG

soln. contg. galvinoxyl. SOLUTION IN RADICALS PHENOXYL 65 ␤-Tocopheroxyl ␤ ϫ 4 -Toc-O• 4 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. No effect of

O2 . 66 ␥-Tocopheroxyl ␥ ϫ 4 -Toc-O• 4.5 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. 67 ␦-Tocopheroxyl ␦ ϫ 5 -Toc-O• 1.5 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. Little effect

of O2 . 68 2,3-Dihydro-2,2,4,6-tetramethylbenzofuran-5-oxyl ϫ 2 BOM–O• 7.0 10 EtOH 310 Chem. D.k. of ESR signal in deaerated 00WAT/NOG

.Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. soln. contg. galvinoxyl. 69 2,3-Dihydro-2,2-dimethyl-4,6-di-tert-butylbenzofuran-5-oxyl BOB–O• 1.1 EtOH 310 Chem. D.k. of ESR signal in deaerated 00WAT/NOG soln. contg. galvinoxyl. 70 2,3-Dihydro-2,2-dipentyl-4,6-di-tert-butylbenzofuran-5-oxyl BO–653-O• 1.1 EtOH 310 Chem. D.k. of ESR signal in deaerated 00WAT/NOG soln. contg. galvinoxyl. 71 2,3-Dihydro-2,4,6,7-tetramethylbenzofuran-5-oxyl ϫ 3 TMBF–O• 4 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. 72 5,7,8-Trimethyl-3,4-dihydrobenzothiopyran-6-oxyl ϫ 2 TMTP–O• 2 10 benzene 296 photo. D.k. of ESR signal in 85BUR/DOB deoxygenated soln. contg. di-tert-butyl peroxide. kϭ7ϫ102

in the presence of O2 . 121 2 .NT N .GRODKOWSKI J. AND NETA P. 122 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

73 7-͑2-Amino-2-carboxyethyl͒-3-carboxy-3,4-dihydro-2H-1,4-benzothiazine-5-oxyl ϫ 7 BT-O• 2.7 10 7.0 water RT p.r. D.k. at 330 nm in N2O-satd. soln. 99NAP/DID contg. bromide.

74 1,2-Benzosemiquinone ϫ 8 1,2-C6H4(OH)O• 3.9 10 2.0 water RT f.p. D.k. at 350 nm in deoxygenated 78KHU/KUZ soln. 75 1,2-Benzosemiquinone anion Ϫ ϫ 7 1,2-C6H4(O )O• 1.1 10 7.0 water RT p.r. D.k. at 300 nm in N2O-satd. soln. 93LAN contg. azide. Decay mostly via Ϫ ϩ 2-(O )C6H4O• 2-(OH)C6H4O •. 76 4-t-Butyl-1,2-benzosemiquinone ϫ 8 4-t-Bu-1,2-C6H3(OH)O• 9.0 10 3.0 water RT p.r. D.k. at 310 nm in N2O-satd. soln. 79RIC 77 4-t-Butyl-1,2-benzosemiquinone anion Ϫ ϫ 6 4-t-Bu-1,2-C6H3(O )O• 4 10 7.3 water RT p.r. D.k. at 310 nm in N2O-satd. soln., 79RIC 2k is upper limit for decay of semiquinone anion, observed decay involves also neutral semiquinone ϭ ϭ ϫ 9 (pKa 5.2). k 1.2 10 estd. for the mixed decay of neutral and anion. 78 Dopa semiquinone anion Ϫ ϫ 7 Dopa(O )O• 9.8 10 7.7 water RT p.r. D.k. at 305 nm in N2O-satd. soln. 85THO/LAN contg. azide. 79 4-Methoxy-1,2-benzosemiquinone anion Ϫ ϫ 8 4-(CH3O)-1,2-C6H3(O )O• 2.5 10 7.0 water RT p.r. D.k. at 320 nm in N2O-satd. soln. 87COO/LAN contg. azide. 80 3,5-Di-tert-butyl-1,2-benzosemiquinone ϫ 6 Ϸ 3,5-(t-Bu)2-1,2-C6H2(OH)O• 6.0 10 toluene 193–233 0 f.p. D.k. of UV-vis abs. in 83TUM/PRO deoxygenated soln. Kinetic isotope ϭ effect kH /kD 12.5 for deuteriated OH group. 81 3,6-Di-tert-butyl-1,2-benzosemiquinone ϫ 7 3,6-(t-Bu)2-1,2-C6H2(OH)O• 1 10 toluene RT photo. D.k. of UV-vis abs 75TUM/PRO 2.2ϫ106 toluene 193–233 Ϸ0 f.p. D.k. of UV-vis abs. in 83TUM/PRO deoxygenated soln.

Kinetic isotope effect kH /kD ϭ14.5 for deuteriated OH group. 82 2-S-Cysteinyldopa semiquinone anion 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

Ϫ ϫ 7 2-S-Cysteinyldopa(O )O• 8.8 10 7 water RT p.r. D.k. at 320 nm in N2O-satd. soln. 85THO/LAN contg. azide. 83 5-S-Cysteinyldopa semiquinone anion Ϫ ϫ 8 5-S-Cysteinyldopa(O )O• 1.8 10 7 water RT p.r. D.k. at 310 nm in N2O-satd. soln. 85THO/LAN contg. azide. ϫ 8 1.7 10 7.0 water RT p.r. D.k. at 320 nm in N2O-satd. soln. 99NAP/DID contg. bromide. 84 2,5-Di͑S-cysteinyl͒dopa semiquinone anion Ϫ ϫ 8 2,5-Di(S-cysteinyl)dopa(O )O• 1.1 10 7 water RT p.r. D.k. at 340 nm in N2O-satd. soln. 85THO/LAN contg. azide. 85 3-tert-Butyl-5-triphenylmethyl-1,2-benzosemiquinone ϫ 6 Ϸ 3-t-Bu-5-(Ph3C)-1,2-C6H2(OH)O• 5.5 10 toluene 193–233 0 f.p. D.k. of UV-vis abs. in 83TUM/PRO deoxygenated soln. Kinetic isotope SOLUTION IN RADICALS PHENOXYL ϭ effect kH /kD 23 for deuteriated OH group. 86 3,5-Di-tert-butyl-6-chloro-1,2-benzosemiquinone ϫ 6 Ϸ 3,5-(t-Bu)2-6-Cl-1,2-C6H(OH)O• 5.6 10 toluene 193–233 0 f.p. D.k. of UV-vis abs. in 83TUM/PRO deoxygenated soln. Kinetic isotope ϭ effect kH /kD 8.6 for deuteriated OH group. 87 Pyrogallol semiquinone anion Ϫ ϫ 8 1,2,3-C6H3(OH)(O )O• 3.0 10 6.7 water RT p.r. D.k. at 300 nm in N2O-satd. soln. 88DEE/PAR contg. bromide. 88 n-Propyl gallate semiquinone anion Ϫ ϫ 8 3,4,5-(OH)(O )(O•)C6H2CO2C3H7 8.0 10 6.7 water RT p.r. D.k. in N2O-satd. soln. contg. 88DEE/PAR bromide. 89 1,3-Benzosemiquinone ͑3-hydroxyphenoxyl͒ ϫ 9 1,3-C6H4(OH)O• 3.5 10 2.0 water RT f.p. D.k. at 420 nm in deoxygenated 78KHU/KUZ soln.

.Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 90 5-Methyl-1,3-benzosemiquinone ϫ 9 5-(CH3)-1,3-C6H3(OH)O• 3.5 10 2.0 water RT f.p. D.k. at 450 nm in deoxygenated 78KHU/KUZ soln. 91 Phloroglucinol semiquinone ϫ 9 1,3,5-C6H3(OH)2O• 1.7 10 2.5 water RT p.r. D.k. at 495 nm in N2O/O2-satd. 94WAN/GYO soln. 92 1,4-Benzosemiquinone ϫ 8 1,4-C6H4(OH)O• 2.7 10 EtOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 1.9ϫ108 2-PrOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 1.5ϫ109 2-PrOH 293 11.8 15.5 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 1.7ϫ108 2-BuOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 1.6ϫ108 2-Me-1-PrOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 123 2 .NT N .GRODKOWSKI J. AND NETA P. 124 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

1.7ϫ108 benzyl alcohol 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln.

5.4ϫ109 dioxane 293 12.6 16.3 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 7.3ϫ108 acid MeOH RT p.r. D.k. at 410 nm in deoxygenated 70LAN/SWA Ϫ1 soln. contg. 0.01 mol L H2SO4 . 1.1ϫ109 2 water RT p.r. D.k. at 410 nm in deoxygenated 67ADA/MIC soln. 7.3ϫ108 acid MeOH RT p.r. D.k. at 410 nm in deoxygenated 70LAN/SWA Ϫ1 soln. contg. 0.01 mol L H2SO4 . 1.1ϫ109 2 water RT p.r. D.k. at 410 nm in deoxygenated 67ADA/MIC soln. 7ϫ108 2.4 water 298 f.p. D.k. at 425 nm in deoxygenated 72DAV/GOL soln., 2kϭ1.7ϫ107 in 10% sodium dodecylsulfate and 3.4ϫ106 in 10% Tween-80. 1.8ϫ109 0 water/2- 293 f.p. D.k. at 415 nm in deoxygenated 75KUZ/DAV PrOH soln. contg. 10% 2-PrOH. ⌬H ϭ5.4 kJ molϪ1, ⌬SϭϪ50 J KϪ1 molϪ1. 1.2ϫ109 2.6 water/2- RT p.r. D.k. at 410 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. 3.5ϫ108 2-PrOH/ 293 11.4 16 photo. D.k. ͑rotating sector͒ of ESR signal 78ELL/EGA toluene in deoxygenated soln. contg. 15% toluene and the quinone. ϫ 9 1.1 10 1.7 water RT p.r. D.k. at 430 nm in N2O-satd. soln. 94SHO/MIT contg. 1 mol LϪ1 2-PrOH. 93 1,4-Benzosemiquinone anion Ϫ ϫ 8 1,4-C6H4(O )O• 1.7 10 7 water RT p.r. D.k. at 430 nm in deoxygenated 67ADA/MIC soln. 1.2ϫ108 4.6 water/2- 293 f.p. D.k. at 425 nm in deoxygenated 75KUZ/DAV PrOH soln. contg. 10% 2-PrOH. Decay Ϫ ϩ mainly via 4-(O )C6H4O• 4- ͑ ͒ ⌬ ϭ Ϫ1 HO C6H4O•. H 25.5 kJ mol , ⌬SϭϪ4.2 J KϪ1 molϪ1. 5.5ϫ107 9.2 water/2- RT p.r. D.k. at 430 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. Decay includes reaction

with the protonated radical. pKa ϭ4.0 for semiquinone radical. 1.2ϫ108 7.0 water RT f.p. D.k. at 425 nm in deoxygenated 78KHU/KUZ soln. Decay involves reaction also with neutral semiquinone. 1.8ϫ109 1.1 water RT f.p. D.k. at 415 nm in deoxygenated 78KHU/KUZ soln. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference ϫ 7 8.5 10 5.5 water RT p.r. D.k. at 430 nm in N2O-satd. soln. 94SHO/MIT contg. 1 mol LϪ1 2-PrOH. 94 2-Methyl-1,4-benzosemiquinone ϫ 9 ͑ ͒ 2-(CH3)-1,4-C6H3(OH)O• 1.6 10 toluene/2- 293 11.7 14 photo. D.k. rotating sector of ESR signal 78ELL/EGA PrOH in deoxygenated soln. contg. 10% 2-PrOH, 0.1 mol LϪ1 2-methylhydroquinone, and the quinone. 95 2-tert-Butyl-1,4-benzosemiquinone ϫ 9 Ͻ 2-(t-Bu)-1,4-C6H3(OH)(O•) 1.3 10 4 water 295 p.r. D.k. at 411 nm in N2-satd. soln. 95DOH/BER contg. 2-PrOH and acetone. Rate constants are reported also for the

radical anion and for the radical SOLUTION IN RADICALS PHENOXYL ϩradical anion from pH dependence but values may be affected by reactions with the radical derived from t-BuOH. 96 2-Carboxymethyl-1,4-benzosemiquinone anion Ϫ Ϫ ϫ 7 2,5-(O )(O•)C6H3CH2CO2 6.8 10 11.5 water RT p.r. D.k. at 315 nm in N2O-satd. soln. 87ERB/BOR 97 2,5-Dimethyl-1,4-benzosemiquinone anion Ϫ ϫ 8 2,5-(CH3)2-1,4-C6H2(O )O• 1.2 10 7.2 water RT p.r. D.k. at 435 nm in deoxygenated 82SUT/SAN soln. contg. 0.2 mol LϪ1 2-PrOH and 0.01 mol LϪ1 acetone. 98 2,6-Dimethyl-1,4-benzosemiquinone ϫ 9 ͑ ͒ 2,6-(CH3)2-1,4-C6H2(OH)O• 1.4 10 2-PrOH/ 293 10.9 10 photo. D.k. rotating sector of ESR signal 78ELL/EGA toluene in deoxygenated soln. contg. 15% toluene, 0.1 mol LϪ1 phenol, and the quinone. 99 Tetramethyl-1,4-benzosemiquinone ͑Durosemiquinone͒ 8

.Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. ϫ (CH3)4-1,4-C6(OH)O• 3 10 2.7– EtOH/water 292 f.p. D.k. at 410 nm in deoxygenated 58BRI/POR 5.7 ͑1/1͒ soln., k corrected for new value of ␧. 7.3ϫ108 2-PrOH 293 11.0 13.8 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 2.9ϫ109 dioxane 293 12.3 15.9 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 4.4ϫ108 acid MeOH RT p.r. D.k. at 420 nm in deoxygenated 70LAN/SWA Ϫ1 soln. contg. 0.01 mol L H2SO4 . 7.4ϫ108 n-PrOH RT f.p. D.k. at 410 nm in deoxygenated 76CLA/BAC soln., 2k decreases with pressure to 4.6ϫ108 at 245 MPa. 7.2ϫ108 3.0 water/2- RT p.r. D.k. at 420 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. 2.8ϫ108 2-PrOH/ 293 10.25 11 photo. D.k. ͑rotating sector͒ of ESR signal 78ELL/EGA

toluene in deoxygenated soln. contg. 15% 125 toluene and the quinone. 2 .NT N .GRODKOWSKI J. AND NETA P. 126 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

7.8ϫ108 2-PrOH/toluene 293 11.3 14 photo. D.k. ͑rotating sector͒ of ESR signal 78ELL/EGA in deoxygenated soln. contg. 15% toluene, 0.1 mol LϪ1 phenol, and the quinone. 2.1ϫ109 toluene/2-PrOH 293 11.6 13 photo. D.k. ͑rotating sector͒ of ESR signal 78ELL/EGA in deoxygenated soln. contg. 10% 2-PrOH and the quinone. 4.0ϫ107 cyclohexanol 303 12.5 28 photo. D.k. ͑rotating sector͒ of ESR signal 78ELL/EGA in deoxygenated soln. contg. the quinone. 100 Tetramethyl-1,4-benzosemiquinone anion ͑Durosemiquinone anion͒ Ϫ ϫ 6 (CH3)4-1,4-C6(O )O• 3.4 10 7.8– EtOH/water 292 f.p. D.k. at 435 nm in deoxygenated 58BRI/POR ͑ ͒ ␧ 9.1 1/1 soln., kcor. for new value of . 2.9ϫ107 9.0 water/2-PrOH RT p.r. D.k. at 440 nm in deoxygenated 73RAO/HAY soln. contg. (1 – 3) mol LϪ1 2-PrOH. Decay includes reaction with the ϭ protonated radical. pKa 5.1 for semiquinone radical. 2.3ϫ108 7.2 water RT p.r. D.k. at 440 nm in deoxygenated 82SUT/SAN soln. contg. 0.2 mol LϪ1 2-PrOH and 0.01 mol LϪ1 acetone. 2k ϭ1.5ϫ108 in 0.6 mol LϪ1 2-PrOH. 101 Ubisemiquinone ͑30͒ Ubi(OH)O 4.8ϫ107 acid MeOH RT p.r. D.k. at 420 nm in deoxygenated 70LAN/SWA • Ϫ1 soln. contg. 0.01 mol L H2SO4 . 102 2,5-Bis͑carboethoxyamino͒-3,6-diaziridinyl-1,4-benzosemiquinone anion Ϫϩ Ϫϩ ϩ → ϫ 5 ϳ AZQ• AZQ• 2H AZQ 8.9 10 7.0 water RT p.r. D.k. at 500 nm in soln. contg. 87BUT/HOE ϩ Ϫ AZQH2 formate. Mixed decay of AZQ• with AZQH•. 103 2,5-Bis͑2-hydroxyethylamino͒-3,6-diaziridinyl-1,4-benzosemiquinone radical anion Ϫϩ Ϫϩ ϩ → ϫ 5 ϳ BZQ• BZQ• 2H BZQ 4.6 10 7.0 water RT p.r. D.k. at 500 nm in soln. contg. 87BUT/HOE ϩ Ϫ BZQH2 formate. Mixed decay of BZQ• with BZQH•. 104 Tetraﬂuoro-1,4-benzosemiquinone anion Ϫ ϫ 8 1,4-C6F4(O )O• 5.6 10 1.7 water RT p.r. D.k. at 435 nm in N2O-satd. soln. 94SHO/MIT Ϫ1 ϭ contg. 1 mol L 2-PrOH. pKa Ϫ1 for radical. 105 Tetrachloro-1,4-benzosemiquinone ϫ 8 1,4-C6Cl4(OH)O• 1.7 10 2-PrOH 293 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 7.6ϫ108 dioxane 293 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 106 Tetrachloro-1,4-benzosemiquinone anion 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

Ϫ ϫ 6 1,4-C6Cl4(O )O• 4 10 EtOH 295 f.p. D.k. of ESR signal in 70HAL/BOL deoxygenated soln. 1.2ϫ107 MeOH 295 f.p. D.k. of ESR signal in 70HAL/BOL deoxygenated soln. 107 1,2-Naphthosemiquinone ͑ ͒ ϫ 7 1,2-Np OH O• 3.0 10 2.0 water RT f.p. D.k. at 400 nm in deoxygenated 78KHU/KUZ soln. 108 2,3-Naphthosemiquinone anion Ϫ ϫ 8 2,3-Naph(O )(O•) 6.1 10 11.5 water RT p.r. D.k. at 366 nm in N2O-satd. soln. 87ERB/BOR contg. azide. 109 1,4-Naphthosemiquinone 1,4-Np͑OH͒͑O ͒ 2.6ϫ108 EtOH 293 f.p. D.k. of ESR signal in 73AYS/SEA

• SOLUTION IN RADICALS PHENOXYL deoxygenated soln. 2.2ϫ108 2-PrOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 2.3ϫ108 2-PrOH 293 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 1.2ϫ108 2-BuOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 1.4ϫ108 2-Me-1-PrOH 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 1.2ϫ108 Benzyl alcohol 293 f.p. D.k. of ESR signal in 73AYS/SEA deoxygenated soln. 9.0ϫ108 dioxane 293 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 1.3ϫ109 3.0 water/2- RT p.r. D.k. at 370 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. 110 1,4-Naphthosemiquinone anion

.Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. Ϫ ϫ 8 1,4-Np(O )O• 1.0 10 9.2 water/2- RT p.r. D.k. at 390 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. Decay includes reaction

with the protonated radical. pKa ϭ4.1 for semiquinone radical. 111 2-Methyl-1,4-naphthosemiquinone ϫ 9 2-(CH3)-1,4-Np(OH)O• 1.3 10 3.0 water/2- RT p.r. D.k. at 370 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. 2.5ϫ108 2-PrOH/ 293 10.9 14 photo. D.k. ͑rotating sector͒ of ESR signal 78ELL/EGA toluene in deoxygenated soln. contg. 15% toluene and the quinone. 112 2-Methyl-1,4-naphthosemiquinone anion Ϫ ϫ 8 2-(CH3)-1,4-Np(O )O• 1.6 10 9.2 water/2- RT p.r. D.k. at 395 nm in deoxygenated 73RAO/HAY PrOH soln. contg. (1 – 3) mol LϪ1 2-PrOH. Decay includes reaction 127 with the protonated radical. pKa ϭ4.5 for semiquinone radical. 2 .NT N .GRODKOWSKI J. AND NETA P. 128 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

4ϫ107 7.2 water RT p.r. D.k. at 390 nm in deoxygenated 82SUT/SAN soln. contg. 0.2 mol LϪ1 2-PrOH and 0.01 mol LϪ1 acetone. 2k ϭ1.6ϫ108 in 0.6 mol LϪ1 2-PrOH. 113 2-Hydroxy-1,4-naphthosemiquinone ͑ ͒ ͑ ͒ ϫ 7 2- OH -1,4-Np OH O• 2.1 10 1.8 water/2- RT p.r. D.k. at 360–370 nm in soln. contg. 96RAT/PAL 2.1ϫ107 6.7 PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 ϫ 7 1.5 10 10.3 acetone. pKa of radical 5.5 and 1.5ϫ107 13 10.1. 3.6ϫ107 2-PrOH RT p.r. D.k. at 360–370 nm. 96RAT/PAL 114 5-Hydroxy-1,4-naphthosemiquinone ͑ ͒ ͑ ͒ ϫ 9 5- OH -1,4-Np OH O• 1.0 10 1.2 water RT p.r. D.k. at 370 nm in soln. contg. 87MUK formate. pKa of radical 3.7. 115 5-Hydroxy-1,4-naphthosemiquinone anion Ϫ ϫ 8 5-(OH)-1,4-Np(O )O• 6.0 10 6.4 water RT p.r. D.k. at 385 nm in soln. contg. 87MUK 6.9ϫ108 10.5 formate. 116 5,8-Dihydroxy-1,4-naphthosemiquinone ϫ 9 1,4,5,8-Np(OH)3O• 2.0 10 1.2 water RT p.r. D.k. in soln. contg. formate. 83LAN/MUKb 117 5,8-Dihydroxy-1,4-naphthosemiquinone anion Ϫ ϫ 9 1,4,5,8-Np(OH)2(O )O• 1.0 10 4.7 water RT p.r. D.k. in soln. contg. formate. For 83LAN/MUKb 8 ϭ ϫ 7 8ϫ10 9.5 reverse reaction kr 7 10 at pH 9.2ϫ108 11 9.5. 7ϫ107 Ͼ14 water RT p.r. D.k. in soln. contg. formate. 83LAN/MUKb 118 1,4-Naphthoquinone-2-oxyl ϫ 7 1,4-NQ-2-O• 7 10 7.0 water RT p.r. D.k. at 340 or 450 nm in N2O-satd. 96RAT/PAL soln. contg. azide. 119 1,4-Naphthoquinone-5-oxyl ϫ 8 1,4-NQ-5-O• 4.3 10 10.4 water RT p.r. D.k. at 420 or 540 nm in N2O-satd. 96RAT/PAL soln. contg. azide. 120 Kalafungin semiquinone (Kalafunginϭpyranonaphthoquinone antibiotic) ϫ 9 Kalafungin-H• 1.5 10 2 water RT p.r. D.k. at 385 nm in N2O-satd. soln. 99AND/BRI ϫ 9 Ϫ1 1.1 10 7 contg. 0.1 mol L formate. pKa ϭ1.9 for radical. 121 5-Hydroxy-7-O-methylkalafungin semiquinone ϫ 8 KF2-H 8.3 10 2 water RT p.r. D.k. at 395 nm in N2O-satd. soln. 99AND/BRI • 8 Ϫ1 1.2ϫ10 7 contg. 0.1 mol L formate. pKa ϭ4.6 for radical. 122 5-Hydroxy-7-deoxykalafungin semiquinone ϫ 8 KF3-H 8.2 10 2 water RT p.r. D.k. at 395 nm in N2O-satd. soln. 99AND/BRI • 8 Ϫ1 1.5ϫ10 7 contg. 0.1 mol L formate. pKa ϭ2.0 for radical. 123 5-epi-7-O-Methylkalafungin semiquinone ϫ 9 KF4-H• 2.7 10 2 water RT p.r. D.k. at 385 nm in N2O-satd. soln. 99AND/BRI ϫ 8 Ϫ1 6.5 10 7 contg. 0.1 mol L formate. pKa ϭ4.9 for radical. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

124 5-epi-7-Deoxykalafungin semiquinone ϫ 9 KF5-HPY 1 10 2 water RT p.r. D.k. at 385 nm in N2O-satd. soln. 99AND/BRI 8 Ϫ1 4.8ϫ10 7 contg. 0.1 mol L formate. pKa ϭ2.3 for radical. 125 9,10-Anthrasemiquinone ͑ ͒ ϫ 9 9,10-An OH O• 1.2 10 dioxane 293 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 7.5ϫ108 2.0 water/2-PrOH RT p.r. D.k. at 380 nm in soln. contg. 94PAL/MUKa 5 mol LϪ1 2-PrOH and 1 mol LϪ1

acetone. pKa of radical 4.4. Decay of semiquinone anion very slow. 1.5ϫ108 acid MeOH RT p.r. D.k. at 375 nm. 90MAY/KRA 126 9,10-Anthrasemiquinone anion SOLUTION IN RADICALS PHENOXYL Ϫ ϫ 7 9,10-An(O )(O•) 4.9 10 2-PrOH 293 photo. D.k. of ESR signal in 72WON/SYT deoxygenated soln. 127 1-Piperidino-9,10-anthrasemiquinone ͑ ͒ ϫ 8 1-Piperidino-9,10-An OH O• 7.0 10 1.7 water RT p.r. D.k. at 400 nm in soln. contg. 72HUL/LAN formate. 128 2-Piperidino-9,10-anthrasemiquinone ͑ ͒ ϫ 8 2-Piperidino-9,10-An OH O• 6.2 10 1.7 water RT p.r. D.k. at 400 nm in soln. contg. 72HUL/LAN formate. 129 9,10-Anthrasemiquinone-1-sulfonate Ϫ ϫ 9 1-(SO3 )-9,10-An(OH)O• 3.0 10 1.7 water RT p.r. D.k. at 400 nm in soln. contg. 72HUL/LAN ϭ formate. pKa 5.4 for semiquinone; anion decays more slowly to a mixture with the quinone and the hydroquinone.

130 9,10-Anthrasemiquinone-2-sulfonate Ϫ .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. ϫ 9 2-(SO3 )-9,10-An(OH)O• 3.2 10 1.7 water RT p.r. D.k. at 400 nm in soln. contg. 72HUL/LAN ϭ formate. pKa 3.25 for semiquinone; anion decays more slowly to a mixture with the quinone and the hydroquinone. 1.3ϫ109 4 water RT p.r. D.k. at 390 or 505 nm in 77CLA/STO deoxygenated soln. contg. formate. 131 9,10-Anthrasemiquinone-2-sulfonate anion Ϫ Ϫ ϫ 8 2-(SO3 )-9,10-An(O )O• 1.8 10 7.2 water RT p.r. D.k. at 505 nm in deoxygenated 82SUT/SAN soln. contg. 0.2 mol LϪ1 2-PrOH and 0.01 mol LϪ1 acetone. 132 9,10-Anthrasemiquinone-1,5-disulfonate Ϫ ϫ 8 1,5-(SO3 )2-9,10-An(OH)O• 2.7 10 2.0 water RT p.r. D.k. at 385 nm in deoxygenated 91PAL/PALb soln. contg. formate. pKa of radical 6.1. 133 9,10-Anthrasemiquinone-1,5-disulfonate anion 129 3 .NT N .GRODKOWSKI J. AND NETA P. 130 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

Ϫ Ϫ Ͻ 7 1,5-(SO3 )2-9,10-An(O )O• 10 8.4 water RT p.r. D.k. at 500 nm in deoxygenated 91PAL/PALb soln. contg. formate. pKa of radical 6.1. Decay is via radicalϩradical anion. 134 9,10-Anthrasemiquinone-2,6-disulfonate Ϫ ϫ 8 2,6-(SO3 )2-9,10-An(OH)O• 8.0 10 1.4 water RT p.r. D.k. at 390 nm in deoxygenated 91PAL/PALb 7 4.2ϫ10 7.0 soln. contg. formate. pKa of radical 3.0. Decay at pH 7 is via radical ϩradical anion. 135 9,10-Anthrasemiquinone-2,6-disulfonate anion Ϫ Ϫ ϫ 7 2,6-(SO3 )2-9,10-An(O )O• 8.0 10 7.0 water RT f.p. D.k. at 520 nm in deoxygenated 78KHU/KUZ soln. contg. 2% 2-PrOH. Decay includes reaction with the neutral semiquinone radical. 136 1-Amino-9,10-anthrasemiquinone ϫ 8 Ϫ1 1-(NH2)-9,10-An(OH)O• 2.7 10 2.0 water/2- RT p.r. D.k. in soln. contg. 5 mol L 94PAL/MUKa PrOH 2-PrOH and 1 mol LϪ1 acetone. pKa of radical 5.8. Decay of semiquinone anion very slow. 137 1-Hydroxy-9,10-anthrasemiquinone ͑ ͒ ͑ ͒ ϫ 9 1- OH -9,10-An OH O• 1.0 10 2.0 water/2- RT p.r. D.k. at 390 nm in soln. contg. 94PAL/MUKa PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1

acetone. pKa of radical 4.6. Decay of semiquinone anion very slow. 138 2-Hydroxy-9,10-anthrasemiquinone ͑ ͒ ͑ ͒ ϫ 8 2- OH -9,10-An OH O• 5 10 1.5 water/2- RT p.r. D.k. at 375 nm in soln. contg. 94PAL/MUKb PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 139 1,4-Diamino-9,10-anthrasemiquinone anion Ϫ 9 Ϫ1 1,4-(NH2)2-9,10-An(O )O 2.5ϫ10 14 water/2- RT p.r. D.k. in soln. contg. 5 mol L 92PAL/PALa • Ϫ 1.6ϫ109 3.5 PrOH 2-PrOH and 1 mol L 1 acetone. 1.1ϫ109 1 140 1,5-Diamino-9,10-anthrasemiquinone ϫ 8 1,5-(NH2)2-9,10-An(OH)O• 7.0 10 2-PrOH RT p.r. D.k. in deoxygenated soln. 91PAL/PALa 141 1-Amino-4-hydroxy-9,10-anthrasemiquinone anion Ϫ 9 Ϫ1 1-(NH2)-4-(OH)-9,10-An(O )O 6.7ϫ10 14 water/2- RT p.r. D.k. in soln. contg. 5 mol L 92PAL/PALa • Ϫ 1.5ϫ109 1.5 PrOH 2-PrOH and 1 mol L 1 acetone. 142 1,4-Dihydroxy-9,10-anthrasemiquinone ϫ 8 1,4-(OH)2-9,10-An(OH)O• 5.1 10 1.2 water/2- RT p.r. D.k. in deoxygenated aqueous soln. 90MUK/SWA PrOH contg. 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 143 1,4-Dihydroxy-9,10-anthrasemiquinone anion Ϫ ϫ 8 1,4-(OH)2-9,10-An(O )O• 3.8 10 5.5 water/2- RT p.r. D.k. in deoxygenated aqueous soln. 90MUK/SWA PrOH contg. 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. Mixed decay of neutral and anion. Decay of anion at higher pH much slower. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

144 1,5-Dihydroxy-9,10-anthrasemiquinone ϫ 8 1,5-(OH)2-9,10-An(OH)O• 1.6 10 2-PrOH RT p.r. D.k. in deoxygenated soln. 91PAL/PALa 7.7ϫ108 1.3 water/2- RT p.r. D.k. in aqueous soln. contg. 91PAL/PALc PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 145 1,5-Dihydroxy-9,10-anthrasemiquinone anion Ϫ ϫ 9 1,5-(OH)2-9,10-An(O )O• 1.5 10 14 water/2- RT p.r. D.k. in aqueous soln. contg. 91PAL/PALc PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 146 2,6-Dihydroxy-9,10-anthrasemiquinone ϫ 8 2,6-(OH)2-9,10-An(OH)O• 4 10 1.5 water/2- RT p.r. D.k. at 400 nm in soln. contg. 94PAL/MUKb PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. SOLUTION IN RADICALS PHENOXYL 147 1,8-Dihydroxy-9,10-anthrasemiquinone ϫ 8 1,8-(OH)2-9,10-An(OH)O• 1.7 10 2-PrOH RT p.r. D.k. in deoxygenated soln. 91PAL/PALa 4.6ϫ108 1.3 water/2- RT p.r. D.k. in aqueous soln. contg. 91PAL/PALc PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 148 1,8-Dihydroxy-9,10-anthrasemiquinone anion Ϫ ϫ 9 1,8-(OH)2-9,10-An(O )O• 1.6 10 14 water/2- RT p.r. D.k. in aqueous soln. contg. 91PAL/PALc PrOH 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 149 1,4-Dihydroxy-9,10-anthrasemiquinone-2-sulfonate Ϫ ϫ 9 2-(SO3 )-1,4-(OH)2-9,10-An(OH)O• 1.3 10 1.1 water RT p.r. D.k. at 475 and 720 nm in 88MUK/LAN deoxygenated soln. contg. formate. 150 1,4-Dihydroxy-9,10-anthrasemiquinone-2-sulfonate anion Ϫ Ϫ ϫ 8 2-(SO3 )-1,4-(OH)2-9,10-An(O )O• 9.9 10 5.7 water RT p.r. D.k. at 475 and 720 nm in 88MUK/LAN deoxygenated soln. contg. formate. Mixed decay of neutral and anionic .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. radicals. 151 9,10-Anthraquinone-1,4-semiquinone anion ͑ ͒͑ ͒ ϫ 8 1,4- OH O• -9,10-AQ 6.0 10 14 water RT p.r. D.k. in N2O-satd. soln. contg. 92PAL/PALb Ͻ107 11 azide. 152 9,10-Anthraquinone-1,5-semiquinone anion Ϫ ϫ 8 1,5-(O )(O•)-9,10-AQ 6.0 10 11 water RT p.r. D.k. in N2O-satd. soln. contg. 91PAL/PALc 1.3ϫ1010 14 azide. 153 9,10-Anthraquinone-1,8-semiquinone anion Ϫ ϫ 9 1,8-(O )(O•)-9,10-AQ 4.1 10 11 water RT p.r. D.k. in N2O-satd. soln. contg. 91PAL/PALc 1.4ϫ109 14 azide. 154 9,10-Anthraquinone-2-sulfonate-1,4-semiquinone Ϫ ϫ 9 1,4-(OH)(O•)-9,10-AQ-2-SO3 5.7 10 1 water RT p.r. D.k. in N2O-satd. soln. contg. 92PAL/PALb ethylene glycol. 155 9,10-Anthraquinone-2-sulfonate-1,4-semiquinone anion Ϫ Ϫ ϫ 8 1,4-(O )(O•)-9,10-AQ-2-SO3 5.5 10 14 water RT p.r. D.k. in N2O-satd. soln. contg. azide 92PAL/PALb or bromide. 131 156 9,10-Anthraquinone-6-sulfonate-1,4-semiquinone 3 .NT N .GRODKOWSKI J. AND NETA P. 132 .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference

Ϫ ϫ 9 1,4-(OH)(O•)-9,10-AQ-6-SO3 4.4 10 1 water RT p.r. D.k. in N2O-satd. soln. contg. 92PAL/PALb ethylene glycol. 157 9,10-Anthraquinone-6-sulfonate-1,4-semiquinone anion Ϫ Ϫ ϫ 8 1,4-(O )(O•)-9,10-AQ-6-SO3 4.3 10 14 water RT p.r. D.k. in N2O-satd. soln. contg. azide 92PAL/PALb or bromide. 158 Adriamycin semiquinone anion Ϫ ϫ 8 Adria(O )O• 5.6 10 13 water RT p.r. D.k. at 720 nm in soln. contg. 85LAN/MUK formate. 159 Adriamycin semiquinone ͑ ͒ ϫ 9 Adria OH O• 1.3 10 1.1 water RT p.r. D.k. at 720 nm in soln. contg. 85LAN/MUK formate. 160 Indole-5,6-semiquinone anion Ϫ ϫ 8 Indole-5,6-(O )(O•) 1.8 10 8.8 water RT p.r. D.k. at 325 nm in N2O-satd. soln. 91ALK/ONE contg. azide. 161 Indole-5,6-semiquinone ͑ ͒͑ ͒ ϫ 9 Indole-5,6- OH O• 3.8 10 5.5 water RT p.r. D.k. at 325 nm in N2O-satd. soln. 91ALK/ONE contg. azide. pKa of radical 6.8. 162 N-Methylindole-5,6-semiquinone anion Ϫ ϫ 8 N-Me-Indole-5,6-(O )(O•) 1.0 10 8.8 water RT p.r. D.k. at 325 nm in N2O-satd. soln. 91ALK/ONE contg. azide. 163 2-Hydroxyestradiol semiquinone (radicalϩanion) Ϫ ϫ 7 2,3-Estr(O )(O•) 3.1 10 7.0 water RT p.r. D.k. at 320 nm in N2O-satd. soln. 93LAN contg. azide. Decay mostly via Ϫ 2,3-Estr(O )(O•) ϩ 2,3-Estr(OH)(O•) 164 Catechin semiquinone anion ϫ 5 Catechin-O• 5.9 10 11.5 water RT p.r. D.k. at 315 nm in N2O-satd. soln. 87ERB/BOR contg. azide. 165 Epicatechin semiquinone anion ϫ 5 Epicatechin-O• 5.3 10 11.5 water RT p.r. D.k. at 315 nm in N2O-satd. soln. 87ERB/BOR contg. azide. 166 Fisetin semiquinone anion ϫ 7 Fisetin-O• 1.2 10 8.5 water RT p.r. Decay and formn. kinetics at 370 95BOR/MIC nm and 460–590 nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. 167 Kaempferol semiquinone anion ϫ 8 Kaempferol-O• 1.1 10 8.5 water RT p.r. Decay and formn. kinetics at 370 95BOR/MIC nm and 460–590 nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. ϫ 8 1.4 10 11.5 water RT p.r. D.k. at 545 nm in N2O-satd. soln. 87ERB/BOR contg. azide or thiocyanate. 168 Luteolin semiquinone anion ϫ 7 Luteolin-O• 5.8 10 8.5 water RT p.r. Decay and formn. kinetics at 370 95BOR/MIC nm and 460–590 nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. 169 Quercetin semiquinone anion 2 TABLE 1. Self-reactions of phenoxyl radicals (RϩR→products, Ϫd͓R͔/dtϭ2k͓R͔ , values of 2k are tabulated͒ —Continued

Phenoxyl 2k T Ea No. structure or reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ log 2A (kJmolϪ1) Method Comments Reference ϫ 7 Quercetin-O• 6.0 10 8.5 water RT p.r. Decay and formn. kinetics at 370 95BOR/MIC nm and 460–590 nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. ϫ 6 3.3 10 11.5 water RT p.r. D.k. at 525 nm in N2O-satd. soln. 87ERB/BOR contg. azide or thiocyanate. 170 Dihydroquercetin semiquinone anion ϫ 6 Dihydroquercetin-O• 1.3 10 8.5 water RT p.r. Decay and formn. kinetics at 367 95BOR/MIC nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. 171 Rutin semiquinone anion ϫ 7 Rutin-O• 1.0 10 8.5 water RT p.r. Decay and formn. kinetics at 370 95BOR/MIC nm and 460–590 nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. SOLUTION IN RADICALS PHENOXYL .Py.Ce.Rf aa o.3,N.1 2005 1, No. 34, Vol. Data, Ref. Chem. Phys. J. 133 134 P. NETA AND J. GRODKOWSKI

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

1 GalvinoxylϩIodine atom ϩ ϫ 9 Galv-O• I• 4.0 10 CCl4 298 f.p. D.k. at 432 nm in soln. contg. I2 83KHU/TAT and galvinoxyl radical. Ea ϭ8kJmolϪ1. ϫ 10 1.2 10 n-hexane 298 f.p. D.k. at 432 nm in soln. contg. I2 83KHU/TAT and galvinoxyl radical. 2 PhenoxylϩSuperoxide ϩ Ϫ ϫ 9 C6H5O• O2• 2.0 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 87% electron transfer. 3 4-MethylphenoxylϩSuperoxide ϩ Ϫ ϫ 9 4-CH3C6H4O• O2• 1.7 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 83% electron transfer. 4 4-tert-ButylphenoxylϩSuperoxide ϩ Ϫ ϫ 8 4-(t-Bu)C6H4O• O2• 7.0 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 74% electron transfer.

