Part T. a Study of Tpîe Influence Of

PART T.

A STUDY OF TPÎE INFLUENCE OF ELECTipNEQATIVE SUBSTITUENTS

ON THE cls-trans ISOMERIZATION OF AZ03ENZENE

PART II.

A STUDY OF CERTA.IN DERIVATIVES OF CARBONYL COMPOUNDS

DISSERTATION

Presented in Partial Pulfillmsnt of the Requirements

for the Degree Doctor of Philosophy in the

Graduate School of the Ohio State

University

IIELVIH KAPIAN, B.8 .

The Ohio State University

195h

Approved hyt

Advisor ACKN0I7LEDGS.ÎENTS

I wish to thank Dr. Earl W. ^^almberg for the guidance and

encouragement he has so patiently given during the course of the

inve E ti gati on,

Appreciation is also expressed to the tlhivarsity Committee

for the Allocation of Research Foundation Grants and the Alumni

Association Development F^or.d of the Chic State University for the

fsllovshins vhioh sunnorted this work» TA3LE OF CONTENTS Page

PART I

I. INTRODUCTION ...... 1

II. STATEMENT OF THE P R O B L E M ...... 8

III. DISCUSSION OF RESULTS ...... 10

A. Synthesis of Necessary Compounds ...... 10

B. Measurement of the Rates of Isomerization . . . lU

C. Diphenylketene Reaction and Catalyzed Isomerization 27

D. Absorption Spectra of the Azo Compounds

1. Ultraviolet and Visible Absorption Spectra . 35

2. Infra Red Absorption Spectra 37

IV. EXPERIMENTAL

A o Ma te rx al So.o.....o....o 38

B. Synthesis of the Desired Substituted Azobenzenos

1. Preparation of Nitrosobensene ..... o 38

2. Preparation of 3-Nltroazoben§ene . . . . « 39

3. Preparation of ii-Kitroazobenzene . . » . . 39

A. Synthesis of 3,A '-Dinitroazobenzene

(a) Preparation of 3-Nitrosonitrobenzene . . AO

(b) Alternate preparation of 3-Nitrosonitro benzene ...... Ao

(d) Coupling Reaction of 3-Nitrosobenzene and A-Nitroaniline ...... Al

11 Page

(e) CoTjpling Reaction of U-Nitrosobenaene and 3-Nitroaniline ...... h2

5. Preparation of 3,3'-Dinltroaaobenzene • • • h2

6 . Preparation of U,U'-I)initroaaobenzene • • • h2

7. Synthesis of 3,5-K.nitroaaobenaene . • • . U3

(a) Preparation of 3,5-Dinitroaniline , , « h3

(b) Preparation of SocHnin Formaldehyde B i s ^ f i t e ...... h3

(d) Coupling Reaction of 3,o-Dinitroaniline and Anillne-u>-!nethane Sulfonic Acid . e Wi

(e) Deamination of 3,3-Binitrc-U'—aiainoazo- benzene * * o

So Synthesis of 3 .,Ù-Dinitroasob3nsene

(a) Preparation of 3 ,i4-Dinitrcacetariilide @ k6

(b) Nitration of 3,li-Dinitroacetanilida , « hi

(d) Coupling of 3sli-=Bini troaniline and the Sodium Salt of Anilinethane Sulfonic Acid (with Sulfuric Acid in the Diasotising So-Lution) c c 9 * » * o 9 9 9 9 hi

(e) Coupling of 3 Ünitrcaniline and the Sodium Salt of A.nilins-w

(f) Dsamination of 3 ;h-Dlnitrc-l;'-aminca3 obenzene 30

9 . Synthesis of U—Sulfamoylasobensens « « . o . 51

10» Synthesis of ii-.(Dim3 thylsulfamoyl)asobensene

(a) Preparation of h-(Dlm@thylsulfamoyl)a2ob9n29ne >2

iii Page

(b) Condensation of L-(Dimethylsulfamoyl) aniline and Witrosobenzene • « • . • 52

11. Synthesis of U~(Piperidinosulfonyl)azobenz0ne

(a) Preparation of U-(Piperidinosulfonyl)aniline 53

(b) Condensation of U— (Piperidinosiilfonyl)aniline and Nitrosobensene ...... 53

12. Synthesis of 3-Sulfamoylazobenaene

(a) Preparation of m-Sulfamoylnitrobenzene . , 5U

(b) Reduction of m-Sulfamoylnitrobenzene . . . 5U

13. Synidiesis of 3-(Dimethylsulfamoyl)azobenzene . 55

(a) Preparation of m-(Dimeijiylsulfamoyl)nitro be nzene ...... 5 5

(b) Reduction of m-(Dimethylsulfamoyl)nitro

benzene . 0 0 . 0 0 . 00^0 0 55

(c) Coupling Reaction of m-( Dime thy], sulfamoyl ) aniline and Nitrosobensene * . . . . . 56 llfft Synthesis of 3—(Piperidinosulfonyl)azobenzGne

(a) Preparation of m-(Piperidinosulfonyl)nitro- be nzene ...... o.. 56

(b) Reduction of m-(Piperidinosulfonyl)nitro- V. rf-w rr »2s _ _ ^ /

(c) Condensation of ra-(Pip0ridinoEulfonyl)aniline and Nitrosobensene ...... 57 l5« Synüiesis of 3-Nitro-it-methylazobenzene

(a) Preparation of 3-Nitro-Ji-me1diylaniline . . 58

(b) Coupling Reaction of 3-Mtro-U-niethylanilino and Nitrosobenzene ...... 58

iv Page

16, Synthesis of 3-Methyl-ii-nitroazobenzene

(a) Preparation of 3-Methyl-l.t-nltroaniline , 59

(b) Coupling Reaction of 3-Methyl-U-nitroaniline and Nitrosobenzene...... 59

C, Synthesis of Diphenylketene

1, Preparation of Benzil Monohydrazone • , • • 60

2c Oxidation of Benzil Monohydrazone , • . • • 6 l

D, Reaction of Diphenylketene and cis Azo Confounds, , 62

E« Preparation of the cis Isomers •••«• * . 62

Fo Msasuï*ement of the Rates of Isomerization » * » 65

G, Calculations for Determining Rate of Isomerization « 65

H, Calculation of the Activation Energies and Frequency F a c t o r s 66

F # SUTiDjARI' oooo^ftooodoAedOOOOo o8

PART II

I * INTRODUCTION eaeeeooeoee«o«oc ?0

II. STATEMENT OF THE PROBLEM ...... 73

III. DISCUSSION OF RESULIS « ...... ih

IF. EXPERIMENTAI,

lo Synthesis of L-(o-nitrophenyl)semicarbazide

(a) Preparation of o-Nitrcphenylurea « o o . ?6

(b) Preparation of ii-(o—Nitrophenyl)semicarbazide ?6

( d) 83mthe sis of n-Butyraldehy^. and Me thyle thyl Ketone Derivatives of U— (oa.Nitrophenyl)semicar= bazide 77 Pago

