I a Study of the Basicities of Some Aryl Methyl Sulfoxides Ii a Study of the Hydrolysis of Arenesulfinamides in Basic Aqueous Ethanol

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I A STUDY OF THE BASICITIES OF SOME ARYL METHYL SULFOXIDES II A STUDY OF THE HYDROLYSIS OF ARENESULFINAMIDES IN BASIC AQUEOUS ETHANOL

JOSEPH BRIAN BIASOTTI

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Recommended Citation BIASOTTI, JOSEPH BRIAN, "I A STUDY OF THE BASICITIES OF SOME ARYL METHYL SULFOXIDES II A STUDY OF THE HYDROLYSIS OF ARENESULFINAMIDES IN BASIC AQUEOUS ETHANOL" (1968). Doctoral Dissertations. 871. https://scholars.unh.edu/dissertation/871

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BIASOTTI, Joseph Brian, 1942- I. A STUDY OF THE BASICITIES OF SOME ARYL METHYL SULFOXIDES H. A STUDY OF THE HYDROLYSIS OF ARENESULFINAMIDES IN BASIC AQUEOUS ETHANOL. University of New Hampshire, Ph.D., 1968 Chemistry, organic

University Microfilms, Inc., Ann Arbor, Michigan I. A STUDY OF THE BASICITIES OF SOME ARYL METHYL SULFOXIDES

. A STUDY OF THE HYDROLYSIS OF ARENESULFINAMIDES IN BASIC AQUEOUS ETHANOL

j T b r i a n b i a s o t t i B. S., Boston College, 1964

A THESIS Submitted to the University of New Hampshire In Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY

Graduate School Department of Chemistry June, 1968 ABSTRACT

I. A STUDY OF THE BASICITIES OF SOME ARYL METHYL SULFOXIDES

II. A STUDY OF THE HYDROLYSIS OF ARENESULFINAMIDES IN BASIC AQUEOUS ETHANOL

J. BRIAN BIASOTTI

I. There exists a minimum of quantitative data con cerning the basicities of sulfoxides. In this work ten meta- and para-substituted phenyl methyl sulfoxides were titrated potentiometrically using perchloric acid as the titrant and acetic anhydride as the solvent. Their apparent pKa values were determined by placing the values for the half-neutralization potentials on a straight line determined by plotting the pKa values vs. the half-neutralization potential for some amines whose pKa values were known. £- Anisyl methyl sulfoxide was found to be the strongest base (pKa = +0.55) and £-nitrophenyl methyl sulfoxide the weakest base (pKa = -3.51). A good Hammett plot correlation was obtained with p = 3.79, a correlation coefficient of 0.993, and a standard deviation of 0.169. Utilizing Taft's method for determining specific resonance effects, a resonance value of -0.26 was obtained for £-anisyl methyl sulfoxide indicating that electron donation by the substituent is greater in the protonated than in the unprotonated state. Such electron accepting type conjugation necessitates sulfur to expand its octet to ten electrons, causing (p->d)TT bonding between sulfur and carbon. The large rho value ob tained from the Taft treatment indicates that a large change in charge at sulfur is occurring between the protonated and unprotonated states, reflecting the double bond character of the sulfur oxygen bond. pKa values were also determined for dimethyl sulfoxide, diphenyl sulfoxide, cis-4-(4- chlorophenyl)-thiane-l-oxide, trans-4-(4-chlorophenyl)- thiane-1-oxide, S ,S-diphenyl-N-benzenesulfonylsulfilimine, and the S,S-dimethyl-, S,S-diphenyl-, and S-phenyl-S-methyl- N-£-toluenesulfonylsulfilimines. A plot of the pKa values for the S,S-diphenyl, S,S-dimethyl, and S-phenyl-S-methyl-N- jD-toluenesulfonylsulfilimines vs. the pKa values for the corresponding diphenyl, dimethyl, and phenyl methyl sulfoxides did not yield a straight line.

II. In considering nucleophilic substitution reac tions at tricoordinate sulfur, little is known about the influence of the sulfur compound's structure on reactivity. Also the question of the existence of an intermediate of higher coordination number than that of the substrate has never been unequivocally answered. It was the purpose of this investigation to explore these two aspects. A series of nine meta- and para-substituted N-mesityl benzenesulfinamides were prepared and the kinetics of their reaction with hydroxide ion in aqueous ethanol studied. Second order rate constants were obtained. The reaction was shown to be first order in base and first order in sulfinamide. Activation parameters were determined with AH ^ = +20.0 kcal/mole and AS = -8.9 eu. The rate constants gave a good correlation with Hammett’s cr constants (p = +1.3) indicating that the transition state is being stabilized by electron withdrawing substituents. The procedure of Taft for determining specific resonance effects was applied to the sulfinamides. A resonance value of (-0.08) was obtained for N-mesityl £- methoxybenzenesulfinamide indicating that the resonance contribution to the resonance hybrid is greater in the ground state than in the transition state. No significant resonance value (+0.03) was observed for the ]D-nitro substituent. The resonance contribution to the resonance hybrid for N-mesityl £-nitrobenzenesulfinimide is of the same magnitude for both the ground state and the transition state. The lack of a significant resonance value for the £-nitro substituent argues against the formation of an unstable addition inter mediate. Mass spectra were measured for the nine substituted N-mesityl benzenesulfinamides. The base peak at 134 m/e was assigned to (CH3 )3NH+ . A plot of log ([XC^H^S0+ ]/

[C6 H2 (CH3 )3NH+ ]) for X = £-N02 , R-CH3, £-CH30, m-CF3 , £-Cl, and H versus the Hammett substituent constants gave a straight line with p of -1 .1 . This thesis has been examined and approved.

iIlItMMX aA m . JyfHtsii AI (vweU>7H/M

(Li/rrJy? /)

A ljU^uux C f lUJL

17 i 1^6 if ACKNOWLEDGEMENT

The author wishes to extend his sincere gratitude to Dr. Kenneth K. Andersen, whose guidance and encouragement aided greatly in the completion of this work. The author would like to thank Dr. J. J. Uebel for making many helpful suggestions in the writing of this thesis and to Anne Kohl for her excellent typing. Thanks are also due to the entire organic staff for their coopera tion and assistance and in particular Dr. J. John Uebel. Financial support from the National Science Foundation is gratefully acknowledged. The author wishes to dedicate this thesis to his wife, Phyllis, as an expression of gratitude for her en couragement and confidence. TABLE OF CONTENTS Page

List of Tables...... vi List of Figures...... vii

PART I

INTRODUCTION...... 1

RESULTS AND DISCUSSION...... 4

Determination of pKa values for sulfoxides and sulfilimines...... 4 Effects of structure on basicity...... 9 Taft’s method for determining specific resonance effects..11 Application of Taft’s method to sulfoxides...... 12

EXPERIMENTAL...... 20

Materials...... 20 Titration procedure...... 21 Titration data...... 22

BIBLIOGRAPHY...... 55

PART II

INTRODUCTION...... 58

RESULTS AND DISCUSSION...... 64

Effects of structure on reactivity...... 64 Kinetic order of the reaction...... 64

Activation parameters for the reaction...... 66 Taft’s method for determining specific resonance effects..69 Application of Taft's method to sulfinamides...... 69 Possibility of an unstable addition intermediate...... 75 iv Page

Mass spectra...... 78 Ultraviolet spectra...... 96

EXPERIMENTAL...... 104

Materials...... 105 Kinetic procedure...... 121 Kinetic data...... 123

BIBLIOGRAPHY...... 140

SUMMARY...... 144

V LIST OF TABLES

PART I

Page

Table 1 - pKa Values for sulfoxides and sulfilimines..... 5 Table 2 - Specific resonance effects...... 14 Table 3 - Sulfoxides titrated...... 22 Table 4 - Standards and sulfilimines titrated...... 24 Table 5 - Accuracy for sulfoxide titrations...... 46

Table 6 - Accuracy for standards and sulfilimines titrates...... 48 Table 7 - Half-neutralization-potentials of sulfoxides.... 51

Table 8 - Half-neutralization-potentials of standards and sulfilimine...... 53

PART II

Table 1 - Rate constants for the hydrolysis of sulfinamides...... 65 Table 2 - Dependence of rate constants for the base hydrolysis of N-mesityl £-chlorobenzene-

sulfinamide on hydroxide ion concentration..... 6 6 Table 3 - Rate constants and activation parameters for the hydrolysis of N-mesityl £-chlorobenzene- sulf inamide...... 67 Table 4 - Specific resonance effects...... 72 Table 5 - Major fragments in the mass spectra of aryl sulf inamides...... 81

Table 6 - Ultraviolet absorption of arenesulfinamides....96 LIST OF FIGURES

PART I

Page Figure 1 - Results obtained by Streuli...... 2 Figure 2 - A plot of Streuli1s pKa values for the amines vs. HNP...... 7

Figure 3 - A plot of log K/K0 for phenyl methyl sulfoxides vs. Hammett cr constants...... 10 Figure 4 - A plot of K/Kc for phenyl methyl sulfoxides vs . c r ° ...... 13 Figure 5 - A plot of the pKa values for the S,S-diphenyl, S,S-dimethyl, and S-phenyl-S-methyl-N-£- toluenesulfonylsulfilimines v s . the pKa values for the corresponding diphenyl, dimethyl, and phenyl methyl sulfoxides...... 19

Figure 6 - Titration curve for phenyl methyl sulfoxide....44

PART II

Figure 1 - A plot of log k/kQ for arenesulfinamides

vs . c r ...... 6 8 Figure 2 - A plot of log k/kG for arenesulfinamides vs. O' ° ...... 71

Figure 3 - A plot of log [XC5 H4 SO+ ] / [MesNH+ ] vS # 35 [C6 H5 SO+]/[MesNHt]

Figure 4 - Mass spectrum of N-mesityl m-a,a,a-trifluoro-

toluenesulf inamide...... 86 Figure 5 - Mass spectrum of N-mesityl m-toluenesulfinamide...... 87 Page

Figure 6 - Mass spectrum of N-mesityl m-chlorobenzene-

sulf inamide...... 88 Figure 7 - Mass spectrum of N-mesityl m-nitrobenzenesulf inamide...... 89

Figure 8 - Mass spectrum of N-mesityl benzenesulfinamide..90 Figure 9 - Mass spectrum of N-mesityl p-toluenesulf inamide...... 91 Figure 10 - Mass spectrum of N-mesityl p-chlorobenzene- sulf inamide...... 92 Figure 11 - Mass spectrum of N-mesityl p-methoxybenzene- sulf inamide...... 93 Figure 12 - Mass spectrum of N-mesityl p-nitrobenzenesulf inamide...... 94 Figure 13 - Mass spectrum of N-p_-toluenesulf inamide...... 95 Figure 14 - Ultraviolet spectra of N-mesityl m-toluenesulfinamide and N-mesityl p-toluenesulfinamide...... 98 Figure 15 - Ultraviolet spectra of N-mesityl p_-methoxybenzenesulfinamide and N-mesityl benzene sulf inamide ...... 99 Figure 16 - Ultraviolet spectra of N-mesityl m-nitrobenzenesulfinamide and N-mesityl m-a,a,a-tri-

fluorotoluenesulf inamide...... 1 0 0 Figure 17 - Ultraviolet spectra of N-mesityl £-nitro-

benzenesulf inamide...... 1 0 1 Figure 18 - Ultraviolet spectra of N-mesityl p-chlorobenzenesulfinamide and N-mesityl m-chloro-

benzenesulf inamide...... 1 0 2 Figure 19 - Ultraviolet spectrum of N-p.-tolyl p-toluenesulf inamide...... 103

viii PART I.

A STUDY OF THE BASICITIES OF SOME

ARYL METHYL SULFOXIDES INTRODUCTION

While it is well known that sulfoxides are weakly basic, little quantitative work has been done to determine 1 the basicities of various sulfoxides. An early study by 2 Nylen shows that the aliphatic members of the series, e.g. dimethyl or diethyl sulfoxide, have pK values around 0.0. 3l Since completion of our work, two articles have appeared 3 relating to the basicity of sulfoxides. Haake and Cook , by measuring chemical shifts in aqueous sulfuric acid found dimethyl sulfoxide and phenyl methyl sulfoxide to have pKa's of -2.78 and -3.38 respectively. Montanari and co-workers^ in a study of the acid-catalysed reduction of sulfoxides by iodide ion have reported pKa values of -2.3 and -1.6 for m- chlorophenyl methyl sulfoxide and p-tolyl methyl sulfoxide. It was of interest to us to determine the basicities of numerous sulfoxides of this type as well as the basicities of several sulfilimines. Since water is itself such a strong base, a direct potentiometric determination of pKa 's in aqueous solutions is impossible for weak bases. The addition of an acid to an aqueous solution of a weak base would protonate the solvent without effecting the compound under investigation. In 1958, Streuli^ potentiometrically titrated a number of neutral and anionic bases using perchloric acid in glacial acetic acid as the titrant and acetic anhydride as the solvent. The pKa values in water were known for these compounds. A linear relationship was obtained when the known pBU values of the neutral compounds were plotted a against the half-neutralization potentials (HNP).

-1- 2

(1 ) P W O ) - kHNP(Ac9 0) + C

The graph reproduced below indicates the results Streuli obtained.

PKa

(h2 o) neutral 0 bases

univalent anionic bases

BOO mv

Fig. 1 - Results obtained by Streuli The compounds represented on this graph are given in the chart below. a . Tri-n-butylamine A. Acetate b . N ,N-dimethylbenzylamine B. Formate c . N,N-diethylaniline C. Nitrate d. N-ethyl N-methylaniline D. Chloride e . N,N-dimethylaniline E. Bromide f . Methylurea F. Iodide g- Urea h. Caffein i . Phenylurea j • Acetamide • 3

Streuli then titrated in acetic anhydride a variety of molecules with unknown or poorly defined pKa values. By utilizing the appropriate calibration line in Fig. 1, calcu lated pKa values with respect to water were obtained. Streuli extrapolated this method to dimethyl sulfoxide and determined—itrs~"~pKa as—1.0. The sulfoxide gave an excellent titration curve with quantitative results; it was completely titrated. Thus, it appears possible to indirectly determine the pKa's of numerous sulfoxides and sulfilimines. The pKa values obtained in this way must be regarded as apparent. It is not certain that sulfoxides or sulfilimines fall on Streuli's pKa vs. HNP plot. In 1960, R. W. Taft^ proposed a method for evaluating resonance effects between the substituted benzene ring and the reaction center bonded to it. A more detailed discussion of this method will appear later in this work. An applica tion of this method to the pKa data obtained for the sulfox ides of the type shown below (1} would give information

S-CH R 1

where R=H, E.-NO2 5 £-Cl, jv-OCH^, £-CHg, m-NC^> m-Cl,

m-CH^, m-OCH^, m-CF^ concerning the electronic requirements of sulfoxides in both the protonated and unprotonated state. 4

RESULTS AND DISCUSSION

5 In this work, the procedure developed by Streuli for determining pK 1 s of weak bases has been used to deter- S i mine the apparent pKa's of various sulfoxides and sulfilimines. The compounds listed in Table 1 were titrated potentiometrically in acetic anhydride using perchloric acid in glacial acetic acid as the titrant. The half-neutralization poten tials of the amines listed, when plotted against their pKa values obtained by Streuli, gave a good straight line (Fig. 2). This line was then used for calibration. By extrapolat ing the half-neutralization potentials of the sulfoxides and sulfilimines to this line, their pKa values with respect to water were obtained. In considering the substituted phenyl methyl sulfoxides, p-anisyl methyl sulfoxide was found to be the strongest base (pKa = +0.55) and p-nitrophenyl methyl sulfoxide the weakest base (pKa = -3.51). This spread of over 4 pKa units is somewhat large when compared to studies carried out on other similarly substituted systems . Stewart and Yates^ in their study of substituted benzamides report a difference of 1.4 pKa units between jD-methoxybenzamide and p-nitrobenzamide acting as weak bases and measured in aqueous acid. A similar difference is also reported for _p-methoxybenzoic acid and jj- nitrobenzoic acid acting as weak bases and measured in aqueous acid.^ A possible explanation for the large spread in pKa is that the straight line obtained by plotting the half-neutralization potential of the amines against their pKa values may have yielded a slope which is too steep for the sulfoxides. 5

TABLE 1

Compound HNP PK, 7oErrorC

N,N-Diethylaniline 230+1 6.55 +2.53 N,N-Dimethylaniline 292+2 5.25 -3.39 Caffein 500+1 0.49 +2.10

Substituted Phenyl Methyl Sulfoxides

£-CH3 0 498+4 0.550 +0.76 p-CH3 523+3C 0.014 +1.25

H 544+2 -0.488 +2.37 m-CH3 551+2 -0.646 +2.12

m-CH30 575+1 -1.19 - 0.10

E-Cl 592+1C -1.57 +1.53 m-Cl 616+1 - 2.11 +0.63 m-CF3 635+5 -2.54 -0.53 m-NO^ 665+4 -3.22 +0.22

2 ~N0 2 678+5c -3.51 +4.63

dimethyl sulfoxide 482+3 0.911 -1.41 diphenyl sulfoxide 681+1 -3.58 -0.32 cis-4-(4-chlorophenyl)- thiane-l-oxide 478+1 1.00 +3.72 trans-4-(4-chlorophenyl)- thiane-l-oxide 474+0 1.09 +0.90 5 .5-dimethyl-N-p- toluenesulfonylsulfilimine 497+1 0.573 + 1.74 5 .5-diphenyl-N-£- toluenesulfonylsulfilimine 682+2 -3.60 + 1.84 6

Table 1 (continued)

Substituted Phenyl PK Methyl Sulfoxides HNP %Error

S-methy1-S-phenyl-N• £-1oluenesulfony1- sulfilimine 609+1 -1.96 +2.21 S,S-diphenyl-N- benzenesulfonylsulfilimine 705+2 -4.02 -0.83

sl b Half neutralization potential in millivolts. The pKa values for the amines are taken from C. A. Streuli (ref. 5). The pKa values for the sulfoxides are calculated from the equation pKa = 11.79-0.02257 HNP derived from a least squares treatment of the amine data. cCalculated from the actual volume of titrant minus the expected volume over the expected volume times 100. ^Ref. 8 . 7

N,N-Diethylaniline

N ,N-Dimethylaniline 5.0

3.0

1.0

Caffein

300 400 500 HNP(mv)

Fig. 2 - A plot of Streuli*s pKa values for the amines vs. HNP. 8

A large pK difference may be indicative of protona- cl tion on sulfur rather than oxygen (eq 1). Systems which

CH. CH. 1 I ArSO+ ^ ArSO + H+ (1) I H protonate on the first atom from the benzene ring generally 9 give a larger pK spread. N. F. Hall reports a pK differ- a a ence of 3.2 between j)-methoxy and £-nitroanilinium ions. In the case of the benzenethiols a pK difference of 3.3 is 10 a observed. A rather special example is that of the acetophenones.^ The difference between £-methoxyacetophenone and p-nitroacetophenone is 3.1 pK units. Although protona- ci tion occurs at the oxygen, a carbonium ion is formed.