5 4-(2-Aminoethyl)phenoxyl (Tyramine phenoxyl)ϩSuperoxide ϩ Ϫ ϫ 9 4-(H2NCH2CH2)C6H4O• O2• 1.0 10 11 water RT p.r. D.k. at 400–410 nm in 00DAL/BIA N2O/O2-satd. soln. contg. azide and formate. Reaction mainly via addn. 6 TyrosylϩSuperoxide ϩ Ϫ ϫ 9 TyrO• O2• 1.7 10 9.5 water RT p.r. D.k. at 407 nm in N2O/O2-satd. 87CUD/JOS soln. contg. azide and formate. ϫ 9 1.5 10 9 water RT p.r. D.k. at 405 nm in N2O-satd. 93JIN/LEI soln. contg. azide and formate. Product analysis suggests reaction via addn. 7 4-(2-Hydroxyethyl)phenoxyl (Tyrosol phenoxyl)ϩSuperoxide ϩ Ϫ ϫ 9 4-(HOCH2CH2)C6H4O• O2• 2.3 10 11 water RT p.r. D.k. at 400–410 nm in 00DAL/BIA N2O/O2-satd. soln. contg. azide and formate. Reaction mainly via addn. 8 4-CyanophenoxylϩSuperoxide ϩ Ϫ ϫ 8 4-NCC6H4O• O2• 2.1 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 92% electron transfer. ϫ 8 4.5 10 11 water RT p.r. D.k. at 436 nm in N2O/O2-satd. 00DAL/BIA soln. contg. azide and formate. Reaction proceeds mainly via addition. 9 4-AminophenoxylϩSuperoxide ϩ Ϫ ϫ 8 4-H2NC6H4O• O2• 9.7 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 60% electron transfer at pH 7. 10 4-MethoxyphenoxylϩSuperoxide ϩ Ϫ ϫ 8 4-CH3OC6H4O• O2• 8.4 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 56% electron transfer.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 135

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

11 4-FluorophenoxylϩSuperoxide ϩ Ϫ ϫ 9 4-FC6H4O• O2• 2.9 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1mmol LϪ1 of the phenol. 91% electron transfer. 12 2-Methoxy-4-methylphenoxylϩSuperoxide ϩ Ϫ ϫ 9 2-(CH3O)-4-(CH3)C6H3O• O2• 1.1 10 11 water RT p.r. D.k. at 400–420 nm in 00DAL/BIA N2O/O2-satd. soln. contg. azide and formate. Reaction proceeds mainly via addn. ϫ 9 1.4 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 30% electron transfer. 13 2,4,6-TrimethylphenoxylϩSuperoxide ϩ Ϫ ϫ 9 2,4,6-(CH3)3C6H2O• O2• 1.2 10 11 water RT p.r. D.k. at 400–420 nm in 00DAL/BIA N2O/O2-satd. soln. contg. azide and formate. Reaction proceeds mainly via addn. ϫ 9 1.2 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 40% electron transfer. 14 4-Carboxy-2,6-dimethoxyphenoxylϩSuperoxide Ϫ ϩ Ϫ ϫ 9 4-(CO2 )-2,6-(CH3O)2C6H2O• O2• 1.2 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 60% electron transfer. 15 4-tert-Butyl-2,6-dimethoxyphenoxylϩSuperoxide ϩ Ϫ ϫ 9 4-(t-Bu)-2,6-(CH3O)2C6H2O• O2• 3.0 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 50% electron transfer. 16 3,5-DiiodotyrosylϩSuperoxide ϩ Ϫ ϫ 9 3,5-I2-TyrO3,5-I2-TyrO• O2• 6.5 10 7.4 water RT p.r. D.k. at 350 nm in N2O-satd. 96DAS 9 Ϫ 5ϫ10 12 soln. contg. N3 and H2O2 . k similar in the absence of azide. k reported for reaction of

diiodotyrosyl with O2 are probably in error and are due to reaction with superoxide. 17 2,4,6-TrichlorophenoxylϩSuperoxide ϩ Ϫ ϫ 9 2,4,6-Cl3C6H2O• O2• 1.6 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 94% electron transfer. 18 2,4,6-TribromophenoxylϩSuperoxide ϩ Ϫ ϫ 9 2,4,6-Br3C6H2O• O2• 1.2 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 88% electron transfer. 19 2,4,6-TriiodophenoxylϩSuperoxide ϩ Ϫ ϫ 9 2,4,6-I3C6H2O• O2• 1.1 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 75% electron transfer.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 136 P. NETA AND J. GRODKOWSKI

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

20 Pyrogallol radicalϩSuperoxide Ϫ ϩ Ϫ ϫ 8 1,2,3-C6H3(OH)(O )O• O2• 1.5 10 6.7 water RT p.r. D.k. at 300 nm in N2O-satd. 88DEE/PAR soln. contg. bromide. Reaction probably forms hydroxy-o-quinone. 21 n-Propyl gallate radicalϩSuperoxide ϩ Ϫ ϫ 8 3,4,5-(OH)(O•)C6H2CO2C3H7 O2• 1.6 10 6.7 water RT p.r. D.k. in N2O-satd. soln. contg. 88DEE/PAR bromide. Reaction probably forms the hydroxy-o-quinone of propyl gallate. 22 Trolox phenoxyl radicalϩSuperoxide ϩ Ϫ ϫ 8 TxO• O2• 4.5 10 7 water RT p.r. D.k. at 440 nm in soln. contg. 89CAD/MER Ϫ1 Ϫ 0.5 mol L HCO2 , 0.05 mol LϪ1 BrϪ, 1 mmol LϪ1 Trolox, satd. with

O2 or N2O. ϫ 8 5.5 10 9.2 water RT p.r. D.k. at 400–550 nm in O2-satd. 93JON/LIN soln. contg. 0.2 mol LϪ1 Ϫ Ϫ1 Ϫ HCO2 , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 11% electron transfer. 23 ␣-TocopheroxylϩSuperoxide ␣ ϩ Ϫ Ϸ 9 -Toc-O• O2• 10 MeOH RT f.p. D.k. at 430 nm. Electron 91BIS/PAR transfer. 24 2,4,6-Tri(tert-butyl)phenoxylϩtert-Butyl ϩ ϫ 9 ͑ ͒ 2,4,6-(t-Bu)3C6H2O• (CH3)3C• 2 10 n-heptane Kinetic ESR rotating sector in 89RUE/FIS soln. contg. di-t-butyl peroxide and di-t-butylketone. 25 2,6-Di(tert-butyl)-4-methylphenoxyl ϩ ͑ ͒ ͑ ͒ Ϸ ϫ 9 ͑ ͒ 1-Hydroxyethyl2,6- t-Bu 2-4- CH3 C6H2O• 3 10 1,2-epoxybutane photo. Kinetic ESR rotating sector in 89RUE/FIS ϩ CH3CH•(OH) /EtOH 1,2-epoxybutane soln. contg. 6.5 mol LϪ1 EtOH and 2 mol LϪ1 di-t-butyl peroxide. k estd. from data in paper. 26 2,6-Di(tert-butyl)phenoxylϩ2-Hydroxy-2-methylethyl ϩ ϫ 8 ͑ ͒ 2,6-(t-Bu)2C6H3O• (CH3)2C•OH 9.0 10 2-PrOH 275 photo. Kinetic ESR rotating sector in 88RUE/FIS soln. contg. di-t-butyl peroxide. ϭ Ϫ1 Ea 19.8 kJ mol , log A log Aϭ12.7. 27 4-Methylphenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 4-CH3C6H4O• HOC(CH3)2CH2• 5.6 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 28 4-tert-Butylphenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 4-(t-Bu)C6H4O• HOC(CH3)2CH2• 6.0 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH Ϫ1 Ϫ , 0.01 mol L N3 , and 1 mmol LϪ1 of the phenol. 29 4-Cyanophenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 9 4-NCC6H4O• HOC(CH3)2CH2• 1.0 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 30 4-Aminophenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 4-H2NC6H4O• HOC(CH3)2CH2• 3.9 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 137

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

31 4-Methoxyphenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 4-CH3OC6H4O• HOC(CH3)2CH2• 5.0 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 32 2-Methoxy-4-methylphenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 2-CH3O-4-CH3C6H3O• HOC(CH3)2CH2• 3.3 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 33 2,4,6-Trimethylphenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 2,4,6-(CH3)3C6H2O• HOC(CH3)2CH2• 4.3 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 34 4-Carboxy-2,6-dimethoxyphenoxylϩ2-Hydroxy-2,2-dimethylethyl Ϫ ϫ 8 4-(CO2 )-2,6-(CH3O)2C6H2O• 2.5 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN ϩ HOC(CH3)2CH2• N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 35 2,4,6-Trichlorophenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 2,4,6-Cl3C6H2O• HOC(CH3)2CH2• 5.2 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 36 2,4,6-Tribromophenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 2,4,6-Br3C6H2O• HOC(CH3)2CH2• 5.6 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 37 2,4,6-Triiodophenoxylϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 9 2,4,6-I3C6H2O• HOC(CH3)2CH2• 1.5 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 38 Trolox phenoxyl radicalϩ2-Hydroxy-2,2-dimethylethyl ϩ ϫ 8 TxO• HOC(CH3)2CH2• 1.5 10 9.2 water RT p.r. D.k. at 400–550 nm in 93JON/LIN N2O-satd. soln. contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol. 39 4-(2-Hydroxyethyl)phenoxylϩMethylperoxyl ϩ ϫ 9 4-(HOCH2CH2)C6H4O• CH3O2• 1.1 10 11 water RT p.r. D.k. at 400–410 nm in 00DAL/BIA N2O/O2-satd. soln. contg. azide and dimethyl sulfoxide. 40 4-Methylphenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 4-CH3C6H4O• HOC(CH3)2CH2O2• 8.2 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 41 4-tert-Butylphenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 4-(t-Bu)C6H4O• HOC(CH3)2CH2O2• 6.0 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the

phenol, satd. with N2O/O2 .

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 138 P. NETA AND J. GRODKOWSKI

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

42 4-(2-Hydroxyethyl)phenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϫ 8 4-(HOCH2CH2)C6H4O• 8.9 10 11 water RT p.r. D.k. at 400–410 nm in 00DAL/BIA ϩ HOC(CH3)2CH2O2• N2O/O2-satd. soln. contg. azide and t-BuOH. 43 4-Cyanophenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 9 4-NCC6H4O• HOC(CH3)2CH2O2• 2.0 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 44 4-Aminophenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 4-H2NC6H4O• HOC(CH3)2CH2O2• 2.5 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 45 4-Methoxyphenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 4-CH3OC6H4O• HOC(CH3)2CH2O2• 8.8 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 46 2-Methoxy-4-methylphenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϫ 8 2-CH3O-4-CH3C6H3O• 4.1 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN ϩ Ϫ1 HOC(CH3)2CH2O2 contg. 1 mol L t-BuOH, • Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 47 2,4,6-Trimethylphenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 2,4,6-(CH3)3C6H2O• HOC(CH3)2CH2O2• 4.8 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 48 4-Carboxy-2,6-dimethoxyphenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl Ϫ ϫ 8 4-(CO2 )-2,6-(CH3O)2C6H2O• 1 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN ϩ Ϫ1 HOC(CH3)2CH2O2 contg. 1 mol L t-BuOH, • Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 49 2,4,6-Trichlorophenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 2,4,6-Cl3C6H2O• HOC(CH3)2CH2O2• 8.8 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 50 2,4,6-Tribromophenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 2,4,6-Br3C6H2O• HOC(CH3)2CH2O2• 9.3 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 51 2,4,6-Triiodophenoxylϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 9 2,4,6-I3C6H2O• HOC(CH3)2CH2O2• 1.0 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 of the phenol,

satd. with N2O/O2 . 52 Trolox phenoxyl radicalϩ2-Hydroxy-2,2-dimethylethylperoxyl ϩ ϫ 8 TxO• HOC(CH3)2CH2O2• 1.6 10 9.2 water RT p.r. D.k. at 400–550 nm in soln. 93JON/LIN contg. 1 mol LϪ1 t-BuOH, Ϫ1 Ϫ 0.01 mol L N3 ,and 1 mmol LϪ1 Trolox, satd. with

N2O/O2 .

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 139

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

53 2,4,6-Tri-t-butylphenoxylϩCyclohexylperoxyl ϩ ϫ 8 2,4,6-(t-Bu)3C6H2O• c-C6H11OO• 9.9 10 cyclohexane 293 f.p. D.k. at 400 nm in soln. contg. 89NIK/SAF the phenol and oxygen in cyclohexane. Similar k for the mixture of peroxyl radicals formed in n-hexane and a 30% lower value in tridecane. 54 ␣-Tocopheroxylϩ2-Cyano-2,4-dimethylbutylperoxyl ␣ ϩ Ϸ ϫ 8 -Toc-O• (CH3)2CHCH2C(CH3)(CN)OO• 4 10 PhCl 318 Therm. Radicals generated by reaction 95BOW/ING of 2,2Ј-azobis͑2,4- dimethylvaleronitrile͒. Monitored absorbance at 424 nm vs 440 nm. 55 2,4,6-Tri-t-butylphenoxylϩCumylperoxyl ϩ ϫ 8 2,4,6-(t-Bu)3C6H2O• PhCMe2OO• 2 10 benzene 303 chem. Decay of ESR signal of the 73GRI/DEN phenoxyl radical in deoxygenated soln. 1.1ϫ108 cyclohexane 293 f.p. D.k. at 625 nm in deoxygenated 87VAR/SAF soln. contg. tetraphenylhydrazine and cumene hydroperoxide. 56 2,2,5,7,8-Pentamethylchroman-6-oxylϩ2,6-di-tert-butyl-4-methylphenoxyl ϩ ϫ 5 PMC-O• 2,6-(t-Bu)2-4-MeC6H2O• 1.8 10 benzene 323 therm. Steady-state ESR signal in 87ROG/KRA deoxygenated soln. contg. the phenol and di-tert-butyl hyponitrite. 57 Kaempferol semiquinone anionϩAscorbate radical anion ϩ Ϫ ϫ 8 Kaempferol-O• Asc• 3.4 10 8.5 water RT p.r. Decay and formn. kinetics at 95BOR/MIC 370 nm and 460–590 nm in

N2O-satd. soln. contg. 0.01 mol LϪ1 azide. Electron transfer. 58 Luteolin semiquinone anionϩAscorbate radical anion ϩ Ϫ ϫ 6 Luteolin-O• Asc• 2.0 10 8.5 water RT p.r. Decay and formn. kinetics at 95BOR/MIC 370 nm and 460–590 nm in

N2O-satd. soln. contg. 0.01 mol LϪ1 azide. Electron transfer. 59 Fisetin semiquinone anionϩAscorbate radical anion ϩ Ϫ ϫ 7 Fisetin-O• Asc• 7.1 10 8.5 water RT p.r. Decay and formation kinetics at 95BOR/MIC 370 nm and 460–590 nm in

N2O-satd. soln. contg. 0.01 mol LϪ1 azide. Electron transfer. 60 Quercetin semiquinoneϩAscorbate radical anion ϩ Ϫ ϫ 7 Quercetin-O• Asc• 1.5 10 8.5 water RT p.r. Decay and formn. kinetics at 95BOR/MIC 370 nm and 460–590 nm in

N2O-satd. soln. contg. 0.01 mol LϪ1 azide. Electron transfer. 61 Rutin semiquinone anionϩAscorbate radical anion ϩ Ϫ ϫ 7 Rutin-O• Asc• 3.5 10 8.5 water RT p.r. Decay and formn. kinetics at 95BOR/MIC 370 nm and 460–590 nm in

N2O-satd. soln. contg. 0.01 mol LϪ1 azide. Electron transfer.

62 Dihydroquercetin semiquinone anionϩAscorbate radical anion ϩ Ϫ ϫ 7 Dihydroquercetin-O• Asc• 4.7 10 8.5 water RT p.r. Decay and formn. kinetics at 95BOR/MIC 367 nm in N2O-satd. soln. contg. 0.01 mol LϪ1 azide. Electron transfer.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 140 P. NETA AND J. GRODKOWSKI

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference ϩ 63 9,10-Anthrasemiquinone-2,6-disulfonate anion 4-(2-Bromoethyl)-2,2,6,6-tetramethyl-1-piperidinyloxyl (R2NO•) Ϫ Ϫ ϩ ϫ 5 2,6-(SO3 )2-9,10-An(O )O• R2NO• 1.9 10 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU → Ϫ ϩ Ϫ ͑ ͒ 2,6-(SO3 )2-9,10-An(O)2 R2NO n-PrOH n-PrOH/water 2/1 . ϩ 64 9,10-Anthrasemiquinone-2-sulfonate anion 4-Hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxyl radical (R2NO•) Ϫ Ϫ ϩ ϫ 3 2-(SO3 )-9,10-An(O )O• R2NO• 4.0 10 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU → Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 R2NO n-PrOH soln. contg. 20% n-PrOH. Ea ϭ24.7 kJ molϪ1, log Aϭ7.5. ϩ 65 9,10-Anthrasemiquinone-2,6-disulfonate anion 4-Hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxyl radical(R2NO•) Ϫ Ϫ ϩ ϫ 2 2,6-(SO3 )2-9,10-An(O )O• R2NO• 9.5 10 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU → Ϫ ϩ Ϫ 2,6-(SO3 )2-9,10-An(O)2 R2NO n-PrOH soln. contg. 20% n-PrOH. Ea ϭ28.0 kJ molϪ1, log Aϭ7.7. ϩ ͑ ͒ 66 9,10-Anthrasemiquinone-2,6-disulfonate anion 2,2,4,5,5-Pentamethyl-1-imidazolinyloxyl R2NO• Ϫ Ϫ ϩ ϫ 4 2,6-(SO3 )2-9,10-An(O )O• R2NO• 4.4 10 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU → Ϫ ϩ Ϫ 2,6-(SO3 )2-9,10-An(O)2 R2NO n-PrOH soln. contg. 20% n-PrOH. ϩ 67 9,10-Anthrasemiquinone-2,6-disulfonate anion 2,2,5-Trimethyl-5-phenyl-1-imidazolinyloxyl radical (R2NO•) Ϫ Ϫ ϩ → ϫ 4 2,6-(SO3 )2-9,10-An(O )O• R2NO• 1.5 10 water/n- RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU soln. contg. Ϫ ϩ Ϫ 2,6-(SO3 )2-9,10-An(O)2 R2NO PrOH 20% n-PrOH. ϩ 68 9,10-Anthrasemiquinone-2-sulfonate anion 2,2,5-Trimethyl-5-phenyl-3-oxo-1-imidazolinyloxyl radical (R2NO•) Ϫ Ϫ ϩ ϫ 7 2-(SO3 )-9,10-An(O )O• R2NO• 4.5 10 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU → Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 R2NO n-PrOH soln. contg. 20% n-PrOH. ϩ 69 Durosemiquinone anion (RArNO•)

Ϫ ϩ ϫ 7 C6(CH3)4(O )O• RArNO• 1.2 10 water/ RT f.p. D.k. at 440 nm in deoxygenated 81TAT/KHU → ϩ Ϫ C6(CH3)4(O)2 RArNO n-PrOH soln. contg. 20% n-PrOH. ϩ 70 2-Methyl-1,4-naphthosemiquinone anion (RArNO•)

Ϫ ϫ 6 2-(CH3)-1,4-Np(O )O• 2.0 10 water/ RT f.p. D.k. at 390 nm in deoxygenated 81TAT/KHU ϩ → RArNO• 2-(CH3)-1,4-Np(O)2 n-PrOH soln. contg. 20% n-PrOH. ϩRArNOϪ ϩ 71 9,10-Anthrasemiquinone-2-sulfonate anion (RArNO•)

Ϫ Ϫ ϩ ϫ 8 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU 2-(SO3 )-9,10-An(O )O• RArNO• 2.6 10 → Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 RArNO n-PrOH soln. contg. 20% n-PrOH. Ea ϭ9.6 kJ molϪ1, log Aϭ10.1. ϩ 72 9,10-Anthrasemiquinone-2,6-disulfonate anion (RArNO•)

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 141

ϩ → Ϫ ϭϪ ϭ ͒ TABLE 2. Reactions of phenoxyl radicals with other radicals (R1 R2 products, d͓R1͔/dt d͓R2͔/dt k͓R1͔͓R2͔, values of k are tabulated —Continued

Phenoxylϩother radical k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

Ϫ Ϫ ϩ ϫ 8 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU 2,6-(SO3 )2-9,10-An(O )O• RArNO• 1.6 10 → Ϫ ϩ Ϫ 2,6-(SO3 )2-9,10-An(O)2 RArNO n-PrOH soln. contg. 20% n-PrOH. Ea ϭ17.6 kJ molϪ1 log Aϭ11.2. 73 2,6-Di-tert-butyl-4-isopropylphenoxylϩ2,2-Diphenyl-1-picrylhydrazyl ϩ 2,6-(t-Bu)2-4-(i-Pr)C6H2O• DPPH• 0.7 benzene 293 Chem. Kinetic ESR in deaerated soln. 67AYS/RUS 1.3 313 contg. DPPH• radicals and the ϭ Ϫ1 2.5 333 phenol. Ea 26 kJ mol , log Aϭ4.5. 74 Durosemiquinone anionϩTriphenylverdazyl Ϫ ϩ ϫ 5 C6(CH3)4(O )O• TPV–N• 5.9 10 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU → ϩ Ϫ C6(CH3)4(O)2 TPV–N n-PrOH soln. contg. 20% n-PrOH. 75 9,10-Anthrasemiquinone-2-sulfonate anionϩTriphenylverdazyl Ϫ Ϫ ϩ ϫ 7 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU 2-(SO3 )-9,10-An(O )O• TPV–N• 1.5 10 → Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 TPV–N n-PrOH soln. contg. 20% n-PrOH. 76 9,10-Anthrasemiquinone-2,6-disulfonate anionϩTriphenylverdazyl Ϫ Ϫ ϫ 7 water/ RT f.p. D.k. at 500 nm in deoxygenated 81TAT/KHU 2,6-(SO3 )2-9,10-An(O )O•TPV–N• 3.8 10 → Ϫ ϩ Ϫ 2,6-(SO3 )2-9,10-An(O)2 TPV–N n-PrOH soln. contg. 20% n-PrOH. 77 2,2,5,7,8-Pentamethylchroman-6-oxylϩDihydrolipoic acid disulfide anion radical ϩ Ϫ 9 HPMC LS2 2.2ϫ10 8.5 water RT p.r. Decay and formn. kinetics in 94BOR/MIC • • Ϫ soln. contg. MeCN and N3 . Electron transfer. 78 Trolox phenoxyl radicalϩDihydrolipoic acid disulfide anion radical ϩ Ϫ ϫ 8 TxO• LS2• 4.4 10 8.5 water RT p.r. D.k. and p.b.k. in soln. contg. 94BOR/MIC MeCN and azide. Derived from fitting to a complex mechanism. Electron transfer. 79 2,2,5,7,8-Pentamethylchroman-6-oxylϩglutathione disulfide radical anion ϩ Ϫ ϫ 10 HPMC• GSSG• 2.8 10 8.0– water RT p.r. D.k. and p.b.k. in soln. contg. 94BOR/MIC 8.5 MeCN and azide. Derived from fitting to a complex mechanism. Electron transfer. 80 Trolox phenoxyl radicalϩglutathione disulfide radical anion ϩ Ϫ ϫ 9 TxO• GSSG• 1.5 10 8.0– water RT p.r. D.k. and p.b.k. in soln. contg. 94BOR/MIC 8.5 MeCN and azide. Derived from fitting to a complex mechanism. Electron transfer.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 142 P. NETA AND J. GRODKOWSKI

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

1 4-Nitrophenoxyl ϩ Ϫ ϫ 5 2 Ϫ2 Ϫ1 ϫ 7 4-O2NC6H4O• 2 SCN 5.2 10 (L mol s ) 1.4 10 11–12 0.5 p.r. D.k. at 500 nm in 90LIN/SHE Ϫϩ Ϫ 4-O2NC6H4O (SCN)2• N2O-satd. soln. 2 Phenoxyl ϩ Ϫ Ϫϩ ϫ 4 ϫ 7 C6H5O• ClO2 C6H5O ClO2• 6.3 10 1.6 10 13 p.r. P.b.k. at 405 nm in 88MER/LIN N2O-satd. soln. 1.3ϫ105 3.5ϫ107 11–12 1.0 p.r. Kinetics at 402 nm in 90LIN/SHE

N2O-satd. soln. 3 4-Methylphenoxyl ϩ Ϫ ϫ 4 ϫ 8 4-CH3C6H4O• ClO2 2 10 2.4 10 11–12 1.0 p.r. Kinetics at 412 nm in 90LIN/SHE Ϫϩ 4-CH3C6H4O ClO2• N2O-satd. soln. 4 4-Acetylphenoxyl ϩ Ϫ ϫ 7 ϫ 6 4-CH3COC6H4O• ClO2 1.2 10 1.4 10 11–12 1.0 p.r. Kinetics at 445 nm in 90LIN/SHE Ϫϩ 4-CH3COC6H4O ClO2• N2O-satd. soln. 5 4-Fluorophenoxyl ϩ Ϫ Ϫϩ ϫ 4 ϫ 7 4-FC6H4O• ClO2 4-FC6H4O ClO2• 7 10 5.1 10 11–12 1.0 p.r. Kinetics at 396 nm in 90LIN/SHE N2O-satd. soln. 6 4-Chlorophenoxyl ϩ Ϫ Ϫϩ ϫ 4 ϫ 7 4-ClC6H4O• ClO2 4-ClC6H4O ClO2• 9 10 2.5 10 11–12 0.2 p.r. Kinetics at 420 nm in 90LIN/SHE N2O-satd. soln. 7 4-Bromophenoxyl ϩ Ϫ Ϫϩ ϫ 5 ϫ 7 4-BrC6H4O• ClO2 4-BrC6H4O ClO2• 1.8 10 1.7 10 11–12 0.2 p.r. Kinetics at 430 nm in 90LIN/SHE N2O-satd. soln. 8 4-Iodophenoxyl ϩ Ϫ Ϫϩ ϫ 5 ϫ 7 4-IC6H4O• ClO2 4-IC6H4O ClO2• 2.8 10 3.5 10 11–12 0.2 p.r. Kinetics at 500 nm in 90LIN/SHE 5 ϫ 7 1.9ϫ10 2.8 10 1.0 N2O-satd. soln. 9 Galvinoxyl ϩ ϩ Galv-O• Co(acac)2 Galv-OH Co(III) 1.1 f.p. D.k. at 432 nm in 79VOE/KHU deoxygenated n-PrOH soln. contg. the phenol

and RuCl3 at 333 K. log Aϭ12.5, Ea Eaϭ79.5 kJ molϪ1. 10 1,2-Benzosemiquinone ϩ 2ϩ→ ϫ 8 1,2-C6H4(OH)O• Cu complex 5 10 2.0 f.p. D.k. at 350 nm in 78KHU/KUZ deoxygenated soln. Complex formed decays by a second order reaction with 2kϭ1.6 ϫ106 LmolϪ1 sϪ1. 11 1,3-Benzosemiquinone ϩ 2ϩ→ ϫ 7 1,3-C6H4(OH)O• Cu complex 3.0 10 2.0 f.p. D.k. at 420 nm in 78KHU/KUZ deoxygenated soln. Complex formed decays by a ﬁrst order reaction with kϭ3.0ϫ103 sϪ1 to form Cuϩ. 12 1,4-Benzosemiquinone anion Ϫ ϩ 2ϩ→ ϫ 8 1,4-C6H4(O )O• Cu complex 6 10 7.0 f.p. D.k. at 425 nm in 78KHU/KUZ deoxygenated soln. Complex formed decays by a second order reaction with 2kϭ1.6 ϫ106 LmolϪ1 sϪ1. 13 5-Methyl-1,3-benzosemiquinone ϩ 2ϩ→ ϫ 7 5-(CH3)-1,3-C6H3(OH)O• Cu complex 3.0 10 2.0 f.p. D.k. at 450 nm in 78KHU/KUZ deoxygenated soln. Complex formed decays by a ﬁrst order reaction with kϭ3.0ϫ103 sϪ1 to form Cuϩ. 14 1,2-Naphthosemiquinone ϩ 2ϩ→ ϫ 6 1,2-Np(OH)O• Cu complex 3.2 10 2.0 f.p. D.k. at 400 nm in 78KHU/KUZ deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 143

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

15 9,10-Anthrasemiquinone-2,6-disulfonate anion Ϫ Ϫ ϩ 2ϩ ϫ 6 2,6-(SO3 )2-9,10-An(O )O• Cu 1.0 10 7.0 f.p. D.k. at 400 nm in 78KHU/KUZ →complex deoxygenated soln. 16 1,4-Benzosemiquinone ϩ 2ϩϩ ϩ ϳ ϫ 5 1,4-C6H4(OH)O• Fe H 1.5 10 0 f.p. D.k. at 415 nm at 293 K 75KUZ/DAV → ϩ 3ϩ 1,4-C6H4(OH)2 Fe in deoxygenated soln. contg. 10% 2-PrOH. Observed decay includes radical–radical reactions; k derived from ﬁtting to both reactions. 17 1,4-Benzosemiquinone ϩ 3ϩ ϳ ϫ 5 1,4-C6H4(OH)O• Fe 7 10 0 f.p. D.k. at 415 nm at 293 K 75KUZ/DAV → ϩ 2ϩϩ ϩ 1,4-C6H4(O)2 Fe H in deoxygenated soln. contg. 10% 2-PrOH. Observed decay includes radical–radical reactions; k derived from ﬁtting to both reactions. 18 1,4-Benzosemiquinone anion Ϫ ϩ 2ϩϩ ϩ ϫ 5 1,4-C6H4(O )O• Fe 2H 4.3 10 4.6 f.p. D.k. at 425 nm in 75KUZ/DAV → ϩ 3ϩ 1,4-C6H4(OH)2 Fe deoxygenated soln. contg. 10% 2-PrOH at 293 K. ⌬H ⌬Hϭ15 kJ molϪ1, ⌬S ϭϪ88 J KϪ1 molϪ1. 19 Phenoxyl ϩ 4Ϫ ϫ 8 C6H5O• Fe(CN)6 1 10 p.r. 02JON/LIN 20 4-Methoxyphenoxyl ϩ 4Ϫ ϫ 6 ϫ 4 4-CH3OC6H4O• Fe(CN)6 1.1 10 2.8 10 13.5 p.r. D.k. at 420 nm in 90JOV/STE Ϫϩ 3Ϫ 4-CH3OC6H4O Fe(CN)6 N2O-satd. soln. contg. 0.9 mol LϪ1 ethylene glycol. 21 3,4-Dimethoxyphenoxyl ϩ 4Ϫ ϫ 5 ϫ 4 3,4-(CH3O)2C6H3O• Fe(CN)6 6.5 10 2.7 10 13.5 p.r. D.k. at 430 nm in 91JOV/TOS ͓ Ϫϩ 3Ϫ 3,4-(CH3O)2C6H3O Fe(CN)6 N2O-satd. soln. 22 3,4-Methylenedioxyphenoxyl ͑Sesamoxyl͒ ϩ 4Ϫ ϫ 5 ϫ 5 Sesamol-O• Fe(CN)6 8.2 10 2.4 10 13.5 p.r. D.k. at 435 nm in 91JOV/TOS Ϫϩ 3Ϫ Sesamol-O Fe(CN)6 N2O-satd. soln. 23 Tryptophan-5-oxyl ϩ 4Ϫ ϫ 4 ϫ 6 5-Trp-O• Fe(CN)6 2.7 10 1.6 10 13.5 p.r. P.b.k. in N2O-satd. soln. 90JOV/STE Ϫϩ 3Ϫ Ϫ1 5-Trp-O Fe(CN)6 contg. 0.1 mol L azide. 2.8ϫ104 2.1ϫ106 13.5 f.p. P.b.k. 90JOV/STE ϫ 6 ϫ 4 2.8 10 2.5 10 9.1 p.r. D.k. in N2O-satd. soln. 90JOV/STE contg. 0.1 mol LϪ1 thiocyanate. 24 Tryptamine-5-oxyl ϩ 4Ϫ ϫ 5 ϫ 6 5-(O•)-Tryptamine Fe(CN)6 1 10 5.9 10 13.5 f.p. P.b.k. 90JOV/STE Ϫ ϩ 3Ϫ 5-(O )-Tryptamine Fe(CN)6 25 Galvinoxyl ͑2,6-di-tert-butyl-␣-͑3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene͒-p-tolyloxyl͒ ϩ → ϩ Galv-O• Fe(acac)2 Galv-OH Fe(III) 6.0 f.p. D.k. at 432 nm in 79VOE/KHU deoxygenated n-PrOH soln. contg. the phenol

and RuCl3 at 333 K. ϭ log A 9.1, Ea ϭ51.9 kJ molϪ1. 26 Mitomycin C semiquinone anion Ϫ ϩ ϫ 6 Mito(O )O• Fe(III)EDTA 9.0 10 7.0 p.r. D.k. at 510 nm in 85BUT/HOE → ϩ Mito(O)2 Fe(II)EDTA soln. contg. formate.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 144 P. NETA AND J. GRODKOWSKI