2. Synthesis of 1:- (p-Nitrophenyl) semicarbazido

(a) Preparation of p-Nltrcphenylurea , . • 77

(b) Preparation of U-(p-Nitrophenyl)semicarbazide 78

3. Chromatographic Properties of l(n—Butyl)U-(2-nitro- phexDyl)semicarbazid.es, l-( sec-Eutyl)-L-( 2-nitrophenyl) semicarbazides, 1— (n—Butyl)-h-(h-ni trophenyl)semi— carbazida and l-(sec-Butyl)-li-(It-nitrophenyl)semi— carbazide ••••••» 79

ii. Synthesis of (o-nitrophenyl-N-ethyl)semicarbazide

(a) Prepamtion of p-Toluenesulfonyl-o-nitro— anii1 de 80

(b) Preparation of p-Toluenesulfonyl-o-nitro-N- ethylanilide eo.o. .»•«*» 80

ethylanillde *06000080.0 8 l

(d) Preparation of N-Ethyl-N-(o-nitrophenyl) carbamoyl Chloride ©cooo.o.o 8l

(e) Preparation of h-Ethyl-Ii-( o-ni trophenyl) semicarbazi de oooo * . . * . . o 32

5o Preparation of Propionaldéhyde Semicarbazone * * 83

V 6 SUI.'I?.IA Hf *660.00 09**600*000 8^

APPENDIX ...... 86

REBEPEWCE-S...... l62

AUTOBIOGR/^rHÏ oaeaoaooooo.se* l66

Vi PART I. A Study of the Influence of Electrone^tlve Substituents

on iiie ci8»trans Isomerization of Asobenzene

I, INTRODUCTION

Geometric isomerism in structures which have restricted rotation as the result of multiple bonds between two aterns constitutes a general phenomenon in organic chemistry* The first valid interpretation of

this phenomenon for ethylenic ccnç»aunds was included in the paper in which van't Hoff used the tetrahedral carbon atom to explain optical isonerism. This explanation is as satisfactory geometrically as the modem view of the electronic structure of the multiple linkage* la

either case y the extension of this idea to atoms other than carbon has proved very fruitful, and a aujsber of classes of ccsapounds which have geometric isomerism involving doubly bonded nitrogen are kncnmo

Those compounds are of particular interest because in place of tho second substituant on an ©thylenie carbon, these nitrogen ccanpounds have an unshared pair of electrons «

A number of coz^ounds in this class such as the oximas, dinitrophenylhydrazonesg diaaocyam.des, diasohydroxy and asoxy cosç>ounds^ have been fcnmd to exist in two geomstrically iscsmeric formso 2 In 1938 Hartley established th© ©xistance of geometrical isoi^riom in

üie aso coz^ounde by prepare, ti on and isolation of a aecond form of aac® beasenoo The new form was prepared by irradiation of a solution of i±io

stable isomer and isolated by czys tallizati on * 'Hie new isomer was 2

converted to the stable form slowly at room tenparatnre and rapidly at

elevated teaparatores * Continuous irradiation of a solution of the

stable or unstable forms results in the same photos ta tionaiy state. This behavior can be represented as followsî

heat \ N fl l i ^ t energy ^ \ li^t energy ^

/ cis-Azobangene ij^ia-Azobensene (unstable isomer) (stable isomer)

The thermal rates of isomérisation of cis«agob©azen9 in the pure

liquid statej, carbon tetrachlorddSj, benzene^ acetic acid, acetone and

TTster were studied and the reaction kinetics was found to be mono—

molecularo An activation energy of 23 kcal» par mole was calculated

for asobenzene* Experiments on catalysis in aqueous medium with base

or salts had no effect on the rate of Isomerization; aqueous acid of

Oc3 ^ strength was required to give any appreciable increase in the

rate of isomeriaation«, From studies with electron donating substitua

©ats (where X s «05^) in the para-posltion of the

asobenzen® molecule, the new isomers of these coupounds wars found to

be much less stable than the new isomer of un substituted asobensone;

however, with (p^phenylaaophonyl)trinethylammonium nitrate in aqueous

medium, a compound containing an electron withdrawing substituent, th© n«w ie

Further evidence for identifying this new form as the ciB«>isomer is as follows: (a) The eis-form has a dipole moment of 3*0 D. in benz ene solution, idiile the trans-form is zoro^*^ (b) Molecular weight determinations exclude the possibility of the new form being a polymer,

(c) Coïaplete X-ray diffraction determination of the crystal structures of both the cis and trans forms of azobenaene have been smde^)^*^. The trana—azobenzene molecule is nearly ccplamr, while the cis—azobenzene molecule is not as the result of steric interaction between the ortho hydrogen atoms, each benzene ring is twisted about 50° from th® planar position* The N=N bonds were found to bo 1*23 A® long in the cis and the trana forms, however, tho C-N bonds were found to bo 1*1<6 A® and lo^jl A®, roepsctively® The increase in double bond character in tho

C»N bond evidenced by tho shortening of the bond length is proof for resonance in the coplanar coafiguiation of the trans form* Tho demon strated arrangement in space of tho two benzene rings in the cis and tyans forms is uncquivocal evidence that the isomerism is geometric^

Further corrolation of the structural results can be made by considering certain thermochemical Investigations* From measurement of the heat of ccmbustioa of the two forms, Corruccini and Gilbert® found that the :traas isomer was more stable by 10 kcal* par mole* This difference in roson- anc© energy is further evidence for the coplanarity of the trans form.

(d) Chemieal differentiation between the isomers of azobenzene was h effected by Cook and Jonea^ by the addition reaction with diphenyl-

Iwtene; the cis isomer reacts vigorously at room tentera tu re to give

U-kete*l,2,3,3-tetraphonyldimethylene—1,2-diiinine, while the trans is

Cook and coworkers^®*^^ in 1939 reported the preparation of a number of azohenzenes in the cis form with a wider variety of sub stituents than reported by Hartley, Separation of the two isomers was effected by selective adsorption on a column of alumina. From the results of qualitative observations. Cook rated the stabilities of nitro substituted asobenzenes in the following manner:

Nitroazobensena Stability of cls-lsomer

o«,oo*-j pp«— Isoaerides not detected, asm«ra Normal stability. Very stable.