Although the large pKcL spread obtained for the sulfoxides would seem to support protonation on sulfur, it is not a concept easy to accept. The fact that the oxygen atom possesses a higher electron density than sulfur would lead one to expect protonation to occur at oxygen. It is possible for the non-bonding electrons on sulfur to participate in bonding with certain electrophiles. For example, the reaction of dimethyl sulfoxide and methyl iodide + - 12 has been reported to form a stable adduct (CH.).SO I . 13 Cotton and Francis have reported a large number of complexes of dimethyl sulfoxide with cobalt and nickel, however bonding is thought to occur between the metal and oxygen. Complexes with metals such as platinum and palladium, however, have 14 been shown to bond to sulfur. The formation of these adducts, however, can be explained according to the principle 15 of hard and soft acid and bases (SHAB principle) . '■ The SHAB principle states that a greater stabilization will be achieved between an acid and a base if both the acid and base are hard, or if both are soft. Since sulfur is a soft base and methyl 9 iodide and the metals are soft acids, one would expect bonding at sulfur to occur. Likewise, since a proton is a hard acid and oxygen is a hard base, protonation at the oxygen should take place. Sulfoxides have long been known 16 to form hydrogen bonds. Infrared studies have shown that the SO stretching frequency undergoes a shift to lower frequencies in going from carbon tetrachloride solutions to chloroform or to carbon tetrachloride containing methanol. Such a shift is compatible with hydrogen bond formation at oxygen and not at sulfur. With this evidence in hand, it would appear that equation 1 is untenable. In Fig. 3 log K/Kq values for the substituted sul foxides are plotted against

~~CH 0 CH q i 3 , i 3 Ar-Jj>-0H v ..- Ar-S-0 + H (2)~~

~~0 0 It _ + Ar-G-OH . Ar-C-0 + H (3) 10~~

~~.0 m-N0 2~~

~~m-Cl log K/Kq~~

~~E-Cl 1.0~~

~~0.0~~

~~- 1.0 • 2.-0CH~~

~~- 0.2 0.0 0.2 0.4 0.6 0.8 cr~~

~~Fig. 3 - A plot of log K/Kq for phenyl methyl sulfoxides vs. Hammett cr constants. 11~~

In 1960, Taft proposed a method for evaluating resonance effects between the substituted benzene ring and the reaction center bonded to it. In evaluating the effect of structure on reactivity for a given equilibrium or rate, the approach was taken that the substituent was considered to be the entire substituted benzene ring. In examining the wide variety of reaction series, a select group of meta substituents were compiled which exhibited a minimum devia tion from the Hammett linear free energy relationship. The mean sigma values for these substituents were designated as d”°. In general, the substituents obeyed the Hammett equa tion with a standard error of +0.03 or less and each meta substituted compound did not deviate from the relationship log (k/kQ) = p cr o by more than +0.07 sigma units. No select group of para substituted phenyl substituents could be found to meet this criteria. Taft ascribes the precision obtained for the meta substituted phenyl substituents to the absence of direct conjugation with the reaction center. The substit uent is considered to effect the reaction site solely by an inductive effect. In effect what has been accomplished is a generaliz ing of the Hammett relationship with more precise represen tative meta sigma values. Hammett in arriving at his linear free energy relationship studied the effects of corresponding m- and £-substituents on the rates of saponification of ethyl benzoates and on the ionization of benzoic acids in water. The latter was chosen as the standard reaction series. If one uses the select group of meta sigma values (cT°) to define rho for a given reaction series, then effec tive sigma values for para substituents can be obtained from the relationship = 1/P (log k/kG). It should be noted that cr values are a measure of contribution from both 12

resonance and induction. In order to obtain inductive sigma constants ( < f ° values) for para substituted phenyl substit uents, several reactions involving compounds of the type ArCH^Y were selected. The assumption was made that the resonance effect would be constant due to the interposed methylene group. Good precision was obtained for these reactions with a standard deviation of +0.03. The differ ence (cr- <5 o) is then a measure of the specific resonance interaction between the para-substituted phenyl ring and the reaction center Y. In an effort to obtain useful information on the electronic distribution of sulfoxides in both the protonated and unprotonated state, the Taft method has been applied to the m- and £-substituted sulfoxides. In Fig. 4, log (K/Kq) is plotted vs.

~~£-N0~~

~~t m-NO~~

~~•A- cf~~

~~m-Cl log K/K,~~

~~• e -ci 1 .0 -~~

~~a-CH 0 .0- • H~~

~~• E-CH~~

~~-1 .0 _ • 2 -OCH~~

~~- 0.2~~

~~Fig. 4 - A plot of K/Kq for phenyl methyl sulfoxides vs. cT °. TABLE 2 Specific Resonance Effects (cf-cr0) Ionization Reactions~~

Protonated Phenyl Methyl Benzoic Anilinium Thio- Protonated Subst. Sulfoxidesa Acidsb Ionsc phenols Acetophenones p -c h 3o -0.26 -0.15 -0.15 +0.03 -0.59 p -c h 3 -0.08 -0.02 -0.06 +0.04 -0.24 p-Cl -0.06 -0.04 -0.07 +0.02 -0.13 +0.14 +0.03 p -n o 2 -0.07 -0.04 +0.13 P - 3.61 +1.00 +2.78 +3.06 +2.01 r = 0.983 1.00 0.986 0.981 S = 0.22 0.026 0.108 0.128 cl This work. Difference between Hammett* s o' constants and c r °; see ref. 6. CRef. 9. pKa values for aniline and m-nitroaniline were taken from N. A. Lange, Handbook of Chemistry, Handbook Publishers, Inc., Sandusky, Ohio, 7th ed., 1949, p. 1408 and I. Heilbron, Dictionary of Organic Compounds, Oxford University Press, New York, 1953, Vol 3, p. 629, respectively.

^Ref. 10. eRef. 11. The mathematical procedure used to determine p , and the definitions of the correlation coefficient, r, and the standard deviation, S, are given in ref. 17. 15 resulting from the methoxy group directly conjugating with 18 the reaction center. If this is the case, then the resonance contribution by the methoxy group is more important in the protonated state than in the unprotonated state. Resonance structure 2^ contributes more to the resonance hybrid of the protonated molecule than 4 does to that of the unprotonated molecules.

~~c h 3o X n -l/2~~

~~/ ° " CH„0~~

~~X 0 H~~

The resonance effect obtained for the £-methoxy substituent is in accord with expectation. Analogously, in considering the sulfoxides, the large negative value of the ( CT— o' °) resonance value for the £-methoxyphenyl group indicates that electron donation by the substituent is greater in the protonated than in the unprotonated state. 16

~~CH3 0-(/ \ V s O H CH3°~~

~~+ H+~~

~~CtUO SOH CHoO~~

~~6 8~~

Such electron accepting type conjugation necessitates sulfur to expand its octet to ten electrons, causing (p->d)7T bonding between sulfur and carbon. Such evidence for sulfur 19 extending its octet is not without precedent. Bordwell in a series of papers has established that sulfonyl, sulfinyl, sulfonium and sulfonate groups can enter into electron acceptor-type conjugation. This argument for (p->d)TT bonding must take into account the case of the anilinium ions. £-Methoxyanilinium ion has a (ar~ °) value of -0.15, yet expansion of nitro gen' s octet is unlikely. A more reasonable explanation is that this resonance value is due to the polarizing power of the positive nitrogen. It is unlikely that sulfur is such a powerful polarizing atom that its (& o) value could be due to this factor alone. The reaction constant p obtained for the sulfoxides is somewhat larger than that obtained for the other reaction g series in Table 2. Taft in an examination of existing data has shown that the reaction constants obtained for the select group of meta substituted phenyl substituents in acid ioniza- 17 tion equilibria in aqueous solution can be described by the 1 i relationship p = (2 .8 + 0 .5) , where i = the number of saturated links intervening between the benzene ring and the atom at which there is a unit decrease in formal charge on ionization of the proton. Implicit in this relation is that p can reflect a change of the electron density at the reaction center. In the case of the sulfoxides one has to take into account the fact that the studies were carried out in non-aqueous media. Rho values for acid-base equilibria generally increase as one goes from aqueous to less polar non-aqueous solvents. This may be the cause of the some what larger rho obtained. However, this large value further strengthens the argument that a large change in charge at the sulfur is taking place. If this is the case then the linkage between sulfur and oxygen has to be double bond in character. That is structure 9_ is more important rela tive to 1 0 than 1 1 is relative to 1 2 .

~~OH 0 u u s -CH3 Ar-s -CH3~~

~~9 11 1 1 +0H 0 I I II Ar-S-CH3 Ar-S-CH3~~

~~10 12~~

~~N-£-toluenesulfonyl-substituted sulfilimines were also titrated in acetic anhydride and their pK& values calculated. 18~~

~~p-Tosyl-N-H+ II (4) R-S-R' R-S-R'~~

A plot of the pKa values for the S , S-diphenyl, S,S-dimethyl, and S-phenyl-S-methyl-N-£-toluenesulfonylsulfilimines vs. the pKa values for the corresponding diphenyl, dimethyl, and phenyl methyl sulfoxides is shown in Fig. 5. As can be seen, the expected straight line was not obtained. While the reason for this is not entirely clear, steric effects may have a greater effect than expected. Fig. 5 - A plot of the pKa values for the S , S-diphenyl, S,S- S,S- , S the for S-diphenyl, values pKa the of plot -A 5 Fig. pKa (sulfilimines) - - -3.0 0 . 1 0 . 2 dimethyl, and S-phenyl-S-methyl-N-£-toluenesulfonyl- S-phenyl-S-methyl-N-£-toluenesulfonyl- and dimethyl, ihnl dmty, n hnlmty sulfoxides. methyl phenyl and corresponding the for dimethyl, values pKa diphenyl, the vs. sulfilimines -5.0 -3.0 K (sulfoxides) pKa - 0 . 1 + 0 . 1 19 20

~~EXPERIMENTAL~~

Solvent. - Acetic anhydride (Fisher Certified Reagent Grade, Catalogue No. A-10). Titrant. - 0.1N Perchloric acid in glacial acetic acid (Fisher Certified Reagent Grade, Catalogue No. So-P- 339) . Sulfoxides. - Diphenyl Sulfoxide (Fisher, Catalogue No. 1583) was recrystallized twice from petroleum ether; mp 90 70-71°, lit mp 70-71°. Dimethyl Sulfoxide (Fisher Analyt ical Reagent, Catalogue No. D-136) was dried over Linde Molecular Sieves No. 13X. All other sulfoxides were ob tained from R. Strecker, University of New Hampshire, Durham, N. H. Amines. - Caffein (Fisher, Catalogue No. 355) was recrystallized from benzene, mp 235-237°, lit^ mp 234-235° . __N,N-Dimethylaniline (Fisher Certified Reagent Grade, Catalogue No. A-746) was distilled shortly before use, 99 bp 49-50° (0.3 mm), lit bp 41° (1 mm). N,N-Diethylaniline (Eastman Kodak Yellow Label) was distilled shortly before 99 use, bp 58° (0.6 mm), lit bp 63° (2 mm). Sulfilimines. - All sulfilimines were obtained from Dr. K. K. Andersen, University of New Hampshire, Durham, N. H.: S,S-Diphenyl-N-£-toluene sulfonylsulfilimine, mp 9 3 111-112°, lit mp 113°; S-Methyl-S-phenyl-N-£-toluenesulfonylsulfilimine, mp 128-129°, lit^ mp 132°j S,S- Dimethyl-N-£-toluenesulfonylsulfilimine, mp 158-159°, lit^^ mp 157-158°; S,S-Diphenyl-N-phenylsulfonylsulfilimine, mp 124-125.5°. 21

Titration Procedure. - The titrations were performed using 200 ml of solvent in a standard 250 ml beaker. Mag netic stirring was provided. A standard 10.00 ml buret was used for the delivery of the titrant. The quantity of base used in each titration was such as to require 4.0 - 6.0 ml of 0.1 N perchloric acid. The electrodes used were Beckman No. 4990-80 and No. VB-39270 respectively. They were connected to a Beckman Model H2 pH Meter in the normal fashion. The instrument was carefully grounded. When not in use, the glass electrode was stored in water, while the calomel was stored in saturated potassium chloride solution. To standardize, they were wiped with tissue and placed in 2 0 0 ml of solvent, at which time the instrument was standardized at 0 mv using the appropriate controls. After standardization, the titration was per formed in the usual fashion. A plot was then made of potential vs. ml added and the half-neutralization-potential was read from the graph in the usual way. It should be noted that best results were obtained when the instrument was restandardized at successive intervals during titration, verifying the zero point potential at 0 . 0 0 mv each time. 22

~~TABLE 3 Sulfoxides Titrated~~

~~Compound Run No.~~

~~£-H 1 -a~~

~~11 1 -b 11 1 -c~~

~~11 1 -d m-CHg 2 -a n 2 -b n 2 -c £-CH^O 3-a II 3-b 11 3-c m-CH3 0 4-a ii 4-b u 4-c m-CF^ 5-a ii 5-b ii 5-c m-Cl 6 -a I! 6 -b~~

~~11 6 -c m-N02 7-a 11 7-b ii 7-c 23~~

~~TABLE 3 (continued)~~

~~Compound Run No.~~

~~Dimethyl 8 -a Sulfoxide II 8 -b~~

~~II 8 -c Diphenyl 9-a Sulfoxide II 9-b II 9-c Cis-4-(4-chloro- 1 0 -a phenyl) - thiane- 1 -oxide ii 1 0 -b Trans-4-(4-chloro- 1 1 -a phenyl)-thiane- 1 -oxide ii 1 1 -b 24~~

~~TABLE 4 Standards and Sulfilimines Titrated~~

~~Compound Run No.~~

~~Caffein 12-a~~

~~" 1 2 -b~~

" 1 2 -c N,N-Dimethyl- 13-a aniline " 13-b " 13-c N,N-Diethyl- 14-a aniline " 14-b " 14-c " 14-d 5.5-Dimethyl- 15-a N-£-toluenesulfonylsulfilimine " 15-b ’’ 15-c 5.5-Diphenyl- 16-a N-£-toluenesulfonylsulfilimine " 16-b " 16-c S-Methyl-S- 17-a phenyl-N-£-toluenesulfonylsulfilimine " 17-b " 17-c 5.5-Diphenyl-N- 18-a benzenesulfonylsulfilimine 18-b 18-c 25

~~Run No. 1-a Run No. 1-b~~

~~Vol. (ml) E (mv) Vol. (ml) E (mv)~~

0.00 90 0.00 90 0.50 460 0.50 460 0.75 490 0.75 490 1.00 500 1.00 500 1.50 510 1.50 520 2.00 520 2.00 530 2.50 530 2.50 540 3.00 540 3.00 550 3.50 550 3.50 560 4.00 560 4.00 570 4.50 580 4.50 590 5.00 610 5.00 620 5.50 700 5.50 700 6.00 740 6.00 740 6.50 760 6.50 760 7.00 770 7.00 770 7.50 775 7.50 775 8.00 780 8.00 780 8.50 785 8.50 785 9.00 790 9.00 790 26

~~Run No. 1-c Run No. 1-d~~

~~Vol. (ml) E (mv Vol. (ml) E (mv)~~

0 . 0 0 1 0 0 0 . 0 0 106 0.50 470 0.50 476 1 . 0 0 495 1 . 0 0 496 1.50 570 1.50 506 2 . 0 0 520 2 . 0 0 516 2.50 528 2.50 521 3.00 535 3.00 531 3.50 542 3.50 536 4.00 550 4.00 541 4.50 555 4.50 546 5.00 562 5.00 546 5.50 570 5.50 551 6 . 0 0 580 6 . 0 0 556 6.50 590 6.50 561 7.00 610 7.00 566 7.50 650 7.50 576 8 . 0 0 725 8 . 0 0 581 8.50 745 8.50 591 8.75 755 9.00 606 9.00 760 9.50 626 1 0 . 0 0 775 1 0 . 0 0 676 10.50 726 1 1 . 0 0 741 11.50 751 1 2 . 0 0 751 12.50 751 27

Run No. 2-a Run No . 2-b Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 125 0.00 125 0.50 495 0.50 505 1.00 520 1.00 520 1.50 535 1.50 535 2.00 545 2.00 540 2.50 555 2.50 550 3.00 565 3.00 560 3.50 580 3.50 570 4.00 595 4.00 585 4.50 635 4.50 610 5.00 750 5.00 650 5.50 780 5.50 750 6.00 790 6.00 780 6.50 795 6.50 795 7.00 800 7 . 0 0 800 7.50 805 7.50 805 8.00 805 8.00 805

~~Run No. 2-c Vol. (ml) E (mv)~~

~~0.00 125 0.50 500 1.00 520 1.50 530 2.00 540 2.50 545 3.00 555 3.50 565 4.00 575 4.50 585 5.00 605 5.50 660 6.00 750 6.50 775 7.00 785 7.50 790 8.00 795 8.50 797 9.00 800 28~~

Run No. 3-a Run No. 3-b Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 i 100 0.00 130 0.50 440 0.50 410 1.00 460 1.05 445 1.50 470 1.50 460 2.00 480 2.00 465 2.50 490 2.50 475 3.00 500 3.00 485 3.50 510 3.50 490 4.00 520 4.00 500 4.50 540 4.5Q, 505 5.00 600 5.00 515 5.50 730 5.50 525 6.00 765 6.00 535 6.50 780 6.50 545 7.00 785 7.00 560 7.50 790 7.50 595 8.00 795 8.00 715 8.50 795 8.50 765 8.75 775 9.00 780 Run No. 3-c 9.50 785 ,rl r. / \ 9.75 790 V° 1-.: (m^-) E (rov) 10.00 792 0.00 125 0.50 420 1.00 450 1.50 465 2.00 480 2.50 490 3.00 498 3.50 505 4.00 512 4.50 522 5.00 535 5.50 550 6.00 575 6.50 700 7.00 765 7.50 780 8.00 790 8.50 798 9.00 800 9.50 802 29

~~Run No. 4 -a Run No. 4-b Vol. (ml) E (mv) Vol. (ml) E (mv)~~

0.00 130 0.00 130 0.50 525 0.50 525 1.00 545 1.00 545 1.50 560 1.50 555 2.00 570 2.00 565 2.50 575 2.50 575 3.00 590 3.00 585 3.50 605 3.50 595 4.00 620 4.00 610 4.50 665 4.50 640 5.00 765 5.00 740 5.50 785 5.50 775 6.00 795 6.00 785 6 .50 800 6.50 790 7.00 805 7.00 795 7.50 807 7.50 800 8.00 810 8 . 0 0 800 8.50 810

~~Run No. 4-c Vol. (ml) E (mv)~~

~~0.00 130 0.50 525 1.00 545 1.50 560 2.00 570 2.50 580 3.00 595 3.50 605 4.00 630 4.50 720 5.00 775 5.50 790 6 .00 795 6.50 800 7.00 805 7.50 807 8.00 809 8.50 810 30~~

~~Run No. 5-a Run No. 5-b .. (ml) E (mv) Vol. (ml) E (mv'~~

0 . 0 0 150 0 . 0 0 1 1 0 0.25 530 0.25 530 0.50 560 0.50 555 0.75 580 1 . 0 0 580 1 . 0 0 590 1.50 600 1.50 610 2 . 0 0 610 2.05 620 2.50 625 2.50 630 3.00 635 3.00 640 3.50 650 3.50 650 4.00 660 4.00 655 4.50 680 4.50 670 5.00 710 5.00 690 5.50 765 5.25 705 6 . 0 0 790 5.50 720 6.50 800 5.75 740 7 . 0 0 805 6 . 0 0 765 7.50 810 6.25 780 8 . 0 0 810 6.50 , 790 7 . 0 0 800 7.50 805 8 . 0 0 810 8.50 815 9.00 815 9.50 815

~~Run No. 5-c . (ml) E (mv)~~

~~0 . 0 0 1 2 0 0.25 550 0.50 570 1 . 0 0 595 1.50 610 2 . 0 0 625 2.50 635 3.00 650 3.50 660 4.00 675 4.50 690 5.00 720 5.50 770 6 . 0 0 795 6.50 810 7 . 0 0 815 7.50 820 8 . 0 0 825 8.50 825 31~~