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

27 Adriamycin semiquinone anion Ϫ ϩ ϫ 8 Adria(O )O• Fe(III)EDTA 2.8 10 7.0 p.r. D.k. at 720 nm in 85BUT/HOE → ϩ Adria(O)2 Fe(II)EDTA soln. contg. formate. 28 Mitomycin C semiquinone anion Ϫ ϩ ϫ 7 Mito(O )O• Fe(III)DETAPAC 2.4 10 7.0 p.r. D.k. at 510 nm in 85BUT/HOE → ϩ Mito(O)2 Fe(II)DETAPAC soln. contg. formate. ͑diethylenetriaminepentaacetate͒ 29 Adriamycin semiquinone anion Ϫ ϩ ϫ 8 Adria(O )O• Fe(III)DETAPAC 7.0 10 7.0 p.r. D.k. at 720 nm in 85BUT/HOE → ϩ Adria(O)2 Fe(II)DETAPAC soln. contg. formate. 30 Mitomycin C semiquinone anion Ϫ ϩ Ͻ ϫ 4 Mito(O )O• Fe(III)desferrioxamine 6 10 7.0 p.r. D.k. at 510 nm in 85BUT/HOE → ϩ Mito(O)2 Fe(II)desferrioxamine soln. contg. formate. 31 Adriamycin semiquinone anion Ϫ ϩ Ͻ ϫ 4 Adria(O )O• Fe(III)desferrioxamine 4 10 7.0 p.r. D.k. at 720 nm in 85BUT/HOE soln. contg. formate. 32 Mitomycin C semiquinone anion Ϫ ϩ Ͻ ϫ 4 Mito(O )O• Fe(III)ATP 6 10 7.0 p.r. D.k. at 510 nm in 85BUT/HOE → ϩ Mito(O)2 Fe(II)ATP soln. contg. formate. 33 Adriamycin semiquinone anion Ϫ ϩ ϫ 6 Adria(O )O• Fe(III)ATP 8 10 7.0 p.r. D.k. at 720 nm in 85BUT/HOE → ϩ Adria(O)2 Fe(II)ATP soln. contg. formate. 34 2,5-Dimethyl-1,4-benzosemiquinone anion Ϫ ϫ 5 2,5-(CH3)2-1,4-C6H2(O )O• 3 10 7.2 p.r. P.b.k. at 555 nm in 82SUT/SAN ϩ III → methemoglobin(Fe ) 2,5-(CH3)2- deoxygenated soln. ϩ II Ϫ1 1,4-C6H2(O)2 methemoglobin(Fe ) contg. 0.2 mol L 2-PrOH and 0.007 mol LϪ1 acetone. 35 Durosemiquinone anion Ϫ ϩ III ϫ 6 C6(CH3)4(O )O• methemoglobin(Fe ) 5.5 10 7.2 p.r. P.b.k. at 555 nm in 82SUT/SAN → ϩ II C6(CH3)4(O)2 methemoglobin(Fe ) deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH and 0.007 mol LϪ1 acetone. 36 2-Methyl-1,4-naphthosemiquinone anion Ϫ ϫ 7 2-(CH3)-1,4-Np(O )O• 1.5 10 7.2 p.r. P.b.k. at 555 nm in 82SUT/SAN ϩ III → methemoglobin(Fe ) 2-(CH3)- deoxygenated soln. ϩ II Ϫ1 1,4-Np(O)2 methemoglobin(Fe ) contg. 0.2 mol L 2-PrOH and 0.007 mol LϪ1 acetone. 37 9,10-Anthrasemiquinone-2-sulfonate anion Ϫ Ϫ ϫ 7 2-(SO3 )-9,10-An(O )O• 9 10 7.2 p.r. P.b.k. at 555 nm in 82SUT/SAN ϩ III → Ϫ methemoglobin(Fe ) 2-(SO3 )- deoxygenated soln. ϩ II Ϫ1 9,10-An(O)2 methemoglobin(Fe ) contg. 0.2 mol L 2-PrOH and 0.007 mol LϪ1 acetone. 38 2,5-Dimethyl-1,4-benzosemiquinone anion Ϫ ϫ 7 2,5-(CH3)2-1,4-C6H2(O )O• 1.0 10 7.2 p.r. P.b.k. at 550 nm in 82SUT/SAN ϩ III → Cyt C(Fe ) 2,5-(CH3)2- deoxygenated soln. ϩ II Ϫ1 1,4-C6H2(O)2 Cyt C(Fe ) contg. 0.2 mol L 2-PrOH and 0.007 mol LϪ1 acetone. 39 Durosemiquinone anion Ϫ ϩ III ϫ 8 C6(CH3)4(O )O• Cyt C(Fe ) 1.2 10 7.2 p.r. P.b.k. at 550 nm in 82SUT/SAN → ϩ II C6(CH3)4(O)2 Cyt C(Fe ) deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH and 0.007 mol LϪ1 acetone. 40 2-Methyl-1,4-naphthosemiquinone anion Ϫ ϩ III ϫ 8 2-(CH3)-1,4-Np(O )O• Cyt C(Fe ) 2.7 10 7.2 p.r. P.b.k. at 550 nm in 82SUT/SAN → ϩ II 2-(CH3)-1,4-Np(O)2 Cyt C(Fe ) deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH and 0.007 mol LϪ1 acetone.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 145

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

41 9,10-Anthrasemiquinone-2-sulfonate anion Ϫ Ϫ ϩ III ϫ 9 2-(SO3 )-9,10-An(O )O• Cyt C(Fe ) 1.9 10 7.2 p.r. P.b.k. at 550 nm in 82SUT/SAN → Ϫ 2-(SO3 )-9,10-An(O)2 deoxygenated soln. ϩCyt C(FeII) contg. 0.2 mol LϪ1 2-PrOH and 0.007 mol LϪ1 acetone. 42 3,4-Dimethoxyphenoxylϩ(N,N-Dimethylamino)methylferrocene ϩ ϫ 7 ϫ 5 3,4-(CH3O)2C6H3O• DMAMFc 2.9 10 8.7 10 7.0 p.r. D.k. at 430 nm in 91JOV/TOS Ϫϩ ϩ 3,4-(CH3O)2C6H3O DMAMFc N2O-satd. soln. 43 3,5-DimethoxyphenoxylϩFerrocenedicarboxylate anion ϩ ϫ 9 ϫ 5 3,5-(CH3O)2C6H3O• FcDC 1.1 10 6 10 7.0 p.r. D.k. at 505 nm in 91JOV/TOS Ϫϩ ϩ 8 ϫ 6 3,5-(CH3O)2C6H3O FcDC 7.0ϫ10 2 10 8.0 N2O-satd. soln. 44 Methyl gallate semiquinone anionϩFerrocene monocarboxylate anion Ϫ ϫ 6 ϫ 5 3,4,5-(OH)(O )(O•)C6H2CO2CH3 1.9 10 4 10 7 p.r. UV-vis kinetics in 95JOV/HAR ϩ Ϫ Fc(CO2 ) 3,4,5-(OH)3C6H2 N2O-satd. soln. contg. ϩ Ϫ ϩ Ϫ CO2CH3 Fc(CO2 ) N3 . 45 4-Cyanophenoxyl ϩ Ϫ ϫ 6 ϫ 4 4-NCC6H4O• 2I 1 10 7 10 11– 1.0 p.r. P.b.k. at 385 nm in 90LIN/SHE Ϫϩ Ϫ 2 Ϫ2 Ϫ1 4-NCC6H4O I2• (L mol s ) 12 N2O-satd. soln. 46 4-(4Ј-Hydroxyphenylthio)phenoxyl Ј ϩ Ϫ ϫ 7 ϫ 8 Ϸ 4,4 -HOC6H4SC6H4O• 2I 1.1 10 1.1 10 7 p.r. D.k. at 380 nm in 99MOH/MIT Ј ϩ Ϫ 2 Ϫ2 Ϫ1 4,4 -HOC6H4SC6H4OH I2• (L mol s ) N2O-satd. soln. 47 2-Methoxy-4-(2Ј-acetylvinyl)phenoxyl ϭ 5 ϫ 9 2-(CH3O)-4-(CH3COCH CH) 4.5ϫ10 5.1 10 6 p.r. P.b.k. at 360 nm in 99PRI/DEV ϩ Ϫ C6H3O• N3 2-(CH3O)-4- N2O-satd. soln. contg. ϭ ϩ Ϫ (CH3COCH CH)C6H3OH N3• N3 . 48 Tyrosyl ϩ Ͻ ϫ 3 TyrO• O2 1 10 9 p.r. D.k. at 405 nm in 93JIN/LEI N2O-satd. soln. contg. azide and formate. Product analysis suggests reaction via addition. 49 4-Acetaminophenoxyl ϩ Ͻ 5 4-CH3CONHC6H4O• O2 10 p.r. D.k. 88BIS/TAB 50 2,4,6-Tri-t-butylphenoxyl ϫ 2 2 (2,4,6-(t-Bu)3C6H2O•) 4 10 Chem. Decay of ESR signal of 73GRI/DEN ϩ → 2 Ϫ2 Ϫ1 O2 addition (L mol s ) the phenoxyl radical in benzene soln. at 347 K. log AϭϪ14.5, Ea Eaϭ114 kJ molϪ1. 51 ␣-Tocopheroxyl ␣ ϩ Ӷ -Toc-O• O2 6.5 f.p. Kinetic ESR in benzene 84DOB/BUR soln. contg. 9% di-t-butyl peroxide. No

effect of O2 up to the saturation level of 9.2 mmol LϪ1. 52 4-Methyl-1,2-benzosemiquinone anion Ϫ ϩ р ϫ 5 4-CH3-1,2-(O )(O•)C6H3 O2 1 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → 4-CH3-1,2-(O)(O)C6H3 N2O-satd. soln. contg. ϩ Ϫ O2• azide. 53 4-Methoxy-1,2-benzosemiquinone anion Ϫ ϩ Ͻ 5 ϫ 9 4-(CH3O)-1,2-C6H3(O )O• O2 10 8.7 10 7.0 p.r. D.k. in soln. contg. azide 88LAN ͑ 4-(CH3O)-1,2-C6H3(O)2 for kf); P.b.k. in soln. ϩ Ϫ O2• contg. formate and O2 ͑ for kr). Ͻ105 8.7ϫ108 7.0 p.r. D.k. at 320 nm in soln. 87COO/LAN ͑ contg. azide for kf); P.b.k. at 320 nm in soln.

contg. formate and O2 ͑ for kr).

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 146 P. NETA AND J. GRODKOWSKI

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

54 3,4-Dihydroxyphenylalanine semiquinone anion Ϫ ϩ → ϩ Ϫ р ϫ 5 Dopa(O )(O•) O2 Dopa(O)(O) O2• 1 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR N2O-satd. soln. contg. azide. 55 3,4-Dihydroxyphenethylamine semiquinone anion Ϫ ϩ р ϫ 5 Dopamine(O )(O•) O2 1 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ Dopamine(O)(O) O2• N2O-satd. soln. contg. azide. 56 Epinephrin semiquinone anion Ϫ ϩ р ϫ 5 Epinephrin(O )(O•) O2 1 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ Epinephrin(O)(O) O2• N2O-satd. soln. contg. azide. 57 5-S-Cysteinyldopa semiquinone anion Ϫ ϩ р ϫ 5 5-S-Cysteinyldopa(O )(O•) O2 1 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ 5-S-Cysteinyldopa(O)(O) O2• N2O-satd. soln. contg. azide. 58 2-Hydroxyestradiol semiquinone anion Ϫ ϩ р ϫ 5 2-Hydroxyestradiol(O )(O•) O2 1 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ 2-Hydroxyestradiol(O)(O) O2• N2O-satd. soln. contg. azide. 59 1,4-Benzosemiquinone anion Ϫ ϩ ϫ 4 ϫ 9 1,4-C6H4(O )O• O2 5 10 1 10 7 p.r. From equilibrium 75MEI ϩ Ϫ 1,4-C6H4(O)2 O2• constant and kr from 73PAT/WIL ͑p.b.k. at 430 nm in soln. contg. 2-PrOH͒. 60 2-Methyl-1,4-benzosemiquinone anion Ϫ ϩ ϫ 6 ϫ 8 2-(CH3)-1,4-C6H3(O )O• O2 1.1 10 7.6 10 7 p.r. From equilibrium 75MEI 2-(CH3)-1,4-C6H3(O)2 constant and kr from ϩ Ϫ ͑ O2• 73PAT/WIL p.b.k. at 430 nm in soln. contg. 2-PrOH͒. 61 2-tert-Butyl-1,4-benzosemiquinone anion Ϫ ϩ ϫ 6 ϫ 8 2-(t-Bu)-1,4-C6H3(O )(O•) O2 1.6 10 1.1 10 6.9 0.1 p.r. P.b.k. at 430 nm in 95DOH/BER ϩ Ϫ 2-(t-Bu)-1,4-C6H3O2 O2• O2-satd. soln. contg. formate. 62 2,3-Dimethyl-1,4-benzosemiquinone anion Ϫ ϩ ϫ 7 ϫ 8 2,3-(CH3)2-1,4-C6H2(O )O• O2 2.4 10 4.5 10 7 p.r. From equilibrium 75MEI ϩ Ϫ 2,3-(CH3)2-1,4-C6H2(O)2 O2• constant and kr from 73PAT/WIL ͑p.b.k. at 430 nm in soln. contg. 2-PrOH͒. 63 2,5-Dimethyl-1,4-benzosemiquinone anion Ϫ ϩ ϫ 6 ϫ 8 2,5-(CH3)2-1,4-C6H2(O )O• O2 3.4 10 1.7 10 7 p.r. P.b.k. at 430 nm in soln. 75MEI ϩ Ϫ 2,5-(CH3)2-1,4-C6H2(O)2 O2• contg. 2-PrOH and equilibrium constant. 4.8ϫ106 1.7ϫ108 7.2 p.r. D.k. at 430 nm in 76ILA/CZA deoxygenated soln. contg. formate. 64 2,6-Dimethyl-1,4-benzosemiquinone anion Ϫ ϩ ϫ 6 ϫ 8 2,6-(CH3)2-1,4-C6H2(O )O• O2 8.8 10 2.2 10 7 p.r. P.b.k. at 430 nm in soln. 75MEI ϩ Ϫ 2,6-(CH3)2-1,4-C6H2(O)2 O2• contg. 2-PrOH and equilibrium constant. 65 2,5-Bis͑carboethoxyamino͒-3,6-diaziridinyl-1,4-benzosemiquinone anion Ϫϩ ϩ Ϫ ϫ 7 ϫ 8 ϳ AZQ• O2 AZQ O2• 1.1 10 2.7 10 7.0 p.r. P.b.k. at 500 nm in 87BUT/HOE soln. contg. formate. 66 2,5-Bis͑2-hydroxyethylamino͒-3,6-diaziridinyl-1,4-benzosemiquinone anion Ϫϩ ͓ ϩ Ϫ ϫ 8 ϳ ϫ 5 ϳ BZQ• O2c BZQ O2• 8.2 10 1.5 10 7.0 p.r. D.k. at 500 nm in 87BUT/HOE soln. contg. formate. 67 Durosemiquinone anion Ϫ ϩ ϫ 8 ϫ 7 C6(CH3)4(O )O• O2 2.2 10 1.0 10 7 p.r. D.k. at 445 nm in soln. 75MEI/CZA ϩ Ϫ C6(CH3)4(O)2 O2• contg. formate.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 147

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

2.0ϫ108 4.5ϫ106 7 p.r. D.k. at 440 nm in soln. 73PAT/WIL contg. 5 mol LϪ12- PrOH and 2 mol LϪ1 acetone. 68 Mitomycin C semiquinone anion Ϫ ϩ → ϩ Ϫ ϫ 8 Mito(O )O• O2 Mito(O)2 O2• 2.2 10 7.0 p.r. D.k. at 510 nm in soln. 85BUT/HOE contg. formate. 69 5-Hydroxy-1,3-benzosequinone ϩ Ͻ ϫ 5 5-(OH)-1,3-C6H3(OH)O• O2 4 10 2.5 p.r. D.k. at 495 nm in 94WAN/GYO N2O/O2-satd. soln. 70 5-Hydroxy-1,3-benzosequinone anion Ϫ ϩ ϫ 8 5-(OH)-1,3-C6H3(O )O• O2 2.1 10 6.9 p.r. D.k. at 550 nm in 94WAN/GYO N2O/O2-satd. sol. k derived from measured k (1.5ϫ108) for mixture of unreactive neutral radical and anion radical ϭ and pKa 6.5. k at pH 10.5 is 1.4ϫ108 but the reacting species is formulated as the keto form of the phenoxyl radical. 71 2-Hydroxy-1,4-benzosemiquinone anion Ϫ ϩ ϫ 6 1,2,4-C6H3(OH)(O )(O•) O2 2.5 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ 1,2,4-C6H3(OH)(O)2 O2• N2O-satd. soln. contg. azide. 72 2,4,5-Trihydroxyphenylalanine semiquinone anion Ϫ ϩ ϫ 6 6-Hydroxydopa(O )(O•) O2 2.7 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ 6-Hydroxydopa(O)(O) O2• N2O-satd. soln. contg. azide. 73 2,4,5-Trihydroxyphenethylamine semiquinone anion Ϫ ϩ ϫ 6 6-Hydroxydopamine(O )(O•) O2 8.3 10 6.4 p.r. D.k. at 310 nm in 88KAL/KOR → ϩ Ϫ 6-Hydroxydopamine(O)(O) O2• N2O-satd. soln. contg. azide. 74 1,4-Naphthosemiquinone ϩ → ϩ ϫ 5 1,4-Np(OH)O• O2 1,4-Np(O)2 HO2• 6.2 10 f.p. D.k. at 370 nm in 97TAT toluene/2-PrOH ͑9/1͒. 2.3ϫ105 f.p. D.k. at 370 nm in 97TAT 2-PrOH. 75 2-Methyl-1,4-naphthosemiquinone anion Ϫ ϩ ϫ 8 ϫ 7 2-(CH3)-1,4-Np(O )O• O2 2.4 10 3.8 10 7 p.r. D.k. at 400 nm in soln. 75MEI/CZA ϩ Ϫ 2-(CH3)-1,4-Np(O)2 O2• contg. formate. 76 2,3-Dimethyl-1,4-naphthosemiquinone anion Ϫ ϩ ϫ 8 ϫ 6 2,3-(CH3)2-1,4-Np(O )O• O2 2 10 4 10 neutral p.r. D.k. at 400 nm in soln. 73PAT/WIL Ϫ1 2,3-(CH3)2-1,4-Np(O)2 contg. 5 mol L ϩ Ϫ Ϫ1 O2• 2-PrOH and 1 mol L acetone. 77 2-Methyl-3-phytyl-1,4-naphthosemiquinone anion Ϫ ϩ ϫ 8 Ͻ ϫ 5 2-(CH3)-3-phytyl-1,4-Np(O )O• O2 2 10 2 10 neutral p.r. D.k. at 400 nm in soln. 73PAT/WIL Ϫ1 2-(CH3)-3-phytyl-1,4-Np(O)2 contg. 7 mol L ϩ Ϫ Ϫ1 O2• 2-PrOH and 1 mol L acetone. 78 5-Hydroxy-1,4-naphthosemiquinone anion Ϫ ϩ ϫ 7 ϫ 8 5-(OH)-1,4-Np(O )O• O2 1.4 10 1.5 10 7 p.r. P.b.k. at 385 nm in soln. 87MUK ϩ Ϫ 5-(OH)-1,4-Np(O)2 O2• contg. formate. 79 5,8-Dihydroxy-1,4-naphthosemiquinone anion Ϫ ϩ ϫ 8 ϫ 8 1,4,5,8-Np(OH)2(O )O• O2 1.1 10 5.8 10 5.2 p.r. P.b.k. in soln. contg. 83LAN/MUKa ϩ Ϫ 1,4,5,8-Np(OH)2(O)2 O2• formate. Ϫ ϩ ϫ 8 ϳ 1,4,5,8-Np(OH)(O )2O• O2 1.1 10 14 p.r. D.k. in soln. contg. 83LAN/MUKa → Ϫ ϩ Ϫ 1,4,5,8-Np(O )2(O)2 O2• formate. 80 Kalafungin semiquinone anion Ϫϩ ϩ Ϫ ϫ 7 ϫ 8 KF• O2 KF O2• 1.2 10 6.2 10 7 p.r. Kinetics at 385 nm in 99AND/BRI soln. contg. 0.1 mol LϪ1

formate and O2 .

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 148 P. NETA AND J. GRODKOWSKI

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

81 5-Hydroxy-7-O-methylkalafungin semiquinone anion Ϫϩ ϩ Ϫ ϫ 7 ϫ 8 KF2• O2 KF2 O2• 8.7 10 1.6 10 7 p.r. Kinetics at 395 nm in 99AND/BRI soln. contg. 0.1 mol LϪ1

formate and O2 . 82 5-Hydroxy-7-deoxykalafungin semiquinone anion Ϫϩ ϩ Ϫ ϫ 7 ϫ 8 KF3• O2 KF3 O2• 4 10 2.0 10 7 p.r. Kinetics at 395 nm in 99AND/BRI soln. contg. 0.1 mol LϪ1

formate and O2 . 83 5-epi-7-O-Methylkalafungin semiquinone anion Ϫϩ ϩ Ϫ ϫ 8 ϫ 7 KF4• O2 KF4 O2• 1.6 10 8 10 7 p.r. Kinetics at 385 nm in 99AND/BRI soln. contg. 0.1 mol LϪ1

formate and O2 . 84 5-epi-7-Deoxykalafungin semiquinone anion Ϫϩ ϩ Ϫ ϫ 7 ϫ 8 KF5• O2 KF5 O2• 5 10 1.4 10 7 p.r. Kinetics at 385 nm in 99AND/BRI soln. contg. 0.1 mol LϪ1

formate and O2 . 85 9,10-Anthrasemiquinone ϩ ϫ 8 9,10-An(OH)O• O2 2.2 10 f.p. D.k. at 375 nm in 97TAT → ϩ 9,10-An(O)2 HO2• benzene soln. contg. 3.3% 2-PrOH. kϭ2.0 ϫ108 with 5% 2-PrOH, kϭ1.0ϫ108 with 5%

(CD3)2CDOD, kH /kD ϭ2.0. 2.3ϫ108 f.p. D.k. at 375 nm in 97TAT toluene. 9.2ϫ107 f.p. D.k. at 375 nm in 97TAT toluene soln. contg. 7.5% 2-PrOH. 1.1ϫ108 f.p. D.k. at 375 nm in 97TAT dioxane. kϭ4.7ϫ107 in

dioxane-d8 , kH /kD ϭ2.4. 1.0ϫ108 f.p. D.k. at 375 nm in 97TAT dioxane soln. contg. 5% 2-PrOH. kϭ4.0ϫ107

with dioxane-d8 and 5.6% (CD3)2CDOD, ϭ kH /kD 2.6. 1.5ϫ108 f.p. D.k. at 375 nm in 97TAT chloroform. 9.5ϫ107 f.p. D.k. at 375 nm in 97TAT chloroform soln. contg. 5% 2-PrOH. kϭ8.1 ϫ 7 10 in CDCl3 with 5.6% (CD3)2CDOD, ϭ kH /kD 1.2. 1.1ϫ108 f.p. D.k. at 375 nm in ethyl 97TAT acetate. 1.2ϫ108 f.p. D.k. at 375 nm in 97TAT acetonitrile soln. contg. 5% 2-PrOH and Ϫ2 Ϫ1 10 mol L H2SO4 . kϭ1.1ϫ108 with 5.7% 2-PrOH, kϭ7.6ϫ107 with 5.7%

(CD3)2CDOD, kH /kD ϭ1.5. 5.1ϫ106 f.p. D.k. at 375 nm in DMF 97TAT soln. contg. 1.4% 2-PrOH and Ϫ2 Ϫ1 10 mol L H2SO4 .

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 149

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

8.2ϫ105 f.p. D.k. at 375 nm in 97TAT DMSO soln. contg. 1.8% 2-PrOH and Ϫ2 Ϫ1 10 mol L H2SO4 . 3.9ϫ106 f.p. D.k. at 375 nm in 97TAT pentanol soln. contg. Ϫ2 Ϫ1 10 mol L H2SO4 . 3.8ϫ106 f.p. D.k. at 375 nm in 97TAT 3-methyl-1-butanol soln. contg. 10Ϫ2 mol LϪ1

H2SO4 . 2.8ϫ106 f.p. D.k. at 375 nm in 97TAT 2-PrOH soln. contg. Ϫ2 Ϫ1 10 mol L H2SO4 . 6ϫ106 f.p. D.k. at 375 nm in MeOH 97TAT soln. contg. Ϫ2 Ϫ1 10 mol L H2SO4 . 1.6ϫ107 f.p. D.k. at 375 nm in 97TAT aqueous soln. contg. 14% 2-PrOH and Ϫ2 Ϫ1 10 mol L H2SO4 . 86 9,10-Anthrasemiquinone anion Ϫ ϩ ϩ Ϫ ϫ 8 ϫ 6 9,10-An(O )O• O2 9,10-An(O)2 O2• 3.2 10 3.2 10 alk. p.r. D.k. at 400 nm and 485 90MAY/KRA nm in MeOH. 87 9,10-Anthrasemiquinone-1-sulfonate anion Ϫ Ϫ ϩ ϫ 8 1-(SO3 )-9,10-An(O )O• O2 4.2 10 7 p.r. D.k. at 500 nm in soln. 72HUL/LAN → Ϫ ϩ Ϫ 1-(SO3 )-9,10-An(O)2 O2• contg. formate. 88 9,10-Anthrasemiquinone-2-sulfonate anion Ϫ Ϫ ϩ ϫ 8 2-(SO3 )-9,10-An(O )O• O2 4.6 10 7 p.r. D.k. at 500 nm in soln. 72HUL/LAN → Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 O2• contg. formate. 1.7ϫ109 7.0 p.r. D.k. at 500 nm in soln. 91PAL/PALb contg. formate. 89 9,10-Anthrasemiquinone-1,5-disulfonate anion Ϫ Ϫ ϩ ϫ 9 1,5-(SO3 )2-9,10-An(O )O• O2 1.4 10 8.4 p.r. D.k. at 500 nm in soln. 91PAL/PALb → Ϫ ϩ Ϫ 1,5-(SO3 )2-9,10-An(O)2 O2• contg. formate. 90 9,10-Anthrasemiquinone-2,6-disulfonate anion Ϫ Ϫ ϩ ϫ 8 2,6-(SO3 )2-9,10-An(O )O• O2 6.0 10 7.0 p.r. D.k. at 515 nm in soln. 91PAL/PALb → Ϫ ϩ Ϫ 2,6-(SO3 )2-9,10-An(O)2 O2• contg. formate. 5ϫ108 neutral p.r. D.k. at 520 nm in soln. 71WIL contg. 2-PrOH and acetone. 91 1,4-Dihydroxy-9,10-anthrasemiquinone anion Ϫ ϩ ϫ 7 Ͻ 5 1,4-(OH)2-9,10-An(O )O• O2 1.5 10 10 alk. p.r. D.k. at 395 nm in 91MAY/KRA ϩ Ϫ 1,4-(OH)2-9,10-An(O)2 O2• MeOH. 4.4ϫ107 6.7 p.r. D.k. at 480 nm in 90MUK/SWA 3.7ϫ107 11.1 aqueous soln. contg. 5 mol LϪ1 2-PrOH and 1 mol LϪ1 acetone. 92 1,4-Dihydroxy-9,10-anthrasemiquinone-2-sulfonate anion Ϫ Ϫ ϩ ϫ 8 2-(SO3 )-1,4-(OH)2-9,10-An(O )O• O2 2.3 10 6.3 p.r. D.k. at 385 nm in soln. 88MUK/LAN → Ϫ 8 2-(SO3 )-1,4-(OH)2-9,10-An(O)2 2.2ϫ10 11.0 contg. formate. ϩ Ϫ O2• 93 Adriamycin semiquinone anion Ϫ ϩ ϫ 8 Adria(O )O• O2 3.0 10 7.0 p.r. D.k. at 720 nm in soln. 85BUT/HOE → ϩ Ϫ Adria(O)2 O2• contg. formate. 3.5ϫ108 6.0 p.r. D.k. at 720 nm in soln. 85LAN/MUK ϫ 8 1.7 10 11.5 contg. formate. pKa of radical 2.9; pKa’s of adriamycin 8.2, 9.0, 9.4, 10.1, 13.2. 94 5,5Ј-Indigodisulfonate radical anion Ϫ ϩ ϩ Ϫ ϫ 7 ϫ 5 IDS(O )O• O2 IDS(O)2 O2• 3 10 9 10 7 p.r. D.k. at 550 nm in soln. 75MEI/CZA contg. formate. 95 2,6-Diphenyl-4-octadecyloxyphenoxyl

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 150 P. NETA AND J. GRODKOWSKI

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

ϩ ϫ 6 2,6-Ph2-4-C18H37OC6H2O• 2Rh(III) 4.6 10 f.p. D.k. at 405 nm in 79VOE/KHU →products (L2 molϪ2 sϪ1) deoxygenated n-PrOH soln. contg. the phenol

and RhCl3 at 293 K. 96 Galvinoxyl ϩ → Galv-O• Rh(III) products 3.9 f.p. D.k. at 432 nm in 79VOE/KHU deoxygenated n-PrOH soln. contg. the phenol

and RhCl3 at 333 K. ϭ log A 12.6, Ea ϭ76.6 kJ molϪ1. 97 2,6-Diphenyl-4-octadecyloxyphenoxyl ϩ ϫ 9 2,6-Ph2-4-C18H37OC6H2O• 2Ru(III) 1.8 10 f.p. D.k. at 405 nm in 79VOE/KHU →products (L2 molϪ2 sϪ1) deoxygenated n-PrOH soln. contg. the phenol

and RuCl3 at 293 K. 98 Galvinoxyl ϩ → ϫ 1 Galv-O• Ru(III) products 2.2 10 f.p. D.k. at 432 nm in 79VOE/KHU deoxygenated n-PrOH soln. contg. the phenol

and RuCl3 at 333 K. ϭ log A 9.0, Ea ϭ47.7 kJ molϪ1. 99 Phenoxyl ϩ 2Ϫ Ϫϩ Ϫ ϫ 7 ϫ 5 C6H5O• SO3 C6H5O SO3• 1 10 6 10 11.1 0.1– p.r. D.k. about 400 nm in 84HUI/NET 0.5 N2O-satd. soln. 100 4-Methoxyphenoxyl ϩ 2Ϫ Ͻ ϫ 6 4-CH3OC6H4O• SO3 1 10 8 p.r. D.k. at 420 nm. 95KHA/ALF 101 2-Chlorophenoxyl ϩ 2Ϫ ϫ 7 2-ClC6H4O• SO3 4.7 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 2-ClC6H4O SO3• N2O-satd. soln. 102 3-Chlorophenoxyl ϩ 2Ϫ ϫ 8 3-ClC6H4O• SO3 1.1 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 3-ClC6H4O SO3• N2O-satd. soln. 103 4-Chlorophenoxyl ϩ 2Ϫ ϫ 7 4-ClC6H4O• SO3 1.0 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 4-ClC6H4O SO3• N2O-satd. soln. 104 4-Bromophenoxyl ϩ 2Ϫ ϫ 7 4-BrC6H4O• SO3 1.2 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 4-BrC6H4O SO3• N2O-satd. soln. 105 2,3-Dichlorophenoxyl ϩ 2Ϫ ϫ 8 2,3-Cl2C6H3O• SO3 1.2 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 2,3-Cl2C6H3O SO3• N2O-satd. soln. 106 3,5-Dichlorophenoxyl ϩ 2Ϫ ϫ 8 3,5-Cl2C6H3O• SO3 3.4 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 3,5-Cl2C6H3O SO3• N2O-satd. soln. 107 2,6-Dichlorophenoxyl ϩ 2Ϫ ϫ 8 2,6-Cl2C6H3O• SO3 1.0 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫϩ Ϫ 2,6-Cl2C6H3O SO3• N2O-satd. soln. 108 2,4,5-Trichlorophenoxyl ϩ 2Ϫ ϫ 8 2,4,5-Cl3C6H2O• SO3 1.4 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET → Ϫ 2,4,5-Cl3C6H2O N2O-satd. soln. ϩ Ϫ SO3• 109 Pentachlorophenoxyl ϩ 2Ϫ→ Ϫ ϫ 8 C6Cl5O• SO3 C6Cl5O 1.5 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET ϩ Ϫ SO3• N2O-satd. soln. 110 Pentaﬂuorophenoxyl ϩ 2Ϫ→ Ϫϩ Ϫ ϫ 8 C6F5O• SO3 C6F5O SO3• 4.4 10 11 0.01 p.r. D.k. about 400 nm in 95KHA/NET N2O-satd. soln. 111 2,4,6-Tri(tert-butyl)phenoxyl ϩVanadyl acetylacetonate ϩ ϫ 1 2,4,6-(t-Bu)3C6H2O• VO(acac)2 1.2 10 Chem. Kinetic ESR in 81HOW/TAI →Products deoxygenated tert-butylbenzene soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 151

TABLE 3. Reactions of phenoxyl radicals with inorganic compounds ͑in aqueous solution at room temperature, except where noted otherwise͒—Continued

Phenoxyl kf kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1)pH I Method Comments Reference

7.0 Chem. Kinetic ESR in 81HOW/TAI deoxygenated 1,2-dichlorobenzene soln. 4.9 Chem. Kinetic ESR in 81HOW/TAI deoxygenated toluene soln. Ϫ1 Eav16.7 kJ mol , log Aϭ3.7. k increases to 1.2ϫ102 in the presence of methanol. 112 Galvinoxyl ϩ → Galvinoxyl radical VO(acac)2 Products 0.6 Chem. Kinetic ESR in 81HOW/TAI deoxygenated toluene soln. Rate constant increases to 22 in the

presence of CH3OH and to 4.6 in the presence of

CH3OD. The reaction is completely inhibited by pyridine.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 152 P. NETA AND J. GRODKOWSKI

TABLE 4. Reactions of phenoxyl radicals with hydrocarbons, alcohols, oleﬁns, fatty acid esters