Tho relatively high stability reported for cis=3«nitrwzobenzen@ as ccBmarad to ci3--3.3 ^-dLnitroazobenzene prompted a more vigorous study of the rates of isomerization of substituted azo cospdumds, 12 Cook, Jones and Polya studied the absorption spectra in the visible and near ultra violet regions of the cis and ±rans aso eoi^oundo» in the visible region the absorption maximum is at aboit the same wavelength but the extinction coefficients of tho cis isomers are appro ximately twice those of the trans, Howovcr, in the near ultraviolet region tho absorption spectra of the pairs of cis and trans isomers show no uaifom coipffclatien ^ t h respect to wavelength or intensity of absorption. With respect to effect of solvent, Bimbaum and ccrrrorlters^ 5 reported that the major absozptlon mazlmom for d s ~ azobenaene in the ultraviolet region le only sli^tly shifted to Icmrer imvelengths as the solvent is changed from chloroform to ethanol to nwhexame, Halpem,

Brady and Winkler^ studied the kinetics of the cis-trane isomerization of unshbstituted azobenzene and found an increase in the rate vrith non polar solvents as conçÆred to polar solvents « The reaction was found to be consistently first order* No appreciable variation of the activa tion energy with tenqoeiatare was observed^ Arrhenius plots showed ne deviations frca linearity* The activation energies range from 22*8 te

2ii©75 kcal* per sole in n-heptane and methanol, respectively. The abnormally low activation energy (23*0 kcal© per mole) for the isomeriza— tion in water was attributed to the H ion catalysis*

The mt© of oxidation of cis-aaobengene with perbensoie acid was moro rapid than with the trans isomer.This reaction was attributed to th© higher electron density at the aZo linlcage in cis-asobanzeneo

The activation energies for the reaction of cis or trans-asobansone with perbsnsoic acid was 12*3 and l2j*8 kcal© per molo, respectively*

Badger and Lewis^^ also invectlgnted the o]cidation of substituted tmne«=» aaobeasenos and found that electron releasing substituents increased the rate of oxidation as coogiared to electron attracting substituents which decreased the rate of cod.dation© The activation energies for the extreme cases of Uf>ii®«”diiaetha3^aaobenEene and h^c=nltroazobenzene was

13*1^ and l6*9 kcal© per mole, respectively* The results obtained indicated a linear relationship bstweon the rate constants and HaEEaetts^”^ 6

"sigma” constant for the substitnent* One of the most interesting of

Badger*8 results Tvas the fact in the sigma—rho treatment, the effect of the same substituent in the 3,3*— or U,U*— positions of azobenzene iras found to be additive* One unfortunate aspect of their work is that in unsyimaetrical azo confounds the position taken by an azoxy oxygen was not investigated*

Magee, Shand and Eyrlng^® have treated the cis-trans iaranerization reaction by the Iheory of absolute reaction rates» Rrom experimental evidence reported on the cis—trans isomerization of ethylenic struc tures (maleic acid, butene-2 , stilbene, etc*) tt?o distinct mechanisms are apparent© (l) A rotation involving a singlet electronic state of th© molecule, the case uhera ih© coupling of the TT electrons is un changed, but where the rotation around the carbon—carbon bond is forced against the resisting torsion of the TT bond* In ethylenic ccsa pounds this is the usual mechanism for molecules which have a phenyl group attachod to an othylonic carbon^ This nschanism has a charac— toristic h i ^ frequency factor on the order of 1 0 ^^ seCo'^^ and a high activatioia energy in the range of 35 to U5 kcal* por Qole© Stilbeao and ^ —cyanostyren© ax-e examples of compounds which isoneriso by the singlet state E^chanlsm* (2) An intermediate triplet state in which the spins of the electrons are uncoupled, a mechanism which has a rolativoly lew frequency factor (caolO^ sec®”"^) and a low activation

OEier^ in the rang© of 15 to 20 kcal® per mole* Ikileic acid and butene-

2 are eitai^lae of conpounds which ieomerize by the triplet mechanism*

On® of th© two mechanisms can b© saleetod for a particular case by 7 o Glaring the activation energy and frequency factor to the chcracter- istio values listed above* From these results with ethylenic c(abounds it was concluded that azobenzene probably istaaorized by the singlet state mechanism; however, one cannot conçjletely rule out the triplet state mechanism*

Calvin and Alter^^ investigated the thermal isomerization of substituted stilbenes and discussed their experimental results in terms of these two nechanisms* Energies of activation and frequency factors showed the isomerization of p-nitro-p* —aaino stilbene by the triplet mechanism, while p-aethoxy stilbene, p-nitro stilbene and p=. methoxy-p’-nitro stilbene nay isomorize by both mechanisms#, 8

II. SmTEMENT OF THE PROBLEM.

The gtu4y of reactions In organic chemistry has shown that the major factors to be considered in the constitution of the molecule# are steric and electrical. One of the difficulties in a detailed

study of various reactions is that when substituent grovçs are changed

to alter one effect, the other effect is also changed. The most its» portant reason for an intensive study of this isomerization reaction is

that in this monoraolecular reaction, the isolation of the variable

electrical factors is possible. Groups of different electrical character

can bs substituted in the me ta and para position with no significant

steric effect* Furthermore, th@ reaction does not depend in any

critical way on interaction with a second molecule in the formation of

a transition state, as does a bimolecular reaction.

The effect of electron withdrawing substituents in the me ta or para

position on the stability of the rcLa fozm of azobenzene is the subject

of the present investigation* The coEpounds iTith nitro and sulfaaoyl-»

groups, boih mono-» or di-»substitutod, ware to ba used in these studies.