~~Run N o . 6 -a Run No. 6 -b Vol. (ml) E (mv) Vol. (ml) E (mVj~~

0 . 0 0 1 0 0 0 . 0 0 1 1 0 0.25 515 0.25 520 0.50 540 0.50 545 0.75 560 0.75 560 1 . 0 0 570 1 . 0 0 570 1.50 585 1.50 580 2 . 0 0 600 2 . 0 0 592 2.50 610 2.50 608 3.05 620 3.00 615 3.50 628 3.50 630 4.00 635 4.00 640 4.50 650 4.50 650 5.00 660 5.00 665 5.50 680 5.50 690 6 . 0 0 740 6 . 0 0 750 6.50 770 6.50 775 7 .00 785 7.00 790 7.50 792 7.50 795 8.05 800 8 . 0 0 800 8.50 802 8.50 805 9.00 805 9.00 808 9.50 808 9.50 810 1 0 . 0 0 810

~~Run N o . 6 -c Run No. 6 -c (cont Vol. (ml) E (mv) Vol. (ml) E (mv~~

0 . 0 0 1 0 0 7.50 790 0.25 510 8 . 0 0 795 0.50 530 8.50 800 0.75 550 9.00 802 1 . 0 0 560 1.50 580 2 . 1 0 590 2.50 605 3.00 615 3.50 625 4.00 635 4.50 645 5.00 665 5.50 700 6 . 0 0 760 6.50 780 7.00 785 Run No. Vol. (ml) E (mv)

~~0 . 0 0 109 0.50 604 0.75 614 1 . 0 0 624 1.50 639 2 . 0 0 649 2 .50 654 3.00 664 3.50 669 4.00 679 4.50 689 5.00 699 5.50 714 6 . 0 0 734 6.50 754 7.00 774 7.50 784 8 . 0 0 789 8.50 794 9.00 794~~

Run No. 7-c Vol. (ml) E (mv) 0.00 84 0.50 609 1.00 634 1.50 649 2.00 654 2.50 664 3.00 674 3.50 679 4.00 689 4.5D ' 699 5.00 709 5.50 719 6.00 739 6.50 764 7.00 784 7.50 794 8.00 799 8.50 804 9.00 804 32

Run No. 7-a Run No. 7-b Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 109 0.00 114 0.50 604 0.50 614 0.75 614 1.00 644 1.00 _ 624 1.50 654 1.50 ' 639 2.00 662 2.00 649 2.50 669 2.50 654 3.00 679 3.00 664 3.50 689 3.50 669 4.00 704 4.00 679 4.50 719 4.50 689 5.00 744 5.00 699 5.50 774 5.50 714 6.00 789 6.00 734 6.50 799 6.50 754 7.00 804 7.00 774 7.50 807 7.50 784 8.00 809 8.00 789 8.50 812 8.50 794 9.00 794

Run No. 7-c Vol. (ml) E (mv) 0.00 84 0.50 609 1.00 634 1.50 649 2.00 654 2.50 664 3.00 674 3.50 679 4.00 689 4.50 699 5.00 709 5.50 719 6.00 739 6.50 764 7.00 784 7.50 794 8.00 799 8.50 804 9.00 804 33

~~Run No. 8-a Run No. 8-b Vol. (ml) E (mv) Vol. (ml)~~

0 . 0 0 125 0 . 0 0 125 0.50 480 0.50 450 1 . 0 0 485 1 . 0 0 460 1.50 485 1.50 465 2 . 0 0 485 2 . 0 0 465 2.50 485 2.50 470 3.00 485 3.00 475 3.50 485 3.50 477 4.00 487 4.00 480 4.50 495 4.50 485 5.00 500 5.00 495 5.50 515 5.60 505 6 . 0 0 550 6.00 520 6.50 695 6.50 550 7.00 745 7.00 675 7.50 765 7.50 745 8 . 0 0 775 8.00 760 8.50 780 8.50 770 9.00 785 9.00 775 9.50 785 9.50 777 10.00 785 10.00 780 10.50 783 Run No. 8 -c Vol. (ml) E (mv)

~~0 . 0 0 125 0.50 460 1 . 0 0 465 1.50 470 2 . 0 0 475 2.50 480 3.00 483 3.50 489 4.00 495 4.50 506 5.00 525 5.50 550 6 . 0 0 695 6.50 750 7.00 765 7.50 770 8 . 0 0 775 8.50 778 9.00 780 34~~

~~Run No. 9-a Run No. 9-b Vol. (ml) E (mv) Vol. (ml) E (mv)~~

0 . 0 0 125 0.00 130 0.50 625 0.50 630 1 . 0 0 645 1.00 650 1.50 655 1.50 665 2 . 0 0 665 2.00 675 2.50 675 2.50 680 3.00 685 3.00 685 3.50 690 3.50 690 4.00 697 4.00 700 4.50 710 4.50 715 5.00 725 5.00 730 5.50 750 5.50 750 6 . 0 0 770 6.00 770 6 .50 775 6.50 780 7.00 780 7.00 785 7.50 785 7.50 790 8.00 785 8.00 795 8.50 800 Run No. 9-c Vol., (ml) E (mv) 0.00 130 0.50 625 1.00 645 1.50 655 2.00 665 2.50 675 3.00 685 3.50 695 4.00 700 4.50 715 5.00 725 5.50 745 6 . 0 0 770 6.50 785 7.00 795 7.50 800 8 . 0 0 805 8.50 805 35

~~Run No. 10-a Run No. 10-b~~

~~Vol. (ml) E (mv Vol. (ml) E (mv)~~

0 . 0 0 4 0 . 0 0 4 0.50 414 0.50 409 0.75 432 0.75 428 1 . 0 0 439 1 . 0 0 441 1.25 449 1.25 449 1.60 459 1.50 454 1.75 464 2 . 0 0 464 2 .00 469 2.25 469 2.50 476 2.50 474 3.00 485 3.00 484 3.25 490 3.25 489 3.50 495 3.50 496 3.75 503 4.00 512 4.00 508 4.25 522 4.25 519 4.50 533 4.50 529 4.75 552 4.75 544 5.00 602 5.00 584 5.50 749 5.50 742 6 . 0 0 772 6 . 0 0 764 6.50 779 6.50 774 7.00 785 7.00 777 7.50 789 7.50 781 8 . 0 0 792 8 . 0 0 784 8.50 793 8.50 784 9.00 793 36

~~Run No. 11-a Run No. 11-b~~

~~Vol. (ml) E (mv) Vol. (ml) .gJ.'El~~

0.00 24 0.00 29 0.50 414 0.50 412 0.75 432 0.75 425 1 . 0 0 440 1.00 435 1.25 449 1.25 444 1.50 454 1.50 450 1.75 459 1.75 455 2 . 0 0 465 2.00 461 2.25 471 2.25 465 2.50 474 2.50 472 3.00 484 2.75 476 3.25 490 3.00 482 3.50 495 3.25 487 3.75 504 3.50 494 4.00 513 3.75 499 4.25 523 4.00 508 4.50 535 4.25 517 4.75 562 4.50 527 5.00 629 4.75 544 5.25 732 5.00 583 5.50 754 5.25 709 6.00 773 5.50 744 6.50 779 6.00 764 7.00 784 6.50 774 7.50 787 7.00 779 8.00 789 7.50 784 8.50 791 8.00 786 8.50 791 8.50 789 9.00 789 37

Run No. 12-a Run No. 12-b Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 104 0.00 104 0.50 464 0.50 464 1.00 484 1.00 484 1.50 494 1.50 494 2.00 504 2.00 504 2.50 514 2.50 514 3.00 534 3.00 534 3.50 614 3.50 594 4.00 744 4.00 744 4.50 774 4.50 774 5.00 779 5.00 784 5.50 784 5.50 794 6.00 786 6.00 794 6.50 789 6.50 784 7.00 789 7.00 784

Run No. 12-c Vol. (ml) E (mv) 0.00 60 0.50 400 0.75 420 1.00 430 1.50 455 2.00 465 2.50 480 3.00 500 3.50 510 4.00 520 4.50 525 5.00 535 5.50 570 6.00 700 6.50 750 7.00 765 7.50 775 8.00 780 8.50 785 9.00 790 9.50 790 38

Run No. 13-a Run No, 13-b Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 135 0 . 0 0 80 0.25 230 0.25 2 2 0 0.50 250 0.50 240 0.75 260 0.75 260 1.00 270 1 . 0 0 270 1.25 275 1.50 280 1.50 280 1.75 285 2.00 290 2 . 0 0 288 2.50 300 2.25 290 3.00 315 2.50 300 3.50 330 3.00 310 4.00 360 3.50 320 4.25 610 3.75 330 4.50 745 4.00 340 4.75 780 4.25 360 5.00 790 4.60 630 5.50 800 4.75 730 5.75 800 4.90 760 5.00 770 Run No, 13-c 5.10 780 5.25 782 Vol. (ml) (mv) 5.50 790 0.00 80 5.75 795 0.25 225 6 . 0 0 800 0.50 250 6.30 805 0.75 260 1.00 265 Run No. 13-c (cont.) 1.25 270 Vol. (ml) E (mv) 1.50 275 2.00 285 6 . 0 0 780 2.50 290 6 . 1 0 785 3.00 300 6 .20 790 3.50 305 6 .30 795 3.80 310 6.40 795 4.00 320 6.50 800 4.25 325 6.60 800 4.50 330 4.75 340 5.00 355 5.25 395 5.50 700 5.60 740 5.70 760 5.80 770 39

Run No. 14-a Run No. 14-b Vol. (ml) E (mv) Vol. (ml) E 0.00 105 0.00 115 0.50 185 0.50 185 1.00 205 1.00 205 1.50 215 1.50 215 2.00 225 2.00 225 2.50 233 2.60 235 3.00 245 3.00 245 3.50 255 3.50 260 4.00 275 4.00 290 4.50 625 4.50 740 5.00 765 5.00 795 5.50 805 5.50 810 6.00 815 6.00 815 6.50 820 6.50 820 7.00 820 7.00 823 7.50 825

Run No. 14-c Run No. 14-d Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 80 0.00 80 0.25 165 0.25 170 0.50 190 0.50 190 0.75 200 0.80 200 1.00 205 1.00 210 1.25 210 1.50 220 1.50 219 2.00 230 2.00 225 2.50 235 2.50 230 3.00 250 2.75 235 3.50 260 3.00 240 3.75 275 3.50 255 4.00 310 3.75 260 4.25 675 4.00 270 4.50 760 4.25 290 4.60 765 4.50 355 4.70 780 4.75 725 4.80 780 5.00 765 4.90 785 5.10 770 5.00 790 5.20 780 5.10 795 5.30 785 5.20 795 5.40 785 5.50 790 5.75 795 6.00 800 40

Run No. 15-a Run No. 15-b Vol. (ml) E (mv) Vol. (ml) -E iw). 0 . 0 0 130 0 . 0 0 130 0.50 480 0.50 480 1 . 0 0 485 1 . 0 0 485 1.50 490 1.50 490 2 . 0 0 495 2 . 0 0 493 2.50 500 2.50 498 3.00 505 3.00 505 3.50 520 3.50 520 4.00 535 4.00 536 4.50 605 4.50 600 5.00 755 5.00 765 5.50 780 5.50 787 6 . 0 0 790 6 . 0 0 797 6.50 795 — 6.50 805 7.00 800 7.00 807 7.50 800 7.50 810 8 . 0 0 810 8.50 812 Run No, 15-c Vol. (ml) E (mv) 0.00 130 0.50 475 1.00 480 1.50 485 2.00 490 2.50 493 3.00 500 3.50 510 4.00 520 4.50 540 5.00 585 5.50 760 6.00 785 6.50 795 7.00 800 7.50 805 8.00 807 8.50 810 41

~~Run No. 16-a Run No. 16-b Vol. (ml) E (mv) Vol. (ml) E (mv)~~

0 . 0 0 1 2 0 0 . 0 0 1 2 0 0.50 635 0.50 645 1 . 0 0 660 1 . 0 0 663 1.50 670 1.50 672 2 . 0 0 675 2 . 0 0 677 2.50 680 2.50 684 3.00 6 8 6 3.00 690 3.50 695 3.50 697 4 .00 705 4.00 705 4.50 715 4.50 720 5.00 737 5.00 740 5.50 770 5.50 770 6 . 0 0 785 6 . 0 0 785 6.50 795 6.50 795 7.00 800 7.00 800 7.50 805 7.50 805 8 . 0 0 807 8 . 0 0 807 8.50 810 8.50 810

~~Run No. 16-c Vol. (ml) E (mv)~~

0 . 0 0 1 1 0 0.50 640 1 . 0 0 660 1.50 667 2 . 0 0 675 2.50 680 3.00 6 8 6 3.50 695 4.00 705 4.50 720 5.00 735 5.50 770 6 . 0 0 785 6.50 795 7.00 805 7.50 806 8 . 0 0 810 8.50 813 CM & G No. 17-a Run No. 17- r-4 w w > > o o i i-nnininioiDvovovDvovoNr'i^cooooooo ooinininoinioinmoooincooH ooinininoinioinmoooincooH M0OrNcOMi rl O O rl OM»0\OHrlN«cfOOMyiO o o o o o o o o o oot-irHcMcMcoco

Run No. 17-c V o l . (ml) E (mv) oo Oo 1—Imin I—1 o o Om 00 o • • • • • • • • • . . . . • • • • VO CO mo o 00 LOm r*H CTV O o o inVOvO CMCM o m r—ir—H in o CO O O VO inmOOmm CO VOvO om m mo mo o CM —i 00 O o 00 o O o 00 t o 00 H 43

Run No. 18-a Run No. 18-b Vol. (ml) E (mv) Vol. (ml) E (mv) 0.00 130 0.00 130 0.50 660 0.50 665 1.00 676 1.00 685 1.50 685 1.50 695 2.00 695 2.00 700 2.50 700 2.50 706 3.00 705 3.00 715 3.50 715 3.50 725' 4.00 725 4.00 733 4.50 735 4.50 745 5.00 750 5.00 760 5.50 775 5.50 780 6.00 785 6.00 790 6.50 790 6.50 795 7.00 795 7.00 800 7.50 800 7.50 805 8.00 803 8.00 810 8.50 805

~~Run No. 18-c Vol. (ml) E (mv) 0.00 130 0.50 665 1.00 685 1.50 695 2.00 700 2.50 707 3.00 715 3.50 725 4.00 735 4.50 755 5.00 775 5.50 790 6 . 0 0 800 6.50 805 7 . 0 0 810 7.50 810 8 . 0 0 810 44~~

Using the data obtained, plots were made of volume of acid added vs. potential reading. The curve obtained for phenyl methyl sulfoxide is representative of the curves obtained for the compounds studied.

~~800-~~

~~6 00-~~

~~Pot . 500- (mv)~~

~~400"~~

~~300-~~

~~200-~~

~~1 0 0 -~~

~~Vol. (ml)~~

~~Fig. 6 - Titration curve for phenyl methyl sulfoxide 45~~

The volume of acid required for each of the titra tions could be accurately determined from the titration curves. Sample weights were carefully recorded, and from these sample weights it was possible to calculate the ex pected amount of acid that should have been required. Making use of the equation given below, the per cent of error for each of the titrations was calculated.

~~7 u v ™ _ Actual Volume - Expected Volume 10Q„ /„ Error - Expected Volume X iUU/o~~

~~A tabulation of this data is given in the following tables. 46~~

~~TABLE 5 Accuracy for Sulfoxide Titrations Run Sample Expected Actual Sample No. Weight Volume Volume % Errc (grams) (ml) (ml)~~

~~Substituted phenyl methyl sulfoxides~~

~~£-H 1 -a 0.0724 5.17 5.33 3.09 11 1 -b 0.0730 5.21 5.37 3.07~~

~~II 1 -c 0.1044 7.46 7.53 0.94 11 1 -d 0.1389 9.92 9.89 -0.30 m-CHQ 2 -a 0.071 4.62 4.72 2.16 — 3 it 2 -b 0.0781 5.07 5.20 2.56~~

M 2 -c 0.0850 5.52 5.61 1.63 £-CH30 3-a 0.0862 5.06 5.20 2.76 11 3-b 0.1339 7.88 7.78 -1.27 11 3-c 0.1079 6.35 6.40 0.79 m-CH30 4-a 0.0784 4.61 4.69 1.74 ii 4-b 0.0830 4.88 4.78 -2.05 ir 4-c 0.0743 4.37 4.37 0 . 0 0 5-a 0.1231 5.91 5.77 -2.36 —m-CFo 3 ii 5-b 0.1081 5.20 5.25 0.96 ii 5-c 0.1113 5.35 5.36 -0.18 m-Cl 6 -a 0.1015 5.83 5.91 1.37 ii 6 -b 0.1003 5.76 5.80 . 0.69 ii 6 -c 0.0974 5.60 5.59 -0.18 m-N0o 7-a 0.1142 6.17 6 . 2 0 0.49 — 2 ii 7-b 0.0929 5.02 5.10 1.60 it 7-c 0.1161 6.27 6.18 -1.43 TABLE 5 (continued)

~~Run Sample Expected Actual Sample No. Weight Volume Volume 7o Error (grams) (ml) (ml)~~

~~Dimethyl sulfoxide 8 -a 0.0495 6.35 6.28 - 1.10~~

~~U 8 -b 0.0541 6.94 6.83 -1.59 II 8 -c 0.0459 5.88 5.79 -1.53 Diphenyl sulfoxide 9-a 0.1093 5.41 5.44 0.74 I! 9-b 0.1104 5.47 5.33 -2.59~~

~~II 9-c 0 . 1 1 2 0 5.54 5.59 0.90 Cis-4-(4- chlorophenyl)- thiane-1 -oxide 1 0 -a 0.1135 4.98 5.18 4.02~~

~~II 1 0 -b 0.1133 4.97 5.14 3.42 Trans-4-(4- chlorophenyl)- thiane-1 -oxide 1 1 -a 0.1134 4.96 5.01 1.01~~

~~II 1 1 -b 0.1153 5.06 5.10 0.79 TABLE 6 Accuracy for Standards and Sulfilimines Titrates~~

~~Run Sample Expected Actual Sample No. Weight Volume Volume % Error (grams) (ml) (ml)~~

~~Caffein 1 2 -a 0.0692 3.56 3.65 2.53~~

~~tl 1 2 -b 0.0707 3.64 3.69 1.37~~

!l 1 2 -c 0.1098 5.64 5.80 2.83 N,N-Dimethyl- aniline 13-a 0.0520 4.30 3.94 -8.37 II 13-b 0.0570 4.71 4.50 -4.46 U 13-c 0.0639 5.28 5.42 2.65 N,N-Diethyl- aniline 14-a 0.0627 4.21 4.39 4.28 ii 14-b 0.0626 4.20 4.28 1.90 n 14-c 0.0668 4.48 4.70 4.91 n 14-d 0.0619 4.15 4.11 -0.96 S,S-Dimethyl- N-£-toluenesulfonyl- sulfilimine 15-a 0.1043 4.52 4.63 2.43 II 15-b 0.1059 4.58 4.69 2.40 11 15-c 0.1182 5.12 5.14 0.39 S,S-Diphenyl- N-£-toluenesulfonyl- sulfilimine 16-a 0.1786 5.03 5.11 1.59 11 16-b 0.1800 5.07 5.14 1.38 II 16-c 0.1813 5.11 5.24 2.54 S-Methyl-S- phenyl-N-£- t oluene sulfony1 sulfilimine 17-a 0.1348 4.60 4.73 2.83 ii 17-b 0.1590 5.43 5.50 1.29 i i 17-c 0.1395 4.76 4.88 2.52 49