Phenoxylϩreactant k T No Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

1 2,6-Dimethylphenoxylϩtetralin ϩ Ϸ ϫ 1 2,6-(CH3)2C6H3O• Tetralin-H 1.5 10 tetralin 338 therm. Autoxidation of tetralin 65HOW/ING → ϩ 2,6-(CH3)2C6H3OH Tetralin• initiated by azo-bis-isobutyronitrile upon thermal decomposition and inhibited by the phenol. 2 Phenoxylϩ9,10-dihydroanthracene ϩ → ϩ ϫ 2 C6H5O• AnH2 C6H5OH AnH• 1.1 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR derived from fitting to a complex mechanism. 3 4-Methylphenoxylϩ9,10-dihydroanthracene ϩ → ϫ 1 4-CH3C6H4O• AnH2 4-CH3C6H4OH 9.9 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR ϩ AnH• derived from fitting to a complex mechanism. 4 4-t-Butylphenoxylϩ9,10-dihydroanthracene ϩ ϫ 1 4-(t-Bu)C6H4O• AnH2 8.7 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR → ϩ 4-(t-Bu)C6H4OH AnH• derived from fitting to a complex mechanism. 5 4-Phenylphenoxylϩ9,10-dihydroanthracene ϩ ϫ 1 4-C6H5C6H4O• AnH2 1.2 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR → ϩ 4-C6H5C6H4OH AnH• derived from fitting to a complex mechanism. 6 4-Methoxyphenoxylϩ9,10-dihydroanthracene ϩ ϫ 1 4-CH3OC6H4O• AnH2 3.7 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR → ϩ 4-CH3OC6H4OH AnH• derived from fitting to a complex mechanism. 7 3-Carbethoxyphenoxylϩ9,10-dihydroanthracene ϩ ϫ 3 3-(C2H5OCO)C6H4O• AnH2 1.6 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR → ϩ 3-(C2H5OCO)C6H4OH AnH• derived from fitting to a complex mechanism. 8 2,6-Dimethylphenoxylϩ9,10-dihydroanthracene ϩ ϫ 1 2,6-(CH3)2C6H3O• AnH2 7.8 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR → ϩ 2,6-(CH3)2C6H3OH AnH• derived from fitting to a complex mechanism. 9 3,5-Di-t-butylphenoxylϩ9,10-dihydroanthracene ϩ ϫ 2 3,5-(t-Bu)2C6H3O• AnH2 1.8 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR → ϩ 3,5-(t-Bu)2C6H3OH AnH• derived from fitting to a complex mechanism. 10 1-Naphthoxylϩ9,10-dihydroanthracene ϩ → ϩ ϫ 1 1-Np-O• AnH2 1-Np-OH AnH• 6.2 10 PhCl 333 therm. Chemical analysis. k 75MAH/DAR derived from fitting to a complex mechanism. 11 2,6-Diphenyl-4-octadecyloxyphenoxylϩn-propanol ϫ Ϫ5 2,6-Ph2-4-C18H37OC6H2O• 2.5 10 n-PrOH 333 f.p. D.k. at 405 nm in 79VOE/KHU ϩ → CH3CH2CH2OH products deoxygenated soln. contg. the phenol. log Aϭ3.9, ϭ Ϫ1 Ea 54.4 kJ mol . 12 Galvinoxylϩn-propanol ϩ → ϫ Ϫ6 Galv-O• CH3CH2CH2OH products 2.7 10 n-PrOH 333 f.p. D.k. at 432 nm in 79VOE/KHU deoxygenated soln. log Aϭ1.5, ϭ Ϫ1 Ea 44.8 kJ mol . 13 2,4,6-Tri-tert-butylphenoxylϩ1,4-dioxane ϩ ϫ Ϫ4 2,4,6-(t-Bu)3C6H2O• C4H8O2 3 10 CCl4 /p-dioxane 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR → ϩ 2,4,6-(t-Bu)3C6H2OH •C4H7O2 deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 153

TABLE 4. Reactions of phenoxyl radicals with hydrocarbons, alcohols, oleﬁns, fatty acid esters—Continued

Phenoxylϩreactant k T No Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

14 2,4,6-Tri-tert-butylphenoxylϩmethyl methacrylate ϩ ϫ Ϫ5 2,4,6-(t-Bu)3C6H2O• methyl methacrylate 1.5 10 methyl 333 chem. Decay of ESR signal in 92UTK/SOK → products 3.5ϫ10Ϫ5 methacrylate 343 deoxygenated soln. 1.1ϫ10Ϫ4 353 Phenoxyl radical 2.4ϫ10Ϫ4 363 formed by reaction of the phenol with ferricyanide. log A ϭ ϭ 10.1, Ea 95 kJ molϪ1. 15 2,4,6-Tri-tert-butylphenoxylϩbutyl acrylate ϩ ϫ Ϫ6 2,4,6-(t-Bu)3C6H2O• butyl acrylate 5.4 10 butyl acrylate 333 chem. Decay of ESR signal in 92UTK/SOK → products 1.3ϫ10Ϫ5 343 deoxygenated soln. 3.0ϫ10Ϫ5 353 Phenoxyl radical 6.3ϫ10Ϫ5 363 formed by reaction of the phenol with ferricyanide. log A ϭ ϭ 7.68, Ea 82.4 kJ molϪ1. 16 2,4,6-tri-tert-butylphenoxylϩstyrene ϩ ϫ Ϫ5 2,4,6-(t-Bu)3C6H2O• styrene 3.1 10 styrene 323 chem. Decay of ESR signal in 92UTK/SOK → products 8.0ϫ10Ϫ5 333 deoxygenated soln. 2.1ϫ10Ϫ4 343 Phenoxyl radical formed by reaction of the phenol with ferricyanide. log A ϭ ϭ 9.73, Ea 88.3 kJ molϪ1. 17 2,4,6-Tribromophenoxylϩstyrene ϩ → ϫ Ϫ1 2,4,6-Br3C6H2O• styrene products 5 10 styrene 323 chem. Decay of the parent 92UTK/SOK phenol in soln. contg. azoisobutyronitrile. 18 Tetra(tert-butyl)indophenoxylϩtetracyanoethylene ϩ → → ϫ Ϫ2 TBIP-O• (CN)2C C(CN)2 products 2.2 10 THF 293 chem. Decay of ESR signal of 79KHI/KOS TBIP-O•. Radical produced by oxidation of TBIP-OH with ϭ PbO2 . log A 3.1, Ea ϭ28.5 kJ molϪ1. 19 Galvinoxylϩtetracyanoethylene ϩ → → ϫ Ϫ5 Galv-O• (CN)2C C(CN)2 products 3.6 10 THF 293 chem. Decay of ESR signal of 79KHI/KOS TBIP-O•. Radical produced by oxidation of TBIP-OH with ϭ PbO2 . log A 3.68, Ea ϭ47.7 kJ molϪ1. 20 5,7-Di-iso-propyltocoxylϩethyl stearate ϩ Ͻ ϫ Ϫ5 5,7-(i-Pr)2-Toc-O• ethyl stearate 1 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA deaerated soln. 21 ␣-Tocopheroxylϩmethyl oleate ␣ ϩ Ͻ ϫ Ϫ3 -Toc-O• methyl oleate 3 10 benzene 323 therm. Steady-state ESR signal 91REM/ROG → ␣-Toc-OHϩmethyl oleate radical in deoxygenated soln. contg. the phenol, methyl linoleate, and di-tert-butyl hyponitrite. 22 5,7-Di-iso-propyltocoxylϩethyloleate ϩ ϫ Ϫ5 5,7-(i-Pr)2-Toc-O• ethyl oleate 1.0 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → ϩ 5,7-(i-Pr)2-Toc-OH ethyl oleate radical deaerated soln., H-abstr. 1.0ϫ10Ϫ5 benzene 298 s.f. D.k. at 400–450 nm in 99MUK/OKAb deoxygenated soln. 23 5,7-Diisopropyl-2,2-dimethylchroman-6-oxylϩmethyl linoleate ϩ ϫ Ϫ2 DIDMC-O• methyl linoleate 1.8 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → DIDMC-OHϩmethyl linoleate radical deaerated soln., H-abstr.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 154 P. NETA AND J. GRODKOWSKI

TABLE 4. Reactions of phenoxyl radicals with hydrocarbons, alcohols, oleﬁns, fatty acid esters—Continued

Phenoxylϩreactant k T No Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

24 2,2,5,7,8-Pentamethylchroman-6-oxylϩmethyl linoleate ϩ ϫ Ϫ2 PMC–O• methyl linoleate (SH) 2.3 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/NOG → ϩ PMC–OH S• deaerated soln. contg. galvinoxyl. 25 5,7-Diethyltocoxylϩmethyl linoleate ϩ ϫ Ϫ2 5,7-Et2-Toc-O• methyl linoleate 5.0 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → ϩ 5,7-Et2-Toc-OH methyl linoleate radical deaerated soln., H-abstr. 26 5,7-Diisopropyltocoxylϩmethyl linoleate ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• methyl linoleate 1.9 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → ϩ 5,7-(i-Pr)2-Toc-OH methyl linoleate radical deaerated soln., H-abstr. 27 7-tert-Butyl-5-methyltocoxylϩmethyl linoleate ϩ ϫ Ϫ2 7-t-Bu-5-Me-Toc-O• methyl linoleate 1.6 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → 7-t-Bu- deaerated soln., H-abstr. 5-Me-Toc-OHϩmethyl linoleate radical 28 7-tert-Butyl-5-isopropyltocoxylϩmethyl linoleate ϩ ϫ Ϫ3 7-t-Bu-5-i-Pr-Toc-O• methyl linoleate 1.1 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → 7-t-Bu-5-i-Pr-Toc-OHϩmethyl linoleate radical deaerated soln., H-abstr. 29 5,7-Diethyl-8-methyltocoxylϩmethyl linoleate ϩ ϫ Ϫ2 5,7-Et2-8-Me-Toc-O• methyl linoleate 2.3 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → ϩ 5,7-Et2-8-Me-Toc-OH methyl linoleate radical deaerated soln., H-abstr. 30 5,7-Diisopropyl-8-methyltocoxylϩmethyl linoleate ϩ ϫ Ϫ3 5,7-(i-Pr)2-8-Me-Toc-O• methyl linoleate 3.3 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → 5,7-(i-Pr)2-8-Me-Toc-OH deaerated soln., H-abstr. ϩmethyl linoleate radical 31 ␣-Tocopheroxylϩmethyl linoleate ␣ ϩ ϫ Ϫ2 -Toc-O• methyl linoleate 7.5 10 benzene 323 therm. Steady-state ESR signal 91REM/ROG →␣-Toc-OHϩmethyl linoleate radical in deoxygenated soln. contg. the phenol, methyl linoleate, and di-tert-butyl hyponitrite. 2.7ϫ10Ϫ2 EtOH 310 chem. D.k. of ESR signal in 00WAT/NOG deaerated soln. contg. galvinoxyl. 32 2,3-Dihydro-2,2,4,6-tetramethylbenzo furan-5-oxylϩmethyl linoleate ϩ ϫ Ϫ1 BOM–O• methyl linoleate (SH) 2.4 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/NOG → ϩ BOM–OH S• deaerated soln. contg. galvinoxyl. 33 2,3-Dihydro-2,2-dimethyl-4,6-diisopropylbenzofuran-5-oxylϩmethyl linoleate ϩ ϫ Ϫ2 BF–O• methyl linoleate 2.0 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW →BF–OHϩmethyl linoleate radical deaerated soln., H-abstr. 34 2,3-Dihydro-2,2-dimethyl-4,6-di-tert-butylbenzofuran-5-oxylϩmethyl linoleate ϩ ϫ Ϫ3 BOB–O• methyl linoleate (SH) 2.5 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/NOG → ϩ BOB–OH S• deaerated soln. contg. galvinoxyl. 35 2,3-Dihydro-2,2-dipentyl-4,6-di-tert-butylbenzofuran-5-oxylϩmethyl linoleate ϩ ϫ Ϫ3 BO-653-O• methyl linoleate (SH) 2.8 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/NOG → ϩ BO– 653-OH S• deaerated soln. contg. galvinoxyl. 36 5,7-Di-iso-propyltocoxylϩethyl linoleate ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• ethyl linoleate 1.8 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → ϩ 5,7-(i-Pr)2-Toc-OH ethyl linoleate radical deaerated soln., H-abstr. 1.8ϫ10Ϫ2 benzene 298 s.f. D.k. at 400–450 nm in 89MUK/OKAb deoxygenated soln. 37 ␣-Tocopheroxylϩmethyl linolenate ␣ ϩ ϫ Ϫ2 -Toc-O• methyl linolenate 8.2 10 benzene 323 therm. Steady-state ESR signal 91REM/ROG → ␣-Toc-OHϩmethyl linolenate radical in deoxygenated soln. contg. the phenol, methyl linoleate, and di-tert-butyl hyponitrite. 38 5,7-Di-iso-propyltocoxylϩethyl linolenate ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• ethyl linolenate 3.8 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → ϩ 5,7-(i-Pr)2-Toc-OH ethyl linolenate radical deaerated soln., H-abstr.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 155

TABLE 4. Reactions of phenoxyl radicals with hydrocarbons, alcohols, oleﬁns, fatty acid esters—Continued

Phenoxylϩreactant k T No Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

3.8ϫ10Ϫ2 benzene 298 s.f. D.k. at 400–450 nm in 89MUK/OKAb deoxygenated soln. 39 5,7-Di-iso-propyltocoxylϩethyl arachidonate ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• ethyl arachidonate 4.8 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA → ϩ 5,7-(i-Pr)2-Toc-OH ethyl arachidonate deaerated soln., H-abstr. radical 4.8ϫ10Ϫ2 benzene 298 s.f. D.k. at 400–450 nm in 89MUK/OKAb deoxygenated soln. 40 5,7-Di-iso-propyltocoxylϩethyl cis-4,7,10,13,16,19-docosahexaenoate ϩ ϫ Ϫ2 Toc-O• ethyl docosahexaenoate 9.1 10 benzene 298 chem. D.k. at 417 nm in 90NAG/OKA →Toc-OHϩethyl docosahexaenoate radical deaerated soln., H-abstr.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 156 P. NETA AND J. GRODKOWSKI

TABLE 5. Reactions of phenoxyl radicals with amines, other nitrogen compounds, sulfur compounds

Phenoxylϩamine k T No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ Method Comments Reference

1 Galvinoxylϩdiethylmethylamine ϩ ϫ Ϫ4 Galvinoxyl• (C2H5)2NCH3 1.4 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 2 Galvinoxylϩtriethylamine ϩ ϫ Ϫ4 Galvinoxyl• (C2H5)3N 1.7 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 3 Galvinoxylϩn-butyldimethylamine ϩ ϫ Ϫ5 Galvinoxyl• CH3CH2CH2CH2N(CH3)2 9.6 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 4 Galvinoxylϩt-butyldimethylamine ϩ ϫ Ϫ4 Galvinoxyl• (t-Bu)N(CH3)2 2.5 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 5 Galvinoxylϩtri(n-propyl)amine ϩ ϫ Ϫ4 Galvinoxyl• (CH3CH2CH2)3N 2.1 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 6 Galvinoxylϩtri-n-butylamine ϩ ϫ Ϫ4 Galvinoxyl• (CH3CH2CH2CH2)3N 2.5 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 7 Galvinoxylϩtetramethylethylenediamine ϩ ϫ Ϫ4 Galvinoxyl• (CH3)2NCH2CH2N(CH3)2 3.6 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 8 Tetra͑tert-butyl͒indophenoxylϩaniline ϩ → ϩ ϫ Ϫ2 TBIP–O• C6H5NH2 TBIP–OH C6H5NH• 4 10 o-xylene 303 chem. Decay of ESR signal of 66BID/POK ϫ Ϫ2 5.9 10 313 TBIP–O•. Radical 8.7ϫ10Ϫ2 323 produced by oxidation of TBIP–OH with ϭ PbO2 . log A 3.85, Ea ϭ30.5 kJ molϪ1. 3.7ϫ10Ϫ2 o-xylene 303 chem. Decay of ESR signal of 66POK/BID TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 9 Tetra͑tert-butyl͒indophenoxylϩaniline-d2 ϩ → ϩ ϫ Ϫ2 TBIP–O• C6H5ND2 TBIP–OH C6H5ND• 2.4 10 o-xylene 303 chem. Decay of ESR signal of 66POK/BID TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 10 Tetra͑tert-butyl͒indophenoxylϩ4-methylaniline ϩ ϫ Ϫ1 TBIP–O• 4-CH3C6H4NH2 2.1 10 o-xylene 303 chem. Decay of ESR signal of 66POK/BID → ϩ TBIP–OH 4-CH3C6H4NH• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 11 Tetra͑tert-butyl͒indophenoxylϩ4-methoxyaniline ϩ TBIP–O• 4-CH3OC6H4NH2 1.9 o-xylene 303 chem. Decay of ESR signal of 66POK/BID → ϩ TBIP–OH 4-CH3OC6H4NH• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 12 Tetra͑tert-butyl͒indophenoxylϩ4-bromoaniline ϩ → ϫ Ϫ2 TBIP-O• 4-BrC6H4NH2 TBIP–OH 2.3 10 o-xylene 303 chem. Decay of ESR signal of 66POK/BID ϩ 4-BrC6H4NH• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 .

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 157

TABLE 5. Reactions of phenoxyl radicals with amines, other nitrogen compounds, sulfur compounds—Continued

Phenoxylϩamine k T No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ Method Comments Reference

13 GalvinoxylϩN,N,-dimethylaniline ϩ ϫ Ϫ4 Galvinoxyl• C6H5N(CH3)2 1.6 10 toluene 307 chem. Decay of the solvent 90SCR/HER → electron transfer aromatic proton NMR signal shift. 14 Tetra͑tert-butyl͒indophenoxylϩdiphenylamine ϩ → ϩ ϫ Ϫ4 TBIP–O• Ph2NH TBIP–OH Ph2N• 5.0 10 o-xylene 303 chem. Decay of ESR signal of 66BID/POK ϫ Ϫ4 7.4 10 313 TBIP–O•. Radical 9.4ϫ10Ϫ4 323 produced by oxidation of TBIP–OH with ϭ PbO2 . log A 1.30, Ea ϭ26.8 kJ molϪ1. 15 Tetra͑tert-butyl͒indophenoxylϩdiphenylamine-d ϩ ϫ Ϫ4 TBIP–O• Ph2ND 4.8 10 o-xylene 313 chem. Decay of ESR signal of 66POK/BID → ϩ TBIP–OH Ph2N• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 16 Tetra͑tert-butyl͒indophenoxylϩo-nitrodiphenylamine ϩ → ϫ Ϫ3 TBIP–O• o-NO2 –Ph2NH TBIP-OH 1.5 10 o-xylene 323 chem. Decay of ESR signal of 66BID/POK ϩ o-NO2 –Ph2N• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 17 Tetra͑tert-butyl͒indophenoxylϩm-nitrodiphenylamine ϩ ϫ Ϫ3 TBIP–O• m-NO2-Ph2NH 2.1 10 o-xylene 323 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP–OH m-NO2 –Ph2N• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 18 Tetra͑tert-butyl͒indophenoxylϩp-nitrodiphenylamine ϩ ϫ Ϫ3 TBIP-O• p-NO2 –Ph2NH 2.4 10 o-xylene 323 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP–OH p-NO2 –Ph2N• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 19 4-Methoxyphenoxylϩ1,4-phenylenediamine ϩ ϫ 8 ͑ ͒ 4-CH3OC6H4O• 4-H2NC6H4NH2 6.6 10 water 13.5 RT p.r. P.b.k. at 480 nm in 79STE/NET → Ϫϩ 4-CH3OC6H4O 4-H2NC6H4NH• N2O-saturated solution containing 1 mol LϪ1 ethylene glycol.

Reported krev probably incorrect. 20 Tetra͑tert-butyl͒indophenoxylϩ1,4-phenylenediamine ϩ TBIP–O• 4-NH2C6H4NH2 2.8 o-xylene 303 chem. Decay of ESR signal of 66POK/BID → ϩ TBIP–OH 4-NH2C6H4NH• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 21 PhenoxylϩTMPD ϩ ϫ 9 ͑ ͒ C6H5O• 4-(CH3)2NC6H4N(CH3)2 3.8 10 water 13.5 RT p.r. P.b.k. at 565 nm in 79STE/NET → Ϫϩ ϩ C6H5O 4-(CH3)2NC6H4N(CH3)2• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. ϫ 8 5 10 CCl4 RT p.r. P.b.k. at 572 nm in 84GRO/NET N2-satd. soln. contg. 0.17 mol LϪ1 phenol. 22 4-MethoxyphenoxylϩTMPD ϩ ϫ 9 ͑ ͒ 4-CH3OC6H4O• 4-(CH3)2NC6H4N(CH3)2 2.2 10 water 13.5 RT p.r. P.b.k. at 565 nm in 79STE/NET → Ϫ 4-CH3OC6H4O N2O-satd. soln. contg. ϩ ϩ Ϫ1 4-(CH3)2NC6H4N(CH3)2• 1 mol L ethylene glycol. ϫ 9 ͑ ͒ 1.5 10 water 13.5 293 p.r. P.b.k. in N2O-satd. soln. 90JOV/STE contg. 0.9 mol LϪ1 ethylene glycol.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 158 P. NETA AND J. GRODKOWSKI

TABLE 5. Reactions of phenoxyl radicals with amines, other nitrogen compounds, sulfur compounds—Continued

Phenoxylϩamine k T No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ Method Comments Reference ϫ 8 1.5 10 CCl4 RT p.r. P.b.k. at 572 nm in 84GRO/NET N2-satd. soln. contg. 0.06 mol LϪ1 4-methoxyphenol. 23 1,3-Benzosemiquinone anionϩTMPD Ϫ ϩ ϫ 9 ͑ ͒ 3-(O )C6H4O• 4-(CH3)2NC6H4N(CH3)2 1.2 10 water 11.6 RT p.r. P.b.k. at 565 nm in 79STE/NET → Ϫ Ϫϩ ϩ ϫ 9 ͑ ͒ 3-(O )C6H4O 4-(CH3)2NC6H4N(CH3)2• 1.7 10 water 13.5 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. k reported for reverse reaction probably incorrect. 24 3,4-MethylenedioxyphenoxylϩTMPD ϩ ϫ 9 ͑ ͒ sesamol-O• 4-(CH3)2NC6H4N(CH3)2 1.5 10 water 13.5 293 p.r. P.b.k. in N2O-satd. soln. 91JOV/TOS → Ϫϩ ϩ sesamol-O 4-(CH3)2NC6H4N(CH3)2• 25 2,6-DimethoxyphenoxylϩTMPD ϫ 9 ͑ ͒ 2,6-(CH3O)2C6H3O• 1.2 10 water 13.5 293 p.r. Kinetics in N2O-satd. 91JOV/TOS ϩ → 4-(CH3)2NC6H4N(CH3)2 soln. 2,6-(CH3O)2C6H3O- ϩ ϩ 4-(CH3)2NC6H4N(CH3)2• 26 PhenoxylϩNADH ͑nicotinamide adenine dinucleotide, reduced͒ ϩ → ϩ ϫ 8 C6H5O• NADH C6H5OH NAD• 1.1 10 water RT p.r. Kinetics in N2O-satd. 83GRO/NET ͑7–13.5͒ soln. 27 4-MethoxyphenoxylϩNADH ϩ Ͻ ϫ 5 ͑ ͒ 4-CH3OC6H4O• NADH 1 10 water 7 RT p.r. Kinetics in N2O-satd. 83GRO/NET soln. 28 Trolox phenoxyl radicalϩNADH ϩ → ϩ Ͻ ϫ 5 ͑ ͒ TxO• NADH TxOH NAD• 1 10 water 7 RT p.r. D.k. at 430 nm in 88DAV/FOR N2O-satd. soln. contg. azide. 29 4-AminophenoxylϩNADH ϩ Ͻ ϫ 5 ͑ ͒ 4-NH2C6H4O• NADH 1 10 water 7 RT p.r. Kinetics in N2O-satd. 83GRO/NET soln. 30 1,2-BenzosemiquinoneϩNADH Ϫ ϩ Ͻ ϫ 5 ͑ ͒ 1,2-C6H4(O )O• NADH 1 10 water 7 RT p.r. Kinetics in N2O-satd. 83GRO/NET soln. 31 1,3-BenzosemiquinoneϩNADH ϩ → ϫ 6 ͑ ͒ 1,3-C6H4(OH)O• NADH 1,3-C6H4(OH)2 8 10 water 7 RT p.r. Kinetics in N2O-satd. 83GRO/NET ϩ Ͻ ϫ 5 ͑ ͒ soln. for mixture of NAD• 1 10 water 9.3 semiquinone neutral

and anion. pKa of 1,3-C6H4(OH)O•v6.4 ͑86JIN/MAD͒. 32 1,4-BenzosemiquinoneϩNADH Ϫ ϩ Ͻ ϫ 5 ͑ ͒ 1,4-C6H4(O )O• NADH 1 10 water 7 RT p.r. Kinetics in N2O-satd. 83GRO/NET soln. 33 ␣-Tocopheroxylϩhistamine ␣ ϩ ϫ 2 -Toc-O• 2-(4-imidazolyl)ethylamine 1 10 n-BuOH RT chem. Decay of ESR signal of 93OND/MIS → products ␣-tocopheroxyl radical, produced by reaction of ␣-tocopherol with DPPH, in the presence of various concentrations of histamine. Decay ␣ includes -Toc-O• ϩ␣ -Toc-O• and ␣ ϩ -Toc-O• histamine. 34 Phenoxylϩ2,2Ј-azinobis(3-ethylbenzothiazoline-6-sulfonate ion) ͑ABTS͒ ϩ 2Ϫ → Ϫϩ Ϫ ϫ 9 C6H5O• ABTS C6H5O ABTS• 3.8 10 water RT p.r. P.b.k. at 415 nm. 89NET/HUI 35 4-MethoxyphenoxylϩABTS ϩ 2Ϫ ϫ 7 ͑ ͒ 4-CH3OC6H4O• ABTS 1.0 10 water 5.9 RT p.r. P.b.k. at 415 nm. k 95KHA/ → ϩ Ϫ 4-CH3OC6H4OH ABTS• much lower at pH 8. ALF 36 2,6-Di-tert-butyl-4-isopropylphenoxylϩ2,2-diphenyl-1-picrylhydrazine

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 159

TABLE 5. Reactions of phenoxyl radicals with amines, other nitrogen compounds, sulfur compounds—Continued

Phenoxylϩamine k T No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ Method Comments Reference ϩ 2,6-(t-Bu)2-4-(i-Pr)C6H2O• DPPH-H 1.3 benzene 293 chem. ESR kinetics in 67AYS/RUS → ϩ 2,6-(t-Bu)2-4-(i-Pr)C6H2OH DPPH• 2.7 313 deaerated soln. contg. 4.8 333 DPPH radicals and the ϭ phenol. log A 4.8, Ea ϭ26 kJ molϪ1.For

reverse reaction kr ϭ0.18 at 293 K, 0.39 at 313 K, 0.77 at 333 K. 37 ␣-Tocopheroxylϩ3-methyl-1-͓2-(2-naphthyloxy)ethyl͔-2-pyrazolin-5-one ␣ ϩ → ϫ 3 -Toc-O• nafazatrom Products 3.1 10 n-BuOH RT chem. Decay of ESR signal of 93OND/MIS ␣-tocopheroxyl, produced by reaction of ␣-tocopherol with DPPH, in the presence of various concentrations of nafazatrom. Decay ␣ includes -Toc-O• ϩ␣ -Toc-O• and ␣ -Toc-O• ϩnafazatrom. 38 ␣-Tocopheroxylϩ2,8-dimethyl-2,3,4,4a,5,9b-hexahydro-1H-pyrido(4,3b)indole ␣ ϩ ϫ 2 -Toc-O• stobadine-OH 2.5 10 n-BuOH RT chem. Decay of ESR signal of 93OND/MIS → ␣ ϩ ␣ -Toc-OH stobadine-O• -tocopheroxyl radical, produced by reaction of ␣-tocopherol with DPPH, in the presence of various concentrations of stobadine. Decay ␣ includes -Toc-O• ϩ␣ -Toc-O• and ␣ ϩ -Toc-O• stobadine. 39 Trolox phenoxyl radicalϩcysteamine ϩ Ͻ ϫ 5 ͑ ͒ TxO• NH2CH2CH2SH 1 10 water 7 RT p.r. D.k. at 430 nm in 88DAV/FOR → ϩ TxOH NH2CH2CH2S• N2O-satd. soln. contg. azide. ϩ Ϫ Ͻ ϫ 5 ͑ ͒ TxO• NH2CH2CH2S 1 10 water 10 RT p.r. D.k. at 430 nm in 88DAV/FOR → Ϫϩ ϫ 5 ͑ ͒ TxO NH2CH2CH2S• 2 10 water 13 N2O-satd. soln. contg. azide. 40 2,2,5,7,8-Pentamethylchroman-6-oxylϩdihydrolipoic acid thiolate anion ϩ Ϫ → Ϫϩ Ϫ ϫ 2 ͑ ͒ HPMC• L(SH)S LS2• HPMC 5.1 10 water 8.5 RT p.r. D.k. and p.b.k. in soln. 94BOR/MIC contg. acetonitrile and azide. Derived from ﬁtting to a complex mechanism. 41 Trolox phenoxyl radicalϩdihydrolipoic acid thiolate anion ϩ Ϫ → Ϫϩ Ϫ ϫ 2 ͑ ͒ TxO• L(SH)S LS2• TxO 3.5 10 water 8.5 RT p.r. D.k. and p.b.k. in soln. 94BOR/MIC contg. acetonitrile and azide. Derived from ﬁtting to a complex mechanism. 42 ␣-Tocopheroxylϩglutathione ␣ ϩ → ␣ ϩ Ϸ ϫ 1 ͑ ͒ -Toc-O• GSH -Toc-OH GS• 2.5 10 water 6.8 RT f.p. D.k. at 430 nm in air 91BIS/PAR satd. soln. contg. CTAC micelles.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 160 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference 1 Phenoxylϩphenoxide ϩ Ϫ Ϫϩ ϫ 8 ͑ ͒ C6H5O• C6H5O C6H5O C6H5O• 1.9 10 water 11.5 RT e.r. ESR line broadening of 76SCH/NET ͑self exchange͒ phenoxyl radical as a function of ͓PhOϪ͔ in

N2O-satd. soln. Self-exchange reaction. 2 4-Iodophenoxylϩphenoxide ϩ Ϫ ϫ 8 ͑ ͒ 4-IC6H4O• C6H5O 6 10 water 11–12 RT p.r. D.k. at 500 nm in 90LIN/SHE → Ϫϩ 4-IC6H4O C6H5O• N2O-satd. soln. Electron transfer reaction. For reverse ϭ ϫ 8 reaction kr 1.6 10 . Iϭ0.1. 3 2,4,6-Tri-t-butylphenoxylϩphenol ϩ 2,4,6-(t-Bu)3C6H2O• C6H5OH 6.2 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ϩ 2,4,6-(t-Bu)3C6H2OH C6H5O• deoxygenated soln. 1.7ϫ101 benzene 333 s.f. D.k. at 400 or 630 nm in 67MAH/DAR deoxygenated soln. 3.8 benzene 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 8.5 333 deoxygenated soln. 1.6ϫ101 PhCl 333 s.f. D.k. at 400 or 630 nm in 67MAH/DAR deoxygenated soln. 4.1 PhCl 293 5.9 30.5 chem. Decay of ESR signal in 76PRO/MAL deaerated soln. Radical formed by photolysis of 2,4,6-tri-tert-butyl-4- bromocyclohexadienone. 5.7 hexane 297 chem. Decay of ESR signal in 76PRO/MAL deaerated soln. Radical formed by photolysis of 2,4,6-tri-tert-butyl-4- bromocyclohexadienone. 7.9 CCl4 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 1.6ϫ101 333 deoxygenated soln. k decreases upon increasing fraction of acetonitrile or p-dioxane as a co-solvent. 4 Galvinoxylϩphenol ϩ Galvinoxyl• C6H5OH 0.34 CCl4 293 36.0 chem. D.k. at 435 nm. 78NIS/OKA → ϩ Galvinoxyl-H C6H5O• 0.43 298 0.55 303 0.30 benzene 298 chem. D.k. at 435 nm. Soln. 78NIS/OKA

satd. with H2O. ϩ Galvinoxyl• C6H5OD 0.26 benzene 298 chem. D.k. at 435 nm. Soln. 78NIS/OKA → ϩ Galvinoxyl-D C6H5O• satd. with D2O. 5 Tetra(tert-butyl)indophenoxylϩphenol ϩ TBIP-O• C6H5OH 0.08 o-xylene 303 6.49 43.9 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP-OH C6H5O• 0.14 313 TBIP–O•. Radical 0.23 323 produced by oxidation of TBIP–OH with

PbO2 . 6 Galvinoxylϩ4-methylphenol ϩ Galvinoxyl• 4-CH3C6H4OH 5.3 CCl4 293 31.0 chem. D.k. at 435 nm. 78NIS/OKA → ϩ Galvinoxyl-H 4-CH3C6H4O• 6.7 298 8.0 303 7 Tetra(tert-butyl)indophenoxylϩ4-methylphenol ϩ TBIP–O• 4-CH3C6H4OH 0.08 o-xylene 303 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP–OH 4-CH3C6H4O• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 8 2,4,6-Tri-t-butylphenoxylϩ3-tert-butylphenol ϩ ϫ 1 2,4,6-(t-Bu)3C6H2O• 3-(t-Bu)C6H4OH 2.1 10 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ϩ 2,4,6-(t-Bu)3C6H2OH 3-(t-Bu)C6H4O• deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 161

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

9 2,4,6-Tri-t-butylphenoxylϩ4-tert-butylphenol ϩ ͑ ͒ ϫ 1 2,4,6-(t-Bu)3C6H2O• 4- t-Bu C6H4OH 9.3 10 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ͑ ͒ ϩ 2,4,6- t-Bu 3C6H2OH 4-(t-Bu)C6H4O• deoxygenated soln. 2.5ϫ102 benzene 333 s.f. D.k. at 400 or 630 nm in 67MAH/DAR deoxygenated soln. 4.9ϫ101 benzene 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 1.3ϫ102 333 deoxygenated soln. 2.2ϫ102 PhCl 333 s.f. D.k. at 400 or 630 nm in 67MAH/DAR deoxygenated soln. 5.1ϫ101 PhCl 303 5.3 21 s.f. D.k. at 400 or 630 nm in 70MAH/DARa 6.7ϫ101 313 deoxygenated soln. 1.1ϫ102 333 ϫ 1 9.5 10 CCl4 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 2.2ϫ102 333 deoxygenated soln. 10 Galvinoxylϩ4-t-butylphenol ϩ Galvinoxyl• 4-(t-Bu)C6H4OH 6.8 benzene 298 chem. D.k. at 435 nm. Soln. 78NIS/OKA → ϩ Galvinoxyl-H 4-(t-Bu)C6H4O• satd. with H2O. ϩ Galvinoxyl• 4-(t-Bu)C6H4OD 3.2 benzene 298 chem. D.k. at 435 nm. Soln. 78NIS/OKA → ϩ Galvinoxyl-D 4-(t-Bu)C6H4O• satd. with D2O. 11 2,4,6-Tri-t-butylphenoxylϩ4-phenylphenol ϩ ϫ 2 2,4,6-(t-Bu)3C6H2O• 4-C6H5C6H4OH 2.5 10 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ϩ 2,4,6-(t-Bu)3C6H2OH 4-C6H5C6H4O• deoxygenated soln. Isotope effect for OH deuteriated phenol phenolϾ7.5. 12 2,4,6-Tri-t-butylphenoxylϩ3-cyanophenol ϩ 2,4,6-(t-Bu)3C6H2O• 3-NCC6H4OH 0.16 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ϩ 2,4,6-(t-Bu)3C6H2OH 3-NCC6H4O• deoxygenated soln. 13 2,4,6-Tri-t-butylphenoxylϩ4-cyanophenol ϩ 2,4,6-(t-Bu)3C6H2O• 4-NCC6H4OH 0.15 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ϩ 2,4,6-(t-Bu)3C6H2OH 4-NCC6H4O• deoxygenated soln. 14 Galvinoxylϩ4-cyanophenol ϩ ϫ Ϫ3 Galvinoxyl• 4-NCC6H4OH 7.3 10 CCl4 293 63.2 chem. D.k. at 435 nm. 78NIS/OKA → ϩ ϫ Ϫ3 Galvinoxyl-H 4-NCC6H4O• 9.3 10 298 1.7ϫ10Ϫ2 303 15 2,4,6-Tri-t-butylphenoxylϩ4-carbomethoxyphenol 2,4,6-(t-Bu)3C6H2O• 0.42 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH ϩ 4-(CH3OCO)C6H4OH deoxygenated soln. → 2,4,6-(t-Bu)3C6H2OH ϩ 4-(CH3OCO)C6H4O• 16 2,4,6-Tri-t-butylphenoxylϩ3-carbethoxyphenol 2,4,6-(t-Bu)3C6H2O• 1.2 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH ϩ 3-(C2H5OCO)C6H4OH deoxygenated soln. → 2,4,6-(t-Bu)3C6H2OH ϩ 3-(C2H5OCO)C6H4O• 0.59 benzene 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 1.4 333 deoxygenated soln. 0.43 PhCl 303 4.8 30 s.f. D.k. at 400 or 630 nm in 70MAH/DARa 0.76 313 deoxygenated soln. 1.3 333