The rate of isomerization is a direct method of evaluating the rolativo

stabilities and the electrical effect of certain groups in the molscule;

the first order character of the reaction under different conditions

can be verified as wall© The esperimontal results will contribute t&

further understanding of the problem of electrical offsets in this and

other organic reactions. In tho course of the study, measuraments of

the ultraviolet, visible and infra-red absorption spectra of these

compounds world add to the knowledge of abaoiption spectra of closely

related organic conç>ounds. 9

The problem included two aspects t first the synthesis of the substituted azo conç)Ounds in the cis and trans forms, and second, the measurement of the rate of ele to trans isomerization under different conditions as to tenqperature and solvent* The results were to be examined by the Hsunmett "sigma—rhe treatmentwhich correlates electrical effects in organic reactions or by any other interpretation which suggested itself. Whan the Hammett method proved to be inapplic able two different methods of evaluating the electron density at the azo nitrogen atoms were studied* 10

III. DISCUSSION OF BESULTS

■Rie pr<^osad investigation required the synthesis of the substituted asobenzenes of greatest interest, the ms a sûrement of the rates of isomerization to determine the stability of the cds isomers, and the measurement of the spectra of the azo conç>oonds« "Ruese three parts are treated in that order in the following discussion*

A a Synthesis of the necessary compounds* A conventional method

for synthesizing unsymetrical azo confounds is the condensation of an aromatic amine and a nitrosobenzene*

Glacial -NO N=rN Acetic / Acid 4- HgO

This method ttss foumd satisfactory in the préparation of the following

substituted asobenzen® given in Table I© TABLE I

SIHTHESIS OF SUBSTITUTED AZOBENZENES

!• nitrosobanzens -f- ,3“*nitroanilino — f 3-ni tr oa a obenzoQO

2o aitrosobsnzen© -h li^nitroanilino ii«ni tr oazobenzane

3o 3-nitronitr©sobensan0 +- 3=nitroaai.lin0 3,3*-dinitroazobenzeno

iio iwîitronitrosobenzenQ +- li«nitroanilino It ,ii-dlni troazobenzone

3mnitronitro3ob©nzQna ^ ü-nitroanilin© 3 ,U* -cünitr oazobanzene# U-nitronitrosobenzano + 3=»nitroanllina J

60 nitrosobanzeno + S^nitro-U-methylanj-linQ C=l- « X A ^ | ^ 3-ni tro-li-me thylazobenzene

7. nitrosobonzene + 3«aetbyl-Ji«nit£*oaniliûG «gu»a 3"%'^ 3«fli8thyl«li-nitroa2ob0na0no*

8. nitrosobensene + 3=sulfamoylaniline --- > 3«sulfanioyla2obenz9ne

9o nitrosobensene 4- iiosulfamoylardlino U-sulTamoylazobenzeno

1 0 . nitrosobenzene + 3=(dim9thylsulfQmoyl)anilin®*K- c a « n . 4 3 ^ 3-( dime thylsulfamo7l)azobena0ne* llo nitrosobenzaa© + i^(dimethyl8iafamoyl)aiiilin9 Jt-»( diiB9thylsulfamoyl)azobon29ne»

I2e nitrosobeasono + 3®(pip9ridinosnlfonyl)anilina-ii- 3-( piperidinosulfonyl)azobenaene* U«(piperldiaosulfonyl)azobenaone* 13. nitrosobenzene + i}=.(piperidiaosulfonyl)anilinQ ----^ 12

% l 8 method failed in the condensation of nitrosobenzene with 3,$- dinitroaniline and 3»U-dinitroaniline» Variations in the tei^erature or the time of reaction did not yield the desired product* To counter balance the electrical effect of the negative substituents on the amino conç)oundj different catalytic amounts of concentrated sulfuric acid were added to increase tho reactivity of the nitroso coHÇ)onent; this change however, was of no avail because the nitroso conç>ound appar« ently underwent other types of reactions©

A new general method of synthesis was developed for two new compounds, 3,^-dinitroazobenzene and 3 dinitroasobenzonc« This series of reactions is generally applicable to the preparation of unsymetrical aae cospounds which have electronegative substituentso The method is based on the ability of the sodium salt of anilinô>-o-®©than© sulfonic acid to couple with diazonium conç^ouads to f o m th© as© linkage and on the fact that the —NHCH2S0 ^Na group which facilitates the eoxçiling can later be removed* The reactions which remo'/e the coHHCHgSO^Ha group do not interfere with the desired substituents* The first step is th© On 21 preparation of the N-substituted aniline salt*" *

HgCsO -H NaHSO^ — ^ HgC(OH)SO^Na

The renaining steps in the synthesis are shown for the preparation of

3gS=dinltroazobenzene (TZ)© 13

NO NO Coinpovmd NaNO I > N N- NaOAc NO

NaNO HOI? NaOH o°c.

6 0 -7 0 °C.rA / H3P02

The coupling method is^ particularly useful with electron attracting

substituents in the diaaonium component because the coupling power is 2p strongly enhanced* The coupling, hydrolysis and deamination are all

rather critical reactions, and it was only bÿ chromatographing the

various intemediates and products togeiSier crith a prediction of tho

chromatographic prope rties of the desired product that this me-îâied was successfule The synthesis of the 3^«.dinitro compound was carried

out with a procedure similar to the one described for tlie 3 @$-cowpound and the product of the coupling reaction turned out to be 3«.nitro»=U-=>

chloro«>U’«eamlnoasoben3eneo Raplacoment of the nitro group in the para position of substituted aniline has bean enconatered by other workers

it occurs as a result of the activation of the para position by the

diasonium group to attack by a nucleophilie group such as Cl“ s Sulfuric

acid was therefore, used in place of hydrochloric acid in the diaaotlsa®

tion of 3 ,U— dinitroaniline and the desired 3 gl}—dinitro=l*^ —amlno«

sulfonic acid asobsnseno was obtained® Ihe basic hydrolysis of this

oo5pound to yield 3,U«dinitro-l*’«ai3iaoa2obanz0n0 was difficult because lU of its sensitivity to base at elevated températures or l<»g standing at room tenteratares * Subsequent deamination yielded 3,U-dinitroazobenzene#

An alternate synthesis^^ utilising the thionylamine and phenyl— hydraxylaiaina aajr also be applicable in the synthesis of these un- synaietrical azo compounds but the lew yields reported discouraged any further work#

B» Measurement of the Rates of Isomerization* The rates of isomerization were measured spectrophotometrically for the cis to trans reaction at three temperatures corresponding approximately to 39°, L9 °, and 62®C« Both the cis and trans isomers have absolution maxima at about the same wavelength in the visible region of the spectrum^ however, the cis form has a higher absorption in this region (See Figura 19®)o This properly makes it possible to determine the con^osition of solutions of Imcsrm total concentration by measuring the optical density® The sample bottles fitted ui th. screw caps, described by Halpern, Brady and Winkle wore found to be unsatisfactory in the present studÿ due to solvent evaporation at elevated tenperatures<, The reaction vessol=»sampling device shown in Figure 1* was used for the rate measurements# Duplicate rate measurements for B^nitroasobeasene in 9 S-percent ethanol and bens- one at U9«2®, showm in Tables X and XII, were 8o05 z 10"^, 8 ® 0 6 x 10“^ and 1®$U X 1«U8 x 10“^, respectively, A trial measurement on azobenzene at 3 9 in benzene was 6 @6 $ x lO"^, as con^ared to Winklers extrapolated value of 6,U5 x 10“^ at 3 9 in benzeneo 15 The general characteristics of the kinetic data are shown fbr