~~TABLE 6 (continued)~~

~~Run Sample Expected Actual Sample No. Weight Volume Volume % Error (grams) (ml) (ml)~~

~~S,S-Diphenyl-N- benzenesulfonylsulfilimine 18-a 0.1793 5.26 5.24 -0.38 " 18-b 0.1740 5.10 4.95 -2.94 " 18-c 0.1619 4.75 4.79 0.84 y 50~~

Half-neutralization potentials were obtained from each of the titration curves and are listed in the following tables. In addition, the percentage average deviation has been calculated for each set of compounds. The percentage average deviation is obtained by summing the deviations of the individual measurements from the average value and dividing this sum by the number of trials in the set. This value is divided by the average value and then multiplied 25 by 1 0 0 . .51

~~TABLE 7 Half-Neutralization-Potentials of Sulfoxides~~

~~Deviation Percentage Run from Average Sample No. HNP Average Deviation (mv) (mv) Substituted phenyl methyl sulfoxides E-H 1 -a 540 4 0.37~~

~~1 -b 544 0~~

~~1 -c 548 4~~

~~1 -d 544 0 m-CH, 2 -a 552 1 0.18~~

~~2 -b 552 1~~

~~2 -c 550 1 e .-c h 3o 3-a 492 6 0.86~~

~~3-b 500 2~~

~~3-c 503 5 m-CH^O 4-a 574 1 0.06~~

~~4-b 575 0~~

~~4-c 575 0 m-CF3 5 -a 635 0 0.52~~

~~5-b 630 5~~

~~5-c 640 5 52~~

~~TABLE 7 (continued~~

~~Deviation Percentage Run from Average Sample No. HNP Average Deviation (mv) (mv) Substituted phenyl methyl sulfoxides m-Cl 6 -a 618 2 0.22~~

~~I! 6 -b 615 1~~

~~It 6 -c 615 1 m-N0 2 7-a 663 2 0.65~~

~~it 7-b 661 4~~

~~I! 7-c 672 7~~

~~Dimethyl sulfoxide 8 -a 485 3 0.55~~

~~it 8 -b 478 4~~

~~tl 8 -c 483 1~~

~~Diphenyl sulfoxide 9-a 680 1 0.15~~

~~9-b 682 1~~

~~tt 9-c 682 1~~

~~Cis-4-(4-chlorophenyl)-thiane- 1 -oxide 1 0 -a 479 1 0.21~~

~~tt 1 0 -b 477 1~~

~~Trans-4-(4-chlorophenyl)-thiana- 1 -oxide 1 1 -a 474 0 0.00~~

~~it 11-b 474 0 53~~

~~TABLE 8 Half-Neutralization-Potentials of Standards and Sulfilimine~~

~~Deviation Percentage Run from Average Sample No HNP Average Deviation (mv) (mv)~~

~~Caffein 1 2 -a 499 0 0.13~~

~~11 1 2 -b 500 1 ii 1 2 -c 498 1 N ,N-Dimethy1- aniline 13-a 290 2 0.79 II 13-b 290 2 1! 13-c 295 3 N,N-Diethyl- aniline 14-a 229 1 0 . 2 2 II 14-b 229 1~~

~~II 14-c 230 0~~

~~II 14-d 230 0 S jS-Dimethyl- N-p-toluenesulfonyl- sulfilimine 15-a 498 1 0 . 2 0 M 15-b 498 1~~

~~II 15-c 496 1 S ,S-Diphenyl N-p-toluene sulfonylsulfilimine 16-a 681 1 0.24 it 16-b 685 3~~

~~n 16-c 681 1 54~~

~~TABLE 8 (continued)~~

~~Deviation Percentage Run from Average Sample No. HNP Average Deviation (mv) (mv)~~

~~S-Methyl-S- phenyl-N-p- toluenesulfonylsulfilimine 17-a 610 1 0.16~~

~~” 17-b 608 1~~

~~" 17-c 610 1 S ,S-Diphenyl-N- benzenesulfonylsulfilimine 18-a 703 2 0.24 " 18-b 707 2 " 18-c 706 1 55~~

~~BIBLIOGRAPHY~~

~~1. E. M. Arnett in "Progress in Physical Organic Chemistry", Vol. 1, S. G. Cohen, A. Streitwieser, Jr., and R. W. Taft, Ed., Interscience Publishers, Inc., New York, N. Y., 1963.~~

~~2. Paul Nylen, Z. Anorg. Allg. Chem. , 246, 227 (1941).~~

~~3. P. Haake and R. D. Cook, Tetrahedron Lett., 427 (1968).~~

~~4. D. Landini, F. Montanari, G. Modena and G. Scorrano,~~

~~Chem. Commun., 86 (1968).~~

~~5. C. A. Streuli, Anal. Chem., 30.> 9 9 7 (1958).~~

6 . R. W. Taft, Jr., J. Phys. Chem., 64, 1805 (1960). For other papers in this series see R. W. Taft, Jr. and I. C. Lewis, J. Amer. Chem. Soc., £LL, 5354 (1959); R. W. Taft, Jr., S. Ehrenson, R. E. Glick and I. C. Lewis, ibid., 5352, 81 (1959); R. W. Taft, Jr. and I. C. Lewis, ibid., 80, 2436 (1958).

~~7. J. T.Edward, H. S. Chang, K. Yates and R. Stewart, Can. J. Chem., _38, 1518 (1960).~~

~~8 . W. H. Edmonds, B. S. Thesis, University of New Hampshire, Durham, N. H . , 1965.~~

~~9. N. F. Hall, J. Amer. Chem. Soc., 52_, 5115 (1930).~~

~~10. G. Schwarzenbach and E. Rudin, Helv. Chim. Acta, 22, 360 (1939).~~

~~11. R. Stewart and K. Yates, J. Amer. Chem. Soc., {30, 6355 (1958) . 56~~

~~12. S. A. Smith and S. Winstein, Tetrahedron, _3, 317 (1958); R. Kuhn, Angew. Chem., 1_7, 570 (1957); R. Kuhn and H— Trischmann, Ann., 611, 117 (1958) .~~

~~13. F. A. Cotton and R. Francis, J. Inorg. Nucl. Chem., 17, 62 (1961).~~

~~14. J. Weber, University of New Hampshire, personal communication, 1966.~~

~~15. R. G. Pearson, J. Amer. Chem. Soc., 85_, 3533 (1963); R. F. Hudson, Chem. Eng. News, 43 (22), 102 (1965).~~

~~16. D. C. Barnard, J. M. Fabian, and H. P. Koch, J. Chem. Soc., 2442 (1949); M. Tamres and S. Searles, J. Amer. Chem. Soc., 81, 2100 (1959).~~

~~17. H. Jaffe, Chem. Rev., 5_3, 191 (1953).~~

~~18. Ref. 6 and references cited therein.~~

19. F. G. Bordwell and P. J. Boutan, J. Amer. Chem. Soc., 79, 717 (1957) and references cited therein. Some pertinent references to^p-^d)^ bonding in sulfur are G. Cilento, Chem. Rev., 60^, 147 (1960); C. C. Price and S. Oae, "Sulfur Bonding", Ronald Press, New York, N. Y., 1962; L. Goodman and R. W. Taft, J. Amer. Chem. Soc., 87, 4385 (1965); R. W. Taft and J. W. Rakshys, ibid., 87., 4387 (1965).

~~20. R. L. Shriner, H. C. Struck and W. J. Johnson, ibid., 52., 2060 (1930).~~

~~21. E. Fischer and 0. Bromberg, Chem. Ber. , 30^, 219 (1897).~~

~~22. G. W. A. Kahlbaum, Z. Phy. Chem., 26^, 606 (1897).~~

~~23. A. Kucsman, I. Kapovits, and M. Balia, Tetrahedron, 18, 75 (1962). 57~~

~~24. C. King, J. Org. Chem., 2_5, 352 (1960).~~

~~25. D. A. Skoog and D. M. West, "Fundamentals of Analytical Chemistry", Holt, Rinehart and Winston, New York, N. Y., (1963) p 36. PART II.~~

~~A STUDY OF THE HYDROLYSIS OF ARENESULFINAMIDES~~

~~IN BASIC AQUEOUS ETHANOL 58~~

~~INTRODUCTION~~

In recent years much attention has been drawn to sulfur chemistry and in particular towards the mechanistic aspects of nucleophilic substitution at di-, tri- and tetracoordinate sulfur. Dispite this increasing attention, areas still exist where our knowledge is limited. It is our hope to contribute to this general subject. We have narrowed our area of investigation to a specific type of substitution reaction at sulfur, that of tricoordinate sulfur (eq 1 ).

~~• • • • X-S-Z + Nu: -* Nu-S-Z + X: (1) i I Y Y~~

Some specific examples of tricoordinate sulfur compounds which undergo nucleophilic substitution at sulfur (eq 1 ) are sulfoxides (R^SO), sulfinyl chlorides (RS0C1), sulfilimines (R^SNR), sulfonium salts (R^S+) , and sulfinate esters (RS(O)OR). In many cases, nucleophilic substitution reac tions at sulfur are useful for their synthetic utility. The various aspects of the substitution reactions can be conven

~~iently divided into four categories; (1 ) the influence of the~~

nucleophile's structure on reactivity, (2 ) the stereochemistry of the reaction, (3) the influence of the sulfur compound's structure on reactivity, and (4) the possibility of inter mediates of higher coordination number than that of the substrate. Considerable effort has been extended towards the first two categories, while in contrast, minimal attention has been focused on the last two categories. 59

Herbrandson and Dickerson^" in an investigation of the epimerization at sulfur of optically active 1-menthy1 esters of arenesulfinic acids in the presence of low con centrations of hydrogen chloride and tetraethylammonium chloride found the kinetics of the reaction to be third order; first order in hydrogen chloride, first order in chloride ion, and first order in ester. To account for these observations, the authors postulated a reversible reaction of the ester with the two catalysts to give the sulfinyl chloride and 1-menthol via a transition state approximating (i).

2 In a more recent publication, Herbrandson and Cusano reported the kinetics of the ethoxide ion catalyzed ethanol- ysis of (-)-menthyl (+)-g-iodobenzene sulfinate and (-)- menthyl (-)-g-iodobenzene sulfinate in nitrobenzene. The reaction was found to be first order in ethoxide and first order in ester. 60

~~0 i i~~

~~+ - A + EtO - kl I Ar 0 ' OEt (2)~~

~~0 0 II II + EtO _2_ > + EtO - y \ 4I 'Ar Ar •-2 OEt OEt~~

In an exhaustive study of sulfite esters, it was shown by Bunton, de la Mare, Tillet, and co-workers that base hydrolysis of sulfite esters was first order in hydrox ide ion and first order in ester. For the aliphatic sulfites, it was established, through the use of oxygen-18, that the reaction involves nucleophilic attack on sulfur with S-0 bond cleavage and that the second stage of hydrolysis, in volving a second attack on sulfur to liberate sulfur dioxide, follows rapidly. It was assumed that the mechanism adapted by the aromatic sulfites is essentially similar and that 4 initial attack on sulfur is the rate-determining step. The reaction sequence is as follows:

~~R" ° \ , / ° ~ S=0 + o h ” ■» R-O-S + ROH / R-0 0 (3)~~

~~/ ° " R-O-S + OH" -* ROH + S0^“ % * 3 0 61~~

Bunton^ also demonstrated that bromide and chloride ions are very effective in catalyzing the acid hydrolysis of sulfite esters. Also studied was the hydrolysis of methyl 18 toluene sulfinate in acidic and alkaline -dioxane solution. It was found that the reaction results in isotopically normal methanol. Although the basic hydrolysis was too fast for conventional kinetic techniques to follow, the results in acid solution indicated that this sulfinate £ ester reacted in the same manner as did the sulfite esters. Davis^ has also published results of a similar but less extensive study of the hydrolysis of sulfite esters. Q Kice has published a study of the catalytic effects of various nucleophiles on the hydrolysis of aryl sulfinyl sulfones. In this study evidence is presented for the im portance of both the polarizability and the basicity of the attacking nucleophile.

~~P P - u Ar-S-§-Ar + Nu: Ar-S-Nu + ArSCL (4) 0~~

~~9 Johnson has shown that alkoxides readily exchange with alkoxysulfonium salts. Resultant base catalyzed elimi nation leads to carbonyl compounds.~~

~~+ + RO-S^ + R* CH 0" -> RO" + ^S-OCH 2 R'-» /S + R» CHO~~

Extensive studies on the reduction of sulfoxides by 10 iodide ion have been reported by numerous authors. A mechanism involving a rate determining attack of iodide ion on the sulfur of the monoprotonated sulfoxide while a hydron- ium ion acts as an acid catalyst has been postulated. 62

~~Numerous stereochemical studies have been carried 11 out at tricoordinate sulfur. Phillips showed that alcoholysis of alkyl £-toluenesulfinates proceeds with inversion.~~

~~0 . 0 . I ,'** I , .S + R'OH VS + ROH (5) S > / ' v £-CH3 C6 H 4 OR R»0 C6H4CH3~~

Andersen 12 described the synthesis of optically active sulfoxides by the reaction of a sulfinate ester with 13 the Grignard reagent. Mislow and co-workers later showed that the Andersen synthesis proceeded with inversion of configuration.

~~0 . 0 . \ I S" + R ’MgX -> .S' + ROMgX (6 )~~

~~£.-CH3C6 H4r ^OR R* r C6 H 4 CH3~~

~~14 Johnson has demonstrated that alkoxy sulfonium salts react with hydroxide ion with inversion.~~

~~0 OEt 0 ' y Et o b f “ +•-'-* - ho,oh" ' y / Ss — — *— • / % BF* -— * ✓ % R R 1 R R* R» R~~

~~(7)~~

~~Gram and Day^ have reported a stereospecific syn thesis of an optically active sulfilimine (3) from an opti~~

~~cally active sulfoxide (2 ). 63~~

~~B.-C H 3 C6H4S02N=S=0~~

~~C 5H 5N~~

~~NS02 -C6 H 4 CH3-£ 0 CH M \Vs-CH, E-CH3C6H4S02NH2 , ^ 7 / V S-CH3 3 \ J P2 05 , 2(C2 H5)3N \ _ 7~~

~~KOH, CH3OH~~

Based on optical rotatory dispersion (ORD) studies, all three reactions were said to proceed with inversion of configuration. It was the purpose of this work to examine the in fluence of the sulfur compound’s structure on reactivity for one type of tricoordinate sulfur compound, the arenesulfin- ami des , in their reaction with hydroxide ion. A kinetic study on the rates of basic hydrolysis would provide rate constants for use in a Taft-Lewis type of Hammett treatment. In this way, the electronic requirements of this reaction would be determined and information obtained concerning the existence of an intermediate, one coordination number higher than that of the substrate. 64

~~RESULTS AND DISCUSSION~~

A series of nine meta and para substituted N-mesityl benzenesulfinamides were prepared (eq 1 and 2 ) and the kinetics of their reaction with hydroxide ion in aqueous ethanol studied (eq 3). The sulfinamides are listed in Table 1.

~~xc6 h4soci + c6 h 2 (ch3 )3 nh2 -> xc6 h4 sonhc6 h 2 (ch3 ) 3 (1 )~~

~~C6H2 (CH3) 3NSO + XC6H4MgBr X C ^ S O N H C ^ (CH3 >3 (2 )~~

~~xc6h 4 sonhc6 h 2 (ch3 ) 3 + oh” -» xc6 h4 so2 + c 6 h 2 (ch3 )3 nh2 (3)~~

The kinetics were run in 95%. ethanol with the concentrations -2 -3 of base and sulfinamide~10 M. - 10 M. depending upon the solubility of the sulfinamides. Second order rate constants were obtained. The kinetics were followed by titrating the base with dilute acid. Generally, the reaction was followed for one half-life although good second order plots could be obtained for two half-lives. In some runs a random consump tion of base was observed during equilibration of the reaction solutions to bath temperature. This consumption in some runs corresponded to as high as 2 0 % of the sulfinamide present in solution. The reaction rates, however, were apparently not affected in view of their reproducibility.

Several runs were carried out using N-mesityl jd- chlorobenzenesulfinamide in which the sulfinamide concen tration was kept constant while the initial hydroxide concen tration, kept in excess, was varied. The results presented 65

~~TABLE 1~~

~~Rate Constants for the Hydrolysis of XCgH^SONHC^H^(CH^)^ by Hydroxide Ion in 957. Ethanol at 49.80°.~~

~~X k x 10 5 l.m sec~~

~~£-0CH3 5.53 + 0.17 + £-CH3 6.82 0 . 4 6~~

~~ra-CH3 10.94 + 0.14~~

~~H 11.26 + 0 . 1 2~~

~~£-Cl 22.95 + 0.40~~

~~m-Cl 27.45 + 0.14 + s - c f 3 48.59 0 . 0 2~~

~~m-NO, 109.26 + 0.16~~

~~£ - n o 2 143.61 + 3.05~~

~~S i These runs in triplicate except for m-CF^ and m-NO^ which are in duplicatej average deviation given. 66 in Table 2 indicate that the reaction is first order in sulfinamide and first order in base.~~

~~TABLE 2~~

~~Dependence of Rate Constants for the Base Hydrolysis of N-Mesityl £-chlorobenzenesulfinamide on Hydroxide Ion Concentration at 49.80°~~

~~i i "1 Sulfinamide, M o h ", m k x 1 0 ^, sec b k x 10 , l.m sec~~

~~0.0075a 0.05 10.78 t 0.24 22.95 1 0.40~~

~~0.0075b 0.075 16.84 1 0.30 23.58 + 0.54~~

~~0.0075a 0.1125 24.75 t 0.70 2 2 . 6 8 ± 0.60 cl b These runs in triplicate; This run in duplicate; average deviation given.~~

Rates of hydrolysis were also measured at three temperatures for N-mesityl p_-chlorobenzenesulfinamide. 16 Utilizing equation 4 , activation parameters were calculated and the results are collected in Table 3.