1.8 CCl4 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 4.6 333 deoxygenated soln. 17 Galvinoxylϩ4-acetyloxyphenol ϩ → Galvinoxyl• 4-(CH3COO)C6H4OH 0.031 CCl4 293 60.2 chem. D.k. at 435 nm. 78NIS/OKA ϩ Galvinoxyl-H 4-(CH3COO)C6H4O• 0.044 298 0.071 303 18 2,4,6-Tri-t-butylphenoxylϩ4-methoxyphenol ϩ ϫ 3 2,4,6-(t-Bu)3C6H2O• 4-CH3OC6H4OH 6.1 10 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → ϩ 2,4,6-(t-Bu)3C6H2OH 4-CH3OC6H4O• deoxygenated soln. 19 Galvinoxylϩ4-methoxyphenol ϩ → ϫ 2 Galvinoxyl• 4-CH3OC6H4OH 4.2 10 CCl4 293 23.0 chem. D.k. at 435 nm. 78NIS/OKA

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 162 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

ϩ ϫ 2 Galvinoxyl-H 4-CH3OC6H4O• 4.9 10 298 5.7ϫ102 303 5.5ϫ102 benzene 298 chem. D.k. at 435 nm. Soln. 78NIS/OKA

satd. with H2O. ϩ ϫ 2 Galvinoxyl• 4-CH3OC6H4OD 1.6 10 benzene 298 chem. D.k. at 435 nm. Soln. 78NIS/OKA → ϩ Galvinoxyl-D 4-CH3OC6H4O• satd. with D2O. 20 3-hydroxy-5-methoxyphenoxylϩ4-methoxyphenol ϩ ϫ 6 ͑ ͒ 3,5-(OH)(O•)C6H3OCH3 4-CH3OC6H4OH 6.4 10 water 7 293 p.r. Kinetics in N2O-satd. 95JOV/HAR → ϩ Ϫ 3,5-(OH)2C6H3OCH3 4-CH3OC6H4O• soln. contg. N3 .For ϭ reverse reaction kr 1.4 ϫ105. 21 Galvinoxylϩ4-nitrophenol ϩ ϫ Ϫ3 Galvinoxyl• 4-O2NC6H4OH 3.4 10 CCl4 298 chem. D.k. at 435 nm. 78NIS/OKA → ϩ Galvinoxyl-H 4-O2NC6H4O• 22 Tetra(tert-butyl)indophenoxylϩ4-nitrophenol ϩ ϫ Ϫ2 TBIP-O• 4-NO2C6H4OH 8 10 o-xylene 303 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP-OH 4-NO2C6H4O• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 23 Galvinoxylϩ4-ﬂuorophenol ϩ Galvinoxyl• 4-FC6H4OH 1.1 CCl4 293 41.0 chem. D.k. at 435 nm. 78NIS/OKA → ϩ Galvinoxyl-H 4-FC6H4O• 1.5 298 2.0 303 24 Galvinoxylϩ4-chlorophenol ϩ ϫ Ϫ3 Galvinoxyl• 4-ClC6H4OH 4.3 10 p-dioxane 293 59.4 chem. D.k. at 435 nm. Rate 78NIS/OKA → ϩ ϫ Ϫ3 Galvinoxyl-H 4-ClC6H4O• 6.2 10 298 constants are reported 9.6ϫ10Ϫ3 303 for various mixtures of dioxane and cyclohexane. 1.3 cyclohexane 293 36.2 chem. D.k. at 435 nm. Rate 78NIS/OKA 1.6 298 constants are reported 2.1 303 for various mixtures of dioxane and cyclohexane. 25 Phenoxylϩ4-bromophenoxide ϩ Ϫ ϫ 8 ͑ ͒ C6H5O• 4-BrC6H4O 2.0 10 water 11.5 RT p.r. Formn. at 430 nm as a 76SCH/NET → Ϫϩ C6H5O 4-BrC6H4O• function of 4-bromophenoxide ion concentration in

N2-satd. soln. contg. 0.2 mol LϪ1t-BuOH. 26 2,4,6-Tri-t-butylphenoxylϩ4-bromophenol ϩ 2,4,6-(t-Bu)3C6H2O• 4-BrC6H4OH 8.7 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → 2,4,6-(t-Bu)3C6H2OH deoxygenated soln. ϩ 4-BrC6H4O• 5.4 PhCl 303 6.2 32 s.f. D.k. at 400 or 630 nm in 70MAH/DARa 7.5 313 deoxygenated soln. 16 333 4.7 PhCl 293 5.8 28.9 chem. Decay of ESR signal in 76PRO/MAL deaerated soln. Radical formed by photolysis of 2,4,6-tri-tert-butyl-4- bromocyclohexadienone. 27 Galvinoxylϩ4-bromophenol ϩ Galvinoxyl• 4-BrC6H4OH 0.65 CCl4 293 43.0 chem. D.k. at 435 nm. 78NIS/OKA → ϩ Galvinoxyl-H 4-BrC6H4O• 0.76 298 1.2 303 28 2,4,6-Tri-t-butylphenoxylϩ3,5-dimethylphenol ϩ ϫ 1 2,4,6-(t-Bu)3C6H2O• 3,5-(CH3)2C6H3OH 3.1 10 benzene 297 s.f. D.k. at 400 or 630 nm in 67DAR/MAH → 2,4,6-(t-Bu)3C6H2OH deoxygenated soln. ϩ 3,5-(CH3)2C6H3O• 1.8ϫ101 benzene 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 5.7ϫ101 333 deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 163

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

1.6ϫ101 PhCl 303 6.2 29 s.f. D.k. at 400 or 630 nm in 70MAH/DARa 2.9ϫ101 313 deoxygenated soln. 4.7ϫ101 333 ϫ 1 3.9 10 CCl4 303 s.f. D.k. at 400 or 630 nm in 72MAH/DAR 7.4ϫ101 333 deoxygenated soln. 29 2,4,6-Tri-tert-butylphenoxylϩ2,6-di-tert-butylphenol ϫ 1 2,4,6-(t-Bu)3-C6H2O• 5.4 10 hexane 293 3.3 10.5 chem. Decay of ESR signal in 76PRO/MAL ϩ 2,6-(t-Bu)2-C6H3OH deaerated soln. Radical → 2,4,6-(t-Bu)3-C6H2OH formed by photolysis of ϩ 2,6-(t-Bu)2-C6H3O• 2,4,6-tri-tert-butyl-4- bromocyclohexadienone. 30 Tetra(tert-butyl)indophenoxylϩ2,6-di-tert-butylphenol ϩ TBIP-O• 2,6-(t-Bu)2-C6H3OH 3.1 o-xylene 303 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP–OH 2,6-(t-Bu)2-C6H3O• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 31 Lysozyme tyrosyl radicalϩ3,4-methylenedioxyphenol ϩ ϫ 6 Lys-TyrO• sesamol-OH 9.3 10 water/ RT p.r. D.k. at 405 nm in 84HOE/BUT → ϩ ͑ ͒ Lys-TyrOH sesamol-O• micelles 7 N2O-satd. soln. contg. azide and SDS micelles. 32 2,4,6-Tri-tert-butylphenoxylϩ2,6-di-tert-butyl-4-methylphenol ϩ ϫ 2 2,4,6-(t-Bu)3-C6H2O• 2,6-(t-Bu)2 3.4 10 hexane 293 2.5 3.3 chem. Decay of ESR signal in 76PRO/MAL → –4-MeC6H2OH 2,4,6-(t-Bu)3-C6H2OH deaerated soln. Radical ϩ 2,6-(t-Bu)2-4-MeC6H2O• formed by photolysis of 2,4,6-tri-tert-butyl-4- bromocyclohexadienone. 33 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2,6-di-tert-butyl-4-methylphenol ϩ → ϫ 1 MPP–O• 2,6-(t-Bu)2-4-MeC6H2OH 4.8 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/NISa ϩ ͑ ͒ MPP–OH 2,6-(t-Bu)2-4-MeC6H2O• EtOH 2/1 in deaerated soln. 34 Tetra(tert-butyl)indophenoxylϩ2,6-di-tert-butyl-4-methylphenol ϩ → TBIP–O• 2,6-(t-Bu)2-4-Me-C6H2OH 1.0 o-xylene 303 3.84 23.0 chem. Decay of ESR signal of 66BID/POK ϩ TBIP–OH 2,6-(t-Bu)2-4-Me-C6H2O• 1.2 313 TBIP–O•. Radical 1.4 323 produced by oxidation of TBIP–OH with

PbO2 . 35 Tetra(tert-butyl)indophenoxylϩ2,6-di-tert-butyl-4-ethylphenol ϩ TBIP-O• 2,6-(t-Bu)2-4-Et-C6H2OH 0.55 o-xylene 303 chem. Decay of ESR signal of 66BID/POK → ϩ TBIP–OH 2,6-(t-Bu)2-4-Et-C6H2O• TBIP–O•. Radical produced by oxidation of TBIP–OH with

PbO2 . 36 2,4,6-Tri(tert-butyl)phenoxylϩ2,4,6-Tri(tert-butyl)-3,5-dideuteriophenol ϫ 2 2,4,6-(t-Bu)3C6H2O• 2.2 10 CCl4 294 s.f. Kinetic ESR in 68ARI/WEI ϩ 2,4,6-(t-Bu)3C6D2OH deoxygenated soln. → 2,4,6-(t-Bu)3C6H2OH Deuterium isotope ϩ 2,4,6-(t-Bu)3C6D2O• effect k(OH) /k(OD) ϭ1.24. 37 2,4,6-Tri-tert-butylphenoxylϩ2,4,6-trichlorophenol ϩ 2,4,6-(t-Bu)3C6H2O• 2,4,6-Cl3C6H2OH 2.7 PhCl 303 4.6 24 s.f. D.k. at 400 or 630 nm in 70MAH/DARa → 4.0 313 deoxygenated soln. ϩ 2,4,6-(t-Bu)3C6H2OH 2,4,6-Cl3C6H2O• 6.4 333 38 Phenoxylϩ␣-naphthol ϩ␣ → ϩ␣ ϫ 7 C6H5O• -NpOH C6H5OH -NpO• 2.3 10 t-Bu2O2/ f.p. P.b.k. at 510 nm in 94FOT/ING benzene͑3/1͒ deoxygenated soln. contg. 1.4 mol LϪ1 phenol. 39 Phenoxylϩ␤-naphthol ϩ␤ → ϩ␤ ϫ 6 C6H5O• -NpOH C6H5OH -NpO• 4.5 10 t-Bu2O2/ f.p. P.b.k. at 470 nm in 94FOT/ING benzene͑3/1͒ deoxygenated soln. contg. 1.4 mol LϪ1 phenol.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 164 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

40 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2-dimethylchromane ϩ → ϫ 2 MPP–O• DMC–OH MPP–OH 4.1 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK ϩ DMC–O• in deaerated soln. 41 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl ϩ6-hydroxy-2,2,8-trimethylchromane ϩ → ϫ 3 MPP–O• TMC–OH MPP–OH 1.0 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK ϩ TMC–O• in deaerated soln. 42 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2-dimethyl-7-tert-butylchromane ϩ ϫ 3 MPP–O• DMBC–OH 1.4 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK → ϩ MPP–OH DMBC–O• in deaerated soln. 43 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2,5,7-tetramethylchromane ϩ → ϫ 3 MPP–O• TMC–OH MPP–OH 2.0 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK ϩ TMC–O• in deaerated soln. 44 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2,5,8-tetramethylchromane ϩ → ϫ 3 MPP–O• TMC–OH MPP–OH 2.2 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK ϩ TMC–O• in deaerated soln. 45 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2,7,8-tetramethylchromane ϩ → ϫ 3 MPP–O• TMC–OH MPP–OH 2.1 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK ϩ TMC–O• in deaerated soln. 46 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2-dimethyl-5,7-diethylchromane ϩ ϫ 3 MPP–O• DMDEC–OH 1.9 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK → ϩ MPP–OH DMDEC–O• in deaerated soln. 47 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2-dimethyl-5,7-di-isopropylchromane ϩ ϫ 3 MPP–O• DMDIC–OH 2.8 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK → ϩ MPP–OH DMDIC–O• in deaerated soln. 48 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2,5-trimethyl-7-tert-butylchromane ϩ ϫ 3 MPP–O• TMBC–OH 2.3 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK → ϩ MPP–OH TMBC–O• in deaerated soln. 49 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-hydroxy-2,2,5,7,8-pentamethylchromane ϩ → ϫ 3 MPP–O• PMC–OH MPP–OH 4.2 10 EtOH 298 s.f. D.k. at 376 and 580 nm 87MUK/YOK ϩ PMC–O• in deaerated soln. 50 Phenoxylϩ6-hydroxy-2,2,5,7,8-pentamethylchroman ϩ → ϫ 8 C6H5O• HPMC–OH C6H5OH 3.7 10 t-Bu2O2 / f.p. P.b.k. at 430 nm in 94FOT/ING ϩ ͑ ͒ HPMC–O• MeCN 2/1 deoxygenated soln. contg. 1.4 mol LϪ1 phenol. 51 PhenoxylϩTrolox C ϩ → ϩ ϫ 8 ͑ ͒ C6H5O• TxOH C6H5OH TxO• 4.1 10 water 7 RT p.r. P.b.k. at 430 nm in 88DAV/FOR N2O-satd. soln. contg. 0.1 mol LϪ1 azide. 52 2-MethylphenoxylϩTrolox C ϩ Ͻ ϫ 5 ͑ ͒ 2-CH3C6H4O• TxOH 1 10 water 7 RT p.r. P.b.k. at 430 nm in 88DAV/FOR → ϩ 2-CH3C6H4OH TxO• N2O-satd. soln. contg. 0.1 mol LϪ1 azide. 53 3-MethylphenoxylϩTrolox C ϩ ϫ 8 ͑ ͒ 3-CH3C6H4O• TxOH 2.8 10 water 7 RT p.r. P.b.k. at 430 nm in 88DAV/FOR → ϩ 3-CH3C6H4OH TxO• N2O-satd. soln. contg. 0.1 mol LϪ1 azide. 54 4-MethylphenoxylϩTrolox C ϩ ϫ 7 ͑ ͒ 4-CH3C6H4O• TxOH 9.5 10 water 7 RT p.r. P.b.k. at 430 nm in 88DAV/FOR → ϩ 4-CH3C6H4OH TxO• N2O-satd. soln. contg. 0.1 mol LϪ1 azide; yield 53%. 55 Tyrosyl radicalϩTrolox C ϩ → ϩ ϫ 8 ͑ ͒ TyrO• TxOH TyrOH TxO• 3.1 10 water 7 RT p.r. P.b.k. at 420 nm in 89HUN/DES N2O-satd. soln. contg. 10 mmol LϪ1 phosphate, 1 mmol LϪ1 Ϫ1 Tl2SO4 , 0.4 mmol L tyrosine, and 0.01– 0.1 mmol LϪ1 Trolox.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 165

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

3.8ϫ108 water ͑7.0͒ RT p.r. P.b.k. at 440 nm in 84BIS/AHM

N2O-satd. soln. contg. azide or bromide. 3.2ϫ108 water ͑7͒ RT p.r. P.b.k. at 430 nm in 88DAV/FOR

N2O-satd. soln. contg. azide. 56 2-CarboxyphenoxylϩTrolox C Ϫ ϩ ϫ 8 ͑ ͒ 2-(CO2 )C6H4O• TxOH 3 10 water 7 RT p.r. P.b.k. at 430 nm in 88DAV/FOR → Ϫ ϩ 2-(CO2 )C6H4OH TxO• N2O-satd. soln. contg. 0.1 mol LϪ1 azide. 57 2-Methoxy-4-(2Ј-methylvinyl)phenoxylϩTrolox C ϭ ϫ 7 ͑ ͒ 2-(CH3O)-4-(CH3CH CH)C6H3O• 5.4 10 water 10.5 RT p.r. P.b.k. at 430 nm in 00GUH/PRI ϩ Ϫ → TxO 2-(CH3O)-4- N2O-satd. soln. contg. ϭ Ϫϩ (CH3CH CH)C6H3O TxO• azide. 58 2-Methoxy-4-(2Ј-acetylvinyl)phenoxylϩTrolox C ϭ 7 ͑ ͒ 2-(CH3O)-4-(CH3COCH CH) 8.3ϫ10 water 6 RT p.r. D.k. at 360 nm in 99PRI/DEV ϩ → C6H3O• TxOH 2-(CH3O)- N2O-satd. soln. contg. ϭ ϩ 4-(CH3COCH CH)C6H3OH TxO• azide. 59 3,4-Dihydroxyphenylalanine semiquinone anionϩTrolox C ϩ → ϩ ϫ 4 ͑ ͒ DOPA• TxOH DOPA TxO• 7.4 10 water 7 293 p.r. P.b.k. at 425 nm in 94JOV/STE N2O-satd. soln. contg. bromide. 60 Hesperidin semiquinone anionϩTrolox C ϩ → ϫ 8 ͑ ͒ hesperidin-O• TxOH hesperidin-OH 1.9 10 water 7 293 p.r. P.b.k. at 425 nm in 94JOV/STE ϩ TxO• N2O-satd. soln. contg. bromide. 61 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩVitamin K1-chromanol ϩ ϫ 4 MPP–O• K1-Chroman-OH 3.5 10 EtOH 298 7.02 14.3 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH K1-Chroman-O• in deaerated soln. OKAa 62 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩVitamin K1-chromenol ϩ ϫ 4 MPP–O• K1-Chromen-OH 2.5 10 EtOH 298 7.37 17.0 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH K1-Chromen-O• in deaerated soln. OKAa 63 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩUbichromanol ϩ ϫ 2 MPP–O• Ubichroman-OH 4.2 10 EtOH 298 7.49 27.7 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH Ubichroman-O• in deaerated soln. OKAa 64 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩUbichromenol ϩ ϫ 2 MPP–O• Ubichromen-OH 5.6 10 EtOH 298 6.89 23.9 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH Ubichromen-O• in deaerated soln. OKAa 65 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩTocol (6-hydroxy-2-methyl-2-phytylchroman) ϩ → ϩ ϫ 2 MPP–O• Toc-OH MPP–OH Toc-O• 5.6 10 EtOH 298 7.39 27.1 s.f. D.k. at 376 and 580 nm 89MUK/KAG in deaerated soln. 66 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,7-dimethyltocol ϩ ϫ 3 MPP–O• DMToc-OH 2.4 10 EtOH 298 6.48 17.5 s.f. D.k. at 376 and 580 nm 89MUK/KAG → ϩ MPP–OH DMToc-O• in deaerated soln. 67 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,7-diethyltocol ϩ ϫ 3 MPP–O• DEToc-OH 2.0 10 EtOH 298 6.63 18.7 s.f. D.k. at 376 and 580 nm 89MUK/KAG → ϩ MPP–OH DEToc-O• in deaerated soln. 68 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,7-diisopropyltocol ϩ → ϩ ϫ 3 MPP–O• DPToc-OH MPP–OH 2.5 10 EtOH 298 6.71 18.5 s.f. D.k. at 376 and 580 nm 89MUK/KAG in deaerated DPToc-O• soln. 69 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5-methyl-7-tert-butyltocol ϩ ϫ 3 MPP–O• BMToc-OH 3.0 10 EtOH 298 6.59 17.8 s.f. D.k. at 376 and 580 nm 89MUK/KAG → ϩ MPP–OH BMToc-O• in deaerated soln. 70 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5-methyl-8-tert-butyltocol ϩ ϫ 3 MPP–O• BMToc-OH 3.6 10 EtOH 298 6.38 16.1 s.f. D.k. at 376 and 580 nm 89MUK/KAG → ϩ MPP–OH BMToc-O• in deaerated soln. 71 2,6-Di-tert-butyl-4-(4Ј-methylphenyl)phenoxylϩTocol ϩ → ϩ ϫ 2 MPP–O• Toc-OH MPP–OH Toc-O• 6.7 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 72 2,6-Di-tert-butyl-4-phenylphenoxylϩTocol ϩ → ϩ ϫ 3 PP–O• Toc-OH PP–OH Toc-O• 1.1 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 166 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

73 2,6-Di-tert-butyl-4-(4Ј-bromophenyl)phenoxylϩTocol ϩ → ϩ ϫ 3 BPP–O• Toc-OH BPP–OH Toc-O• 1.3 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 74 2,6-Di-tert-butyl-4-(4Ј-nitrophenyl)phenoxylϩTocol ϩ → ϩ ϫ 3 NPP–O• Toc-OH NPP–OH Toc-O• 2.3 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. ϩ 75 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl Tocol-d1 ϩ → ϩ ϫ 1 MPP–O• Toc-OD MPP–OH Toc-O• 3.1 10 EtOD 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 76 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩTocol ϩ → ϩ ϫ 2 MPP–O• Toc-OH MPP–OH Toc-O• 5.6 10 EtOH 298 s.f. D.k. at 376 and 580 nm 88MUK/FUK in deaerated soln. 77 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,7-dimethyltocol ϩ ϫ 3 MPP–O• DMToc-OH 2.4 10 EtOH 298 s.f. D.k. at 376 and 580 nm 88MUK/FUK → ϩ MPP–OH DMToc-O• in deaerated soln. 78 Phenoxylϩ␣-tocopherol ϩ␣ → ϩ␣ ϫ 9 C6H5O• -Toc-OH C6H5OH -Toc-O 1.1 10 t-Bu2O2 / RT f.p. P.b.k. at 440 nm in 94FOT/ING benzene • deoxygenated soln. ͑3/1͒ contg. 1.4 mol LϪ1 phenol. ϫ 8 3.1 10 t-Bu2O2 / RT f.p. P.b.k. at 440 nm in 94FOT/ING MeCN ͑2/1͒ deoxygenated soln. contg. 1.4 mol LϪ1 phenol. 79 Phenoxylϩ␥-tocopherol ϩ␥ → ϩ␥ ϫ 8 C6H5O• -Toc-OH C6H5OH -Toc-O 2.5 10 t-Bu2O2 / RT f.p. P.b.k. at 430 nm in 94FOT/ING • benzene deoxygenated soln. ͑3/1͒ contg. 1.4 mol LϪ1 phenol. ϫ 7 8.9 10 t-Bu2O2 / RT f.p. P.b.k. at 430 nm in 94FOT/ING MeCN ͑2/1͒ deoxygenated soln. contg. 1.4 mol LϪ1 phenol. 80 Phenoxylϩ␦-tocopherol ϩ␦ → ϩ␦ ϫ 7 C6H5O• -Toc-OH C6H5OH -Toc-O• 2 10 t-Bu2O2 / RT f.p. P.b.k. at 430 nm in 94FOT/ING MeCN ͑2/1͒ deoxygenated soln. contg. 1.4 mol LϪ1 phenol. 81 Lysozyme tyrosyl radicalϩ␣-tocopherol ϩ␣ ϫ 4 Lys-TyrO• -Toc-OH 2.6 10 water/ RT p.r. D.k. at 405 nm in 84HOE/BUT → ϩ␣ Lys-TyrOH -Toc-O• micelles N2O-satd. soln. contg. ͑7.0͒ azide and SDS micelles. 82 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␣-tocopherol ϩ␣ → ϫ 3 MPP–O• -Toc-OH MPP–OH 5.1 10 EtOH 298 s.f. D.k. at 376 and 580 nm 86MUK/WAT ϩ␣ -Toc-O• in deaerated soln. 5.1ϫ103 EtOH 298 7.00 18.7 s.f. D.k. at 376 and 580 nm 89MUK/ in deaerated soln. OKAa 89MUK/KAG 1.5ϫ104 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/NISa EtOH ͑2/1͒ in deaerated soln. 83 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␤-tocopherol ϩ␤ → ϫ 3 MPP–O• -Toc-OH MPP–OH 2.2 10 EtOH 298 s.f. D.k. at 376 and 580 nm 86MUK/WAT ϩ␤ -Toc-O• in deaerated soln. 2.2ϫ103 EtOH 298 7.10 21.1 s.f. D.k. at 376 and 580 nm 89MUK/KAG in deaerated soln. 84 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␥-tocopherol ϩ␥ → ϫ 3 MPP–O• -Toc-OH MPP–OH 2.4 10 EtOH 298 s.f. D.k. at 376 and 580 nm 86MUK/WAT ϩ␥ -Toc-O• in deaerated soln. 2.4ϫ103 EtOH 298 7.31 22.2 s.f. D.k. at 376 and 580 nm 89MUK/KAG in deaerated soln. 85 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␦-tocopherol ϩ␦ → ϫ 2 MPP–O• -Toc-OH MPP–OH 5.1 10 EtOH 298 s.f. D.k. at 376 and 580 nm 86MUK/WAT ϩ␦ -Toc-O• in deaerated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 167

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

1.0ϫ103 EtOH 298 7.54 25.6 s.f. D.k. at 376 and 580 nm 89MUK/KAG in deaerated soln. 86 2,6-Di-tert-butyl-4-(4Ј-methylphenyl)phenoxylϩ␣-tocopherol ϩ␣ → ϫ 3 MPP–O• -Toc-OH MPP–OH 7.2 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␣ -Toc-O• deaerated soln. 87 2,6-Di-tert-butyl-4-(4Ј-methylphenyl)phenoxylϩ␤-tocopherol ϩ␤ → ϫ 3 MPP–O• -Toc-OH MPP–OH 4.0 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␤ -Toc-O• deaerated soln. 88 2,6-Di-tert-butyl-4-(4Ј-methylphenyl)phenoxylϩ␥-tocopherol ϩ␥ → ϫ 3 MPP–O• -Toc-OH MPP–OH 3.6 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␥ -Toc-O• deaerated soln. 89 2,6-Di-tert-butyl-4-(4Ј-methylphenyl)phenoxylϩ␦-tocopherol ϩ␦ → ϫ 3 MPP–O• -Toc-OH MPP–OH 1.6 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␦ -Toc-O• deaerated soln. 90 2,6-Di-tert-butyl-4-phenylphenoxylϩ␣-tocopherol ϩ␣ → ϩ␣ ϫ 3 PP–O• -Toc-OH PP–OH -Toc-O• 8.8 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 91 2,6-Di-tert-butyl-4-phenylphenoxylϩ␤-tocopherol ϩ␤ → ϩ␤ ϫ 3 PP–O• -Toc-OH PP–OH -Toc-O• 4.3 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 92 2,6-Di-tert-butyl-4-phenylphenoxylϩ␥-tocopherol ϩ␥ → ϩ␥ ϫ 3 PP–O• -Toc-OH PP–OH -Toc-O• 3.8 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 93 2,6-Di-tert-butyl-4-phenylphenoxylϩ␦-tocopherol ϩ␦ → ϩ␦ ϫ 3 PP–O• -Toc-OH PP–OH -Toc-O• 1.9 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. 94 2,6-Di-tert-butyl-4-(4Ј-bromophenyl)phenoxylϩ␣-tocopherol ϩ␣ → ϫ 4 BPP–O• -Toc-OH BPP–OH 1.1 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␣ -Toc-O• deaerated soln. 95 2,6-Di-tert-butyl-4-(4Ј-bromophenyl)phenoxylϩ␤-tocopherol ϩ␤ → ϫ 3 BPP–O• -Toc-OH BPP–OH 6.1 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␤ -Toc-O• deaerated soln. 96 2,6-Di-tert-butyl-4-(4Ј-bromophenyl)phenoxylϩ␥-tocopherol ϩ␥ → ϫ 3 BPP–O• -Toc-OH BPP–OH 5.3 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␥ -Toc-O• deaerated soln. 97 2,6-Di-tert-butyl-4-(4Ј-bromophenyl)phenoxylϩ␦-tocopherol ϩ␦ → ϩ␦ ϫ 3 BPP–O• -Toc-OH BPP–OH -Toc-O 3.0 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR • deaerated soln. 98 2,6-Di-tert-butyl-4-(4Ј-nitrophenyl)phenoxylϩ␣-tocopherol ϩ␣ → ϫ 4 NPP–O• -Toc-OH NPP–OH 2.2 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␣ -Toc-O• deaerated soln. 99 2,6-Di-tert-butyl-4-(4Ј-nitrophenyl)phenoxylϩ␤-tocopherol ϩ␤ → ϫ 4 NPP–O• -Toc-OH NPP–OH 1.3 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␤ -Toc-O• deaerated soln. 100 2,6-Di-tert-butyl-4-(4Ј-nitrophenyl)phenoxylϩ␥-tocopherol ϩ␥ → ϫ 4 NPP–O• -Toc-OH NPP–OH 1.1 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␥ -Toc-O• deaerated soln. 101 2,6-Di-tert-butyl-4-(4Ј-nitrophenyl)phenoxylϩ␦-tocopherol ϩ␦ → ϩ␦ ϫ 3 NPP–O• -Toc-OH NPP–OH - 6.2 10 EtOH 298 s.f. D.k. at 370–380 nm in 92NAG/KUR deaerated soln. Toc-O• ϩ␣ 102 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl -tocopherol-d1 ϩ␣ → ϫ 2 MPP–O• -Toc-OD MPP–OD 2.2 10 EtOD 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␣ -Toc-O• deaerated soln. ϩ␤ 103 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl -tocopherol-d1 ϩ␤ → ϫ 2 MPP–O• -Toc-OD MPP–OD 1.5 10 EtOD 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␤ -Toc-O• deaerated soln. ϩ␥ 104 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl -tocopherol-d1 ϩ␥ → ϫ 2 MPP–O• -Toc-OD MPP–OD 1.6 10 EtOD 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␥ -Toc-O• deaerated soln. ϩ␦ 105 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl -tocopherol-d1 ϩ␦ → ϫ 1 MPP–O• -Toc-OD MPP–OD 6.4 10 EtOD 298 s.f. D.k. at 370–380 nm in 92NAG/KUR ϩ␦ -Toc-O• deaerated soln. 106 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␣-tocopherol

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 168 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

ϩ␣ → ϫ 3 MPP–O• -Toc-OH MPP–OH 5.1 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR ϩ␣ -Toc-O• nm in deaerated soln. 1.4ϫ104 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 9.5ϫ104 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerted soln. 1.9ϫ105 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 107 Phenoxylϩ2,3-dihydro-5-hydroxy-2,4,6,7-tetramethyl-2-phytylbenzofuran ϩ ϫ 8 C6H5O• HTMPB-OH 2.4 10 t-Bu2O2 f.p. P.b.k. at 430 nm in 94FOT/ING → ϩ C6H5OH HTMPB-O• /MeCN(2/1) deoxygenated soln. contg. 1.4 mol LϪ1 phenol. 108 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2,3-dihydro-5-hydroxy-2,2-dimethylbenzofuran ϩ ϫ 2 MPP–O• DMBF–OH 8.8 10 EtOH 298 8.00 28.8 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH DMBF–O• in deaerated soln. OKAa 109 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ7-tert-Butyl-2,3-dihydro-5-hydroxy-2,2,4-trimethylbenzofuran ϩ ϫ 3 MPP–O• BTMBF–OH 9.1 10 EtOH 298 7.02 17.5 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH BTMBF–O• in deaerated soln. OKAa 110 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2,3-dihydro-5-hydroxy-2,2,4,6-tetramethylbenzofuran ϩ ϫ 3 MPP–O• TMBF–OH 3.5 10 EtOH 298 6.57 17.3 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH TMBF–O• in deaerated soln. OKAa 111 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2,3-dihydro-5-hydroxy-2,2-dimethyl-4,6-diisopropylbenzofuran ϩ ϫ 3 MPP–O• DMDIBF–OH 5.4 10 EtOH 298 6.74 17.2 s.f. D.k. at 376 and 580 nm 89MUK/ → ϩ MPP–OH DMDIBF–O• in deaerated soln. OKAa 112 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2,3-dihydro-5-hydroxy-2,2,4,6,7-pentamethylbenzofuran ϩ → ϩ ϫ 3 MPP–O• PMBF–OH MPP–OH 7.0 10 EtOH 298 6.60 15.8 s.f. D.k. at 376 and 580 nm 89MUK/ PMBF–O• in deaerated soln. OKAa 113 4-methoxyphenoxylϩcatechol ϩ Ϫ Ϫ ϫ 8 ͑ ͒ 4-CH3OC6H4O• 2-(O )C6H4O 8.6 10 water 13.5 RT p.r. D.k. at 420 nm in 79STE/NET → Ϫϩ Ϫ 4-CH3OC6H4O 2-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 114 1,3-Benzosemiquinone anionϩcatechol Ϫ ϩ Ϫ Ϫ ϫ 8 ͑ ͒ 3-(O )C6H4O• 2-(O )C6H4O 7.5 10 water 13.5 RT p.r. D.k. at 450 nm in 79STE/NET → Ϫ Ϫϩ Ϫ 3-(O )C6H4O 2-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 115 Phenoxylϩresorcinol ϩ Ϫ Ϫ ϫ 9 ͑ ͒ C6H5O• 3-(O )C6H4O 1.7 10 water 13.5 RT p.r. P.b.k. at 450 nm in 79STE/NET → Ϫϩ Ϫ C6H5O 3-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 116 4-Carboxyphenoxylϩresorcinol Ϫ ϩ Ϫ Ϫ ϫ 9 ͑ ͒ 4-(CO2 )C6H4O• 3-(O )C6H4O 1.1 10 water 13.5 RT p.r. P.b.k. at 450 nm in 79STE/NET → Ϫ Ϫϩ Ϫ 4-(CO2 )C6H4O 3-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 117 Phenoxylϩhydroquinone ϩ Ϫ ϫ 9 ͑ ͒ C6H5O• 4-HOC6H4O 2.2 10 water 11.6 RT p.r. P.b.k. at 430 nm in 79STE/NET → Ϫϩ Ϫ C6H5O 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 118 Acetaminophenoxylϩhydroquinone ϩ Ϫ Ϫ ϫ 8 ͑ ͒ 4-CH3CONHC6H4O• 4-(O )C6H4O 1.4 10 water 12.6 RT p.r. Kinetics in N2O-satd. 88BIS/TAB → Ϫϩ Ϫ soln. 4-CH3CONHC6H4O 4-(O )C6H4O• 119 Galvinoxylϩhydroquinone ϩ ϫ 3 Galvinoxyl• 4-HOC6H4OH 1.6 10 CCl4 293 17.6 chem. D.k. at 435 nm. 78NIS/OKA → ϩ ϫ 3 Galvinoxyl-H 4-HOC6H4O• 1.8 10 298 2.1ϫ103 303 ϫ 2 9.2 10 CCl4 298 chem. D.k. at 435 nm in soln. 78NIS/OKA satd. with H2O. 1.9ϫ103 benzene 298 chem. D.k. at 435 nm in soln. 78NIS/OKA

satd. with H2O.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 169

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

ϩ ϫ 2 Galvinoxyl• 4-DOC6H4OD 3.2 10 CCl4 298 chem. D.k. at 435 nm in soln. 78NIS/OKA → ϩ Galvinoxyl-D 4-DOC6H4O• satd. with D2O. 4.8ϫ102 benzene 298 chem. D.k. at 435 nm in soln. 78NIS/OKA

satd. with D2O. 120 4-Methoxyphenoxylϩ3,4-dihydroxybenzoate ion ϩ Ϫ Ϫ ϫ 8 ͑ ͒ 4-CH3OC6H4O• 3,4-(O )2C6H3CO2 7 10 water 13.5 RT p.r. D.k. at 420 nm in 79STE/NET → Ϫ 4-CH3OC6H4O N2O-satd. soln. contg. ϩ Ϫ Ϫ Ϫ1 3,4-(O )(O•)C6H3CO2 1 mol L ethylene glycol. 121 4-(N,N-Dimethylamino)phenoxylϩ3,4-dihydroxyphenylacetate ion ϫ 7 ͑ ͒ 4-(CH3)2NC6H4O• 9 10 water 13.5 RT p.r. D.k. at 490 nm in 82STE/NET ϩ Ϫ Ϫ 3,4-(O )2C6H3CH2CO2 N2O-satd. soln. contg. → Ϫ Ϫ1 4-(CH3)2NC6H4O 1 mol L ethylene ϩ Ϫ Ϫ 3,4-(O )(O•)C6H3CH2CO2 glycol. 122 4-(N,N-Dimethylamino)phenoxylϩ3,4-dihydroxyphenylalanine ϫ 7 ͑ ͒ 4-(CH3)2NC6H4O• 7 10 water 13.5 RT p.r. D.k. at 490 nm in 82STE/NET ϩ Ϫ Ϫ 3,4-(O )2C6H3CH2CH(NH2)CO2 N2O-satd. soln. contg. → Ϫϩ Ϫ1 4-(CH3)2NC6H4O 3,4- 1 mol L ethylene Ϫ Ϫ (O )(O•)C6H3CH2CH(NH2)CO2 glycol. 123 ␣-Tocopheroxylϩisoprenaline ͑3,4-dihydroxy-␣-͓͑isopropylamino͒methyl͔benzyl alcohol͒ ␣ ϩ ϫ 3 -Toc-O• isoprenaline-OH 3.2 10 n-BuOH chem. Decay of ESR signal of 93OND/MIS → ␣ ϩ ␣ -Toc-OH isoprenalin-O• -tocopheroxyl radical, produced by reaction of ␣-tocopherol with DPPH, in the presence of various concentrations of isoprenaline. Decay ␣ includes -Toc-O• ϩ␣ ␣ -Toc-O• and - ϩ Toc-O• isoprenaline. 124 ␣-Tocopheroxylϩepinephrin ␣ ϩ ϫ 3 -Toc-O• epinephrin-OH 1.5 10 n-BuOH chem. Decay of ESR signal of 93OND/MIS → ␣ ϩ ␣ -Toc-OH epinephrin-O• -tocopheroxyl radical, produced by reaction of ␣-tocopherol with DPPH, in the presence of various concentrations of epinephrin. Decay ␣ includes -Toc-O• ϩ␣ ␣ -Toc-O• and - ϩ Toc-O• epinephrin. 125 3,6-Di-tert-butyl-1,2-benzosemiquinoneϩ3,6-di-tert-butylcatechol ϩ ϫ 8 3,6-(t-Bu)2-2-HOC6H2O• 3,6-(t-Bu)2 7 10 CCl4 298 10.9 11.7 chem. ESR line broadening in 74ZAV/PRO → -2-HOC6H2OH 3,6-(t-Bu)2-2- soln. contg. 3,6-di-tert- ϩ HOC6H2OH 3,6-(t-Bu)2-2-HOC6H2O• butyl-o-quinone and 3,6-di-tert-butylcatechol. 126 1,3-Benzosemiquinone anionϩ2,5-dihydroxyacetophenone Ϫ ϩ Ϫ Ϸ ϫ 9 ͑ ͒ 3-(O )C6H4O• 2,5-(O )2C6H3COCH3 1 10 water 13.5 RT p.r. P.b.k. at 520 nm in 79STE/NET → Ϫ Ϫ 3-(O )C6H4O N2O-satd. soln. contg. ϩ Ϫ Ϫ1 2,5-(O )(O•)C6H3COCH3 1 mol L ethylene glycol. 127 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩtrimethylhydroquinone ϩ ϫ 3 MPP–O• (CH3)3C6H(OH)OH 8.6 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR → ϩ MPP–OH (CH3)3C6H(OH)O• nm in deaerated soln. 2.2ϫ104 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.3ϫ105 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 170 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