3—nitroaBobenaone at three different tonçjeratures in benzene, n-hoptane and ethanol in Rlgores 2—7, The linearity of the plets of log % cis vs. time Indicates ihat the reaction is consistently first order. The resmlts of all rate studies gave the same linear plot, and the slope of this line was used to calculate the rata constant, Hc^ever, because of the large number of rate studies, the greater part of the data are given in tabular form in Tables X — XXXÏII, Second order kinetics are ruled out by a check of the isomerization at a lower overall concentration of aso conçound. In each case a check was made that only the isomeriza tion reaction occurred by measuring the final value of the op tidal density of the reaction solution at infinite time and comparing it to the value calculated from the knorm concentration by ireight and the

Icncrm optical density of a solution of the pure tnana conpoundo In all cases the agreement was within experimental error* The usual check in spectrophotometric work by use of tho isobestic point could not be mad© in this work because of lbs similarity of iiie spectra of the two compoundso T£10 first order rate constant, k, calculated from the slopes of

tbese linear plots is shorm in Table If @

His plot of log k against the reciprocal absolute tengieraturo, is shown in Figuras 8—11 for all solvent-compound combinations for which rate studies were madio The activation energies, E, and the frequency factors. A, were calculated from Uie slopes of these lines by tho Arrh

enius equation, k = Ao“®/RT. The E values shorm in Table III are accur ate to within 200 cal* per moleo l6

Table II

The Hates of Isomerization of SubstLtuted cis Azo Congaoiinds at 62,3°, U9*3°, 39.5°, and 2 k ' ^ C *

Substituent on First Order Hate Constant x 10^ cis Aze Gonspound* )2.3*C. k9.3°C. 39.60c* 2k.9°C, In Ethanol

3-^ip e ri di nosul f onyl— 2.23 0.520 0.171 3 , 3 '-dinit ro- 2 .k8 0*585 0.190 3 -dime thylsulfamoyl- 2.60 0.625 0 . 2 0 0 3-nitro— 3.78 0.911 0.297 3—sulfamoyl— 0,322 3 -nitro-U-ma thyl- U .60 1 . 0 6 0,32k nono (azobenzene)## 5.28 1 . 2 2 0 . 3 8 6 U-sulf‘amoyl- 0*705 3 ,5-dinitro- 12.9 2.99 loOk it-piperi dinosull onyl- Ik.5 3.L6 1 . 0 1 U-dime thyl sulfamoyl- 17.1 3*56 1 .1 k 3 -1? e thyl— L-nitro— 37.0 13.0 2 ,2k li—nitro- 75.8 26.3 k,17

In Benzene

3 «pips id. dinosulfonyl— ho9k 1.15 0,356 3j,3*=dinitrc« ko97 1 . 2 2 0 .kl6 3 — dime thylsulfamoyl— 5*0 6 1.19 0.39k 3-nitro- 6.38 io55 0.505 none (asobenzen®)## 6.38 1.96 o,6k5 3 =nl tro-Ai-me thyl- 8.k7 1.76 0.501 i}-plperidinosulfonyl- 22.3 ko82 lo6 l 3 g5-dinitro- 22.8 5.30 1*59 U-dime thylsul famoyl— 27.0 5*29 1.69 3«^ethyl—U—nitro— 2 5 . 1 8 .6 k lo38 nitre— khol 15 o6 2 ok6

In a-H©ptane

3 -nitro- 9.7k 2 .1 k 0.723 none (azobenzene)** 8*20 2.62 0.879 U-nitro— 31.6 10.9 1 .7k

# In the case of the 3,U-and the U^lj’-dinitroazobesisenes no stable isomer -was detected* The 3jU'-dinitroazobenzene gave a sli^tly stable isomer» . ## Interpolated from Winkler's^ data on azobenzene© Table III

The Actii^’ation Energies and Frequency Factors of Substituted Azo Compounds

Log A Azo Confound E (kcülo per mole)

Benzene Ethanol n-Heptan© Benzene E+Jhanol n-Heptane

23.2 13.08 12,93 12.98 3«nitro=’ 23.6 23.7 3,3tdinitro=» 23 oO 2iioO 12 .n 12.95 13.88 ii-nitro- 22*1 22.2 22.ii 13.51 13.51 3-ni tro«ii-®e thyl» 26.2 25.0 IU.95 13,91 13.75 13.55 3=aethyl-L-m tro - 22.8 22.2 lli.l2 3j^dinitro« 2ii.il 23,6 13Jil 15.05 lU.59 iwdimethylsulfamoyl - 22,2 25.2 12.72 3-dimetbylsulfamoyl*- 23.8 23,7 13.11 lli.18 il^piperidinosulfonyl- 2ii.if 2l.!i 13.99 3-piperidinosulfonyl*- 2li.2 23,9 13.3Ü 12.52 none (azobenzene 23.3 2iio3 22.8 13.10 13.57 12.68

* From Winkler9 8^^ dati on azobenzene, 18

In the examination of these expérimental results in the light of the Eÿring^® treatment of ge

The activâtion energies in the isomerization of azohenzenes, 22 to 2^ kcal. per mole, are more closely conparablo to the values of E for the triplet isomerization in the ethylenic coaçjounds than to the singlet* However, the -.IT5N— is characterized by an unshared pair of electrons, and it is not surprising ttiat the azohenzenes and related compounds such as aldoxiraes, diazocyanides, and asosybenzeno all have approximatoly this energy of activations hut have no other evidence for a triplet mechanism* The reaction occurs with the help of some inter action of the77^electrons with the rest of the molecule, and the esse of electronic interaction of unshared electrons on an atom attached in “I p an aromatic ring is well established* The frequency factors of 10^ l5 10 are coaç^letely in accord with a singlet mechanism, and since the low frequency factor for a triplet state represents a low probability of uncoupling of the TT electrons, it should be eoiiçjarabi© in both th© ethylenic and aso serlos*

Ahy departure of tho Arrhenius plot from linearity, specifically concave upward, would indicate a possibility that both mechanisms were escurring at aeasurabl© rates* If any compound with values of A in th® lower range were found to also exhibit a curvature of the Arrhenius plot, there would be evidence for simultaneous occurrence of two mech anisms* However, only on© Arrhenius plot shows a detectable amount of 19 ourvatare (Figura 11, U<>(dimethyl8ulfaiiioyl)asobanseiie) and for 'this oasa ths frequency factor is in the upper range* In any case, the linearity of the Arrhenius plot does not eliminate the possibility that both nechaxxiSB^ operate simultaneously* As for M m most reactions, the measurement of the rate over larger te literature ranges Is not experimentally feasible* Within the molecular orbital treatment of