~~kr = (KT/h)eAS" (4)~~

Log k/kQ values for the substituted sulfinamides were plotted against cr (Fig. 1) A good linear correlation was obtained with p = +1.3, a correlation coefficient of 0.994, and a standard deviation of 0.061.^ 67

~~TABLE 3~~

~~Rate Constants and Activation Parameters for the Hydrolysis of N-Mesityl p-chlorobenzenesulfinamide~~

~~4 - 1 T (°C) k x 10 , l.m sec Activation Parameters~~

~~30 2.85 ± 0.05a 40 8.62 ± 0.10a M^^i/mole) AS (eu) ZU • U *o • ✓ 50 22.95 t 0.40b~~

~~3. b These runs in duplicate; These runs in triplicate; average deviation given.~~

~~One can simply view displacement reactions as a bond forming, bond breaking process. In considering the transi tion state of such a process, one of three situations may exist.~~

~~Nu -- > S -- > L (5)~~

The transition may resemble the reactants in that bond for mation is slower than bond breaking, it may resemble products in that bond formation is faster than bond breaking, or a synchronous process may occur in which bond formation occurs to the same degree as bond breaking. Depending on which of these situations exists in the transition state, the electron density at S will be greater, equal or less than in the ground state. The rho value obtained from a Hammett plot is a measure of the sensitivity of the reaction to substituent change, and qualitatively a measure of the change in electron density at the reaction site. If the electron density at S is less in the transition state than in the ground state, electron donating substituents will exert a stabilizing in- Fig. 1 - A plot of log k/kQ vs.k/kQlog of -plot cT 1 A Fig. log k/k( - -0.4 0.4 0.2 « .2 .8 .6 .0 .2 0 r - 0.2 £-och £-CH 0.0 0.2 cr £-Cl m-Cl • 0.4 m-CF m-NC 0.6 jd -NO >2 0.8 68 69 fluence and rho will be negative. If the electron density at S is greater in the transition state than in the ground state, electron withdrawing substituents will exert a stabilizing influence and rho will be positive. Alkaline hydrolysis of sulfinamides yielded a positive rho, indicating that bond formation is occuring faster than bond breaking. 18 In 1960 Taft proposed a method for evaluating resonance effects between the substituted benzene ring and the reaction center bonded to it. In evaluating the effect of structure on reactivity for a given equilibrium or rate, the approach was taken that the substituent was considered to be the entire substituted benzene ring. A select group of meta substituents are used whose sigma constants do not vary greatly for a large number of rate and equilibrium studies. These sigma constants are defined as cr °. The assumption is made that there is no resonance interaction between the substituted benzene ring and the reaction center bonded to it. If one uses the select group of meta sigma values ((r°) to define rho for a given reaction series, then effective sigma values for para substituents can be obtained from the relationship ar = 1/p (log k/kQ) . In order to obtain inductive sigma constants (

~~log k/k 1.2 1.0 0.6 0.8 0.4 0.2 0.0 0.2 0.4 m-CH - 0.2 " £-OCH • e - h c 3~~

~~m-CF £-Cl ® m-Cl # 0.4 m-NO' £-N0 71 TABLE 4~~

~~Specific Resonance Effects (cr-~~

~~e.-c h 3o -0.08 - 0.11 +0.03 -0.59 -0.26 e-ch3 -0.07 +0.02 +0.04 -0.24 -0.08~~

~~£-Cl -0.03 - 0.02 +0.02 -0.13 -0.06 e-no2 p ;= +1.32 +2.51 +3.06 +2.01 3.61~~

~~r = 0.983 0.998 0.986 0.981 0.983~~

~~s = 0.346 0.005 0.108 0.128 0.22~~

~~This work. bRef. 19. CRef. 20, ^Ref. 21. 6Part one of this thesis and Ref. 22.~~

~~The mathematical procedure used to determine p, and the definitions of the correlation coefficient, r, and the standard deviation, s, are given in Ref. 17.~~

~~•^i N>~~

~~I 73~~

~~2. i~~

In contrast, no significant resonance effect is ob tained for N-mesityl j3-nitrobenzenesulf inamide. This, of course, does not negate the possibility of sulfur exerting a stabilizing influence by donation of its non-bonded electrons. It does mean, however, that in the ground state the contribu tion of resonance structure 7_ to the resonance hybrid is of the same magnitude as resonance structure 8_ in the transition state. 74

Further examination of Table 4 shows that for the ethyl benzoate esters a resonance value of -0 . 1 1 is obtained for ethyl £-methoxybenzoate. This means that electron dona tion by the £-methoxy substituent is greater in the ground state than in the transition state. Resonance structure 11_ contributes more to the resonance hybrid in the ground state than 12 does in the transition state.

~~0 CH3 0 ^^y<|-0 Et OH 10 12~~

In considering N-mesityl £-methoxybenzenesulfinamide a similar argument may be applied. Here the reaction rate is decreased. Resonance structure 15^ contributes more to the resonance hybrid in the ground state than 16_ does in the transition state. An intermediate is taken to approximate the transition state. 75

~~CH3 O '/ V'S-NH CH„0 S-NH~~

~~S-NH c h 3o S-NH H' CH^O OH CH 14 16~~

However, in view of the magnitude of the resonance effect (-0.08), which is small, the difference in contribu tion of resonance structures 15_ and 16_ is minimal. In analogy to their carbon analogues, substitution reactions at an unsaturated sulfur may theoretically proceed

through one of two mechanisms: (1 ) a direct displacement mechanism, or (2) an addition - elimination mechanism. While the formation of unstable addition intermediates have been shown to exist for a large variety of carboxylic acid derivatives, i.e. benzoate esters, benzoic anhydride, 2 A’ benzoyl chlorides , the existence of such an intermediate has never been unequivocally demonstrated for a tri-coordinate sulfur compound. 25 Bunton and co-workers have studied the alkaline hydrolysis of ethylene sulfite. In an effort to determine whether an addition intermediate exists, isotopically en- 18 riched water (H9 0) was used. Upon recovery of the unreacted 18 sulfite ester, a slight incorporation of 0 was found to 76

18 occur. Bunton concluded from this data that exchange of 0 does not occur in significant competition -with the hydrolysis Davis , however, interpreted this data as indicating that an addition intermediate of the type shown below does exist.

~~•o 18o h~~

~~+ 1 8 oh- -» NSvS<—— I Products -o/ S o X o-~~

~~(6 )~~

Andersen and Strecker"^ in a study of iodine ion attack on a series of meta and para substituted phenyl methyl sulfoxides have presented evidence arguing against a possible addition intermediate in the reduction process. A case for the existence of such intermediates can be based on the existence of SF^ (17) . If such a species can and does exist, then it would not be unreasonable for a similar structure (18) to be predicted, e.g.

~~OH <'X* : — S F HN CH 17 CH~~

As shown previously a positive rho was obtained for the alkaline hydrolysis of the N-mesityl benzenesulfinamides. The electron density at sulfur is greater in the transition state than in the ground state. In other words, an actual 77 build up in negative charge is at its maximum when an addi tion intermediate is formed. A strong electron withdrawing substituent i.e. , would be expected to exert a stabil izing influence. On examination of Table 4 for the arenesulfinamides the p_-nitro substituent was shown to exert no exhalted resonance effect. In a qualitative sense, this resonance value is a measure of the charge present on the first atom from the benzene ring. For example, with the protonation of jd- methoxyphenyl methyl ketone, a large resonance effect (-0.59) was observed reflecting the formation of a carbonium ion. A smaller value (-0.26) was obtained for ]D-anisyl methyl sulfoxide, the sulfur oxygen bond being less single bond in character in the protonated state. 78

In considering the formation of an intermediate for the hydrolysis of N-mesityl £-nitrobenzenesulfinamide, the negative charge would reside predominantly on the second atom from the benzene ring. Even so, it would seem reason able to expect the £-nitro substituent to exert a stabilizing influence. In view of this, we conclude that the lack of a resonance effect for N-mesityl £-nitrobenzenesulfinamide argues against the existence of an addition intermediate for the alkaline hydrolysis of arenesulfinamides. Mass spectra have been measured for the following meta and para substituted arenesulfinamides.

~~S-N-R1~~

~~(1 ) X=m-CF3, R* =Mesityl (!) X=£-CH3 , R’=Mesityl~~

~~(2) X=m-CH3, R'=Mesityl (Z) X=£-C1, R>=Mesityl~~

~~(1 ) X=m-Cl, R»=Mesityl (8 ) X=£-0CH3 , R'=Mesityl~~

~~(4) X^m-NO^, R’ =Mesityl (i) X=£-N02 , R’ -Mesityl~~

~~(I) X=H, R»=Mesityl (1 0 ) X=£-CH3 , R1 =£-Tolyl~~

The fragments observed for the sulfinamides 1^ to-10 can best be rationalized as shown in Scheme I. It is assumed that all of the major fragments originate from ionization at nitrogen. It is less likely that the molecular ion is formed by ionization at sulfur since sulfur has some positive charge character. Furthermore, the radical ion species formed by ionization at nitrogen can be stabilized by orbital overlap with the neighboring benzene ring. m/e 125 m/e 134 m/e 135 Scheme I 80

In all cases except one, the amount of molecular ion was less than 2%. The instability of the molecular ion may reflect both the positive charge character of sulfur and the ready formation of highly stable mesidine fragments. For N-p_-tolyl p_-toluenes ulfinamide (10) , 107o of the molecular ion was formed. This somewhat higher percentage is probably due to the absence of the two ortho methyl groups. The mesidine fragment resulting from decomposition of the N-mesityl sulfinamides is stabilized to a greater extent by the electron donating ability of its ortho methyl groups and this product stability is reflected by its increased rate of formation. 27 In analogy to sulfoxides , the sulfinamides exhibited significant sulfur-carbon bond cleavage. The molecular ion readily decomposes to products through either sulfur-nitrogen or nitrogen-carbon cleavage. Cleavage of the sulfur-nitrogen bond (path a) gives the fragments R*NH+ and R* NH2 + , cleavage of N and NH respectively then gives R’H+ . Cleavage of the nitrogen-carbon bond (path b) gives the fragment R ’H+ directly. R*H+ upon losing CH^Cl^ • results in the formation of the stable tropylium ion postulated by Rylander, Myerson, 28 and Grubb to explain the ready loss of ring methyl groups in xylenes. Cleavage of the sulfur-nitrogen bond (path c) with the positive charge residing on sulfur occurs to a much lesser extent. In Table 5 a compilation of the major fragments is shown. It is interesting to note that with all of the meta substituted sulfinamides the base peak is R* H+ while for the para substituted sulfinamides the base peak is R* NH+ . The concentration of an ion is dependent on its rate of formation and depletion as represented in the following scheme. TABLE 5 Major Fragments in the Mass Spectra of Aryl Sulfinamides + + + + M+ R'NH+ R»NH2+ R'H RSO R-C,H, C7H7 6 4 111/ c /o 111/ / o / o /n -1 ,/fi_

~~1 sl-cf3 134 57 135 83 1 2 0 100 91 19 193 2 145 8.6~~

~~2 m-CH^ - - 134 81 135 81 1 2 0 1 0 0 91 87 139 0.8 91 87~~

~~3 m-Cl — 134 59 135 83 1 2 0 100 91 2 0 _ 1 1 1 3.1~~

~~4 m-N0 2 - 134 58 135 80 1 2 0 100 91 29 - - 122 1.2~~

~~5 -H 259 1.5 134 1 0 0 135 47 1 2 0 51 91 2 0 125 5 77 21~~

~~6 e-ch3 273 2 134 1 0 0 135 46 1 2 0 37 91 50 139 10 91 50 1 0 — 1 7 1 293 0 . 8 134 1 0 0 135 42 1 2 0 30 91 9 159 4 1 1 1 3.6~~

~~8 £-och3 289 2 134 1 0 0 135 6 8 1 2 0 61 91 31 155 16 107 00~~

~~00 9 r-no2 -- 134 1 0 0 135 59 1 2 0 98 91 30 170 1 122 0 . 8~~

~~10 e-ch3 245 1 0 106 1 0 0 107 34 - - 91 33 139 19 91 33 82~~

~~+ kln MesNH ------>~~

~~.+ M (7)~~

~~+ k2 n xc6h4so — --- »~~

~~If one assumes steady-state conditions eqs 8 and 9 are obtained~~

~~d[XC6 H4 SO+ ]/dt = 0 = k2 [M+] - £ > 2 n [XC6 H4 SO+ ] (8 )~~

~~d[MesNH+ ]/dt = 0 = ^ [MesNH+ ] (9) where k2n + ^ k ^ n are the rate constants for the processes leading to the disappearance of the ions XC^H4 S0+ and MesNH+ , respectively. Upon rearrangement:~~

~~J k [XC H SIT ] [MesNH+ ] [Mfj = ^ 2" 6 4---- = - IB- (1 0 ) 2 1~~

~~tXC6H4SO+1 _ k2 ^ kXn (1 1 ) [MesNH+ ] kl^-k2n~~

~~[XC.H, S0+ ] / [MesNH+ ] k?21k k° £k° log = log - £ --- ±JL_±------^12^~~

[C6 H 5 SO+ ] / [MesNH+] k2 ^ kl n ^ k2n 83 29 Bursey and McLafferty in a study of the mass spectra of substituted,benzophenones have reported a reac tion constant of 0.0 for the formation of CgH,-+ (eq 13).

~~+ + C6H5~~

~~p =0.0 (13)~~

~~p=-0.5 + X xc6H4co~~

~~Based on McLafferty* s observation that substituent effects in XCLH,C0CLHc do not influence (p = 0.0), we may write: 6 4- o j i~~

~~k° 2 k In — — 1 0 = 1.0 (14) k 1 , 5 2 k°In~~

~~Then:~~

~~[XC6 H4 SO+ ]/ [MesNH+ ] k 2 ^ k2 n log log ------= per (15) [C6H 5 SO+ ]/ [MesNH+] k° Vk 2^-2n O k2 Zk2 n log ^ = log = per = (p2 + 2 p2n^cr K2 " Z k2 n~~

Since the ion abundance of (R* NH + R* NH2 ) is relatively constant in every case, it would be expected that the ion abundance of R*H+ resulting from its decomposition would show the same constancy. On examination of Table 5 it can be seen that this is not the case. Another source for the formation of R*H is necessary; pathway b is the most probable. Since R*H+ can be formed by competing reac tion paths it is impossible to determine what influence 84

substituents exert on the nitrogen-carbon bond breaking. Studying the splitting patterns at a lower ionization voltage might effectively eliminate one of the two pathways. As shown in Scheme I, a secondary cleavage (path c) occurs involving sulfur-nitrogen bond breaking with the positive charge residing on the sulfur. Substituents which stabilize XChH,SO+ should increase its rate of formation. 6 4 In this case, electron donating substituents should stabilize the product XC^H^SO in a way analogous to their stabiliza tion of XC^H,CO+ . Thus a negative rho value is predicted. D H- Indeed a plot of log [(SC^H^SO )/(MesNH+) ] versus the appropriate Hammett sigma values gives a good straight line with a rho value of -1.1 (Fig. 3). This result is interesting for two reasons. First, the ionizing voltage was 80 V. so the molecular ion must be very energetic when first formed. Results from photochem istry show that the ordinary ground state substituent effects are not generally applicable to the first excited states, yet we obtained a good Hammett plot. If excited state molecular ions are formed, they must first decay to a vibrationally excited ground state before sulfur-nitrogen bond cleavage occurs. There one would expect a linear Hammett plot. Inspection of eq 16 shows that rho is the sum of two or more rho constants, the rho value for the initial cleav

age and the rho values for subsequent reactions of XC^H^S0 + . One of these subsequent reactions might be the formation of X-CgH,. . Since no Hammett plot is obtained for the formation of the ions, another pathway for its formation is likely; for example, path d. It may well be that is small so that

~~its contribution to the overall p of -1 . 1 is negligible. 85~~

~~• 2.-0CH~~

~~0.4~~

~~- 1.1 # R-CH~~

~~0.2~~

~~0.0 + + o cn • R-Cl CD cn a 0) a + O - 0.2 cn o cn K LO vO a vO >< a~~

~~oo o -0.4 m-CF~~

~~- 0.6~~

~~2.-N0~~

~~0.2 0.0 0.2 0.4 0.6 0.8~~

[XC6 H4 SO' ]/[MesNH+ ] Fig. 3 - A plot of log v s . cT [C6 H5 SO+ ]/[MesNH+] Relative Abundance (%) Relative Abundance (%) 100 Fig. 4 - Mass spectrum of N-mesityl m-a,a,a-trifluorotoluene- ofN-mesityl spectrum - 4Mass Fig. 100 50 - 30 “ 0 1 50 - 70- 30- 0 1

~~170 1 - 1 sulfinamide 50 210 230190 90 m/e m m / e 110 130 CH 290250 270 CH 86 170150 310 87~~

~~100 -i~~

~~50 -~~

~~90 110 130 150 170 m/e~~

~~1 0 0 -i~~

~~70 - S-N 50 - CD CH O njG 30 - ml § 10 -~~

~~170 190 2 1 0 230 250 270 290 310 m/e Fig. 5 - Mass spectrum of N-mesityl m-toluenesulfinamide Relative Abundance (%) Relative Abundance (%) 100 1 100 Fig. 100 50 - 70 - 50 - 0 1 70 -~~

~~- 1 6 - Mass spectrum ofm-chlorobenzenesulfinamide spectrum - N-mesityl Mass 50 210 230250 170190 m/e 90 m/e 110 S-N 130 CH 150 CH 88 170 310270 290 89~~

~~100~~

~~50 -~~

~~0 30 - G cti 1 10 - G t 3 Q - a) •H> 4J Ctf t—I~~

~~30 70 90 110 130 150 170 m/e~~

~~100 -i~~

~~70-~~

~~50 '~~

170 190 210 230 250270 290 310 m/e Fig. 7 - Mass spectrum of N-mesityl m-nitrobenzenesulfinamide Fig. Relative Abundance (%) Relative Abundance (%) 100 lOO-i 70 - 0 1 30 - 50 - 70 - 0 1 30 - - 7 190 170 8 : 30 - Mass spectrum of N-mesityl benzenesulfinamide of N-mesityl - spectrum Mass 210 230 m/e 90 m/e 110 5 7 290 270 250 S-N 130 CH 150 CH 90 170 310 Relative Abundance (%) Relative Abundance (%) 100 100 Fig. 9 - Mass spectrum of N-mesityl £-toluenesulfinamide of N-mesityl spectrum - 9Mass Fig. 50 ’ 0 1 30 - 70 - 50 - 30 - 70 - 0 1 - - 170 <• > 050 30 9 5 290 250 190 210 70 230 m/e 90 m/e HCH CH 110 S-N 130 150 91 170 310270 92

~~1001~~

~~70-~~

~~50-~~

~~o 30' c oj ■g 1 0 J d C d) S+J cti~~

~~2 -~~

~~30 130 1 5 0 1 7 0 m/e~~

~~100 1~~

~~70 "~~

~~Q) d 30- tti tJ a d CH~~

~~170190 210 230 250 270 290 310 m/e Fig. 10 - Mass spectrum of N-mesityl £-chlorobenzenesulfinamide 93~~

~~100 -i~~

~~70 -~~

~~50 -~~

~~1 0 -~~

•H

~~90 110 130 150 170 m/e~~

~~1 0 0 "1~~

~~70 - CH 0 CH~~

190 210 230170 270 290 310250 m/e Fig. 11 - Mass spectrum of N-mesityl £-methoxybenzenesulfinamide Fig. 12 - Mass spectrum of N-mesityl £-nitrobenzenesulfinamide of - spectrum N-mesityl 12Mass Fig. Relative Abundance (7>) Relative Abundance (7o) 100 I 100 70 “ 50 - 10 50 - 70 - 10 30 - -

~~- 170 i 30 190 210 3 250 230 m/e 90 m/e NO 110 S-N 7 290 270 130 CH CH CH 150 94 310 170 95~~

~~100~~

~~70 -~~

~~50 -~~

~~Cl) •H> ■U ccS T—l CD Pi~~

~~110 150130 170 m/e~~

~~1 0 0 -i~~

~~70- CH S-N~~

~~50 - CD 10 o d dccS c d <3 CD •S +J i—iccS CD Pi~~

~~170 190 210 230 250 270 290 310 m/e Fig. 13 - Mass spectrum of N-jv-tolyl ]3-toluenesulfinamide TABLE 6~~

~~Ultraviolet Absorption of Arenesulfinamides~~

~~Second primary Sulfinamide band Primary band Secondary band~~

~~N-Mesityl m-toluene- 234(4.21) 268(3.81) sulfinamide 276(3.75 •~~

~~N-Mesityl £-toluene- 240(4.31) 262s(4.08) sulfinamide~~

~~N-Mesityl £-methoxy- 244(4.30) 279s (3.14) benzenesulfinamide 266s(3.53)~~

~~N-Mesityl benzene- 234(4.18) 260s(3.96) sulfinamide i~~

~~N-Mesityl m-nitro- 257(4.31) benzenesulfinamide 234(4.26)~~

~~N-Mesityl m-a,a,a- 227s(4.03) 265s(3.47) trifluorotoluenesulfinamide~~

~~N-Mesityl £-nitrobenzene- 267(4.30) sulfinamide 235(4.25) 264(4.29) 235(4.25)' TABLE 6 (continued)~~