128 Phenoxylϩ2,3-dimethoxy-5-methylhydroquinone ͑ubiquinol-0͒ ϩ → ϩ ϫ 7 C6H5O• UQH2 C6H5OH UQH• 9.1 10 t-Bu2O2/ f.p. P.b.k. at 430 nm in 94FOT/ING benzene deoxygenated soln. contg. 1.4 mol LϪ1 phenol. ͑3/1͒ 129 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩUbiquinol-0 ϩ → ϩ ϫ 3 MPP–O• UQH2 MPP–OH UQH• 2.9 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.7ϫ103 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.3ϫ104 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.0ϫ104 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. ϩ → ͑ ͒ 130 Phenoxyl 2,3-dimethoxy-5-methyl-6-͓(CH2CH C(CH3)CH2)10H͔-hydroquinone ubiquinol-10 ϩ → ϩ ϫ 7 C6H5O• UQH2 C6H5OH UQH• 8.4 10 t-Bu2O2/ f.p. P.b.k. at 430 nm in 94FOT/ING benzene deoxygenated soln. ͑3/1͒ contg. 1.4 mol LϪ1 phenol. 131 ␣-TocopheroxylϩUbiquinol-10 ␣ ϩ → ␣ ϩ ϫ 5 -Toc-O• UQH2 -Toc-OH UQH• 3.7 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 2.2ϫ105 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 132 5,7-Dimethyltocoxyl radicalϩUbiquinol-10 ϩ → ϩ ϫ 5 DMToc-O• UQH2 DMToc-OH UQH• 4.4 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 2.7ϫ105 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 133 5,7-Diethyltocoxyl radicalϩUbiquinol-10 ϩ → ϩ ϫ 5 DEToc-O• UQH2 DEToc-OH UQH• 2.9 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 1.4ϫ105 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 134 5,7-Diisopropyltocoxyl radicalϩUbiquinol-10 ϩ → ϩ ϫ 4 DPToc-O• UQH2 DPToc-OH UQH• 8.5 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 3.6ϫ104 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 135 5-Methyl-7-tert-butyltocoxyl radical ϩUbiquinol-10 ϩ → ϩ ϫ 4 BMToc-O• UQH2 BMToc-OH UQH• 7.7 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 3.5ϫ104 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 136 5-Isopropyl-7-tert-butyltocoxyl radical ϩUbiquinol-10 ϩ → ϩ ϫ 3 BPToc-O• UQH2 BPToc-OH UQH• 7.1 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 3.7ϫ103 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 137 5,7-Diethyl-8-methyltocoxylϩUbiquinol-10 ϩ → ϩ ϫ 5 DEToc-O• UQH2 DEToc-OH UQH• 1.6 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 8.2ϫ104 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 138 5,7-Diisopropyl-8-methyltocoxylϩUbiquinol-10 ϩ → ϩ ϫ 4 DPToc-O• UQH2 DPToc-OH UQH• 1.6 10 benzene 298 s.f. D.k. at 425 nm. 90MUK/KIK 8.6ϫ103 EtOH 298 s.f. D.k. at 425 nm. 90MUK/KIK 139 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl) phenoxylϩUbiquinol-10 ϩ → ϩ ϫ 3 MPP–O• UQH2 MPP–OH UQH• 5.2 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 3.9ϫ103 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.1ϫ104 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.1ϫ104 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 140 1,2-Benzosemiquinone anionϩ1,2,4-trihydroxybenzene Ϫ ϩ Ϫ ϫ 6 ͑ ͒ 2-(O )C6H4O• 1,2,4-C6H3(O )3 9.0 10 water 13.5 RT p.r. P.b.k. at 430 nm in 79STE/NET → Ϫ Ϫϩ Ϫ 2-(O )C6H4O 1,2,4-C6H3(O )2(O•) N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 171

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

141 3-Hydroxy-1,2-benzosemiquinone anionϩ1,2,4-trihydroxybenzene Ϫ ϩ Ϫ Ϫ Ϸ ϫ 5 ͑ ͒ 1,2,3-(O )2C6H3O• 1,2,4-(O )2C6H3O 1 10 water 13.5 RT p.r. P.b.k. at 430 nm in 79STE/NET → Ϫ Ϫ 1,2,3-(O )2C6H3O N2O-satd. soln. contg. ϩ Ϫ Ϫ1 1,2,4-(O )2C6H3O• 1 mol L ethylene glycol. 142 4-(N,N-Dimethylamino)phenoxylϩ6-hydroxydopamine Ϸ ϫ 8 ͑ ͒ 4-(CH3)2NC6H4O• 5 10 water 13.5 RT p.r. D.k. at 490 nm in 82STE/NET ϩ Ϫ (O )3C6H2CH2CH2NH2 N2O-satd. soln. contg. → Ϫ Ϫ1 4-(CH3)2NC6H4O 1 mol L ethylene ϩ Ϫ (O )2(O•)C6H2CH2CH2NH2 glycol. 143 Lysozyme tyrosyl radicalϩn-propyl gallate ϩ ϫ 6 Lys-TyrO• 3,4,5-(HO)3C6H2CO2C3H7 9.9 10 water/ RT p.r. D.k. at 405 nm in 84HOE/BUT → Lys-TyrOH micelles N2O-satd. soln. contg. ϩ Ϫ ͑ ͒ 3,4,5-(OH)(O )(O•)C6H2CO2C3H7 7.0 azide and SDS micelles. 144 Trolox phenoxyl radicalϩpropyl gallate ϩ Ͻ ϫ 5 ͑ ͒ TxO• 3,4,5-(HO)3C6H2CO2C3H7 1 10 water 7 RT p.r. D.k. at 430 nm in 88DAV/FOR → TxOH N2O-satd. soln. contg. ϩ Ϫ 3,4,5-(OH)(O )(O•)C6H2CO2C3H7 azide. ϩ ͑ ͒ 145 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl 2-methyl-1,4-dihydroxynaphthalene Vitamin K3 reduced ϩ ϫ 5 MPP–O• MeNp(OH)OH 1.1 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR → ϩ MPP–OH MeNp(OH)O• nm in deaerated soln. 1.5ϫ104 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.8ϫ106 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. Ͼ1ϫ107 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. ϩ ͑ ͒ 146 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxyl 2-methyl-3-phytyl-1,4-dihydroxynaphthalene Vitamin K1 reduced ϩ → ϩ ϫ 5 MPP–O• VitK1H2 MPP–OH VitK1H• 1.6 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.3ϫ105 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.5ϫ106 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. Ͼ1ϫ107 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 147 4-(N,N-Dimethylamino)phenoxylϩesculetin ͑6,7-dihydroxycoumarin͒ ϩ ϫ 8 ͑ ͒ 4-(CH3)2NC6H4O• esculetin 1.4 10 water 13.5 RT p.r. D.k. at 490 nm in 82STE/NET → Ϫϩ 4-(CH3)2NC6H4O esculetin• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 148 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␣-Tocopherol quinone, reduced ϩ␣ → ϩ␣ ϫ 4 MPP–O• TQH2 MPP–OH TQH• 1.4 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.9ϫ104 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.3ϫ105 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.5ϫ105 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 149 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␤-Tocopherol quinone, reduced ϩ␤ → ϩ␤ ϫ 3 MPP–O• TQH2 MPP–OH TQH• 8.4 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.5ϫ104 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 1.3ϫ105 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 150 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ␥-Tocopherol quinone, reduced ϩ␥ → ϩ␥ ϫ 4 MPP–O• TQH2 MPP–OH TQH• 1.5 10 EtOH 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 3.7ϫ104 diethyl ether 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 2.2ϫ105 benzene 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 172 P. NETA AND J. GRODKOWSKI

TABLE 6. Reactions of phenoxyl radicals with phenols—Continued

Phenoxylϩphenol k T Ea No. Reaction (L molϪ1 sϪ1) Solvent ͑pH͒ ͑K͒ log A (kJmolϪ1) Method Comments Reference

7.6ϫ105 n-hexane 298 s.f. D.k. at 375 and/or 580 93MUK/MOR nm in deaerated soln. 151 Epicatechin semiquinone anionϩepicatechin Ϫ ϩ ϫ 7 ͑ epicatechin(1,3-(O )(O•)) epicatechin 1.1 10 water 7, 293 p.r. D.k. at 450 nm in 95JOV/HAR → ϩ Ϫ ͒ epicatechin epicatechin(1,2-(O )(O•)) 10 N2O-satd. soln. contg. azide. Conversion of a m-too-semiquinone. Intramolecular electron transfer to give the same result is also proposed. 152 Epigallocatechin semiquinone anionϩepigallocatechin Ϫ ϫ 7 ͑ ͒ epigallocatechin(1,3-(O )(O•)) 2.2 10 water 3 293 p.r. D.k. at 450 nm in 95JOV/HAR ϩ → 7 ͑ ͒ epigallocatechin epigallocatechin 3.8ϫ10 water 7 N2O-satd. soln. contg. ϩ Ϫ ϫ 8 ͑ ͒ epigallocatechin(1,2-(O )(O•)) 1.6 10 water 10 azide. Conversion of a m-too-semiquinone. Intramolecular electron transfer to give the same result is also proposed. 153 Epigallocatechin gallate semiquinone anionϩepigallocatechin gallate Ϫ ϫ 8 ͑ ͒ epigallocatechin gallate(1,3-(O )(O•)) 1.3 10 water 3 293 p.r. D.k. at 450 nm in 95JOV/HAR ϩ 8 ͑ ͒ epigallocatechin gallate 3.5ϫ10 water 7 N2O-satd. soln. contg. → epigallocatechin gallate azide. Conversion of a ϩ Ϫ epigallocatechin gallate(1,2-(O )(O•)) m-too-semiquinone. Intramolecular electron transfer to give the same result is also proposed. 154 Galvinoxylϩcatechin ϩ ϫ 2 Gal-O• Catechin-OH 2.3 10 MeCN chem. D.k. at 428 nm in 02NAK/MIY → ϩ Gal-OH Catechin-O• deaerated soln. k is accelerated with increasing ͓Mg2ϩ͔. 155 Galvinoxylϩtrihydrogalvinoxyl ϩ → ϩ Ϸ ϫ 2 G• GH3 GH GH2• 2.5 10 cyclohexane 298 chem. Kinetics of ESR signal. 71ADA/CHI Derived from ﬁtting to a complex mechanism.

For reverse reaction kr Ϸ2.5ϫ104. 156 Tyrosylϩurate ion ϩ Ϫ → Ϫϩ ϫ 8 ͑ ͒ TyrO• urate TyrO urate• 2.4 10 water 7 293 p.r. D.k. at 400 nm in 89HUN/DES N2O-satd. soln. contg. phosphate and Tlϩ. 157 Lysozyme tyrosyl radicalϩurate ion ϩ → ϫ 6 Lys-TyrO• Urate ion Lys-TyrOH 5.4 10 water/ RT p.r. D.k. at 405 nm in 84HOE/BUT ϩ Urate radical anion micelles N2O-satd. soln. ͑7.0͒ contg. azide and SDS micelles. 158 Trolox phenoxyl radicalϩurate ion ϩ → ϩ Ͻ ϫ 5 ͑ ͒ TxO• urate ion TxOH urate radical 1 10 water 7 RT p.r. D.k. at 430 nm in 88DAV/FOR N2O-satd. soln. contg. azide. 159 Tetra(tert-butyl)indophenoxylϩtetrachloro-o-benzoquinone ͑o-chloranil͒ ϩ → ϫ Ϫ3 TBIP-O• o-C6Cl4O2 products 5.4 10 THF 293 8.06 59.8 chem. Decay of ESR signal of 79KHI/KOS TBIP-O•. Radical produced by oxidation of TBIP-OH with

PbO2 . 160 Tetra(tert-butyl)indophenoxylϩtetrachloro-p-benzoquinone ͑p-chloranil͒ ϩ → ϫ Ϫ3 TBIP-O• p-C6Cl4O2 products 6.5 10 THF 293 4.0 36.4 chem. Decay of ESR signal of 79KHI/KOS TBIP-O•. Radical produced by oxidation of TBIP-OH with

PbO2 .

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 173

TABLE 7. Reactions of phenoxyl radicals with ascorbic acid and derivatives

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

1 Phenoxylϩascorbate ion ϩ Ϫ → Ϫϩ Ϫ ϫ 8 C6H5O• AscH C6H5O Asc• 6.9 10 11 water RT p.r. P.b.k. at 360 nm 77SCH ϩHϩ and d.k. at 400 nm

in N2O-satd. soln. 2 2-Fluorophenoxylϩascorbate ion ϩ Ϫ → Ϫ ϫ 8 2-FC6H4O• AscH 2-FC6H4O 9.5 10 11 water RT p.r. P.b.k. at 360 nm 77SCH ϩ Ϫϩ ϩ Asc• H and d.k. at 400 nm in N2O-satd. soln. 3 3-Fluorophenoxylϩascorbate ion ϩ Ϫ → Ϫ ϫ 8 3-FC6H4O• AscH 3-FC6H4O 9.7 10 11 water RT p.r. P.b.k. at 360 nm 77SCH ϩ Ϫϩ ϩ Asc• H and d.k. at 400 nm in N2O-satd. soln. 4 4-Fluorophenoxylϩascorbate ion ϩ Ϫ ϫ 8 4-FC6H4O• AscH 4.6 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 4-FC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 5 2-Chlorophenoxylϩascorbate ion ϩ Ϫ ϫ 9 2-ClC6H4O• AscH 1.1 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 2-ClC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 6 3-Chlorophenoxylϩascorbate ion ϩ Ϫ ϫ 9 3-ClC6H4O• AscH 1.3 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 3-ClC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 7 4-Chlorophenoxylϩascorbate ion ϩ Ϫ ϫ 8 4-ClC6H4O• AscH 7.3 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 4-ClC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 8 2-Bromophenoxylϩascorbate ion ϩ Ϫ ϫ 8 2-BrC6H4O• AscH 7.7 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 2-BrC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 9 3-Bromophenoxylϩascorbate ion ϩ Ϫ ϫ 8 3-BrC6H4O• AscH 8.9 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 3-BrC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 10 4-Bromophenoxylϩascorbate ion ϩ Ϫ ϫ 8 4-BrC6H4O• AscH 8.3 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 4-BrC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 11 4-Iodophenoxylϩascorbate ion ϩ Ϫ ϫ 9 4-IC6H4O• AscH 1.1 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 4-IC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 12 2-Cyanophenoxylϩascorbate ion ϩ Ϫ ϫ 9 2-NCC6H4O• AscH 1.8 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 2-NCC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 13 4-Cyanophenoxylϩascorbate ion ϩ Ϫ ϫ 9 4-NCC6H4O• AscH 2.0 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 4-NCC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 14 2-Carboxyphenoxylϩascorbate ion Ϫ ϩ Ϫ ϫ 7 2-(CO2 )C6H4O• AscH 8.3 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫ Ϫϩ Ϫϩ ϩ 2-(CO2 )C6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 15 4-Carboxyphenoxylϩascorbate ion Ϫ ϩ Ϫ ϫ 8 4-(CO2 )C6H4O• AscH 4.6 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫ Ϫϩ Ϫϩ ϩ 4-(CO2 )C6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln. 16 3-Hydroxyphenoxylϩascorbate ion ϩ Ϫ ϫ 8 3-HOC6H4O• AscH 1.1 10 11 water RT p.r. P.b.k. at 360 nm 77SCH → Ϫϩ Ϫϩ ϩ 3-HOC6H4O Asc• H and d.k. at 400 nm in N2O-satd. soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 174 P. NETA AND J. GRODKOWSKI

TABLE 7. Reactions of phenoxyl radicals with ascorbic acid and derivatives—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

17 4-Aminophenoxylϩascorbate ion ϩ Ϫ ϫ 7 4-H2NC6H4O• AscH 5.1 10 11 water RT p.r. P.b.k. at 360 nm and 77SCH → Ϫϩ Ϫϩ ϩ 4-H2NC6H4O Asc• H d.k. at 400 nm in N2O-satd. soln. 18 4-Methoxyphenoxylϩascorbate ion ϩ Ϫ ϫ 7 4-CH3OC6H4O• AscH 5.2 10 8 water RT p.r. D.k. at 420 nm. 95KHA/ALF → ϩ Ϫ 4-CH3OC6H4OH Asc• 19 Tyrosylϩascorbate ion ϩ Ϫ → ϩ Ϫ ϫ 8 TyrO• AscH TyrOH Asc• 4.4 10 7 water RT p.r. P.b.k. at 360 nm in 89HUN/DES N2O-satd. soln. contg. Ϫ1 1 mmol L Tl2SO4 , 0.4 mmol LϪ1 tyrosine, and 0.01– 0.1 mmol LϪ1 ascorbate. 20 Lysozyme tyrosyl radicalϩascorbate ion ϩ Ϫ → ϩ Ϫ ϫ 7 Lys-TyrO• AscH Lys-TyrOH Asc• 1.1 10 7.0 water/micelles RT p.r. D.k. at 405 nm in 84HOE/BUT ϩ ϩ H N2O-satd. soln. contg. azide and SDS micelles. 21 3,5-Dichlorophenoxylϩascorbate ion ϩ Ϫ ϫ 9 3,5-Cl2C6H3O• AscH 1.6 10 11 water RT p.r. P.b.k. at 360 nm in 95KHA/NET → Ϫϩ Ϫϩ ϩ 3,5-Cl2C6H3O Asc• H N2O-satd. soln. I ϭ0.01. 22 3,5-Diiodotyrosylϩascorbate ion ϩ Ϫ 2- ϫ 9 3,5-I2-TyrO• AscH (Asc ) 2.1 10 7.4 water RT p.r. D.k. at 420 nm in 96DAS → Ϫϩ Ϫϩ ϩ ϫ 8 3,5-I2-TyrO Asc• H 8.5 10 12 N2O-satd. soln. contg. azide. Similar k in the absence of azide. 23 2,4,5-Trichlorophenoxylϩascorbate ion ϩ Ϫ ϫ 9 2,4,5-Cl3C6H2O• AscH 1.1 10 11 water RT p.r. P.b.k. at 360 nm in 95KHA/NET → Ϫϩ Ϫϩ ϩ 2,4,5-Cl3C6H2O Asc• H N2O-satd. soln. I ϭ0.01. 24 Pentaﬂuorophenoxylϩascorbate ion ϩ Ϫ → Ϫϩ Ϫϩ ϩ ϫ 9 C6F5O• AscH C6F5O Asc• H 1.3 10 11 water RT p.r. P.b.k. at 360 nm in 95KHA/NET N2O-satd. soln. I ϭ0.01. 25 Pentachlorophenoxylϩascorbate ion ϩ Ϫ → Ϫϩ Ϫ ϫ 9 C6Cl5O• AscH C6Cl5O Asc• 1.4 10 11 water RT p.r. P.b.k. at 360 nm in 95KHA/NET ϩ ϩ H N2O-satd. soln. I ϭ0.01. 26 Trolox phenoxyl radicalϩascorbate ion ϩ Ϫ → ϩ Ϫ ϫ 7 TxO• AscH TxOH Asc• 1.1 10 8.3 water RT p.r. D.k. at 440 nm in 95BOR/MIC N2O-satd. soln. contg. azide. Derived from ﬁtting to a complex ϭ mechanism. kr 1.0 ϫ104. 8.3ϫ106 7.2 water RT p.r. P.b.k. at 360 nm and 88DAV/FOR d.k. at 430 nm in

N2O-satd. soln. contg. bromide. 27 7-tert-Butyl-5-isopropyltocoxylϩascorbate ion ϩ Ϫ → ϩ Ϫ ϫ 2 Toc-O• AscH Toc-OH Asc• 3.2 10 water/micelles 298 s.f. D.k. at 416 nm in 91MUK/NIS deoxygenated soln. contg. 10% Triton X-100 and 0.1 mol LϪ1 phosphate buffer. k measured as a function of pH between 3 and 10. Ascorbic acid is unreactive.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 175

TABLE 7. Reactions of phenoxyl radicals with ascorbic acid and derivatives—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

28 ␣-Tocopheroxylϩascorbate ion ␣ ϩ Ϫ → ␣ ϩ Ϫ ϫ 5 -Toc-O• AscH -Toc-OH Asc• 9.0 10 7.2 water/micelles 293 s.f. Kinetic ESR in 92LIU/HAN deoxygenated soln. contg. phosphate buffer and 0.015 mol LϪ1 CTAB . Radical produced by reaction of tocopherol with Fremy’s salt in a triple mixing apparatus. k is for overall reaction in the aqueous and the micellar phases. 7.2ϫ107 6.8 water/micelles RT f.p. D.k. at 430 nm in air 91BIS/PAR satd. soln. contg. CTAC micelles. 3.8ϫ104 7.2 water/micelles RT f.p. D.k. at 430 nm in air 91BIS/PAR satd. soln. contg. SDS micelles. 29 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩascorbic acid ϩ → ϩ ϫ 1 MPP–O• AscH2 MPP–OH AscH• 6.1 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ EtOH ͑2/1͒ in deaerated soln. NISa 30 2,2,5,7,8-Pentamethylchroman-6-oxylϩascorbic acid ϩ → ϩ ϫ 4 PMC–O• AscH2 PMC–OH AscH• 9.5 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/ deaerated soln. contg. NOG galvinoxyl. 31 5-Iso-propyl-7-tert-butyltocoxylϩascorbic acid ϩ → ϩ ϫ 1 Toc-O• AscH2 Toc-OH AscH• 7.6 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 32 5,7-Di-iso-propyltocoxylϩascorbic acid ϩ → ϩ ϫ 2 Toc-O• AscH2 Toc-OH AscH• 2.3 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 33 5-Methyl-7-tert-butyltocoxylϩascorbic acid ϩ → ϩ ϫ 2 Toc-O• AscH2 Toc-OH AscH• 3.3 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 34 5,7-Diethyltocoxylϩascorbic acid ϩ → ϩ ϫ 4 Toc-O• AscH2 Toc-OH AscH• 1.7 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 35 5,7-Di-iso-propyltocoxylϩascorbic acid ϩ → ϩ ϫ 2 Toc-O• AscH2 Toc-OH AscH• 5.5 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ EtOH ͑2/1͒ deoxygenated soln. NISa 36 7-tert-Butyl-5-isopropyltocoxylϩascorbic acid ϩ → ϩ ϫ 1 Toc-O• AscH2 Toc-OH AscH• 4.9 10 benzene/ 298 s.f. D.k. at 416 nm in 91MUK/NIS EtOH ͑2/1͒ deoxygenated soln. 37 ␣-Tocopheroxylϩascorbic acid ϩ → ϩ ϫ 5 Toc-O• AscH2 Toc-OH AscH• 1.1 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/ deaerated soln. contg. NOG galvinoxyl. 38 2,3-Dihydro-2,2,4,6-tetramethylbenzofuran-5-oxylϩascorbic acid ϩ → ϩ ϫ 4 BOM–O• AscH2 BOM–OH AscH• 8.3 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/ deaerated soln. contg. NOG galvinoxyl. 39 2,3-Dihydro-2,2-dimethyl-4,6-di-tert-butylbenzofuran-5-oxylϩascorbic acid ϩ → ϩ ϫ 1 BOB-O• AscH2 BOB–OH AscH• 2.9 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/ deaerated soln. contg. NOG galvinoxyl. 40 2,3-Dihydro-2,2-dipentyl-4,6-di-tert-butylbenzofuran-5-oxylϩascorbic acid

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 176 P. NETA AND J. GRODKOWSKI

TABLE 7. Reactions of phenoxyl radicals with ascorbic acid and derivatives—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

ϩ → ϫ 1 BO– 653-O• AscH2 BO– 653-OH 3.3 10 EtOH 310 chem. D.k. of ESR signal in 00WAT/ ϩ AscH• deaerated soln. contg. NOG galvinoxyl. 41 ␣-Tocopheroxylϩ6-O-capryloylascorbic acid ␣ ϩ ϫ 5 -Toc-O• capryloyl-AscH2 3.0 10 7.2 water/micelles 293 s.f. Kinetic ESR in 92LIU/HAN → ␣ ϩ Ϫ -Toc-OH capryloyl-Asc• deoxygenated soln. contg. phosphate buffer and 0.015 mol LϪ1 CTAB. Radical produced by reaction of tocopherol with Fremy’s salt in a triple mixing apparatus. k is for overall reaction in the aqueous and the micellar phases. 42 ␣-Tocopheroxylϩ6-O-lauroylascorbic acid ␣ ϩ ϫ 4 -Toc-O• lauroyl-AscH2 7.0 10 7.2 water/micelles 293 s.f. Kinetic ESR in 92LIU/HAN → ␣ ϩ Ϫ -Toc-OH lauroyl-Asc• deoxygenated soln. contg. phosphate buffer and 0.015 mol LϪ1 CTAB. Radical produced by reaction of tocopherol with Fremy’s salt in a triple mixing apparatus. k is for overall reaction in the aqueous and the micellar phases. 43 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2-O-Octadecylascorbic acid ϩ ϫ 1 MPP–O• Octadecyl-AscH2 3.6 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP–OH Octadecyl-AscH• EtOH 2/1 in deaerated soln. NISa 44 5,7-Di-iso-propyltocoxyl ϩ2-O-Octadecylascorbic acid ϩ ϫ 2 Toc-O• Octadecyl-AscH2 2.2 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Octadecyl-AscH• EtOH 2/1 deoxygenated soln. NISa 45 2,6-Di-tert-butyl-6-methylphenoxylϩ6-O-palmitoylascorbic acid ϩ ϫ 3 2,6-(t-Bu)2-6-MeC6H2O• Palmitoyl-AscH2 2.5 10 benzene 300 therm. Steady-state ESR in 93ROG/STE → 2,6-(t-Bu)2-6-MeC6H2OH deoxygenated soln. ϩ palmitoyl-AscH• contg. the phenol, ascorbyl palmitate, and di-tert- butyl hyponitrite.

46 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-O-Palmitoylascorbic acid ϩ ϫ 1 MPP-O• Palmitoyl-AscH2 7.5 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP-OH Palmitoyl-AscH• EtOH 2/1 in deaerated soln. NISa 47 5,7-Di-iso-propyltocoxylϩ6-O-Palmitoylascorbic acid ϩ ϫ 2 Toc-O• Palmitoyl-AscH2 6.9 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Palmitoyl-AscH• EtOH 2/1 deoxygenated soln. NISa 48 ␣-Tocopheroxylϩ6-O-palmitoylascorbic acid ␣ ϩ ϫ 3 -Toc-O• Palmitoyl-AscH2 3.0 10 7.2 water/micelles 293 s.f. Kinetic ESR in 92LIU/HAN → ␣ ϩ -Toc-OH palmitoyl-AscH• deoxygenated soln. contg. phosphate buffer and 0.015 mol LϪ1 CTAB. Radical produced by reaction of tocopherol with Fremy’s salt in a triple mixing apparatus. k is for overall reaction in the aqueous and the micellar phases.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 177

TABLE 7. Reactions of phenoxyl radicals with ascorbic acid and derivatives—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) pH Solvent ͑K͒ Method Comments Reference

2.8ϫ103 benzene 300 therm. Steady-state ESR in 93ROG/STE deoxygenated soln. contg. the tocopherol, ascorbyl palmitate, and di-tert-butyl hyponitrite. 49 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ6-O-Stearoylascorbic acid ϩ ϫ 1 MPP-O• Stearoyl-AscH2 7.1 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP-OH Stearoyl-AscH• EtOH 2/1 in deaerated soln. NISa 50 5,7-Diethyltocoxylϩ6-O-Stearoylascorbic acid ϩ ϫ 4 Toc-O• Stearoyl-AscH2 4.2 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ → ϩ Toc-OH Stearoyl-AscH• EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 51 5-Methyl-7-tert-butyltocoxylϩ6-O-Stearoylascorbic acid ϩ ϫ 2 Toc-O• Stearoyl-AscH2 6.9 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ → ϩ Toc-OH Stearoyl-AscH• EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 52 5,7-Diisopropyltocoxyl ϩ6-O-Stearoylascorbic acid ϩ ϫ 2 Toc-O• Stearoyl-AscH2 3.5 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ → ϩ Toc-OH Stearoyl-AscH• EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 6.3ϫ102 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ EtOH ͑2/1͒ deoxygenated soln. NISa 53 5-Iso-propyl-7-tert-butyltocoxylϩ6-O-Stearoylascorbic acid ϩ ϫ 1 Toc-O• Stearoyl-AscH2 2.2 10 benzene/ 298 s.f. D.k. at 420 nm in 89MUK/ → ϩ Toc-OH Stearoyl-AscH• EtOH/water deoxygenated soln. NISb ͑2/1/0.1͒ 54 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,6-O-Didocosanoylascorbic acid ϩ ϫ 1 MPP–O• Didocosanoyl-AscH2 5.8 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP–OH Didocosanoyl-AscH• EtOH 2/1 in deaerated soln. NISa 55 5,7-Diisopropyltocoxylϩ5,6-O-Didocosanoylascorbic acid ϩ ϫ 2 Toc-O• Didocosanoyl-AscH2 3.9 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Didocosanoyl-AscH• EtOH 2/1 deoxygenated soln. NISa 56 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,6-O-Dimyristoylascorbic acid ϩ ϫ 1 MPP–O• Dimyristoyl-AscH2 5.0 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP–OH Dimyristoyl-AscH• EtOH 2/1 in deaerated soln. NISa 57 5,7-Diisopropyltocoxylϩ5,6-O-Dimyristoylascorbic acid ϩ ϫ 2 Toc-O• Dimyristoyl-AscH2 4.4 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Dimyristoyl-AscH• EtOH 2/1 deoxygenated soln. NISa 58 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ2,6-O-Dipalmitoylascorbic acid ϩ MPP–O• Dipalmitoyl-AscH2 2.4 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP–OH Dipalmitoyl-AscH• EtOH 2/1 in deaerated soln. NISa 59 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,6-O-Dipalmitoylascorbic acid ϩ ϫ 1 MPP–O• Dipalmitoyl-AscH2 4.4 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP–OH Dipalmitoyl-AscH• EtOH 2/1 in deaerated soln. NISa 60 5,7-Diisopropyltocoxylϩ2,6-O-Dipalmitoylascorbic acid ϩ Toc-O• Dipalmitoyl-AscH2 4.8 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Dipalmitoyl-AscH• EtOH 2/1 deoxygenated soln. NISa 61 5,7-Diisopropyltocoxylϩ5,6-O-Dipalmitoylascorbic acid ϩ ϫ 2 Toc-O• Dipalmitoyl-AscH2 3.1 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Dipalmitoyl-AscH• EtOH 2/1 deoxygenated soln. NISa 62 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,6-O-Dipropanoylascorbic acid ϩ ϫ 1 MPP-O• Dipropanoyl-AscH2 5.0 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP-OH Dipropanoyl-AscH• EtOH 2/1 in deaerated soln. NISa 63 5,7-Diisopropyltocoxylϩ5,6-O-Dipropanoylascorbic acid ϩ ϫ 2 Toc-O• Dipropanoyl-AscH2 3.9 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Dipropanoyl-AscH• EtOH 2/1 deoxygenated soln. NISa 64 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩ5,6-O-Distearoylascorbic acid ϩ ϫ 1 MPP-O• Distearoyl-AscH2 5.5 10 benzene/ 298 s.f. D.k. at 375 and 580 nm 89MUK/ → ϩ ͑ ͒ MPP–OH Distearoyl-AscH• EtOH 2/1 in deaerated soln. NISa 65 5,7-Diisopropyltocoxylϩ5,6-O-Distearoylascorbic acid ϩ ϫ 2 Toc-O• Distearoyl-AscH2 3.3 10 benzene/ 298 s.f. D.k. at 421 nm in 89MUK/ → ϩ ͑ ͒ Toc-OH Distearoyl-AscH• EtOH 2/1 deoxygenated soln. NISa

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 178 P. NETA AND J. GRODKOWSKI