Eyring and coworkers, the Indications are quite clear that these aso conçjounds iscsnerise by the singlet mechanism*

An inspection of the data uill shtsn that the Hammett 6 /^ treatment is not applicable in correlating the electrical effects of the i*ing substituents in the reaction under study* The rates of isomérisation for the 3 »nitro and ■unsubsti•tuted azobsnaone are very much alike 'whil®

üie constants are greatly different,-^0*710 and 0 ©0 0 0 , respec» tively* A comparison of the sigma constants for para and isata nitro group (4-0*778 a n d +-0*710, respectively) shcm that they should have rates of cosparabla magnitude, but actually the presence of the para nitro group results in a rate fas'be r than asobenzenej a result Wiich should correspond to a negative sigma value® It is therefore, clear that the electrical effects influencing the isomérisation do not folloï? the Hamaott treatment « Dozens of reactions of me ta and para substitued aromatic eoi^ounds do foiler this treatsent, including at leaot one monomolecular reaction* Consideration of the (fe-ta for dinitro™ aaobenzenes shows that here the electrical effects depart even further

from conventional views* Para=nltro groups induce very great ease of ■j A isomerization, but no additivity offsets such as those found by Badger 20 and are apparent* When the Haanett method proved to be in applicable, the results were studied to bring out any clue which would lead to an understanding of the experimental results*

One of the leads from which an indication of electrical effects

can be obtained is the effect of solvent on the rate of reaction* When the change in reaction rates in solvent from n—heptane to benzene to

ethanol is studied, it is found that rate decreases from azobenzene and all substituted confounds except ii-nitroazobenzone and 3-Biethyl-ii—nitro-

aaobenzene; in these cases the changes are of comparable magnitude but

are opposite in direction* The nitro group in the para position is

unique among the groups studied as coEpared to the ngta nitro and me ta

and para sulfamoyl groups. Only with the para nitro group can resonance

forms such as

( S = N — />~K. = N -

bo achieved by the molecule. Among the oJ

t-ion which con b© discussed with the Eyring theory in the othylenle

series, the presence of an aromatic ring on an ethylenic carbon appar-»

ontly facilitates the singlet mechanism; this fact is further con

firmation for a singlet mechanism in the case of the azobenzenes* The

valance bond formulation of the separated charge resonanco form, 1 1 ,

of para nitroazobonsone was uded above, but the molecular orbital 21 treatœat is in general more satisfactory for discussing the present problem* The main disadvantage is that the demonstration of the reality of charge distributions sudi as II is a eonq^lex mathematical problem# In all cases for which the calculations have been made# the charge distributions characteristic of the valence bond formulations are found to be qualitatively correct* The molecular orbital treat ment is more accurate for one reason particularly# In conventionally writing forms such as II, the valence bond method withdraws the un shared pair of electrons from the aao nitrogen, udieroas the molecular orbital treatment unequivocally shows that these electrons do not participate but rather the electrons of the JT bond® This molecular orbital treatment then is mo ce valid for discussing the present problem, but Ihe answer to the charge distribution, the samo for both treatments, is most easily obtained from the valence bond meWiod*

If tho molecular orbital pieutra of the asobenseno molecule is used, the overlap of tho p orbitals in the nitrogen atoms with each other and with the aromatic ring (the latter decreased by the non-coplatmrity in trie ois isomer) Ernst be considerado Ths rssistance to torsion shown by a double bond can be retried as the result of th© da crease in energy content when a largo amount of p orbital overlap foms tho ordinary 77^ bond@ If tho oloctron concentration in the overlap is decrsased by an offact as shown in II then the resistance to torsion would be decreased, and isomerization should occur raora readily* For azobenzene itself and for m-nltrcazobcnsone, a form such as II with the

TTithdra^Tsl of electrons by resonance involving the nitro group ia not probable I only tho inductive withdrawal of electrons is possible# 22

As mentioned above^ the effect of eolrent on the rate of isomeriza tion bears out the interpretation given above♦ If the stipulation is made that a resonance effect is transmitted through the molecule itself and an inductive effect throu^ the volume surrounding the molecule as

■well as partly through the molecule, the experimental facts can be justified* The rate of isalcohol because the ease of forma tion of the separated change form II increases as the dielectric con stant of the medium increases* Ibe charge is transmitted throu^ the molecule, so the medium has an effect only in contribution to the stability of the ionic form* The maasurements on the isomerization of

3 -methyl-l4—nitroazobsnzena confirm this picture; the same solvent effect appears, but the rates arc only half as great as for li-nitro- asobenzeaoo Tho presence of an ortho methyl group is to hinder the coplanarity of A nitro group, and hence decrease its resonance interaction trith the aromatic ring* The solvent effect for azobenzene and all compounds with mata nitro groups is opposite in order compared to the para nitro coicpoundSo This class of conpounds also includos all tho sulfamoyl confounds, seta and para* Conparativ© rates in different solvents are shown in Table Iv, together isdth the ratios of ths change in tho rato with solvent»

The values of these ratios of the rates of isomérisation in th©

various solvents for all the coEpounds ©xluding the U-nitro substituted azobenzenes show that those compounds are probably closely related as

to mechanism of isomérisation* In a dcteiiled study of the effect of

solvent, Winkler^ coB^ared the log of the rate constants with th© 23

Table IV

A Conçîarison of the First Order Rate Constants (aclO^) for cls-trans Isomsriaation in Different SolTonts at 39*6 0*

Rati# Aao CoBEpouad n—Heptane Benzene Ethanol n-H / B / E

3 ,3 »-dinitro- O.Ul6 0 . 1 9 0 2. 2 A 3-nitro- 0 .7 2 3 0 .ÿ)$ 0 .2 9 7 2.1* A » 1 A 3 -nitro-1 waethyl 0 * ^ 1 0.321* 1.3 A azobenzene- 0.879 0.61*3 0.386 2.0 / 1.7 A 3yl*-dinitro- 1 .3 9 l.OU 1*6 A 3-piperidinosulfonyl— 0.336 0.171 2.0 A 3—dimethyl sulfamoyl- .391* 0 . 2 0 0 2.0 A 3=»snl famoyl— 0 . 3 2 2 l*-sulfamoyl— 0 .7 0 3 U-piparidinosulfonyl- 1 .6l 1 . 0 1 1. 6 A i*-ditaathyl sulfamoyl— 1 .6 9 l.li* 1 .3 A 3-me thyl-l*-ni tr o- 8.61* 13 «0 O.67A i*-nitro- 1 0 .9 l3.6 26,3 0.1*2/ 0.39A square root of the internal pressure of the solvent and TTith a function of the dielectric constant. However^ no generally ^ p l i c a b l o oorrela-. tion was found, asd there was no attempt at an explanation on a mole cular level®