~~Second primary / Sulfinamide band_____ Primary band Secondary band~~

~~N-Mesityl £-chloro- 225(4.3) 242(4.17) 265s(3.98) benzenesulfinamide~~

~~N-Mesityl m-chloro- 280(3.14) benzenesulfinamide 272(3.33) 248(3.29)~~

~~N-p-Tolyl p-toluenesulfinamide 240(4.29) 268s(3.77)~~

~~^ m a x m/t< ’ Parent^eses j solvent, 95% ethanol unless specified otherwise.~~

~~^In 50%, pentane, 50%, 95 ethanol.~~

~~SShoulder. 98~~

~~ch3 0 H / S-N —ft ^ ■CH,~~

~~CH, CH,~~

~~CH, 4.5* CH S-N CH~~

~~v 4.0- u; Ot>0~~

~~3.5-~~

~~210 230 250 270 290 310 330 350~~

~~Fig. 14 - Ultraviolet spectra of N-mesityl m-toluenesulfinamide and N-mesityl £-toluenesulfinamide 99~~

~~CH 0 3~~

-N

~~4.0~~

~~210 230 250 270 290 310 330 350~~

~~niyU Fig. 15 - Ultraviolet spectra of N-mesityl £-methoxybenzenesulfinamide and N-mesityl benzenesulfinamide 100~~

~~CH3 0 H CHi~~

~~10, ,H'~~

~~S-N CH~~

~~4.0 u; bfl O r~1~~

~~210 230 250 270 290 310 330 350 m/A Fig. 16 - Ultraviolet spectra of N-mesityl m-nitrobenzenesulfinamide and N-mesityl m-a,a,a-trifluorotoluenesulfinamide 101~~

~~ch3~~

~~50:50 mixture, 95% Ethanol, Pentane~~

~~.5 95% Ethanol~~

~~2 1 0 230 250 270 290 310 350330 mju Fig. 17 - Ultraviolet spectra of N-mesityl ]D-nitrobenzenesulfinamide 102~~

~~CH3 0 H Cl-// 'Vs-N-r^-CH3~~

~~S-N~~

~~4.0-~~

~~UJ toO O~~

~~— i 210 230 250 270290 310 330 350 m jJL~~

~~Fig. 18 - Ultraviolet spectra of N-mesityl £-chlorobenzenesulfinamide and N-mesityl m-chlorobenzenesulfinamide 103~~

~~S-N CH~~

~~4.0-~~

~~10 270 290 310 330 350~~

~~in;* Fig. 19 - Ultraviolet spectrum of N-£-tolyl £-toluenesulfinamide 104~~

~~EXPERIMENTAL~~

The infrared absorption spectra were determined using a Perkin-Elmer Model 337 grating infrared spectro photometer. Infrared spectrum of the sulfinamides showed a -1 major absorption at approximately 1050 cm which was attri buted to the sulfur oxygen vibration. This is in good agreement with the sulfur oxygen vibration found in sulfox ides which appears around 1040-1060 cm \ Nuclear magnetic resonance spectra were determined using a Varian Model A-60 nuclear magnetic resonance spectrometer. The ultraviolet absorption spectra were measured with a Cary Model 14 recording spectrophotometer. Mass spectra were recorded on a Hitachi-Perkin Elmer

RMU-6 E mass spectrometer with an ionizing voltage of 80-v electrons. Microanalyses were determined by Schwarzkopf Micro- analytical Laboratory, Woodside, New York. The boiling points and melting points are in degrees centigrade and are uncorrected. 105

Sodium £-toluenesulfinate dihydrate was prepared ------30 according to the procedure of Whitemore and Hamilton by the zinc dust reduction of £-toluenesulfonyl chloride. The desired compound was obtained as white crystals (86.4%, yield) which were air-dried for two days.

£-Toluenesulfinyl chloride was prepared according to the procedure of Kurzer from the reaction of sodium £- toluenesulfinate dihydrate with excess thionyl chloride. The desired product was obtained as a light yellow liquid (60.9% yield), bp 101-104° (0.7 mm), lit. bp 99-102° (0.5 mm).

~~N-Mesityl £-toluenesulfinamide. - Freshly distilled~~

2,4,6 -trimethylaniline (59.0 g, 0.437 mole) was added to a two-liter three-neck flask equipped with a stirrer, a calcium chloride drying tube and containing anhydrous ether (500 ml). The flask was immersed in an ice bath in order to maintain a solution temperature below 10°. A solution of pure £- toluenesulfinyl chloride (34.8 g, 0.20 mole) in anhydrous ether (25 ml) contained in a pressure equalized addition funnel was then added dropwise over a one-half hour period. Stirring was continued for an additional twenty-four hours following the addition. The ether was filtered under aspirator pressure. The white solid was swirled in cold water (one liter), filtered and the process repeated. The remaining sulfinamide was recrystallized several times from acetone, and finally from 95% ethanol giving 30.1 g (55.1%> yield), mp 146-148°; nmr (CDClg) 7.88-7.29 ppm. (m, 4, Ar-H), 6.93 (s, 2, Ar-H), 5.48 (s, 1, N-H), 2.44 (s, 3, Ar-CH3) ,

~~2.37 (s, 6 , Ar-CH3), 2.26 (s, 3, Ar-CH3) . Anal. Calcd for C ^ H ^ N O S : C, 70.30; H, 7.00. Found: C, 70.08; H, 6.92. 106~~

Sodium benzenesulfinate dihydrate was prepared ae o n cording to the procedure of Whitemore and Hamilton by the zinc dust reduction of benzenesulfonyl chloride. The desired compound was obtained as white crystals (40.4%, yield) which were air-dried for two days.

Benzenesulfinyl chloride was prepared according to 31 the procedure of Kurzer from the reaction of sodium ben zenesulf inate dihydrate with excess thionyl chloride. The desired product was obtained as a dark brown liquid (88.4%, yield) and was used without further purification. N-Mesityl benzenesulfinamide. - Freshly distilled

2,4,6 -trimethylaniline (59.0 g, 0.437 mole) was added to a two-liter three-neck flask equipped with a stirrer, a calcium chloride drying tube and containing anhydrous ether (500 ml). The flask was immersed in an ice bath in order to maintain a solution temperature below 10°. A solution of crude benzenesulfinyl chloride (32.0 g, 0.20 mole) in anhydrous ether (25 ml) contained in a pressure equalized addition funnel was then added dropwise over a one-half hour period. Stirring was continued for an additional twenty- four hours upon completing the addition. The ether was filtered under aspirator pressure, and the filtrate concen trated under vacuum. The white solid which precipitated out was added to the white solid which was collected from the first filtration. The white solid was swirled in one liter of cold water, filtered and the process repeated. The re sulting sulfinamide was recrystallized several times from methanol and water giving 35.3 g (68.1% yield), mp 134.5-136°; nmr (CHCl^) 8.42-6.79 ppm. (m, 7, Ar-H), 5'.66 (s, 1, N-H),

~~2.36 (s, 6 , Ar-CH3), 2.26 (s, 3, Ar-CH3) . Anal. Calcd for C ^ H ^ N O S : c7~69.46; H, 6.61. Found: C, 69.54; H, 6.77. 107~~

N-£-Tolyl £-toluenesulfinamide. - Freshly distilled £-toluidine (116.0 g, 1.08 mole) was added to a two-liter three-neck flask equipped with a stirrer, a calcium chloride drying tube and containing anhydrous ether (500 ml). The flask was immersed in an ice bath in order to maintain a solution temperature below 10°. A solution of crude £- toluenesulfinyl chloride (94.0 g, 0.54 mole) in anhydrous ether (25 ml) and contained in a pressure equalized addition funnel was added dropwise over a one-half hour period. Stirring was continued for an additional five hours upon completing the addition. The ether was filtered under aspirator pressure. The white solid was swirled in cold water (two liters), filtered and the process repeated. The remaining sulfinamide was recrystallized several times from ethanol giving 70.0 g (53.0% yield), mp 138-139° with decom position; nmr (CDCl^) 7.66-6.98 ppm. (m, 8 , Ar-H), 6.63 (s, 1, N-H), 2.36 (s, 3, Ar-CH3), 2.25 (s, 3, Ar-CH3) . Anal. Calcd for C ^ H ^ N O S : C, 68.54; H, 6.16; N, 5.72. Found: C, 68.75; H, 5.98; N, 5.72.

£-Chlorobenzenesulfinyl chloride was prepared ac cording to the method of K u r z e r . ^ l Powered sodium £-chloro- benzenesulfinate dihydrate (93.6 g, 0.4 mole) was added in portions at room temperature over a thirty minute period to thionyl chloride (357.6 g, 217 ml, 3.0 mole) contained in a 500-ml single-neck flask, equipped with a magnetic stirrer. A vigorous reaction occurred with the evolution of sulfur dioxide. As the first portions of the sulfinate were added, the temperature of the reaction mixture rose, but it soon dropped below room temperature as the reaction proceeded. After the addition the reaction mixture had jelled so thionyl chloride (50-ml) and anhydrous ether (100-ml) were added. 108

The reaction mixture was set aside for three hours with a calcium chloride tube protecting it from moisture. The greenish yellow mixture was filtered via a glass sintered funnel with nitrogen protecting the liquid from moisture. The liquid was then transferred to a weighed 500-ml single neck flask. The thionyl chloride and ether were distilled off at aspirator pressure with a bath temperature of about 55°. The liquid was washed twice with anhydrous ether (50- ml portions) followed by distillation after each washing to remove the last traces of thionyl chloride. The color of the liquid was greenish yellow; yield 62.1 g (80.0%).

N-Mesityl £-chlorobenzenesulfinamide. - Freshly dis tilled 2,4,6 -trimethylaniline (86.4 g, 0.64 mole) was added to a two-liter three-neck flask equipped with a stirrer, a calcium chloride drying tube and containing anhydrous ether (500-ml). The flask was immersed in an ice bath in order to maintain a solution temperature below 10°. A solution of crude £-chlorobenzenesulfinyl chloride (62.1 g, 0.32 mole) in anhydrous ether (50-ml) and contained in a pressure equalized addition funnel was added dropwise over a one-half hour period. Stirring was continued for an additional twelve hours upon completing the addition. The solution was filtered under aspirator pressure. The white residue was swirled in one liter of cold water and then filtered. The white solid material remaining was recrystallized several times from methanol and finally from acetone giving 55.5 g (58.9% yield), mp 161-162°; nmr (CDCl^) 7.93-7.45 ppm. (m,

~~4, Ar-H), 6.92 (s, 2, Ar-H), 5.58 (s, 1, N-H), 2.36 (s, 6 , Ar-CH3), 2.28 (s, 3, Ar-CH3) .~~

~~Anal. Calcd for c“ h 1 6 N0S: C, 61.32; H, 5.49; N, 4.77. Found: C, 61.51; H, 5.63; N, 4.86. 109~~

2 ,-Nitrobenzenedisulfide was prepared by a modifica- 32 tion of the procedure described by Bogert and Stull. £- Nitrochlorobenzene (157.5 g, 1.0 mole), dissolved in boiling ethanol (250 ml) was added to a two-liter three-neck flask equipped with a reflux condenser. To this solution was added an alcoholic solution of sodium disulfide, prepared from sodium sulfide nonohydrate (184.8 g, 0.77 mole) and sulfur (24.6 g, 0.77 mole) dissolved in 957, ethanol (250-ml) . The sodium disulfide solution was added slowly over a ten minute period. The solution changed to a deep red color. The solution was brought to reflux for two hours and then cooled to room temperature. The solution was filtered under aspirator pressure and the residue, a yellow solid, washed thoroughly with water (600 ml) to remove the sodium chloride. The aqueous solution was filtered and the yellow solid washed three times with 957, ethanol to remove any unreacted £-nitrochlorobenzene; yield of the crude product 138 g (58.2%).

Purification of £-nitrobenzenedisulfide. - The di- ■■■ _ sulfide was purified according to the method of Zincke. The desired product was obtained as yellow crystals (90.37, yield), mp 182-183°, lit. mp 183°.

Sodium jo-nitrobenzenesulfinate was prepared according to the method of Douglass and Farah.^ Pure £-nitrobenzenedisulfide (30.8 g, 0.1 mole), glacial acetic acid (12.0 g, 11.44 ml, 0.20 mole) and anhydrous carbon tetrachloride (150 ml) were added under a stream of nitrogen to a 500-ml three- neck flask equipped with a gas inlet and outlet tube and a stirrer. The solution temperature was lowered to -15°. Chlorine gas was admitted with stirring to the solution (the gas inlet tube being above the solution to prevent clogging). 110

Within approximately the first hour the solution had changed from a bright yellow slurry to a deep orange clear solution indicating formation of the sulfenyl chloride. During the next hour a yellow precipitate began to form, the sulfur trichloride, and the solution changed from a deep orange to a bright yellow slurry. Chlorine was passed into the solu tion for an additional one-half hour with no observed change taking place. The chlorination was stopped and the solution temperature allowed to come to room temperature slowly while stirring was continued. The solution was filtered and the residue collected (27 g). The filtrate was distilled at a bafh temperature of less than 35°. A light yellow powder (18.0 g) remained in the distillation flask. The two fractions were combined. The crude sulfur trichloride was added to two equivalents of water, stirred and heated, with dilute sodium hydroxide solution being added slowly until all the solid had dissolved. The solution was then filtered, and the filtrate cooled. Dilute hydrochloric acid was added slowly, precipitating a light yellow solid, mpof the sulfinic acid was 153-156 s. 132, lit.^ mp 152-154. The sulfinic acid was added to about 150 ml of water and the mixture heated on a steam bath. Sodium hydroxide (50?o) was added slowly. The solution color changed to a deep orange. The solution was again filtered and the filtrate poured into an evaporating dish, and concentrated by means of a steam bath. When a considerable amount of crust had formed, the solution was cooled in an ice bath and filtered. The residue, light orange in color, was allowed to air dry for two days; yield 41.0 grams. Ill

p-Nitrobenzenesulfinyl chloride. - Sodium p-nitrobenzenesulfinate (39.6 g, 0.162 mole) was added in portions at room temperature over a fifteen minute period to thionyl chloride (81.4 ml, 1.13 mole) contained in a 500-ml single neck flask, equipped with a magnetic stirrer. A vigorous reaction occurred with the evolution of sulfur dioxide. During the addition, the temperature of the solution dropped below room temperature. The resulting mixture, a dark brownish liquid containing a brownish solid, was protected from moisture by means of a calcium chloride drying tube. The flask was set aside at room temperature for two hours with stirring. Anhydrous ether (100-ml) was added and a white solid separated out, the liquid turning to a clear yellow. The solution was then filtered under nitrogen and the residue washed with anhydrous ether (100 ml). The fil trate was distilled at aspirator pressure at a bath tempera ture of less than 50°. During the distillation, the solution was washed twice with anhydrous ether (50-ml portions). After the second washing, the solution turned to a light brownish solid which turned reddish in color upon standing; yield 32.2 g (1007,). The solid was refrigerated to prevent decomposition.

N-Mesityl p-nitrobenzenesulfinamide. - p-Nitrobenzene- sulfinyl chloride (33.2 g, 0.162 mole) suspended in dry ether (300 ml) was added to a one-liter three-neck flask, equipped with a stirrer, and a calcium chloride drying tube. The addition was protected from moisture by a stream of'nitrogen gas. An ice bath was used in order to maintain a temperature of 10-15°. A solution of freshly distilled 2,4,6 -trimethylaniline (43.7 g, 0.324 mole) in anhydrous ether (50 ml) was then added dropwise over a fifteen minute period. During the addition of the first few drops, the solution turned to 112 a bright yellow. After completing the addition, the solution was stirred at ice bath temperature for one hour. The solu tion was stirred for an additional twelve hours at room temperature. The solution was filtered under vacuum and the residue, a yellow solid, washed with one liter of water to dissolve the mesidinium hydrochloride. The aqueous solution was then filtered. The sulfinamide was initially recrystallized from a methanol and water mixture and then several times from methanol giving 35.9 g (72.97, yield), mp 152-153.5°; nmr (CDCl^) 8.43-7.98 ppm. (m, 4, Ar-H),

~~6.95 (s, 2, Ar-H), 5.93 (s, 1, N-H), 2.38 (s, 6 , Ar-CH3) , 2.31 (s, 3, Ar-CH3) . Anal. CaTcd for : C, 59.19; H, 5.30; N, 9.20. Found: C, 59.22; H, 5.40; N, 9.02.~~

]D-Methoxybenzenesulfonyl chloride was prepared according to the procedure described in Methoden Der 36 Organischen Chemie by the reaction of anisole with chlorosulfonic acid. The desired compound was obtained as white crystals (65.8% yield), mp 40-41°, lit. mp 41-42°.

Sodium £-methoxybenzenesulfinate was prepared accord- 30 ing to the procedure of Whitmore and Hamilton by the zinc dust reduction of £_-methoxybenzenesulfonyl chloride. The desired compound was obtained as white crystals (55.87, yield) which were air dried for two days.

p_-Methoxybenzenesulfinyl chloride. - Powdered sodium £-methoxybenzenesulfinate dihydrate (37.3 g, 0.162 mole) was added in portions at room temperature over a ten minute period to thionyl chloride (81.4 ml, 1.13 mole) contained in a 500-ml single-neck flask, equipped with a magnetic stirrer. A vigorous reaction occurred with the evolution of sulfur dioxide. The resulting mixture, a clear yellow liquid 113 containing an opaque gell, was protected from moisture by means of a calcium chloride drying tube. The reaction flask was stirred at room temperature for three hours. Dry ether (100 ml) was added and the mixture was allowed to stand for an additional twenty minutes. The sulfinyl chloride was then filtered under suction. During the fil tration, the sulfinyl chloride was protected by a stream of nitrogen. Anhydrous ether (100 ml) was used to wash the salt which remained in the funnel. The excess thionyl chloride was then distilled off at aspirator pressure using a bath temperature of less than 50°. During the distilla tion, four 50-ml portions of anhydrous ether were added to the sulfinyl chloride solution. A yellow liquid remained after the distillation; yield 30.7 g (100%).

N-Mesityl £-methoxybenzenesulfinamide via the sulfinyl chloride. - Freshly distilled 2,4,6 -trimethylaniline (44.6 g, 0.33 mole) was added to a two-liter three-neck flask equipped with a stirrer, a calcium chloride drying tube and containing anhydrous ether (500 ml). The flask was immersed in an ice bath in order to maintain a solution temperature below 1 0 °. A solution of crude ]D-methoxybenzenesulfinyl chloride (30.8 g, 0.162 mole) in anhydrous ether (25 ml) and contained in a pressure equalized addition funnel was added dropwise over a one-half hour period. The solution was stirred for fifteen hours. The solution was filtered under vacuum and the resi due, a white solid, swirled in one liter of cold water to dissolve the mesidinium hydrochloride. The solution was again filtered. The sulfinamide was recrystallized several times from a mixture of acetone and low boiling petroleum ether and finally from methanol giving 1.0 g, mp 143.5-145°. 114

~~Due to the low yield, the Grignard method was used to make this compound; nmr (CDCl^) 7.91-7.13 ppm. (m, 4, Ar-H), 6.93~~

~~(s, 2, Ar-H), 5.44 (s, 1, N-H), 3.88 (s, 3, CH3 0-), 2.38~~

~~(s, 6 , Ar-CH3), 2.28 (s, 3, Ar-CH3) . Anal. Calcd for C-^H^gNC^S: C, 66.41; H, 6.62. Found: C, 66.55; H, 6.72.~~

m-Nitrobenzenesulfonyl chloride was prepared accord- “ --- — 7 37 ing to the procedure of Hodgson and Whitehurst by the reaction of nitrobenzene with chlorosulfonic acid. The desired compound was obtained as white crystals (53.47. yield). Nitrobenzene was purified before use by the pro- 38 cedure described in Vogel.

m-Nitrobenzenedisulfide was prepared according to the procedure of Sheppard by the reaction of m-nitrobenzene sulfonyl chloride with potassium iodide and hydrochloric acid. The desired product was obtained as white crystals (83.07o yield), mp 182-183.5°, lit. mp 182-183°.