TABLE 8. Reactions of phenoxyl radicals with hydroperoxides and peroxides

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

1 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩn-propyl hydroperoxide ϩ ϫ Ϫ2 2,6-(t-Bu)2-4-(MeOPh)C6H2O• n-PrOOH 3.2 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 2,6-(t-Bu)2-4-(MeOPh)C6H2OH n-PrOO• in deoxygenated soln. 2 5,7-Diethyltocoxylϩn-propyl hydroperoxide ϩ → ϫ Ϫ1 5,7-Et2-Toc-O• n-PrOOH 5,7-Et2-Toc-OH 2.7 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW ϩ n-PrOO• in deoxygenated soln. 3 5,7-Di-iso-propyltocoxylϩn-propyl hydroperoxide ϩ ϫ Ϫ1 5,7-(i-Pr)2-Toc-O• n-PrOOH 1.3 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OH n-PrOO• in deoxygenated soln. 4.6ϫ10Ϫ2 benzene/EtOH 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 4 5,7-Di-iso-propyltocoxylϩn-propyl hydroperoxide-O-d ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• n-PrOOD 1.3 10 benzene/EtOD 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OD n-PrOO• in deoxygenated soln. 5 5-Methyl-7-tert-butyltocoxylϩn-propyl hydroperoxide ϩ ϫ Ϫ2 5-Me-7-t-Bu-Toc-O• n-PrOOH 9.3 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-Me-7-t-Bu-Toc-OH n-PrOO• in deoxygenated soln. 6 5-iso-Propyl-7-tert-butyltocoxylϩn-propyl hydroperoxide ϩ ϫ Ϫ3 5-i-Pr-7-t-Bu-Toc-O• n-PrOOH 8.0 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-i-Pr-7-t-Bu-Toc-OH n-PrOO• in deoxygenated soln. 7 5,7-Diethyl-8-methyltocoxylϩn-propyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-8-Me-Toc-O• n-PrOOH 2.0 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-8-Me-Toc-OH n-PrOO• in deoxygenated soln. 8 5,7-Di-iso-propyl-8-methyltocoxylϩn-propyl hydroperoxide ϩ ϫ Ϫ2 5,7-(i-Pr)2-8-Me-Toc-O• n-PrOOH 2.5 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-8-Me-Toc-OH n-PrOO• in deoxygenated soln. 9 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩiso-propyl hydroperoxide ϩ ϫ Ϫ2 2,6-(t-Bu)2-4-(MeOPh)C6H2O• i-PrOOH 5.2 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 2,6-(t-Bu)2-4-(MeOPh)C6H2OH i-PrOO• in deoxygenated soln. 10 5,7-Diethyltocoxylϩiso-propyl hydroperoxide ϩ → ϫ Ϫ1 5,7-Et2-Toc-O• i-PrOOH 5,7-Et2-Toc-OH 6.8 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW ϩ i-PrOO• in deoxygenated soln. 11 5,7-Di-iso-propyltocoxylϩiso-propyl hydroperoxide ϩ ϫ Ϫ1 5,7-(i-Pr)2-Toc-O• i-PrOOH 2.1 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OH i-PrOO• in deoxygenated soln. 6.3ϫ10Ϫ2 benzene/EtOH 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 12 5,7-Di-iso-propyltocoxylϩiso-propyl hydroperoxide-O-d ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• i-PrOOD 1.6 10 benzene/EtOD 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OD i-PrOO• in deoxygenated soln. 13 5-Methyl-7-tert-butyltocoxylϩiso-propyl hydroperoxide ϩ ϫ Ϫ1 5-Me-7-t-Bu-Toc-O• i-PrOOH 1.8 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-Me-7-t-Bu-Toc-OH i-PrOO• in deoxygenated soln. 14 5-iso-Propyl-7-tert-butyltocoxylϩiso-propyl hydroperoxide ϩ ϫ Ϫ2 5-i-Pr-7-t-Bu-Toc-O• i-PrOOH 1.2 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-i-Pr-7-t-Bu-Toc-OH i-PrOO• in deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 179

TABLE 8. Reactions of phenoxyl radicals with hydroperoxides and peroxides—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

15 5,7-Diethyl-8-methyltocoxylϩiso-propyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-8-Me-Toc-O• i-PrOOH 3.7 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-8-Me-Toc-OH i-PrOO• in deoxygenated soln. 16 5,7-Di-iso-propyl-8-methyltocoxylϩiso-propyl hydroperoxide ϩ ϫ Ϫ2 5,7-(i-Pr)2-8-Me-Toc-O• i-PrOOH 4.7 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-8-Me-Toc-OH i-PrOO• in deoxygenated soln. 17 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ2 2,6-(t-Bu)2-4-(MeOPh)C6H2O• n-BuOOH 3.5 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 2,6-(t-Bu)2-4-(MeOPh)C6H2OH n-BuOO• in deoxygenated soln. 18 5,7-Diethyltocoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-Toc-O• n-BuOOH 3.9 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-Toc-OH n-BuOO• in deoxygenated soln. 19 5,7-Di-iso-propyltocoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-(i-Pr)2-Toc-O• n-BuOOH 1.3 10 benzene 298 chem. D.k. at 417 nm in 88MUK/KOH → ϩ 5,7-(i-Pr)2-Toc-OH n-BuOO• deaerated soln., H-abstr. 1.3ϫ10Ϫ1 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 6.4ϫ10Ϫ2 benzene/EtOH 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 20 5,7-Di-iso-propyltocoxylϩn-butyl hydroperoxide-O-d ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• n-BuOOD 1.9 10 benzene/EtOD 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OD n-BuOO• in deoxygenated soln. 21 5-Methyl-7-tert-butyltocoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ1 5-Me-7-t-Bu-Toc-O• n-BuOOH 1.2 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-Me-7-t-Bu-Toc-OH n-BuOO• in deoxygenated soln. 22 5-iso-Propyl-7-tert-butyltocoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ3 5-i-Pr-7-t-Bu-Toc-O• n-BuOOH 7.8 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-i-Pr-7-t-Bu-Toc-OH n-BuOO• in deoxygenated soln. 23 5,7-Diethyl-8-methyltocoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-8-Me-Toc-O• n-BuOOH 2.2 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-8-Me-Toc-OH n-BuOO• in deoxygenated soln. 24 5,7-Di-iso-propyl-8-methyltocoxylϩn-butyl hydroperoxide ϩ ϫ Ϫ2 5,7-(i-Pr)2-8-Me-Toc-O• n-BuOOH 2.9 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-8-Me-Toc-OH n-BuOO• in deoxygenated soln. 25 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩsec-butyl hydroperoxide ϩ ϫ Ϫ2 2,6-(t-Bu)2-4-(MeOPh)C6H2O• sec-BuOOH 6.6 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → 2,6-(t-Bu)2- in deoxygenated ϩ 4-(MeOPh)C6H2OH sec-BuOO• soln. 26 5,7-Diethyltocoxylϩsec-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-Toc-O• sec-BuOOH 6.4 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-Toc-OH sec-BuOO• in deoxygenated soln. 27 5,7-Di-iso-propyltocoxylϩsec-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-(i-Pr)2-Toc-O• sec-BuOOH 2.4 10 benzene 298 chem. D.k. at 417 nm in 88MUK/KOH → ϩ 5,7-(i-Pr)2-Toc-OH sec-BuOO• deaerated soln., H-abstr. 2.4ϫ10Ϫ1 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 180 P. NETA AND J. GRODKOWSKI

TABLE 8. Reactions of phenoxyl radicals with hydroperoxides and peroxides—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

1.0ϫ10Ϫ1 benzene/EtOH 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 28 5,7-Di-iso-propyltocoxylϩsec-butyl hydroperoxide-O-d ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• sec-BuOOD 2.4 10 benzene/EtOD 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OD sec-BuOO• in deoxygenated soln. 29 5-Methyl-7-tert-butyltocoxylϩsec-butyl hydroperoxide ϩ ϫ Ϫ1 5-Me-7-t-Bu-Toc-O• sec-BuOOH 2.1 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-Me-7-t-Bu-Toc-OH sec-BuOO• in deoxygenated soln. 30 5-iso-Propyl-7-tert-butyltocoxylϩsec-butyl hydroperoxide ϩ ϫ Ϫ2 5-i-Pr-7-t-Bu-Toc-O• sec-BuOOH 1.3 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-i-Pr-7-t-Bu-Toc-OH sec-BuOO• in deoxygenated soln. ϩ OH sec-BuOO• 31 5,7-Diethyl-8-methyltocoxyl ϩsec-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-8-Me-Toc-O• sec-BuOOH 3.5 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-8-Me-Toc-OH sec-BuOO• in deoxygenated soln. 32 5,7-Di-iso-propyl-8-methyltocoxylϩsec-butyl hydroperoxide ϩ ϫ Ϫ2 5,7-(i-Pr)2-8-Me-Toc-O• sec-BuOOH 5.0 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-8-Me-Toc-OH sec-BuOO• in deoxygenated soln. 33 2,6-Di-tert-butyl-4-(4Ј-methoxyphenyl)phenoxylϩtert-butyl hydroperoxide ϩ ϫ Ϫ2 2,6-(t-Bu)2-4-(MeOPh)C6H2O• t-BuOOH 9.3 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → 2,6-(t-Bu)2- in deoxygenated ϩ 4-(MeOPh)C6H2OH t-BuOO• soln. 34 2,2,5,7,8-Pentamethylchroman-6-oxylϩtert-butyl hydroperoxide ϩ → ϩ ϫ Ϫ1 PMC-O• t-BuOOH PMC-OH t-BuOO• 3.7 10 EtOH 310 chem. D.k. of ESR signal 00WAT/NOG in deaerated soln. contg. galvinoxyl. 35 5,7-Diethyltocoxylϩtert-butyl hydroperoxide ϩ → 5,7-Et2-Toc-O• t-BuOOH 5,7-Et2-Toc-OH 1.1 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW ϩ t-BuOO• in deoxygenated soln. 36 5,7-Diisopropyltocoxylϩtert-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-(i-Pr)2-Toc-O• t-BuOOH 3.7 10 benzene 298 chem. D.k. at 417 nm in 88MUK/KOH → ϩ 5,7-(i-Pr)2-Toc-OH t-BuOO• deaerated soln., H-abstr. 3.7ϫ10Ϫ1 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 1.7ϫ10Ϫ1 benzene/EtOH 298 s.f. D.k. at 400–450 nm 92NAG/SAW in deoxygenated soln. 37 5,7-Di-iso-propyltocoxylϩtert-butyl hydroperoxide-O-d ϩ ϫ Ϫ2 5,7-(i-Pr)2-Toc-O• t-BuOOD 3.5 10 benzene/EtOD 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-Toc-OD t-BuOO• in deoxygenated soln. 38 5-Methyl-7-tert-butyltocoxylϩtert-butyl hydroperoxide ϩ ϫ Ϫ1 5-Me-7-t-Bu-Toc-O• t-BuOOH 3.5 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-Me-7-t-Bu-Toc-OH t-BuOO• in deoxygenated soln. 39 5-iso-Propyl-7-tert-butyltocoxylϩtert-butyl hydroperoxide ϩ ϫ Ϫ2 5-i-Pr-7-t-Bu-Toc-O• t-BuOOH 1.9 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5-i-Pr-7-t-Bu-Toc-OH t-BuOO• in deoxygenated soln. 40 5,7-Diethyl-8-methyltocoxylϩtert-butyl hydroperoxide ϩ ϫ Ϫ1 5,7-Et2-8-Me-Toc-O• t-BuOOH 6.5 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-Et2-8-Me-Toc-OH t-BuOO• in deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 181

TABLE 8. Reactions of phenoxyl radicals with hydroperoxides and peroxides—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

41 5,7-Di-iso-propyl-8-methyltocoxylϩtert-butyl hydroperoxide ϩ ϫ Ϫ2 5,7-(i-Pr)2-8-Me-Toc-O• t-BuOOH 7.0 10 benzene 298 s.f. D.k. at 400–450 nm 92NAG/SAW → ϩ 5,7-(i-Pr)2-8-Me-Toc-OH t-BuOO• in deoxygenated soln. 42 ␣-Tocopheroxylϩtert-butyl hydroperoxide ␣ ϩ → ␣ ϩ ϫ Ϫ1 -Toc-O• t-BuOOH -Toc-OH t-BuOO• 4.1 10 EtOH 310 chem. D.k. of ESR signal 00WAT/NOG in deaerated soln. contg. galvinoxyl. 43 2,3-Dihydro-2,2,4,6-tetramethylbenzofuran-5-oxylϩtert-butyl hydroperoxide ϩ → ϩ ϫ Ϫ1 BOM-O• t-BuOOH BOM-OH t-BuOO• 2.6 10 EtOH 310 chem. D.k. of ESR signal 00WAT/NOG in deaerated soln. contg. galvinoxyl. 44 2,3-Dihydro-2,2-dimethyl-4,6-di-tert-butylbenzofuran-5-oxylϩtert-butyl hydroperoxide ϩ → ϩ ϫ Ϫ1 BOB-O• t-BuOOH BOB-OH t-BuOO• 1.1 10 EtOH 310 chem. D.k. of ESR signal 00WAT/NOG in deaerated soln. contg. galvinoxyl. 45 2,3-Dihydro-2,2-dipentyl-4,6-di-tert-butylbenzofuran-5-oxylϩtert-butyl hydroperoxide ϩ → ϫ Ϫ1 BO-653-O• t-BuOOH BO-653-OH 1.4 10 EtOH 310 chem. D.k. of ESR signal 00WAT/NOG ϩ t-BuOO• in deaerated soln. contg. galvinoxyl. 46 2,4,6-Tri-tert-butylphenoxylϩcumene hydroperoxide ϩ ϫ Ϫ1 2,4,6-(t-Bu)3C6H2O• PhCMe2OOH 3.7 10 cumene 313 s.f. D.k. at 400 or 630 70MAH/ → ϩ 2,4,6-(t-Bu)3C6H2OH PhCMe2OO• nm in deoxygenated DARb soln. 1.8ϫ10Ϫ1 benzene 303 chem. Decay of ESR 73GRI/DEN signal in deoxygenated soln. The phenoxyl radical produced by oxidation with ϭ PbO2 . log A 7.1, ϭ Ϫ1 Ea 45.6 kJ mol . Data for reverse reaction, derived from ﬁtting to complex ϭ mechanism: kr 4 ϫ103, log Aϭ6.5, ϭ Ϫ1 Ea 16.7 kJ mol . ϫ Ϫ1 2.5 10 CCl4 298 chem. D.k. at 400 nm in 89VAR/DEN deoxygenated soln. The phenoxyl radical produced by oxidation with

PbO2 .

47 2,4,6-Tri-tert-butylphenoxylϩtetralin hydroperoxide ϩ ϫ Ϫ1 2,4,6-(t-Bu)3C6H2O• TOOH 6.9 10 PhCl 297 s.f. D.k. at 400 or 630 67MAH/DAR → ϩ 2,4,6-(t-Bu)3C6H2OH TOO• 2.0 333 nm in deoxygenated soln. 3.4ϫ10Ϫ1 PhCl 303 s.f. D.k. at 400 or 630 70MAH/ 5.5ϫ10Ϫ1 318 nm in deoxygenated DARb 1.0 333 soln. 4.3ϫ10Ϫ1 PhCl/tetralin 303 s.f. D.k. at 400 or 630 70MAH/ 6.6ϫ10Ϫ1 318 nm in deoxygenated DARb 9.7ϫ10Ϫ1 333 soln. 48 2,4,6-Tri-tert-butylphenoxylϩ9,10-dihydroanthracene hydroperoxide ϩ ϫ Ϫ1 2,4,6-(t-Bu)3C6H2O• DHAOOH 2.0 10 benzene 297 s.f. D.k. at 400 or 630 67MAH/DAR → ϩ 2,4,6-(t-Bu)3C6H2OH DHAOO• nm in deoxygenated soln. 1.8ϫ10Ϫ1 PhCl 297 s.f. D.k. at 400 or 630 67MAH/DAR 8.7ϫ10Ϫ1 333 nm in deoxygenated soln.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 182 P. NETA AND J. GRODKOWSKI

TABLE 8. Reactions of phenoxyl radicals with hydroperoxides and peroxides—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

1.5ϫ10Ϫ1 PhCl 303 s.f. D.k. at 400 or 630 70MAH/ nm in deoxygenated DARb soln. 49 5,7-Diisopropyl-2,2-dimethylchroman-6-oxylϩmethyl linoleate hydroperoxide ϩ → ϩ ϫ Ϫ1 DIDMCO• MLOOH DIDMCOH MLOO• 1.3 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW deaerated soln., H-abstr., kϭ1.1 ϫ10Ϫ1 in 5% Triton X-100 micellar soln. 50 5,7-Diethyltocoxylϩmethyl linoleate hydroperoxide ϩ → ϫ Ϫ1 5,7-Et2-Toc-O• MLOOH 5,7-Et2-Toc-OH 2.5 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW ϩ MLOO• deaerated soln., H-abstr. 51 5,7-Di-iso-propyltocoxylϩmethyl linoleate hydroperoxide ϩ ϫ Ϫ1 5,7-(i-Pr)2-Toc-O• MLOOH 1.3 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → ϩ 5,7-(i-Pr)2-Toc-OH MLOO• deaerated soln., H-abstr., kϭ6.9 ϫ10Ϫ2 in 5% Triton X-100 micellar soln. 2.5ϫ10Ϫ3 t-BuOH 298 chem. D.k. at 417 nm in 93MUK/SAW deaerated soln., H-abstr., kϭ6.9 ϫ10Ϫ2 in 5% Triton X-100 micellar soln. 52 5-Methyl-7-tert-butyltocoxylϩmethyl linoleate hydroperoxide ϩ ϫ Ϫ2 5-Me-7-t-Bu-Toc-O• MLOOH 9.1 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → ϩ 5-Me-7-t-Bu-Toc-OH MLOO• deaerated soln., H-abstr. 53 5-Isopropyl-7-tert-butyltocoxylϩmethyl linoleate hydroperoxide ϩ ϫ Ϫ3 5-i-Pr-7-t-Bu-Toc-O• MLOOH 7.8 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → ϩ 5-i-Pr-7-t-Bu-Toc-OH MLOO• deaerated soln., H-abstr. 54 5,7-Diethyl-8-methyltocoxylϩmethyl linoleate hydroperoxide ϩ ϫ Ϫ1 5-Et2-8-Me-Toc-O• MLOOH 1.3 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → ϩ 5-Et2-8-Me-Toc-OH MLOO• deaerated soln., H-abstr. 55 5,7-Di-iso-propyl-8-methyltocoxylϩmethyl linoleate hydroperoxide ϩ ϫ Ϫ2 5-(i-Pr)2-8-Me-Toc-O• MLOOH 2.1 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW → ϩ 5-(i-Pr)2-8-Me-Toc-OH MLOO• deaerated soln., H-abstr. 56 ␣-Tocopheroxylϩmethyl linoleate hydroperoxide ␣ ϩ → ␣ ϩ ϫ Ϫ1 -Toc-O• MLOOH -Toc-OH MLOO• 5.0 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW deaerated soln., H-abstr. 57 2,3-Dihydro-2,2-dimethyl-4,6-diisopropylbenzofuran-5-oxylϩmethyl linoleate hydroperoxide ϩ → ϩ ϫ Ϫ2 BF-O• MLOOH BF-OH MLOO• 8.4 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW deaerated soln., H-abstr. 58 5,7-Di-iso-propyltocoxylϩphosphatidylcholine hydroperoxide ϩ → ϩ ϫ Ϫ2 Toc-O• PCOOH Toc-OH PCOO• 1.1 10 benzene 298 chem. D.k. at 417 nm in 93MUK/SAW deaerated soln., H-abstr., kϭ2.0 ϫ10Ϫ2 in 5% Triton X-100 micellar soln. 4.7ϫ10Ϫ3 t-BuOH 298 chem. D.k. at 417 nm in 93MUK/SAW deaerated soln., H-abstr., kϭ2.0 ϫ10Ϫ2 in 5% Triton X-100 micellar soln. 59 2,4,6-Tri-tert-butylphenoxylϩdi-tert-butylperoxide ϩ ϫ Ϫ4 2,4,6-(t-Bu)3-C6H2O• (t-Bu)OO(t-Bu) 8.7 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL → ϭ products log A 4.6, Ea ϭ41.4 kJ molϪ1.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 183

TABLE 8. Reactions of phenoxyl radicals with hydroperoxides and peroxides—Continued

Phenoxylϩreactant k T No. Reaction (L molϪ1 sϪ1) Solvent ͑K͒ Method Comments Reference

60 4-Phenyl-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϩ ϫ Ϫ4 4-Ph-2,6-(t-Bu)2-C6H2O• (t-Bu)OO(t-Bu) 3.6 10 t-Bu2O2 283 chem. D.k. of ESR signal. 67PRO/SOL → ϭ products /pentane log A 5.0, Ea ϭ46.0 kJ molϪ1. 61 4-(4-Methylphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-MePh)-2,6-(t-Bu)2-C6H2O• 2.4 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.0, Ea → products ϭ46.9 kJ molϪ1. 62 4-(4-Ethylphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-EtPh)-2,6-(t-Bu)2-C6H2O• 2.3 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.0, Ea → products ϭ46.9 kJ molϪ1. 63 4-(4-Isopropylphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-i-PrPh)-2,6-(t-Bu)2-C6H2O• 2.4 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.0, Ea → products ϭ46.9 kJ molϪ1. 64 4-(4-tert-Butylphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-t-BuPh)-2,6-(t-Bu)2-C6H2O• 2.5 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.0, Ea → products ϭ46.9 kJ molϪ1. 65 4-(2-Methoxyphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(2-MeOPh)-2,6-(t-Bu)2-C6H2O• 2.8 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.25, Ea → products ϭ47.7 kJ molϪ1. 66 4-(4-Methoxyphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-MeOPh)-2,6-(t-Bu)2-C6H2O• 1.5 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.4, Ea → products ϭ49.8 kJ molϪ1. 67 4-(4-Acetylphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-CH3COPh)-2,6-(t-Bu)2-C6H2O• 8.7 10 t-Bu2O2 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 4.8, Ea → products /pentane ϭ42.7 kJ molϪ1. 68 4-(4-Chlorophenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-ClPh)-2,6-(t-Bu)2-C6H2O• 6.2 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 4.9, Ea → products ϭ43.9 kJ molϪ1. 69 4-(4-Phenoxyphenyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(4-PhOPh)-2,6-(t-Bu)2-C6H2O• 2.5 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.0, Ea → products ϭ46.9 kJ molϪ1. 70 4-(2-Naphthyl)-2,6-di-tert-butylphenoxylϩdi-tert-butylperoxide ϫ Ϫ4 4-(2-Naphthyl)-2,6-(t-Bu)2-C6H2O• 9.1 10 t-Bu2O2/pentane 283 chem. D.k. of ESR signal. 67PRO/SOL ϩ ϭ (t-Bu)OO(t-Bu) log A 5.0, Ea → products ϭ43.5 kJ molϪ1. 71 Tetra(tert-butyl)indophenoxylϩdi-tert-butylperoxide ϩ → ϫ Ϫ4 TBIP-O• (t-Bu)OO(t-Bu) products 1.3 10 t-Bu2O2/pentane 313 chem. D.k. of ESR signal 68PRO/SOL in deaerated soln. ϭ log A 6.5, Ea ϭ62.3 kJ molϪ1. 72 Galvinoxylϩdi-tert-butylperoxide ϩ → ϫ Ϫ4 Galv-O• (t-Bu)OO(t-Bu) products 1.3 10 t-Bu2O2/pentane 313 chem. D.k. of ESR signal 68PRO/SOL in deaerated soln. ϭ log A 6.5, Ea ϭ62.3 kJ molϪ1.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 184 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

Phenoxyl and semiquinone radicals as oxidants 1 Phenoxylϩ4-methylphenoxide ϩ Ϫ Ϫ ϫ 9 ϫ 7 C6H5O• 4-CH3C6H4O C6H5O 1.3 10 2 10 11–12 p.r. P.b.k. at 412 nm in 90LIN/SHE ϩ 4-CH3C6H4O• N2O-satd. soln. I ϭ0.1. 2 Phenoxylϩtyrosine ϩ Ϫ Ϫϩ ϫ 8 ϫ 7 C6H5O• TyrO C6H5O TyrO• 4.9 10 2.8 10 11–12 p.r. P.b.k. at 416 nm in 90LIN/SHE N2O-satd. soln. I ϭ0.5. 3 4-Methylphenoxylϩ4-methoxyphenol ϩ Ϫ ϫ 9 ϫ 6 4-CH3C6H4O• 4-CH3OC6H4O 1.4 10 5.5 10 11–12 p.r. P.b.k. at 425 nm in 90LIN/SHE Ϫϩ 4-CH3C6H4O 4-CH3OC6H4O• N2O-satd. soln. I ϭ0.2. 4 3,5-Dimethoxyphenoxylϩ4-methoxyphenol ϩ Ϫ ϫ 8 ϫ 6 3,5-(CH3O)2C6H3O• 4-CH3OC6H4O 8.0 10 1.8 10 13.5 p.r. D.k. at 505 nm in 91JOV/TOS Ϫϩ 3,5-(CH3O)2C6H3O 4-CH3OC6H4O• N2O-satd. soln. 5 4-Aminophenoxylϩ4-(N,N-dimethylamino)phenol ϩ Ϫ ϫ 7 ϫ 7 4-H2NC6H4O• 4-(CH3)2NC6H4O 5 10 1 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET Ϫϩ 4-H2NC6H4O 4-(CH3)2NC6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 6 1,3-Benzosemiquinone anionϩ4-(N,N-dimethylamino)phenol Ϫ ϩ Ϫ Ϸ ϫ 7 3-(O )C6H4O• 4-(CH3)2NC6H4O 7 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET Ϫ Ϫϩ 3-(O )C6H4O 4-(CH3)2NC6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ 0.5. Reported kr may be incorrect. 7 Indole-5-oxylϩ4-(N,N-dimethylamino)phenol ϩ Ϫ ϫ 7 Ϸ ϫ 6 5-Ind-O• 4-(CH3)2NC6H4O 3 10 3 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET Ϫϩ 5-Ind-O 4-(CH3)2NC6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 8 Tryptophan-5-oxylϩ4-(N,N-dimethylamino)phenol ϩ Ϫ ϫ 7 ϫ 6 5-Trp-O• 4-(CH3)2NC6H4O 3 10 2 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET Ϫϩ 5-Trp-O 4-(CH3)2NC6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 9 coumarin-7-oxylϩ4-(N,N-dimethylamino)phenol ϩ Ϫ ϫ 8 ϫ 5 7-coumarin-O• 4-(CH3)2NC6H4O 2.4 10 6 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET Ϫϩ 7-coumarin-O 4-(CH3)2NC6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 10 4-Iodophenoxylϩ4-ﬂuorophenoxide ϩ Ϫ Ϫ ϫ 9 ϫ 7 4-IC6H4O• 4-FC6H4O 4-IC6H4O 1.4 10 9 10 11–12 p.r. D.k. at 500 nm in 90LIN/SHE ϩ 4-FC6H4O• N2O-satd. soln. I ϭ0.1. 11 4-Iodophenoxylϩ4-bromophenoxide ϩ Ϫ Ϫ Ϸ ϫ 8 Ϸ ϫ 8 4-IC6H4O• 4-BrC6H4O 4-IC6H4O 7 10 7 10 11–12 p.r. D.k. at 500 nm in 90LIN/SHE ϩ 4-BrC6H4O• N2O-satd. soln. I ϭ0.1. 12 4-Carboxyphenoxylϩ4-iodophenoxide Ϫ ϩ Ϫ ϫ 9 ϫ 7 4-(CO2 )C6H4O• 4-IC6H4O 2.2 10 7 10 11–12 p.r. P.b.k. at 500 nm in 90LIN/SHE Ϫ Ϫϩ 4-(CO2 )C6H4O 4-IC6H4O• N2O-satd. soln. I ϭ0.1. 13 4-Methoxyphenoxylϩ5-hydroxytryptophan ϩ Ϫ Ϫ ϫ 8 ϫ 5 4-CH3OC6H4O• 5-Trp-O 4-CH3OC6H4O 9.6 10 5 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET ϩ 5-Trp-O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 185

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

14 1,3-Benzosemiquinone anionϩ5-hydroxytryptophan Ϫ ϩ Ϫ Ϫ Ϫϩ ϫ 8 ϫ 5 3-(O )C6H4O• 5-Trp-O 3-(O )C6H4O 5-Trp-O• 4 10 5.5 10 13.5 p.r. P.b.k. at 490 nm in 82STE/NET N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 15 4-Carboxy-1,2-benzosemiquinone anionϩTrolox C Ϫ Ϫϩ ϫ 7 ϫ 5 3,4-(O )(O•)C6H3CO2 TxOH 6.1 10 5 10 7 p.r. P.b.k. at 425 nm in 94JOV/STE Ϫϩ 3,4-(OH)2C6H3CO2 TxO• N2O-satd. soln. contg. bromide. 16 3,4-Dihydroxycinnamate semiquinone anionϩTrolox C Ϫ ϭ Ϫϩ ϫ 5 ϫ 4 3,4-(O )(O•)C6H3CH CHCO2 TxOH 2.6 10 3 10 7 p.r. P.b.k. at 425 nm in 94JOV/STE ϭ Ϫϩ 3,4-(OH)2C6H3CH CHCO2 TxO• N2O-satd. soln. contg. bromide. 17 Catechin semiquinone anionϩTrolox C ϩ ϩ ϫ 8 ϫ 6 catechin-O• TxOH catechin-OH TxO• 2 10 6 10 7 p.r. P.b.k. at 425 nm in 94JOV/STE N2O-satd. soln. contg. bromide. 18 Rutin semiquinone anionϩTrolox C ϩ ϩ ϫ 6 ϫ 4 rutin-O• TxOH rutin-OH TxO• 3.6 10 4 10 7 p.r. P.b.k. at 425 nm 94JOV/STE and d.k. at 450 nm in

N2O-satd. soln. contg. bromide. 19 Alanyltyrosylϩguanosine anion ϩ Ϫ ϫ 6 ϫ 7 Alanyltyrosine-O• Guanosine 1 10 1 10 7 p.r. P.b.k. in N2O-satd. 86JOV/HAR Ϫϩ soln. contg. Alanyltyrosine-O Guanosine• bromide or azide. 20 Tyrosine methyl ester phenoxyl radicalϩguanosine anion ϩ Ϫ ϫ 6 ϫ 6 Tyrosine methyl ester-O• Guanosine 5 10 8.9 10 7 p.r. P.b.k. in N2O-satd. 86JOV/HAR Ϫϩ soln. contg.3 Tyrosine methyl ester-O Guanosine• bromide or azide. 21 4-(N-Methylamino)phenoxylϩcatechol ϩ Ϫ Ϫ ϫ 7 ϫ 5 4-(CH3NH)C6H4O• 2-(O )C6H4O 3 10 4.6 10 13.5 p.r. D.k. at 470 nm in 82STE/NET Ϫϩ Ϫ 4-(CH3NH)C6H4O 2-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 22 4-(N,N-Dimethylamino͒phenoxylϩcatechol ϩ Ϫ Ϫ ϫ 7 ϫ 5 4-(CH3)2NC6H4O• 2-(O )C6H4O 3 10 2 10 13.5 p.r. D.k. at 490 nm in 82STE/NET Ϫϩ Ϫ 4-(CH3)2NC6H4O 2-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 23 2-Acetyl-1,4-benzosemiquinone anionϩcatechol Ϫ ϩ Ϫ Ϫ ϫ 7 ϫ 6 2,5-(O )(O•)C6H3COCH3 2-(O )C6H4O 1.9 10 1.5 10 13.5 p.r. D.k. at 520 nm in 79STE/NET Ϫ ϩ Ϫ 2,5-(O )2C6H3COCH3 2-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 24 Trolox phenoxyl radicalϩcatechol ϩ Ϫ Ϫ Ϫϩ Ϫ ϫ 7 ϫ 5 TxO• 2-(O )C6H4O TxO 2-(O )C6H4O• 7 10 3 10 13.5 p.r. D.k. at 430 nm in 82STE/NET N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 25 4-Methylphenoxylϩresorcinol ϩ Ϫ Ϫ ϫ 8 ϫ 5 Ͼ 4-CH3C6H4O• 3-(O )C6H4O 7.1 10 2.7 10 11 p.r. P.b.k. at 440 nm 96ARM/SUN Ϫϩ Ϫ 4-CH3C6H4O 3-(O )C6H4O• and d.k. at 385, 400nmin

N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 186 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

26 Acetaminophenoxylϩresorcinol ϩ Ϫ Ϫ ϫ 7 ϫ 6 4-CH3CONHC6H4O• 3-(O )C6H4O 1.7 10 2.3 10 12.4 p.r. D.k. at 380 and 88BIS/TAB Ϫϩ Ϫ 4-CH3CONHC6H4O 3-(O )C6H4O• 520nmin N2O-satd. soln. Iϭ0.3. 27 4-(N-Methylamino͒phenoxylϩhydroquinone ϩ Ϫ Ϫ Ϸ ϫ 7 Ϸ ϫ 5 4-(CH3NH)C6H4O• 4-(O )C6H4O 7.5 10 3 10 13.5 p.r. D.k. at 470 nm 82STE/NET Ϫϩ Ϫ 4-(CH3NH)C6H4O 4-(O )C6H4O• and p.b.k. at 430 nm in N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 28 4-(N,N-Dimethylamino)phenoxylϩhydroquinone ϩ Ϫ Ϫ ϫ 8 ϫ 5 4-(CH3)2NC6H4O• 4-(O )C6H4O 1 10 3 10 13.5 p.r. D.k. at 490 nm 82STE/NET Ϫϩ Ϫ 4-(CH3)2NC6H4O 4-(O )C6H4O• and p.b.k. at 430 nm in N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 29 1,2-Benzosemiquinone anionϩhydroquinone Ϫ ϩ Ϫ Ͻ ϫ 5 2-(O )C6H4O• 4-HOC6H4O 1 10 7 p.r. P.b.k. at 430 nm in 79STE/NET Ϫϩ Ϫ Ϸ ϫ 5 Ϸ ϫ 4 2-HOC6H4O 4-(O )C6H4O• 8 10 5 10 11.0 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 30 1,2-Benzosemiquinone anionϩhydroquinone Ϫ ϩ Ϫ Ϫ ϫ 6 ϫ 5 2-(O )C6H4O• 4-(O )C6H4O 2.0 10 8.5 10 13.5 p.r. P.b.k. at 430 nm in 79STE/NET Ϫ Ϫϩ Ϫ 2-(O )C6H4O 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 31 3-Carboxy-1,2-benzosemiquinone anionϩhydroquinone Ϫ Ϫϩ Ϫ Ϫ ϫ 5 ϫ 3 2,3-(O )(O•)C6H3CO2 4-(O )C6H4O 4.2 10 9 10 13.5 p.r. P.b.k. at 430 nm in 79STE/NET Ϫ Ϫϩ Ϫ 2,3-(O )2C6H3CO2 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 32 4-Carboxy-1,2-benzosemiquinone anionϩhydroquinone Ϫ Ϫϩ Ϫ Ϫ ϫ 6 ϫ 5 3,4-(O )(O•)C6H3CO2 4-(O )C6H4O 6.0 10 1.2 10 13.5 p.r. P.b.k. at 430 nm in 79STE/NET Ϫ Ϫϩ Ϫ 3,4-(O )2C6H3CO2 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 33 Pyrogallol semiquinone anionϩhydroquinone Ϫ ϩ Ϫ Ϫ Ϸ ϫ 5 Ϸ ϫ 5 1,2,3-(O )2C6H3O• 4-(O )C6H4O 1 10 1 10 13.5 p.r. P.b.k. at 430 nm in 79STE/NET Ϫ ϩ Ϫ 1,2,3-C6H3(O )3 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 34 Ellagic acid semiquinone anionϩhydroquinone ϩ Ϫ Ϫ ϫ 8 Ϸ ϫ 5 ellagic acid(O•) 4-(O )C6H4O 1.1 10 4 10 13.5 p.r. D.k. at 530 nm in 82STE/NET Ϫ ϩ Ϫ ellagic acid(O ) 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 35 Quinalizarin semiquinone anionϩhydroquinone ϩ Ϫ Ϫ 7 ϫ 6 quinalizarin radical 4-(O )C6H4O 2.5ϫ10 3 10 13.5 p.r. D.k. at 700 nm in 82STE/NET ϩ Ϫ quinalizarin 4-(O )C6H4O• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 187