In the case of the It—nitroasobonsea© and tho 3==aethyl-i*-nitro» asobsnsen® lA so css reasonable that the electron withdrawal by the para- nitro group by resonanco accounts for th© instability of the els isomer®

It is mar© difficult to find an interpretation for the behavior of a group of cosqjounds such as azobenzene, 3-nitrcazobensens and 3,3®‘= and

3,3—dinitroazobensene ; in the case of the me ta—substituted cosqjounds, only the inductive effect can operate© It is evident that another type of electrical effect may h& operating in conç)Ouncis such as the meta- nitro substituted asocompounds* A very high rat© of isomérisation was found for p-methoxyasobenzane and other azobanaenas which have electron 2h donating snbstituents• The solvent effect in these cocç)Ounds 1# exactly the same as for aaobansene; the rate of isomerization decreases in the following order* n-Heptane ^ Benzene y Ethanol* This solvent effect indicates that cis-azobenzene may iscmiarlze by the s ame electron donating effect that is operating In the isomerlzatlon of p-meüioxy— azobenzene* The behavior of these confounds which have electron donat ing substituents indicates that the isomerization Is facilitated when there is a h i ^ concentration of electrons at the azo nitrogen. This premise is used in the following discussion*

Ihe hi^i rate of isomerization of cis-azobenaea® in noa-polar

solvents as cos^ared to polar solvents can be explained as follows; cis—azobenzene possesses two strong permanent dipoles as shown

These dipoles in the molecule represent an electron withdrawal

from ths a^o nitrogen* From the above premise, the greater the with«

drawal by this

In other words, any onvioraent in which the dipolo in th® molecule is

smaller will show a greater rato of isomerization* From electrostatic

considerations the magnitude of the dipolo in the molecule m i l bo

greatest in a solvent of high dielectric constant (ethanol) as compered

to a solvent of low dielectric constant (n-heptane)* The predicted

order of the rates of isomerization is therefore; 25

n-heptane ^ benzene ^ ethanol; this rationalization is in agreement -with the exparimental results*

"518 solvent effect on the isomerization of cis—azobenzene can be summarized as followst Electron Cone* Predicted Rate* Solvent Net* Dipole Moment At the Azo Nitrogen of Isomerization n—heptane small largest fastest benzene intermediate intermediate inte rme diate ethanol large smallest slowest

The order of the rates of isomerization of meta-nitro substituted azobenzenes in iWiaptane, benzene and ethanol is the same as for azo benzene (see Table IV) « If the assui^tion that a h i ^ electron concen tration on the aso nitrogen is requii^d for a rapid iscsaarization then the relative sates of the nitro compounds can be explained*

Relative Rate 2 Of Isomerization

(A)

HO m.

(B) N —- N '

(C)

->— ^ (net C-N dipole in a given solvent) * Assuming that the isomerization occurs more rapidly as a result ©f a high electron concentration at the azo nitrogen* 26

In ê&sa 6 tba net C-N dipole is strengthened by the electron eith- drawal of the nitro group. "Rils increase in the stability can be accoun ted for by the decrease in the electron concentration at the aso nitrogen#

In case A the C—N dipole is strengthened in both directiws, greatly decreasing the electron concentration at the a^o nitrogen, therefore accounting for the increased stability of the cis cooçîound#

For as large an increase in the rato of isomerization as is observed for cis- 3 #^-dinitroazobenzane, a second qoposing factor must be enter ing the picture. Explanations can be offered for thi^i^sult, but only on the basis of questionable postulates#

From consideration of the effect of solvent, the sulfamoyl ccisgjounds fall into the same class of isomerization mechanism as azobenzene and the me ta nitro compounds, by a supplying of electrons to the azo nitrogen# The me ta sulfamoyl groups all make the cis form less easily isomeriaed than azobsnzenej those results can be explained throu^ an inductive effect as for 3-nitroasobsnseno as above@

Gonsi(feration of the para sulfamoyl cocgjoimds yields scmo results

Tmich are interesting because of the l i ^ t chad on a classic problem in organic chemistry2 just hOvT effectively doss a sulfonyl group duncticn as an olGctron-Rjithdraulng group. A resonancs form such as for p=nitro= asobcasan© is less important; usually expansion of tho valance shall of sulfur to ten electrons is invoked to explain the general me ta directing eharaetsr* The very sli^t increase in rate for %io para sulfamoyl groups cong)ared to azobenzene and the magnitude and direction of solvent effect shew that in the absence of any strong polarising groupp the resonance interaction for a sulfaiEoyl group is of the order of one»» 27 tenth or less than that of the nitro group* The Influence in the isomérisation reaction is chiefly inductive even for the para sub stituted molecule* The difference nhichesist between the unsubstituted amide nitrogen and the various alkyl groups look interesting — exercise

Ing an effect so far from the reaction center — but no interpretation is apparent#

Considering the solvation effect, Winkler^ found that in mixed

Solvents such as heptane-ethanol the rate of isomerization was not additive# With small percentages of ethanol the rate was much closer to the value for pure ethanol. This result indicates strong solvent effects which agree with the general concept of solvation, Hcswever, a

study of the present results in terms of solvation only, gives no corralationo The reverse effect of solvent on 3->nitroasobenasne and

I4—nitroasobsnzene cannot be explained on a basis of solvation, Scmll

differencos in the activation energr say result from solvation effects, but again no correlation can be found©

Go DiphenylketeEQ Reaction and Catalysed Iscmarizatlonso The understanding of "the thermal iscsiarisation of various substituted asobensenes is predicated upon variations in the electron concentra^»

tions around the azo nitrogen atoms. Two different experimental

approaches were made in an attempt to obtain information on this aspoct©

These two a are discussed b©lcw| the reaction of the cis azo ccnpoimds with diphenylketone and the catalysis of the iscmerisation by liydrogen

chlorido © 28

Diphenylketsne iras found to react rapidly aith cis-agobenzane o to yield a single adduct as Cook reported. However, with cis sub stituted azobenzenes the reaction was very conqplex; chromatographic studÿ' showed six to eight different products formed in the reaction#

The reaction with 3-nitroaaobenzene and 3,3*-dinitroazobenzene was much slower than with azobenzene, a result in agreement with post ulates which have been used to explain the rates of reaction* The

COTÇ)lex reaction mixtures which were obtained discouraged any further experiments along these lines and experiments on ths effect of hydrogen chloride catalyst on the rate of isomérisation were initiated.