~~m-Nitrobenzenesulfinyl chloride. - m-Nitrobenzene disulfide (30.8 g, 0.1 mole), glacial acetic acid (11.44 ml,~~

0 . 2 mole) and anhydrous carbon tetrachloride ( 2 0 0 ml) were added under nitrogen to a 500-ml three-neck flask, equipped with a gas inlet and outlet tube and a mechanical stirrer. The solution temperature was lowered to -15° by means of a Dry Ice-acetone bath. Chlorine gas was admitted with stirring to the solution (the gas inlet tube being above the solution to prevent clogging). Within approximately the first forty-five minutes the solution changed from a bright yellow slurry to a deep orange clear solution indi cating formation of the sulfenyl chloride. During the next one and one-half hours the solution changed in color from a deep orange to a bright yellow. Chlorine was passed into 115 the solution for another forty-five minutes with no observed change taking place. The chlorination was stopped and the solution temperature allowed to come to room temperature slowly while stirring was continued. The solution was dis tilled at a bath temperature of 40° under aspirator pressure. The distillate was collected in a flask immersed in a Dry Ice-acetone bath in order to trap the acetyl chloride. When all of the carbon tetrachloride had been removed, a light yellow liquid remained which upon refrigeration turned into a yellow solid; yield 41.0 g (100%).

N-Mesityl m-nitrobenzenesulfinamide. - m-Nitrobenzene sulfinyl chloride (41.0 g, 0.20 mole) was added to a 500-ml three-neck flask, equipped with a stirrer and a calcium chloride drying tube and containing anhydrous ether (500 ml). The addition was protected from moisture by a stream of nitrogen. An ice bath was used in order to maintain a temperature of 10-15°. A solution of freshly distilled 2 ,4,6-trimethylaniline (54.0 g, 0.40 mole) in anhydrous ether (50 ml) was added dropwise over a one-half hour period. During the addition of the first few drops, a white precipi tate was formed. The mixture was stirred at ice bath temperature for ten hours upon completing the addition. The mixture was filtered under vacuum and the residue washed with cold water (1 1 .) to dissolve the mesidinium hydrochloride. The aqueous mixture was filtered and the washing repeated with cold water. After filtration, the sulfinamide was recrystallized from a mixture of low boiling petroleum ether and acetone giving 32.5 g (54.r% yield), mp 176-177°; nmr (CDCl^) 8.33-6.95 ppm. (m, 4, Ar-H), 6.95

~~(s, 2, Ar-H), 5.60 (s, 1, N-H), 2.40 (s, 6 , Ar-CH3) , 2.30 (s, 3, Ar-CH3). 116~~

~~Anal. Calcd for C15H16N2 03 S: C ’ 59 '19> H ’ 5 -30- Found: C, 59.07; H, 5.34.~~

N-Sulfinylmesidine was prepared according to the procedure of Klamann, Sass and Z e l e n k a . ^ Mesidinium hydrochloride (57.0 g, 0.333 mole) was added to a 500-ml single-neck flask, containing anhydrous benzene (500 ml). Thionyl chloride (23.1 ml) was added to this. A vigorous reaction occurred with the evolution of hydrogen chloride. After twenty minutes the reaction was brought to reflux for two days. The solution turned a deep red color. Benzene was then distilled at aspirator pressure with a bath temperature of 50°. The residue was distilled giving an orange-red liquid, 35.1 g (58.57o yield), bp 77-79 (0.22 mm) . An infrared spectrum showed the characteristic N=S=0 bond at 1150-1180 cm

N-Mesityl m-toluenesulfinamide was prepared accord------4 0 ing to the procedure of Klamann, Sass and Zelenka. m- Bromotoluene (34.2 g, 0.20 mole) in anhydrous ether (50 ml) was added to magnesium turnings (4.9 g, 0.20 mole) in anhy drous ether (100 ml). Upon completing the addition, the mixture was stirred for two hours. The mixture was then brought to ice bath temperature. N-Sulfinyl mesidine (33.2 g, 0.194 mole) in anhydrous ether (50 ml) was added to the Grignard reagent. The solution was then stirred for three hours. Ten percent aqueous ammonium chloride (300 ml) was added slowly over a one hour period with stirring. The solid material which formed was filtered and washed with water (500 ml). Then the solid material was washed with petroleum ether, filtered and recrystallized from ligroin (bp 65-70°) and acetone mixture giving 21 g (40% yield), mp 121-122°; nmr (CDCl^) 7.75-7.28 ppm. (m, 4, Ar-H), 6.91 117

~~(s, 2, Ar-H), 5.55 (s, 1, N-H), 2.46 (s, 3, Ar-CH3), 2.38~~

~~(s, 6 , Ar-CH^), 2.27 (s, 3, Ar-CH3).~~

~~AnaTT Calcd for C 16HigN0s7 G, 70.29; H, 7.01. Found: C, 70.38; H, 7.13.~~

~~]D-Bromoanisole was prepared according to the pro- 41 cedure of Lansbury, Bieron and Klein by the reaction of dimethyl sulfate with £-bromophenol.~~

N-Mesityl ]3-methoxybenzenesulfinamide via the Grignard reaction. - £-Methoxybromobenzene (39.3 g, 0.21 mole) in anhydrous ether (20 ml) was added to magnesium turnings (5.04 g, 0.21 mole) in anhydrous ether (50 ml). Upon completing the addition, the mixture was allowed to stir for three hours. The mixture was brought to ice bath temperature. N-Sulfinyl mesidine (36.2 g, 0.20 mole) in anhydrous ether (20 ml) was added dropwise. After the addition, the mixture was stirred for four hours. Ten percent aqueous ammonium chloride (100 ml) was added slowly. The solution was filtered, and then washed with 5% aqueous sodium bicarbonate. After filtration the sulfinamide was recrystallized four times from a petroleum ether (low boil ing) acetone mixture giving 10.0 g (17.5% yield), mp 143- 145° .

N-Mesityl m-chlorobenzenesulfinamide. - m-Chlorobromo- benzene (38.2 g, 0.20 mole) in anhydrous ether (10 ml) was added to magnesium turnings (4.9 g, 0.20 mole in anhydrous ether (50 ml). The reaction mixture was allowed to stir at room temperature for two hours. The mixture was then brought to ice bath temperature. N-Sulfinylmesidine (34.5 g, 0.19 mole) in anhydrous ether (25 ml) was added to the Grignard reagent. Stirring was continued for an additional four hotirs. Ten percent aqueous ammonium chloride (100 ml) was 118 added dropwise and the reaction mixture stirred for one hour. The mixture was filtered under aspirator pressure and the residue washed with cold water. The washing was repeated with 5 % aqueous sodium bicarbonate and then with water. The sulfinamide was recrystallized several times from a ligroin (bp 65-70°) - acetone mixture giving 26.0 g (46.47> yield), mp 152-153°; nmr (CDCl^) 7.91-7.26 ppm. (m, 4,

~~Ar-H), 6.90 (s, 2, Ar-H), 5.65 (s, 1, N-H), 2.38 (s, 6 , Ar-CH3), 2.28 (s, 3, Ar-CH3). Anal. Calcd for C ^ H ^ N O S : C, 61.32; H, 5.49. Found: C, 61.15; H, 5.59.~~

N-Mesityl m-a,a,a-trifluorotoluenesulfinamide. - m-Bromo-a,a,a-trifluorotoluene (45 g, 0.2 m) in anhydrous ether (25 ml) was added to magnesium turnings (4.9 g, 0.20 mole) in anhydrous ether (75 ml). The reaction mixture was stirred at room temperature for two hours. The mixture was then cooled in an ice bath. N-Sulfinylmesidine (34.5 g, 0.19 mole) in anhydrous ether (25 ml) was added to the Grignard reagent. Stirring was continued for an additional four hours. Ten percent aqueous ammonium chloride (100 ml) was added dropwise and the reaction mixture stirred for one hour. The mixture was filtered under aspirator pressure and the residue washed with cold water. The washing was re peated with 57o aqueous sodium bicarbonate and then with water. The sulfinamide was recrystallized several times from an acetone-petroleum ether (low boiling) mixture giving 23.0 g (37.1% yield), mp 156-157°; nmr (CDC1Q) 8.21-7.68 ppm. (m, 4, Ar-H), 6.93 (s, 2, Ar-H), 5.60 (s, 1, N-H), 2.40 (s,

~~6 , Ar-CH3), 2.30 (s, 3, Ar-CH3). 119~~

~~Anal. Calcd for C ^ H ^ F ^ O S : C, 58.70; H, 4.92. Found: C, 58.37; H, 4.88.~~

Neopentyl £-toluenesulfinate. - Neopentyl alcohol (17.6 g, 0.2 mole) was dissolved in anhydrous ether (500 ml). Dry pyridine (18.0 ml) was added to this solution. The solution was then immersed in an ice bath. £-Toluenesulfinyl chloride in anhydrous ether (50 ml) was then added slowly. Stirring was continued for an additional two hours. The mixture was filtered, washed with dilute base and then dried (MgSO^). Concentration yielded a yellow liquid con taining white crystals. An infrared spectrum of the yellow liquid indicated the presence of both sulfone and sulfinate ester. Distillation of the liquid bp 95-96° (0.3 mm) yielded a white cloudy material. An infrared spectrum again indicated the presence of both sulfone and sulfinate. Thin layer chromatography gave two spots.

Reaction of N-mesityl £-chlorobenzenesulfinamide with sodium hydroxide. - Analytical grade sodium hydroxide (0.20 g, 0.005 mole) dissolved in 95%, ethanol (150 ml) was added to a 500-ml single-neck flask equipped with a magnetic stirrer and a reflux condenser, and containing N-mesityl £- chlorobenzenesulfinamide (1.465 g, 0.005 mole). The solution was brought to reflux for three days. The solution was then cooled to room temperature, ether added ( 2 0 0 ml), and the solution swirled. The organic layer was washed with water (100 ml) and separated. The ether portion was washed once more with water and the aqueous portions combined and set aside. The ether solution was dried (MgSO^), filtered and evaporated, leaving a clear yellow liquid 0.67 g (9 9 .2 %). A sample of the yellow liquid was gas chromatographed on an Aerograph A 90-P3 using a 5* x 1/8" 20%, Carbowax 20M on 120

Chromosorb W 80/100 column. A single peak with a retention time of 100 sec was observed. A sample of 2,4,6 -trimethylaniline was injected into the chromatograph and a single peak with a retention time of 100 sec was observed. An infrared spectrum of the yellow liquid proved to be identi cal with that of 2 ,4,6-trimethylaniline. The aqueous solution was evaporated to dryness over a steam bath. A white powder remained, which was dissolved in approximately 50 ml of water. The solution was acidified with 57o hydrochloric acid, precipitating a white solid. The solution was filtered and the residue, a white solid, collected giving 0.87 g (98-9% yield), mp 98-99°. An infrared spectrum and the mp of the white solid proved to be identical with an original sample of ]3-chlorobenzene- sulfinic acid. A mixed mp of the two substances was 98-99° . Lit. mp 92-93°.42 121

~~Kinetic Procedure~~

Materials. - The sulfinamides studied were obtained by the synthetic procedures described previously. Fisher certified reagent grade sodium hydroxide (S-318) was used to prepare the stock base solutions. Fisher hydrochloric acid solution (So-A-58) was used as the titrant.

Preparation of stock solutions. - The hydrochloric acid solution (0.0333N) was obtained commercially. The base solution was prepared by weighing out the sodium hydroxide pellets in a glass beaker and then transferring them to a 500 ml volumetric. Ethanol (95%) was then added to the volumetric and allowed to stand overnight. The solution was then filtered and standardized with hydrochloric acid. At all times a nitrogen atmosphere was used in the prepara tion of the base solution.

Preparation of reaction vessels. - The reaction vessels were 125 ml Erlenmeyer flasks. Each flask was washed with a soap solution, rinsed, washed with acetone, rinsed several times with tap water and allowed to dry.

Preparation of kinetic solutions. - The sulfinamide was weighed on a glass plate and then transferred to a volumetric flask. Ethanol (95%) was then added, the solu tion was warmed in a water bath until all the compound had dissolved and then allowed to cool to room temperature. Sulfinamide solution was added by pipette to each of the reaction vessels. After the addition of the sulfinamide solution was completed, sodium hydroxide solution was added by pipette to each one of the reaction vessels. It was found that best results were obtained when the pipette was washed with acetone and then dried by flushing with nitrogen 122 before each addition. After each addition of the base solu tion, the vessel was fitted with a serum cap and placed in a constant temperature bath. Approximately five to fifteen minutes was allowed for equilibration of the solution to the bath temperature. After an appropriate time had elapsed, the reaction vessels were withdrawn from the bath and the solutions quenched by direct addition with crushed ice. Five drops of phenophthalein indicator were added and the solutions titrated with hydrochloric acid. The time was recorded after each removal of the reaction vessel from the temperature bath.

Determination of rate constants. - The second-order rate constants were obtained by plotting log (b-x/a-x) vs. time and determining the slope of the line; where b is the original base concentration, a is the original sulfinamide concentration, and x is the amount of base or sulfinamide reacted at time t. The rate constant was obtained from the following equation:

~~i _ 2.303 x (slope) rC — ib-a~~

The pseudo-first-order rate constants were obtained by plotting log c vs. time and determining the slope of the line; where c is the amount of sulfinamide unreacted. The rate constant was obtained from the following equation.

~~k = -2.303 x (slope)~~

~~An IBM 360 digital computer was used for analysis 43 of all data. All of the data was also plotted graphically in order to see if any deviation from linearity was present. 123~~

~~N-Mesityl jD-toluenesulfinamide Run No. 1~~

~~Temp. 49.80':1:.02oC time (sec) (b-x) x 1 0 3M (a-x) x 1 0 '3m log(b-x,~~

~~0 4.755 7.99 0.77460 7200 4.625 6.69 0.83953 14400 4.509 5.53 0.91119 21600 4.381 4.25 1.01300 28800 4.296 3.40 1.10139 32400 4.246 2.90 1.16537~~

~~36000 4.222 2 . 6 6 1.20042~~

~~k=7.51 x 1 0 ”^ l.m sec'-1~~

~~Run N o . 2 Temp . 49.80-.02°C time (sec) (b-x) x 10 3M (a-x) x 10 ~3M log(b-x~~

~~0 4.714 7.98 0.77124 3600 4.630 7.16 0.81174 7200 4.580 6.64 0.83855 10800 4.514 5.98 0.87700 14400 4.429 5.13 0.93602 18000 4.381 4.69 0.97023 21600 4.334 4.18 1.01553 25200 4.317 4.01 1.03206~~

~~-4 -1 k=6.70 x 10 l.m sec 124~~

~~Run N o . 3 Temp . 49.80-.02°C times (sec) (b-x) x 10 2M (a-x) x 10'3M log(b-x~~

~~0 4.680 6 .68 0.84532~~

~~3600 4.612 6 . 0 0 0.88558 7200 4.562 5.50 0.91863 10800 4.512 5.00 0.95523 14400 4.459 4.47 0.99875 18000 4.409 3.97 1.04536 21600 4.379 3.67 1.07651 25200 4.349 3.37 1.11076~~

~~-4 -1 k =6 .26 x 1 0 l.m sec~~

~~N-Mesityl benzenesulfinamide Run N o . 1~~

~~Temp. 49.80±.02°C time (sec) (b-x) x 1 0 _2M (a-x) x 1 0 3M log(b-x,~~

~~0 4.829 8.33 0.76307~~

3600 4.684 6 . 8 8 0.83288 5400 4.645 6.49 0.85459 7200 4.579 5.83 0.89494 9000 4.534 5.38 0.92553 10800 4.466 4.70 0.97764 12600 4.432 4.36 1.00693 14400 4.397 4.01 1.03982 -4 -1 k=ll.24 x 1 0 l.m sec 125

~~Run No. 2~~

~~Temp . 49.80-.02°C time (sec) (b-x) x 10 2M (a-x) x 1 0 '3m log (b->~~

~~0 4.870 8.70 0.74787 1800 4.794 7.94 0.78074 3600 4.724 7.24 0.81442 5400 4.665 6.65 0.84588 7200 4.629 6.29 0 . 8 6 6 6 8 9000 4.529 5.29 0.93238 10800 4.499 4.99 0.95484 12600 4.459 4.59 0.98725~~

~~in-4 t 1 k=ll. 11 x 1 0 l.m sec~~

~~Run N o . 3~~

~~Temp . 49.80-.02°C time (sec) (b-x) x 1 0 2M (a-x) x 10 "3m log (b-x,~~

~~0 4.645 6.67 0.84271 1800 4.592 6.14 0.87368 3600 4.554 5.76 0.89781 5400 4.497 5.19 0.93759 7200 4.444 4.66 0.97921 9000 4 .406 4.28 1.01242 10800 4.362 3.84 1.05516 12600 4.334 3.56 1.08524~~

~~-1 k=ll.44 x 1 0 ^ l.m sec N-Mesityl £-chlorobenzenesulfinamide~~

~~i Run N o . 1~~

~~Temp. 4 9 .80i .02°C time (sec) (b-x(x 10 (a-x)x 10 log(b-x/a~~

~~0 4.970 6.58 0.87797 1800 4.862 5.50_ 0.94628 3600 4.762 4.50 1.02439 5400 4.662 3.50 1.12430 7200 4.612 3.00 1.18655 9000 4.562 2.50 1.26099~~

~~k=23.17 x 10-4 l.m sec'1~~

~~k=10.96 x 10" 5 sec' 1~~

~~Run No. 2~~

~~Temp. 49.80-.02°C time (sec) (b-x)x 10 (a-x)x 10 log(b-x/a~~

~~0 4.970 6.58 0.87797 1800 4.845 5.33 0.95839 3600 4.745 4.33 1.03956 5400 4.679 3.67 1.10529 7200 4.612 3.00 1.18655 9000 4.554 2.42 1.27435~~

~~10800 4.512 2 . 0 0 1.35310 12600 4.462 1.50 1.47345~~

~~k=23.33 x 10“4 l.mi sec "I~~

~~-1 k=10.96 x 10"5 sec Temp. 49.80*.02°C time (sec) (b-x)x 1 0 2M (a-x)x 1 0 log(b-x/a-x)~~

~~0 4.920 6.58 0.87358 1830 4.812 5.50 0.94179 3600 4.720 4.58 1.01289 5400 4.637 3.75 1.09201 7200 4.570 3.08 1.17115 9000 4.520 2.58 1.24329 10800 4.479 2.17 1.31448~~

~~k-22.34 x 10"4 l.m sec" 1~~

~~k=10.41 x 10~ 5 sec" 1~~

~~Run N o . 4~~

Temp. 49.80*.02°C time (sec) (b-x)x 1 0 (a-x)x 1 0 los(b-x/a 0 7.426 6.83 1.03589 1800 7.243 5.00 1.16047 2700 7.173 4.30 1.22170 3600 7.119 3.76 1.27664 4500 7 .060 3.17 1.34734 5400 7.001 2.59 1.43222 6300 6.975 2.32 1.47740 8100 6.913 1.71 1.60740 128