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

36 1,3-Benzosemiquinone anionϩ2,3-dihydroxybenzoate ion Ϫ ϩ Ϫ Ϫ ϫ 7 ϫ 4 3-(O )C6H4O• 2,3-(O )2C6H3CO2 4.7 10 5.2 10 13.5 p.r. D.k. at 450 nm in 79STE/NET Ϫ Ϫϩ Ϫ Ϫ 3-(O )C6H4O 2,3-(O )(O•)C6H3CO2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 37 1,3-Benzosemiquinone anionϩ3,4-dihydroxybenzoate ion Ϫ ϩ Ϫ Ϫ ϫ 8 ϫ 5 3-(O )C6H4O• 3,4-(O )2C6H3CO2 2.5 10 1.9 10 13.5 p.r. D.k. at 450 nm in 79STE/NET Ϫ Ϫϩ Ϫ Ϫ 3-(O )C6H4O 3,4-(O )(O•)C6H3CO2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 38 5-Carboxy-1,3-benzosemiquinone anionϩ3,4-dihydroxybenzoate ion Ϫ Ϫϩ Ϫ Ϫ Ϸ ϫ 7 Ϸ ϫ 5 3,5-(O )(O•)C6H3CO2 3,4-(O )2C6H3CO2 4.2 10 1 10 13.5 p.r. D.k. at 450 nm in 79STE/NET Ϫ Ϫϩ Ϫ Ϫ 3,5-(O )2C6H3CO2 3,4-(O )(O•)C6H3CO2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 39 4-(N,N-dimethylamino)phenoxylϩnorepinephrin ϩ Ϫ ϫ 7 ϫ 5 4-(CH3)2NC6H4O• 3,4-(O )2C6H3CH(CH2NH2)OH 3 10 2 10 13.5 p.r. D.k. at 490 nm in 82STE/NET Ϫϩ ͑ Ϫ͒͑ ͒ 4-(CH3)2NC6H4O 3,4- O O• C6H3CH(CH2NH2)OH N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 40 4-(N,N-Dimethylamino)phenoxylϩdopamine ϩ Ϫ ϫ 7 ϫ 5 4-(CH3)2NC6H4O• 3,4-(O )2C6H3CH2CH2NH2 9 10 3 10 13.5 p.r. D.k. at 490 nm in 82STE/NET Ϫϩ Ϫ 4-(CH3)2NC6H4O 3,4-(O )(O•)C6H3CH2CH2NH2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 41 4-(N,N-Dimethylamino)phenoxylϩ3,4-dihydroxycinnamate anion ϩ Ϫ ϭ Ϫ ϫ 8 ϫ 6 4-(CH3)2NC6H4O• 3,4-(O )2C6H3CH CHCO2 1.5 10 5 10 13.5 p.r. D.k. at 490 nm in 82STE/NET Ϫϩ Ϫ ϭ Ϫ 4-(CH3)2NC6H4O 3,4-(O )(O•)C6H3CH CHCO2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 42 4-(Dimethylamino)phenoxylϩ2-t-Butyl-1,4-hydroquinone ϩ Ϫ ϫ 8 ϫ 5 4-((CH3)2N)C6H4O• 2-((CH3)3C)-1,4-C6H3(O )2 2.9 10 2.7 10 13.5 p.r. D.k. at 490 nm in 95DOH/BER Ϫϩ Ϫ 4-((CH3)2N)C6H4O 2-((CH3)3C)-1,4-C6H3(O )(O•) N2O-satd. soln. contg. ethylene glycol. 43 1,2-Benzosemiquinone anionϩ2,5-dihydroxybenzoate ion Ϫ ϩ Ϫ Ϫ ϫ 5 ϫ 5 2-(O )C6H4O• 2,5-(O )2C6H3CO2 1.8 10 1.2 10 13.5 p.r. P.b.k. at 430 nm in 79STE/NET Ϫ Ϫϩ Ϫ Ϫ 2-(O )C6H4O 2,5-(O )(O•)C6H3CO2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 44 1,2-Benzosemiquinone anionϩ2,5-dihydroxyphenylacetate ion Ϫ ϩ Ϫ Ϫ ϫ 6 ϫ 5 2-(O )C6H4O• 2,5-(O )2C6H4CH2CO2 3.5 10 1 10 13.5 p.r. P.b.k. at 430 nm in 82STE/NET Ϫ Ϫϩ Ϫ Ϫ 2-(O )C6H4O 2,5-(O )(O•)C6H4CH2CO2 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 45 1,2-Benzosemiquinone anionϩmethoxyhydroquinone Ϫ ϩ Ϫ ϫ 7 Ϸ ϫ 5 2-(O )C6H4O• 2,5-(O )2C6H3OCH3 2.0 10 1.3 10 13.5 p.r. P.b.k. at 430 nm in 79STE/NET Ϫ Ϫϩ Ϫ 2-(O )C6H4O 2,5-(O )(O•)C6H3OCH3 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 188 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

46 4-Carboxy-1,2-benzosemiquinone anionϩdurohydroquinone Ϫ Ϫϩ Ϫ ϫ 7 ϫ 5 3,4-(O )(O•)C6H3CO2 1,4-(O )2C6(CH3)4 7.5 10 1 10 13.5 p.r. P.b.k. at 445 nm in 79STE/NET Ϫ Ϫϩ Ϫ 3,4-(O )2C6H3CO2 1,4-(O )(O•)C6(CH3)4 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 47 4-(N,N-Dimethylamino)phenoxylϩ5-hydroxydopamine ϩ Ϫ ϫ 7 ϫ 4 4-(CH3)2NC6H4O• (O )3C6H2CH2CH2NH2 1.2 10 9 10 13.5 p.r. D.k. at 490 nm in 82STE/NET Ϫ 4-(CH3)2NC6H4O N2O-satd. soln. ϩ Ϫ Ϫ1 (O )2(O•)C6H2CH2CH2NH2 contg. 1 mol L ethylene glycol. I ϭ0.5. 48 Rutin semiquinoneϩmethyl gallate ϩ ϫ 5 ϫ 4 rutin-O• 3,4,5-(OH)3C6H2CO2CH3 8.3 10 7 10 7 p.r. Kinetics in 95JOV/HAR ϩ Ϫ rutin-OH 3,4,5-(OH)(O )(O•)C6H2CO2CH3 N2O-satd. soln. contg. azide. 49 1,4-Benzosemiquinone anionϩethyl gallate Ϫ ϩ ϫ 5 ϫ 4 4-(O )C6H4O• 3,4,5-(OH)3C6H2CO2C2H5 3.1 10 2 10 13.5 p.r. D.k. at 490 nm in 82STE/NET Ϫ Ϫϩ Ϫ 4-(O )C6H4O 3,4,5-(OH)(O )(O•)C6H2CO2C2H5 N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 50 4-Methoxyphenoxylϩ4,4Ј-biphenol ϩ Ј Ϫ Ϫ ϫ 9 ϫ 7 4-CH3OC6H4O• 4,4 -(O )C6H4C6H4O 1.6 10 2.7 10 12 p.r. P.b.k. in N2O-satd. 02JON/LIN Ϫϩ Ϫ 4-CH3OC6H4O 4,4Ј-(O )C6H4C6H4O soln. contg. • Ϫ1 Ϫ 1 mol L N3 , 3 – 30 mmol LϪ1 4-methoxyphenol, and 0.07–0.28 mmol LϪ1 4,4Ј-biphenol. I ϭ1. 51 4-(N,N-Dimethylamino)phenoxylϩcatechin ͑2-͑3,4-dihydroxyphenyl͒-3,4-dihydro-2H-1-benzopyran-3,5,7-triol͒ ϩ ϫ 7 ϫ 5 4-(CH3)2NC6H4O• catechin 1.1 10 4.5 10 13.5 p.r. D.k. at 490 nm in 82STE/NET ϩ 4-(CH3)2NC6H4O- catechin• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 52 4-(N,N-Dimethylamino)phenoxylϩepicatechin ϩ ϫ 7 ϫ 5 4-(CH3)2NC6H4O• epicatechin 3 10 4 10 13.5 p.r. D.k. at 490 nm in 82STE/NET ϩ 4-(CH3)2NC6H4O- epicatechin• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 53 1,4-Benzosemiquinone anionϩquercetin(3,3Ј,4Ј,5,7-pentahydroxyﬂavone) Ϫ ϩ Ϫ Ϸ ϫ 6 Ϸ ϫ 5 4-(O )C6H4O• quercetin(O ) 4.5 10 2 10 13.5 p.r. P.b.k. at 530 nm in 82STE/NET Ϫ ϩ 4-(O )C6H4O- quercetin(O•) N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 54 Hesperidin semiquinone anionϩrutin ϩ ϩ ϫ 7 ϫ 5 hesperidin-O• rutin-OH hesperidin-OH rutin-O• 5.0 10 4 10 7 p.r. P.b.k. in N2O-satd. 94JOV/STE soln. contg. bromide. 55 Trolox phenoxyl radicalϩepigallocatechin ϩ ϫ 4 ϫ 3 TxO• epigallocatechin-OH 3.3 10 2 10 7 p.r. Kinetics in 95JOV/HAR ϩ TxOH epigallocatechin-O• N2O-satd. soln. contg. azide. 56 Trolox phenoxyl radicalϩepigallocatechin gallate ϩ ϫ 4 ϫ 3 TxO• epigallocatechin gallate-OH 3.3 10 3 10 7 p.r. Kinetics in 95JOV/HAR ϩ TxOH epigallocatechin gallate-O• N2O-satd. soln. contg. azide.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 189

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

57 4-Methoxyphenoxylϩ1,4-phenylenediamine ϩ ϫ 8 4-CH3OC6H4O• 4-H2NC6H4NH2 6.6 10 13.5 p.r. P.b.k. at 480 nm in 79STE/NET Ϫϩ 4-CH3OC6H4O 4-H2NC6H4NH• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. Reported

krev probably incorrect. 58 4-(N,N-Dimethylamino)phenoxylϩ1,4-phenylenediamine ϩ ϫ 5 ϫ 8 4-(CH3)2NC6H4O• 4-H2NC6H4NH2 4 10 1.1 10 13.5 p.r. P.b.k. at 500 nm in 82STE/NET Ϫϩ 4-(CH3)2NC6H4O 4-H2NC6H4NH• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 59 4-MethoxyphenoxylϩTMPD ϩ ϫ 9 ϫ 5 4-CH3OC6H4O• 4-(CH3)2NC6H4N(CH3)2 2.2 10 3.7 10 13.5 p.r. P.b.k. at 565 nm in 79STE/NET Ϫϩ ϩ 4-CH3OC6H4O 4-(CH3)2NC6H4N(CH3)2• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 60 4-AminophenoxylϩTMPD ϩ ϫ 7 ϫ 8 Ͼ 4-H2NC6H4O• 4-(CH3)2NC6H4N(CH3)2 3.4 10 1.3 10 11 p.r. D.k. at 520 nm 96ARM/SUN Ϫϩ ϩ 4-H2NC6H4O 4-(CH3)2NC6H4N(CH3)2• and p.b.k. at 435 nm in N2O-satd. soln. contg. 0.1 mol LϪ1 azide. 61 4-(N-Methylamino)phenoxylϩTMPD ϩ ϫ 7 ϫ 9 4-CH3NHC6H4O• 4-(CH3)2NC6H4N(CH3)2 1 10 1 10 13.5 p.r. D.k. at 565 nm in 82STE/NET Ϫϩ ϩ 4-CH3NHC6H4O 4-(CH3)2NC6H4N(CH3)2• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 62 4-(N,N-Dimethylamino)phenoxylϩTMPD ϩ ϫ 7 ϫ 8 4-(CH3)2NC6H4O• 4-(CH3)2NC6H4N(CH3)2 1 10 5 10 13.5 p.r. D.k. at 565 nm in 82STE/NET Ϫϩ ϩ 4-(CH3)2NC6H4O 4-(CH3)2NC6H4N(CH3)2• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5.

63 Indole-5-oxylϩTMPD ϩ ϫ 8 ϫ 6 5-Ind-O• 4-(CH3)2NC6H4N(CH3)2 1.1 10 5 10 13.5 p.r. P.b.k. at 565 nm in 82STE/NET Ϫϩ ϩ 5-Ind-O 4-(CH3)2NC6H4N(CH3)2• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. ϫ 8 ϫ 6 8.0 10 7 10 12.2 p.r. P.b.k. in N2O-satd. 90JOV/STE soln. contg. 0.9 mol LϪ1 ethylene glycol. 64 Tryptophan-5-oxylϩTMPD ϩ ϫ 8 ϫ 6 5-Trp-O• 4-(CH3)2NC6H4N(CH3)2 1.0 10 7 10 13.5 p.r. P.b.k. at 565 nm in 82STE/NET Ϫϩ ϩ 5-Trp-O 4-(CH3)2NC6H4N(CH3)2• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.5. 65 4-NitrophenoxylϩN-methylindole ϩ Ϸ ϫ 8 Ϸ ϫ 9 4-O2NC6H4O• N-Me-indole 3 10 1.1 10 11-12 p.r. D.k. at 580 nm in 90LIN/SHE Ϫϩ ϩ 4-O2NC6H4O N-Me-indole• N2O-satd. soln. 66 Tyrosylϩtryptophan ϩ Ϫϩ ϫ 6 ϫ 5 TyrO• TrpH TyrO Trp• 2.4 10 1 10 13 p.r. P.b.k. in N2O-satd. 86JOV/HAR soln. contg . bromide or azide.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 190 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

67 N-Acetyltyrosinamide phenoxylϩtryptophan ϩ ϫ 6 ϫ 5 N-Ac-tyrosinamide-O• TrpH 9 10 2 10 12 p.r. P.b.k. in N2O-satd. 86JOV/HAR Ϫϩ soln. contg. N-Ac-tyrosinamide-O Trp• bromide or azide. 68 Tyrosine methyl ester phenoxylϩtryptophan ϩ Ϫ ϫ 6 1ϫ105 13 p.r. P.b.k. in N O-satd. 86JOV/HAR tyrosine methyl ester-O• TrpH tyrosine methyl ester-O 5 10 2 ϩ soln. contg. Trp• bromide or azide. 69 N-Acetyltyrosinamide phenoxylϩtryptophanamide ϩ ϫ 6 ϫ 6 N-Ac-tyrosinamide-O• tryptophanamide 9 10 3 10 12 p.r. P.b.k. in N2O-satd. 86JOV/HAR Ϫϩ soln. contg. N-Ac-tyrosinamide-O tryptophanamide• bromide or azide. 70 2,2,5,7,8-Pentamethylchroman-6-oxylϩglutathione thiolate anion ϩ Ϫ ϩ Ϫ ϫ 6 ϫ 6 HPMC• GS GS• HPMC 1.3 10 5.0 10 8.0–8.5 p.r. D.k. and p.b.k. in 94BOR/MIC soln. contg. acetonitrile and azide. Derived from ﬁtting to a complex mechanism. 71 Trolox phenoxyl radicalϩglutathione thiolate anion ϩ Ϫ ϩ Ϫ ϫ 6 ϫ 8 TxO• GS GS• TxO 1.8 10 6.0 10 8.0–8.5 p.r. D.k. and p.b.k. in 94BOR/MIC soln. contg. acetonitrile and azide. Derived from ﬁtting to a complex mechanism. 72 Phenoxylϩthiophenol ϩ Ϫ Ϫϩ ϫ 9 ϫ 7 Ͼ C6H5O• C6H5S C6H5O C6H5S• 1.5 10 2.9 10 11 p.r. P.b.k. at 460 nm in 96ARM/SUN N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide. 73 Phenoxylϩ4-bromothiophenol ϩ Ϫ Ϫϩ ϫ 9 ϫ 7 Ͼ C6H5O• 4-BrC6H4S C6H5O 4-BrC6H4S• 1.7 10 7.4 10 11 p.r. P.b.k. at 510 nm in 96ARM/SUN N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide. 74 4-Methylphenoxylϩ4-methylthiophenol ϩ Ϫ ϫ 8 ϫ 8 Ͼ 4-CH3C6H4O• 4-CH3C6H4S 6.4 10 1.1 10 11 p.r. P.b.k. at 500 nm in 96ARM/SUN Ϫϩ 4-CH3C6H4O 4-CH3C6H4S• N2O-satd. soln. contg. 0.05–0.1 mol LϪ1 azide. 75 4-Methoxyphenoxylϩ4-methoxythiophenol ϩ Ϫ ϫ 8 ϫ 8 Ͼ 4-CH3OC6H4O• 4-CH3OC6H4S 1.6 10 4.6 10 11 p.r. P.b.k. at 415 nm 96ARM/SUN Ϫϩ 4-CH3OC6H4O 4-CH3OC6H4S• and d.k. at 530 nm in

N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide. 76 4-Aminophenoxylϩ4-aminothiophenol ϩ Ϫ ϫ 6 ϫ 8 Ͼ 4-H2NC6H4O• 4-H2NC6H4S 3.5 10 2.8 10 11 p.r. P.b.k. at 435 nm 96ARM/SUN Ϫϩ 4-H2NC6H4O 4-H2NC6H4S• and d.k. at 600 nm in

N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide. 77 1,3-Benzosemiquinone anionϩ4-aminothiophenol Ϫ ϩ Ϫ ϫ 8 ϫ 6 Ͼ 3-(O )C6H4O• 4-H2NC6H4S 1.8 10 3 10 11 p.r. P.b.k. at 600 nm 96ARM/SUN Ϫ Ϫϩ 3-(O )C6H4O 4-H2NC6H4S• and d.k. at 440 nm in

N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 191

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

78 4-Aminophenoxylϩ4-hydroxythiophenol ϩ Ϫ Ϫ ϫ 7 ϫ 6 Ͼ 4-H2NC6H4O• 4-(O )C6H4S 2.9 10 3.2 10 11 p.r. P.b.k. at 590 nm 96ARM/SUN Ϫϩ Ϫ 4-H2NC6H4O 4-(O )C6H4S• and d.k. at 450 nm in N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide. 79 1,4-Benzosemiquinone anionϩ4-hydroxythiophenol Ϫ ϩ Ϫ Ϫ Ϸ ϫ 3 ϫ 6 Ͼ 4-(O )C6H4O• 4-(O )C6H4S 7 10 3.9 10 11 p.r. P.b.k. at 427 nm 96ARM/SUN Ϫ Ϫϩ Ϫ 4-(O )C6H4O 4-(O )C6H4S• and d.k. at 595 nm in N2O-satd. soln. contg. 0.05– 0.1 mol LϪ1 azide. 80 1,3-Benzosemiquinone anionϩ1,4-dimercaptobenzene Ϫ ϩ Ϫ Ϫ ϫ 8 ϫ 6 3-(O )C6H4O• 4-(S )C6H4S 5.3 10 1.3 10 13 p.r. P.b.k. at 390 nm in 93ARM/SUN Ϫ Ϫϩ Ϫ 3-(O )C6H4O 4-(S )C6H4S• N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. I ϭ0.2. 81 4-Methoxyphenoxylϩpromethazine ϩ ϩ ϩ ϫ 5 ϫ 6 4-CH3OC6H4O• Pz 4-CH3OC6H4OH Pz• 7.3 10 2.2 10 3 p.r. D.k. in aerated 90JOV/STE soln. contg. 1 mol LϪ1 2-PrOH, 0.05 mol LϪ1 acetone, and 0.05 Ϫ1 mol L CCl4 . 82 3,4,5-Trimethoxyphenoxylϩpromethazine ϩ ϩ ϩ ϫ 6 ϫ 7 3,4,5-(CH3O)3C6H2O• Pz 3,4,5-(CH3O)3C6H2OH Pz• 1 10 2.1 10 3 p.r. Kinetics in 91JOV/TOS N2O-satd. soln. 83 2-(2-Hydroxyphenyl)phenoxylϩpromethazine Ј ϩ ϫ 8 ϫ 7 2,2 -HOC6H4C6H4O• Pz 1.9 10 6.7 10 9.2 p.r. P.b.k. in N2O-satd. 02JON/LIN Ј Ϫϩ ϩ soln. contg. azide 2,2 -HOC6H4C6H4O Pz• and borate. I ϭ0.02. ͑Values in doubt, solubility of promethazine at this pH very low.͒ 84 Indole-5-oxylϩpromethazine ϩ ϩ ϩ ϫ 6 ϫ 8 5-Ind-O• Pz 5-Ind-OH Pz• 1.6 10 1.8 10 3 p.r. D.k. in aerated 90JOV/STE soln. contg. 1 mol LϪ1 2-PrOH, 0.05 mol LϪ1 acetone, and 0.05 Ϫ1 mol L CCl4 . 85 Tryptophan-5-oxylϩpromethazine ϩ ϩ ϩ ϫ 6 ϫ 8 5-Trp-O• Pz 5-Trp-OH Pz• 1.0 10 1.1 10 3 p.r. D.k. in aerated 90JOV/STE soln. contg. 1 mol LϪ1 2-PrOH, 0.05 mol LϪ1 acetone, and 0.05 Ϫ1 mol L CCl4 . 86 Tryptamine-5-oxylϩpromethazine ϩ ϩ ϩ ϫ 5 ϫ 7 5-tryptamine-O• Pz 5-tryptamine-OH Pz• 2.6 10 6.3 10 3 p.r. D.k. in aerated 90JOV/STE soln. contg. 1 mol LϪ1 2- PrOH, 0.05 mol LϪ1 acetone, and 0.05 Ϫ1 mol L CCl4 . 87 1,2-Benzosemiquinone anionϩascorbate ion Ϫ ϩ Ϫ Ϸ ϫ 5 Ϸ ϫ 4 2-(O )C6H4O• AscH 2-HOC6H4O- 5 10 5 10 11 p.r. P.b.k. at 360 nm in 79STE/NET ϩ Ϫϩ ϩ Asc• H N2O-satd. soln. contg. 1 mol LϪ1 ethylene glycol. 88 Trolox phenoxyl radicalϩascorbate ion

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 192 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

ϩ Ϫ ϩ Ϫ ϫ 7 ϫ 4 TxO• AscH TxOH Asc• 1.1 10 1.0 10 8.3 p.r. D. k. at 440 nm in 95BOR/MIC N2O-satd. soln. contg. azide. Derived from ﬁtting to a complex mechanism. 89 Dihydroquercetin semiquinoneϩascorbate ion ϩ Ϫ ϫ 5 ϫ 7 Dihydroquercetin-O• AscH 1.6 10 1.2 10 8.5 p.r. Decay and 95BOR/MIC Ϫϩ Ϫϩ ϩ dihydroquercetin-O Asc• H formation kinetics at 367 nm in

N2O-satd. soln. contg. azide. Derived from ﬁtting to a complex mechanism. 90 Kaempferol semiquinone anionϩascorbate ion ϩ Ϫ ϫ 6 ϫ 6 Kaempferol-O• AscH 5.2 10 2.8 10 8.5 p.r. Decay and formn. 95BOR/MIC Ϫϩ Ϫϩ ϩ kaempferol-O Asc• H kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. 91 Luteolin semiquinone anionϩascorbate ion ϩ Ϫ Ϫϩ Ϫϩ ϩ ϫ 6 ϫ 5 Luteolin-O• AscH luteolin-O Asc• H 9.9 10 1.6 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. 92 Fisetin semiquinone anionϩascorbate ion ϩ Ϫ Ϫϩ Ϫϩ ϩ ϫ 4 ϫ 4 Fisetin-O• AscH ﬁsetin-O Asc• H 8.7 10 3.9 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. 93 Quercetin semiquinone anionϩascorbate ion ϩ Ϫ Ϫϩ Ϫϩ ϩ ϫ 6 ϫ 3 Quercetin-O• AscH quercetin-O Asc• H 4.8 10 1.6 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. 94 Rutin semiquinone anionϩascorbate ion ϩ Ϫ Ϫϩ Ϫϩ ϩ ϫ 6 ϫ 4 Rutin-O• AscH rutin-O Asc• H 1.3 10 5.2 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 193

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

95 Luteolin semiquinone anionϩdehydroascorbate ion ϩ ϭ ϩ Ϫ ϫ 6 ϫ 7 Luteolin-O• dehydroascorbate ion luteolin O Asc• 1.7 10 1.7 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism.

96 Fisetin semiquinone anionϩdehydroacsorbate ion ϩ ϭ ϩ Ϫ ϫ 4 ϫ 3 Fisetin-O• dehydroascorbate ion ﬁsetin O Asc• 6.9 10 3.8 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. 97 Quercetin semiquinone anionϩdehydroascorbate ion ϩ ϭ ϩ Ϫ ϫ 7 ϫ 6 Quercetin-O• dehydroascorbate ion quercetin O Asc• 1.2 10 1.2 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. 98 Rutin semiquinone anionϩdehydroascorbate ion ϩ ϭ ϩ Ϫ ϫ 5 ϫ 4 Rutin-O• dehydroascorbate ion rutin O Asc• 1.7 10 4.1 10 8.5 p.r. Decay and formn. 95BOR/MIC kinetics at 370 nm and 460–590 nm

in N2O-satd. soln. contg. azide. Derived from ﬁt- ting to a complex mechanism. Semiquinone radicals as reductants 99 2,5-Diaziridinyl-3,6-bis(carboethoxy͒amino-1,4-benzosemiquinone anionϩDuroquinone Ϫ ϩ ϩ Ϫ ϫ 7 ϫ 8 AZ(O )O• C6(CH3)4(O)2 AZ(O)2 C6(CH3)4(O )O• 3.8 10 7.8 10 7 p.r. P.b.k. at 430 nm in 81SVI/POW deoxygenated soln. contg. t-BuOH. 100 9,10-Anthrasemiquinone-2-sulfonate anionϩDuroquinone Ϫ Ϫ ϩ ϫ 8 ϫ 6 2-(SO3 )-9,10-An(O )O• C6(CH3)4(O)2 4 10 1.6 10 7 p.r. P.b.k. at 445 nm in 75MEI/NET Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 C6(CH3)4(O )O• deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 101 Adriamycin semiquinone anionϩDuroquinone Ϫ ϩ ϫ 9 ϫ 8 Adria(O )O• C6(CH3)4(O)2 2.2 10 3.8 10 7 p.r. P.b.k. at 430 nm 81SVI/POW ϩ Ϫ Adria(O)2 C6(CH3)4(O )O• and d.k. at 660 nm in deoxygenated soln. contg. 2-PrOH. 102 Daunomycin semiquinone anionϩDuroquinone Ϫ ϩ ϫ 9 ϫ 8 Dauno(O )O• C6(CH3)4(O)2 2.6 10 2.4 10 7 p.r. P.b.k. at 430 nm 81SVI/POW ϩ Ϫ Dauno(O)2 C6(CH3)4(O )O• and d.k. at 700 nm in deoxygenated soln. contg. t-BuOH.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 194 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

103 Mitomycin C semiquinone anionϩDuroquinone Ϫ ϩ ϫ 8 ϫ 8 Mito(O )O• C6(CH3)4(O)2 4.2 10 1.5 10 7 p.r. P.b.k. at 430 nm in 81SVI/POW ϩ Ϫ Mito(O)2 C6(CH3)4(O )O• deoxygenated soln. contg. t-BuOH. 104 1,4-BenzosemiquinoneϩTetrafluoro-1,4-benzoquinone (fluoranil) ϩ ϫ 7 ϫ 8 1,4-C6H4(OH)O• 1,4-C6F4(O)2 4.8 10 3.7 10 1.7 p.r. D.k. at 410 nm 94SHO/MIT ϩ Ϫ ϩ ϩ 1,4-C6H4(O)2 1,4-C6F4(O )O• H and p.b.k. at 435 nm in deoxygenated soln. contg. 1.3 mol LϪ1 2-PrOH. 105 9,10-Anthrasemiquinone-2-sulfonate anionϩTetrafluoro-1,4-benzoquinone Ϫ Ϫ ϩ ϫ 9 2-(SO3 )-9,10-An(O )O• 4-(O)C6F4O 2.6 10 5.6 p.r. D.k. at 500 nm. 94SHO/MIT Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 4-(O )C6F4O• 106 Mitomycin C semiquinone anionϩBenzyl viologen dication Ϫ ϩ 2ϩ ϩ ϩ ϫ 7 ϫ 9 Mito(O )O• BV Mito(O)2 BV• 4.6 10 4.1 10 7 p.r. D.k. at 600 nm in 81SVI/POW deoxygenated soln. contg. 2-PrOH. 107 Adrenochrome semiquinone anionϩBenzyl viologen dication Ϫ ϩ 2ϩ ϩ ϩ ϫ 7 ϫ 8 Adr(O )O• BV Adr(O)2 BV• 1.4 10 7.6 10 7 p.r. D.k. at 600 nm in 81SVI/POW deoxygenated soln. contg. 2-PrOH. 108 1,4-Bis͓(2-hydroxyethyl)amino͔ethylamino-9,10-anthrasemiquinone anionϩBenzyl viologen dication Ϫ ϩ 2ϩ ϩ ϩ ϫ 7 ϫ 7 An(O )O• BV An(O)2 BV• 6.8 10 8.6 10 7 p.r. D.k. at 600 nm in 81SVI/POW deoxygenated soln. contg. 2-PrOH. 109 9,10-Anthrasemiquinone-2-sulfonate anionϩNitrobenzene Ϫ Ϫ ϩ ϫ 6 ϫ 8 2-(SO3 )-9,10-An(O )O• C6H5NO2 8.8 10 5.4 10 7 p.r. P.b.k. at 505 nm in 75MEI/NET Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 C6H5NO2• deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 110 Durosemiquinone anionϩ4-Nitroacetophenone Ϫ ϩ ϫ 6 ϫ 8 C6(CH3)4(O )O• 4-(CH3CO)C6H4NO2 5.6 10 7 10 7 p.r. P.b.k. at 445 nm in 75MEI/NET ϩ Ϫ C6(CH3)4(O)2 4-(CH3CO)C6H4NO2• deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 111 Durosemiquinone anionϩ5-Nitrofuran-2-carboxylate anion Ϫ ϩ ϩ Ϫ ϫ 7 ϫ 8 C6(CH3)4(O )O• Fu-NO2 C6(CH3)4(O)2 Fu-NO2• 2 10 5 10 7 p.r. P.b.k. at 445 nm in 75MEI/NET deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 112 Durosemiquinone anionϩ2-Nitrothiophene Ϫ ϩ ϩ Ϫ ϫ 6 ϫ 8 C6(CH3)4(O )O• T-NO 2 C6(CH3)4(O)2 T-NO 2• 1.9 10 8 10 7 p.r. P.b.k. at 445 nm in 75MEI/NET deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 113 9,10-Anthrasemiquinone-2-sulfonate anionϩ2-Nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 2.0 10 1.3 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ ϫ 5 ϫ 8 2-(SO3 )-9,10-An(O)2 Im-NO2• 7 10 1.3 10 9.2 deoxygenated soln. contg. 1 mol LϪ1 2-PrOH.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 195

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

114 Durosemiquinone anionϩ1-(2Ј-hydroxy-3Ј-methoxypropyl)-2-nitroimidazole Ϫ ϩ ϩ Ϫ ϫ 6 ϫ 8 C6(CH3)4(O )O• Im-NO2 C6(CH3)4(O)2 Im-NO2• 2 10 3 10 7 p.r. P.b.k. at 445 nm in 75MEI/NET deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 1ϫ106 2.9ϫ108 7.0 p.r. P.b.k. at 445 nm in 76WAR/CLA deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH. 115 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-(2Ј-hydroxy-3Ј-methoxypropyl)-2-nitroimidazole Ϫ Ϫ ϩ ϫ 8 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 1.5 10 3.0 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH. 116 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-carbomethoxyethyl-5-methyl-2-nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 6 10 4.5 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH. 117 9,10-Anthrasemiquinone-2-sulfonate anionϩ4-Nitroimidazole Ϫ Ϫ ϩ ϫ 6 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 1.7 10 7.9 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH. 118 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-methyl-5-chloro-4-nitroimidazole Ϫ Ϫ ϩ ϫ 6 ϫ 9 2-(SO3 )-9,10-An(O )O• Im-NO2 4.5 10 1.4 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH. 119 9,10-Anthrasemiquinone-2-sulfonate anionϩ2-Methyl-5-nitroimidazole Ϫ Ϫ ϩ ϫ 6 ϫ 9 2-(SO3 )-9,10-An(O )O• Im-NO2 1.8 10 1.0 10 7 p.r. P.b.k. at 505 nm in 75MEI/NET Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH. 120 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-(2-N-mopholinoethyl)-5-nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 2.6 10 7.6 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH. 121 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-(2-ethylsulfonylethyl)-5-nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 2.4 10 9.6 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH. 122 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-(3-chloro-2-hydroxypropyl)-2-methyl-5-nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 1.9 10 8.4 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 196 P. NETA AND J. GRODKOWSKI

TABLE 9. Electron transfer equilibrium reactions of phenoxyl and semiquinone radicals ͑in water at room temperature͒—Continued

Reactants k f kr No. Reaction (L molϪ1 sϪ1) (L molϪ1 sϪ1) pH Method Comments Reference

123 9,10-Anthrasemiquinone-2-sulfonate anionϩ1,2-Dimethyl-5-nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 9 2-(SO3 )-9,10-An(O )O• Im-NO2 2.0 10 1.2 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.2 mol LϪ1 2-PrOH. 124 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-(2-hydroxy-3-methoxypropyl)-2-methyl-5-nitroimidazole Ϫ Ϫ ϩ ϫ 7 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 1.0 10 7.1 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH. 125 9,10-Anthrasemiquinone-2-sulfonate anionϩ1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole Ϫ Ϫ ϩ ϫ 6 ϫ 8 2-(SO3 )-9,10-An(O )O• Im-NO2 9 10 8.4 10 7.0 p.r. P.b.k. at 505 nm in 76WAR/CLA Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Im-NO2• deoxygenated soln. contg. 0.5 mol LϪ1 t-BuOH or 0.2 mol LϪ1 2-PrOH. 126 9,10-Anthrasemiquinone-2-sulfonate anionϩ5-Nitrouracil Ϫ Ϫ ϩ ϫ 6 ϫ 9 2-(SO3 )-9,10-An(O )O• Ur-NO2 4.1 10 1.3 10 7 p.r. P.b.k. at 505 nm in 75MEI/NET Ϫ ϩ Ϫ 2-(SO3 )-9,10-An(O)2 Ur-NO2• deoxygenated soln. contg. 0.1– 0.2 mol LϪ1 2-PrOH.

J. Phys. Chem. Ref. Data, Vol. 34, No. 1, 2005 PHENOXYL RADICALS IN SOLUTION 197

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Biophys. 209,119͑1981͒. Energ. 7, 331 ͑1973͒.͔ 81TAT/KHU Tatikolov, A. S., Khudyakov, I. V., and Kuz’min, V. A., 73PAT/WIL Patel, K. B. and Willson, R. L., J. Chem. Soc., Faraday Bull. Acad. Sci. USSR, Div. Chem. Sci. 30,769 Trans. 1 69, 814 ͑1973͒. ͑1981͒. 73RAO/HAY Rao, P. S. and Hayon, E., J. Phys. Chem. 77, 2274 82STE/NET Steenken, S. and Neta, P., J. Phys. Chem. 86, 3661 ͑1973͒. ͑1982͒. 74KHU/KUZ Khudyakov, I. V., Kuz’min, V.A., and Emanuel, N. M., 82SUT/SAN Sutton, H. C. and Sangster, D. F., J. Chem. Soc., Dokl. Phys. Chem. 217, 747 ͑1974͒. ͓Translated from Faraday Trans. 1 78, 695 ͑1982͒. Dokl. Akad. Nauk SSSR 217, 880 ͑1974͒.͔ 82TRI/SCH Tripathi, G. N. R. and Schuler, R. H., Chem. Phys. 74ZAV/PRO Zavelovich, E. B. and Prokof’ev, A. I., Chem. Phys. Lett. 88, 253 ͑1982͒. Lett. 29, 212 ͑1974͒. 83GRO/NET Grodkowski, J., Neta, P., Carlson, B. W., and Miller, 75KUZ/DAV Kuz’min, V.A., Davydov, R. M., Khudyakov, I. V., and L., J. Phys. Chem. 87, 3135 ͑1983͒. Burlatskii, S. F., Bull. 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