~~Run N o . 5~~

~~Temp. 49.80*.02°C time (sec) (b-x)x 1 0 (a-x)x 1 0 log(b-x/a-x) log c~~

0 7.434 6 . 8 8 1.03321 -2.16217 1800 7.259 5.14 1.15009 -2.28940 2700 7.183 4.37 1.21561 -2.35954 3600 7.126 3.80 1.27242 -2.41979 4500 7.073 3.27 1.33469 -2.48533 5400 7.021 2.75 1.40607 -2.55991 6300 6.993 2.47 1.45141 -2.60700 9000 6.891 1.46 1.67512 -2.83681

~~k=23.04 x 10 ^ l.m sec ^~~

~~k=16.54 x 10 sec ^~~

~~Run N o . 6~~

~~Temp. 49.80*.02°C time (sec) (b-x)x 1 0 (a-x)x 10 log(b-x/a-x) log c~~

0 11.125 6.75 1.21678 -2.17070 300 11.075 6.25 1.24824 -2.20412 90 CL... 10.995 5.45 1.30456 -2.26360 1380 10.905 4.55 1.37962 -2.34199 1800 10.900 4.50 1.38421 -2.34679 2400 10.820 3.70 1.46576 -2.34180 3300 10.755 3.05 1.54703 -2.51570 4200 10.690 2.40 1.64847 -2.61979

~~-4 -1 k=22.52 x 1 0 l.m sec~~

~~-5 -1 k=24.50 x 10 sec 129~~

~~Run N o . 7~~

~~Temp. 49.80-.02°C time (sec) (b-x)x 1 0 (a-x)x 1 0 log(b-x/a-x) log c~~

~~0 11.140 6.90 1.20782 -2.16115 300 11.090 6.40 1.23853 -2.19382~~

900 1 1 . 0 0 0 5.50 1.30080 -2.25964 1380 10.930 4.80 1.35713 -2.31876 1800 10.855 4.05 1.42817 -2.39254 2400 10.800 3.50 1.48936 -2.45593 3300 10.745 2.95 1.56110 -2.53018 4200 10.700 2.50 1.63144 -2.60206

~~k=23.58 x 10 4 l.m sec ^~~

~~k=25.79 x 10" 5 sec-1~~

~~Run N o . 8~~

~~Temp. 49.80-.02°C time (sec) (b-x)x 1 0 (a-x)x 10 log(b-x/a-x) log c~~

~~0 11.105 6.55 1.22906 -2.18376~~

300 11.060 6 . 1 0 1.25820 -2.21467 900 10.955 5.05 1.33632 -2.29671 1500 10.950 5.00 1.34044 -2.30103 1800 10.880 4.30 1.40291 -2.36653 2400 10.820 3.70 1.46584 -2.43180 3300 10.750 3.00 1.55401 -2.52281 4200 10.690 2.40 1.64847 -2.61979

~~k=21.93 x 10 4 l.m sec ^~~

~~k=23.95 x 10" 5 sec" 1 130~~

~~Run N o . 9~~

~~Temp. 40.17*.02°C time (sec) (b-x) x 10 (a-x) x 10 log(b-x/a-x)~~

~~0 4.879 7.17 0.83274 1800 4.815 6.54 0.86721~~

~~4200 4.762 6 . 1 0 0.89215 7200 4.707 5.45 0.93594 10780 4.629 4.67 0.99596 14400 4.577 4.15 1.04194 18000 4.512 3.51 1.10950 21600 4 .462 3.01 1.17149 -4 -1 k=8 .,52 X 1 0 l.m sec~~

~~Run No. 10~~

~~Temp . 40.17*.02°C~~

~~time (sec) (b-x) X 10 (a-x) x 10 log (b-:~~

~~0 4.874 7.28 0.82532 2400 4.797 6.52 0.86669 4800 4.744 5.99 0.89888 7200 4.679 5.34 0.94274 10800 4.612 4.67 0.99440 14400 4.547 4.02 1.05332 18000 4.502 3.57 1.10043 21600 4.444 2.99 1.17217~~

~~m - 4 •, -1 k =8 .72 X 1 0 l.m sec 131~~

~~Run No. 11~~

~~Temp. 30.07*.02°C time (sec) (b-x) x 10“2M (a-x) x 10 log. (b-3~~

~~0 5.162 7.50 0.83756 5400 5.090 6.78 0.87507 10800 5.057 6.45 0.89407 18000 4.992 5.80 0.93450 25200 4.933 5.22 0.97538 32430 4.895 4.84 1.00509 39600 4.832 4.20 1.06036 45000 4.812 4.00 1.07963~~

~~n -1 k =2 .80 x 1 0 " 4 l.m sec~~

~~Run No. 12~~

~~Temp. 30.07-.02°C time (sec) (b-x) x 1 0 "2M (a-x) x 1 0 log (b-x/a~~

0 5.175 7.47 0.84044 5400 5.108 6.80 0.87558 10800 5.075 6.47 0.89437 18000 4.995 5.67 0.94478 25230 4.945 5.17 0.98050 32430 4.893 4.65 1.02194 39600 4.845 4.17 1.06497 46800 4.809 3.81 1.10093 i o O'* o !—I

~~X -1 k =2 l.m sec 132~~

~~N-Mesityl £_-methoxybenzenesulfinamide~~

~~Run N o . 1~~

~~Temp. 49.80-.02°C time (sec) (b-x) x 10“2M (a-x) x 10 log (b-:~~

~~0 4.862 6.17 0.89653 2700 4.779 5.34 0.95191 4500 4.749 5.04 0.97430 7205 4.715 4.70 1.00095 10800 4.675 4.30 1.03585 16200 4.625 3.80 1.08471 21600 4.570 3.25 1.14733 27000 4.536 2.91 1.19326~~

~~k=5 .38 x 10 “4 l.mi sec - 1~~

~~Run N o . 2~~

~~Temp. 49.80±.02°C time (sec) (b-x) x 1 0 ~2M (a-x) x 1 0 log (b-x/a~~

~~0 4.975 7.13 0.84331 2700 4.912 6.50 0.87804 5400 4.877 6.15 0.89896 9000 4.827 5.65 0.93129 12600 4.777 5.15 0.96691 18000 4.702 4.40 1.02825 23400 4 .644 3.82 1.08449 28800 4.600 3.39 1.13265~~

~~k=5 .46 x 10 4 l.mi sec "I 133~~

~~Run No. 3~~

~~Temp. 49.80*.02°C time (sec) (b-x) x 10~2M (a-x) x 10 3M log (b-x/a-x)~~

~~0 4.875 6.32 0.88726 2700 4.797 5.54 0.93760 5400 4.762 5.19 0.96277 9000 4.712 4.69 1.00213 12600 4.660 4.17 1.04809 18000 4.600 3.57 1.10981 23400 4.557 3.14 1.16183 28560 4.524 2.81 1.20735~~

~~k=5.81 x 1 0 4 l.m sec ^~~

~~N-Mesityl m -toluenesulfinamide~~

~~Run N o . 1~~

~~Temp . 49.80*.02°C time (sec) (b-x) x 10 (a-x) x 10 log (b-:~~

~~0 4.862 7.83 0.79289 3600 4.729 6.50 0.86146 7200 4.629 5.50 0.92461~~

~~10800 4.529 4.51 1 . 0 0 2 1 1 13500 4.464 . 3.86 1.06339 16200 4.429 3.51 1.10128 19800 4.379 3.01 1.16303 21600 4.341 2.62 1.21838~~

~~k=10.95 x 1 0 4 l.m sec ^ 134~~

~~Run N o . 2~~

~~Temp . 49.80*.02°C time (sec) (b-x) x 1 0 ~2M (a-x) x i o "3m -lo &. (b ~2~~

~~0 4 7845 7.84 0.79107 2700 4.762 7.00 0.83235 5400 4.662 6 . 0 0 0.88997 8100 4.579 5.17 0.94692 10800 4.511 4.49 1.00189 13500 4.456 3.94 1.05332 16200 4.412 3.51 1.09953 18900 4.364 3.02 1.15909~~

~~-4 -1 k=ll.14 x 1 0 l.m sec~~

~~Run N o . 3~~

~~Temp . 49.80*.02°C time (sec) (b-x) x 10 2M (a-x) x 1 0 '3m log (b-:~~

~~0 4.845 7.84 0.79107 2700 4.762 7.00 0.83235 5400 4.662 6 . 0 0 0.88997 8100 4.584 5.22 0.94329 10800 4.527 4.66 0.98772 13500 4.462 4.01 1.04665 16200 4.414 3.52 1.09771 18900 4.379 3.17 1.13956~~

~~-1 k=10.72 x 1 0 ^ l.m sec 135~~

~~N-Mesityl j3-nitrobenzenesulfinamide~~

~~Run No. 1~~

~~Temp. 49.80*.02°C time (see) (b-x) x 1 0 2M (a-x) x 1 0 log (b-x/a-x)~~

~~0 4.629 6.84 0.83028 180 4.545 6.00 0.87922 390 4.480 5.35 0.92276 570 4.412 4.67 0.97514 810 4.346 4.01 1.03476~~

~~k=146.40 x 10 4 l.m sec ^~~

~~Run No. 2~~

~~Temp. 49.80*.02°C~~

~~time (sec) (b-x) x 1 0 (a-x) x 10 ~^M log (b-x/a-x)~~

~~0 4.604 6.76 0.83316~~

~~180 4.554 6 .26 0.86166 390 4.476 5.48 0.91195 600 4.397 4.69 0.97181 810 4.346 4.18 1.01673 1050 4.287 3.59 1.07686~~

~~k=145.40 x 10 ^ l.m sec ^ 136~~

~~Run N o . 3~~

~~Temp. 4 9 .80-.02°C time (sec) (b-x) X 10'2M (a-x) x 1 0 log (b-x/a~~

~~0 4.595 6.53 0.84722 210 4.520 5.78 0.89305 390 4.462 5.20 0.93336 630 4.391 4.49 0.99014 840 4.329 3.87 1.04849 1050 4.287 3.45 1.09414~~

~~k=139.04 x 10 ^ l.m sec ^~~

~~-Mesityl m-chlorobenzenesulfinamide~~

~~Run N o . 1 Temp. 49.80*.02°C time (sec) (b-x) x 1 0 2M (a-x) x 1 0 log (b-x/a-x)~~

~~0 5.028 7.17 0.84596 1800 4.879 5.67 0.93461 2700 4.810 4.99 0.98423 3600 4.745 4.34 1.03889 4500 4.694 3.82 1.08925 6300 4.627 3.15 1.16623 8100 4.564 2.52 1.25735 9900 4.509 1.97 1.35892~~

~~i o ”4 i — 1 k=27.45 x 1 0 l.m sec 137~~

~~Run N o . 2~~

~~Temp. 49.80-.02°C time (b-x) x 10~2M (a-x) x 10~3M log (b-x/a-x)~~

0 5.037 7.25 0.84165 1800 4.872 5.60 0.93925 2700 4.800 4.89 0.99213 3600 4.752 4.40 1.03293 4500 4.690 3.79 1.09271 6300 4.629 3.17 1.16405 8100 4.562 2.51 1.26013 9900 4.512 2 . 0 1 1.35181 -4 -1 k=27.24 x 10 l.m sec

~~Run No . 3~~

~~Temp. 49.80-.02°C time (b-x) x 10 (a-x) x 1 0 "3m log (b-:~~

0 5.040 7.28 0.83991 1800 4.865 5.54 0.94380 2700 4.807 4.95 0.98682 3600 4.754 4.42 1.03141 4500 4.695 3.84 1.08747 6300 4.625 3.14 1.16829 8100 4.560 2.49 1.26292 9900 4.509 1.97 1.35891 „ -4 -1 k=27.67 x 10 l.m sec 138

~~N-Mesityl m-nitrobenzenesulfinamide~~

~~Run N o . 1~~

~~Temp. 49.80*.02°C time (sec) (b-x) x 1 0 (a-x) x 1 0 log (b-x/a-x)~~

~~0 1.576 2.17 0.86160 420 1.560 2 . 0 0 0.89161 940 1.552 1.92 0.90686 1500 1.529 1.69 0.95621 1980 1.515 1.56 0.98800 2400 1.504 1.45 1.01692 3000 1.490 1.31 1.05678~~

~~k=109.09 x 10 ^ l.m sec ^~~

~~Run N o . 2~~

~~Temp . 49.80*.02°C time (sec) (b-x) x 10 (a-x) x 10 log (b-:~~

0 1.576 2.16 0.86264 590 1.555 1.96 0.90023 1200 1.538 1.7.8 0.93537 1650 1.524 1.64 0.96782 2400 1.504 1.45 1.01692 2910 1.492 1.33 1.05017 3900 1.465 1.05 1.14411 -4 -1 k=109.43 x 1 0 l.m sec 139 N-Mes ityl m-a,a ,a-trifluorotoluenesulfinamide

~~Run N o . 1~~

~~Temp. 49.80*.02°C time (sec) (b-x) x 10"2M (a-x) x 10 log (b-x/a-~~

~~0 5.000 6.75 0.86950 520 4.928 6.04 0.91186 1095 4.847 5.22 0.96769 1730 4.774 4.49 1.02670 2280 4.712 3.87 1.08519 3180 4.640 3.16 1.16735 4080 4.590 2 . 6 6 1.23756 5340 4.526 2 . 0 1 1.35309~~

~~-1 k = 48.56 x 1 0 ^ l.m sec~~

~~Run No. 2~~

~~Temp. 49 .80*.02°Ci time (sec) (b-x) x 10"2M (a-x).. x 10 log (b-x/a~~

~~0 5.000 6.75 0.86950 550 4.923 5.99 0.91504 1080 4.847 5.22 0.96769 1605 4.790 4.65 1.01244 2325 4.715 3.90 1.08180 3060 4.660 3.35 1.14264~~

~~3920 4.610 2 . 8 6 1.20791 4890 4.539 2.14 1.32649~~

~~-1 k = 48.62 x 1 0 ^ l.m sec 140~~

~~BIBLIOGRAPHY~~

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~~2. H. F. Herbrandson and C. M. Cusano, ibid., 83_, 2124 (1961) .~~

3. J. G. Tillett, J. Chem. Soc., 37 (I960); C. A. Bunton, P. B. D. de la Mare, A. Lennard, D. R. Lleweelyn, R. B. Pearson, J. G. Pritchard, and J. G. Tillett, ibid., 4761 (1958); C. A. Bunton, P. B. D. de la Mare, P. M. Greaseley, D. R. Lleweelyn, N. H. Pratt and J. G. Tillett, ibid., 4751 (1958); C. A. Bunton, P. B. de la Mare, D. R. Lleweelyn, R. B. Pearson and J. G. Pritchard, Chem. Ind. (London), 490 (1956).

~~4. P. B. D. de la Mare, J. G. Tillett and H. F. van Woerden, J. Chem. Soc., 4888 (1962).~~

~~5. C. A. Bunton, P. B. D. de la Mare and J. G. Tillett, ibid., 4754 (1958); E. D. Davies and J. G. Tillett, ibid., 4766 (1958); C. A. Bunton, P. B. D. de la Mare and J. G. Tillett, ibid., 1766 (1959).~~

~~6 . C. A. Bunton and B. N. Hendy, Chem. Ind. (London), 466 (1960).~~

~~7. R. E. Davis, J. Amer. Chem. Soc., 84, 599 (1962).~~

~~8 . J. L. Kice and G. Guaroldi,Tetrahedron Lett., 6135 (1966) .~~

~~9. C. R. Johnson and W. G. Phillips, ibid., 2101 (1965). 141~~

~~10. K. K. Andersen and R. A. Strecker, J. Org. Chem., 33, in press (1968), and references cited therein.~~

~~11. H. Phillips, J. Chem. Soc., 127, 2552 (1925).~~

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~~13. P. Bickart, M. Axelrod, J. Jacobus, and K. Mislow, J. Amer. Chem. Soc., 89_, 697 (1967).~~

~~14. C. R. Johnson and D. McCants, Jr., ibid., 87_, 5404_ (1965); C. R. Johnson, ibid., 85^, 1020 (1963).~~

~~15. J. Day and D. J. Cram, ibid., 8 7 , 4398 (1965).~~

~~16. A. A. Frost and R. G. Pearson, "Kinetics and Mechanism", John Wiley and Sons, Inc., New York, N. Y., 1961, p 99.~~

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18. R. W. Taft, Jr., J. Phys. Chem., 64^, 1805 (1960). For other papers in this series see R. W. Taft, Jr. and I. C. Lewis, J. Amer. Chem. Soc., £fL, 5354 (1959); R. W. Taft, Jr., S. Ehrenson, R. E. Glick and I. C. Lewis, ibid., 5352, 81^, (1959); R. W. Taft, Jr. and I. C. Lewis, ibid., 80^, 2436 (1958).

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~~23. R. W. Taft, Jr., S. Ehrenson, I. C. Lewis and R. E. Glick, J. Amer. Chem. Soc., 81^, 5352 (1959). 142~~

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~~25. C. A. Bunton, P. B. D. de la Hare, P. M. Greaseley, D. R. Lleweelyn, N. H. Pratt and J. G. Tillett, J. Chem. Soc., 4751 (1958).~~

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~~43. The author wishes to thank Prof.^J. J. Uebel for supplying the least squares plot computer program. 144~~

~~SUMMARY~~

I. Ten meta- and para-substituted phenyl methyl sulfoxides were titrated potentiometrically using perchloric acid as the titrant and acetic anhydride as the solvent. Their apparent pK values were determined by placing the cl values for the half-neutralization potentials on a straight line determined by plotting the pKa values vs. the half- neutralization potentials for some amines whose pKa values were known. A good Hammett plot correlation was obtained. Utilizing Taft's method for determining specific resonance effects, evidence was obtained indicating that electron donation by the substituent is greater in the protonated than in the unprotonated state, and that there is a large change in charge at sulfur between the protonated and un protonated states. pKa values were also determined for dimethyl sulfoxide, diphenyl sulfoxide, cis-4-(4-chlorophenyl)- thiane-l-oxide, trans-4-(4-chlorophenyl)-thiane-l-oxide, S,S- diphenyl-N-benzenesulfonylsulfilimine, and the S,S-dimethyl-, S,S-diphenyl-, and S-phenyl-S-methyl-N-jD-toluenesulfonylsulfilimines.

II. A series of nine meta- and para-substituted N- mesityl benzenesulfinamides were prepared and the kinetics of their reaction with hydroxide ion in aqueous ethanol studied. Second order rate constants were obtained. The reaction was shown to be first order in base and first order in sulfinamide. Activation parameters were determined with AH = +20.0 kcal/mole and AS = -8.9 eu. The rate constants gave a good correlation with Hammett’s o' constants (p = +1.3) 145 indicating that the transition state is being stabilized by electron withdrawing substituents. The procedure of Taft for determining specific resonance effects was applied to the sulfinamides. A resonance value of (-0.08) was obtained for N-mesityl £-methoxybenzene-sulfinamide indicating that the resonance contribution to the resonance hybrid is greater in the ground state than in the transition state. No sig nificant resonance value (+0.03) was observed for the £- nitro substituent. The lack of a significant resonance value for the £-nitro substituent argues against the for mation of an unstable addition intermediate. Mass spectra were measured for the nine substituted N-mesityl benzenesulfinamides. The base peak at 134 m/e was assigned to c6 h 2 (ch3 )3 nh+ . a plot of log ([xc6 h4 so+ ]/[c6 h 2 (ch3 )3nh+ ]) for X = £-N02 , £-CHg, £-CH3 0, m-CF^, £-Cl and H versus the Hammett substituent constants gave a straight line with p = - 1 . 1 .