The experiments of Hartley on the catalysis of the asobensen© isoDiarization by dilute hydrochloric acid were inconclusive because of the extremsly large amounts of acid collared to aso compound which were used and because si do reactions were occurring* Similar results were obtained in tho present study frhen ethanol Tzas used as a solvent*

HcvovaXj interesting results were obtained when the effect of hydrogen chloride in benzene was studied© The concentration of hydrogen chloride was varied from 0*07 « 7 oOO times the amount of azobenzene on a molar basis© The thermal and th© catalytic reactions of isomerization are assumed to occur independently; evidence for the fact that hydrogen chlorido does not cossdjBs with eis or trans=»asobsnaone other than a momentary association at the time of reaction is given later in the

discussion. In all cases the measured final optical density of^which

contained hydrogen chlorido agreed with tba value calculated frcan the concentration of azo cœapound for the pure trans isomer© Tho, hydrogen 29 cbl#rlde catalyst, therefore, had no effect on the analytical method.

In all cases with azobenzene in benzene the linearity of the plot of log percent cis—azobenzene versus time indicates the reaction is con sistently first order (see Figure 12) j the slope of these lines irtien multyplied by 2,303 gave the first order rate constant, k, for the thermal and catalytic reaction. The benzene used as solvent was rea gent grade dried with granular anhydrous sodium sulfate (Merck) *

An experiment using benzene which was dried with sodium wire and redistilled gave a first order rate constant of 5»3U x 10**^ for a solution containing 0*058 millimoles hydrogen chloride. The rate constant for the same concentration of hydrogen chloride using benzene

■Hhieh contained as much moisturo as would be tolerated by the hydrogen chloride was $&3h x 10”°^ © At very high concentrations of hydrogen chloride catalyst the rate of isomerization is so rapid that it ic essentially independent of the thermal iscmerisationo Table V shows the effect of varying amounts of hydrogen chloride on the first order rata constant©

The first order rate constants obtained fron the plot of the log percent cis-=azob9nsene vs, g wera plotted against the corrospondiïg hydrogen chloride concentrations (see Figure 13 and lii)© The llnearxi^^

of this plot shows the catalyzed isomerization to be second orderj,

■with the concentration of tho hydrogen chloride component remaining unchanged during the reaction© The purely catalytic ra'tes of isomeriza tion for- azobenzene g tabulated in Table 7 -were plotted a gains the con centration of hydTOgan chlorido at h9o3^ and 39©6° in Figure 18© The 30

Table 7

Bate of Acid Catalysed Isomerization of cis-Azobenzene at Different Concentrations of Hydrogen Chloride (See Figures 13, lU, and 18, Tables XXXIV, XXXV*)

Mlllimolarity Bate Ccmstant XIO^ Hydrogen Chilorid# cia-CAH^NsCAH^ Thermai Catalytic Catalytic

Temp* 3 9 . 6 ±. 0 S^C.

0 . 0 0 0 0*61:3* CB O.Olt? 0 . 6 7 3 1.03 0.39 0.0^3 0.673 1*12 0.38 0.093 0.673 1.37 0*73 0 . 2 2 2 0*673 2.38 1.91* 0 J 466 0.673 1**89 i*.23 0.93 0.673 9.63 9.01 2.30 0*702 23.6 23.0 li..6o 0*70 2 1:8*1 1*7.1*

, i»9.3t.o$°C.

OoOOO 1 .96* 0 . 0 6 6 0.713 2.29 0.33 0 . 0 9 6 0 . 7 0 3 2.81* 0*88 0.382: 0.713 3.38 3.1*2 0.6^9 0.713 7o70 3 .71* ;m Winkler® data on azobensna. catalytic rates for botii températures fall in the same lins indicating

that tho iscmerisation of c i sohenseno with hydrogen chlorido catalyst has a ser-ô activation ener^^o These experimental results can bo under stood in terms of conventional interactions of molecules of this type; the proton of the hydrogen chloride catalyst is attracted to tho unshared pair of electrons on one of the nitrogens atœns in tte aso linkage o

From tho stanc^oint of the molecular orbital theoiy the electrons ad

jacent to the complQxed nitrogen atom can be regarded as being dravm 31 toward the positive center. % e decrease of electron concentration in the p orbitals facilitates the isomerization*

Ihe rate of isomerization of azobenzene with hydrogen chloride catalyst in n-heptane as a solvent was greatly decreased in the latter half of the reaction compared to the values predicted from a first order plot* The deviation first order kinetics is shown in îlgure

1$. (Table XXXVIJ« The final optical density of the solutioh agreed

•with a value obtained for the pure trans-compound* With benzene the hydrogen chloride catal.yst may bo conçlexed wi,th the tT electrons of the ring; ■rd.th n-4ieptane this is not possible*

The hydrogen chloride catalysis for substituted azobenzenes pre sents a more cosplas situation* In the case of cia-a—nitroaaobenzene at low concentrations of hydrogen chloride (Oo09»0«l3 millimolar) a strai^t line is obtained from the plot of log percent cls-ia-nltro- aaobanssne vs@ time; however, with hi^er concentration of hydrogen chloride (0*37-0*7L millimolar) curva-turo in this plot is observed*

(see Figure iS* Tables VI, XXXVII*)

Similar curvature was obtained in the plots for the isomarization of cia-o-nltroagobengeno; however, hi^or concentrations of hydrogen chloride (Oo82 millimolar) were reouirod to effect an appreciable catalytic change (see Figure 17;, Tables VI, XXXVIII)*

2he results shown in Table VI indicate that a more coBplax situa.^ tion is encountered in the case of ‘the mata and para-nitro substituted azobenzene as compared with azobensenoo Further discussion of the re sults in Table VI will be presented la'tor» 32

Tabla VI

Ratas of A.cid Catalyzed Isomerization of Substituted Azo Compounds at Various Concentrations of Hydrogen Chloride at 3 9 in Benzene

Mjlliaiolari ty Rate Constant XIO-

Hydrogen Chloride cis Compound Thermal Catalytic Catalytic eié—3—Ni troaaobenzene

0*000 0.521 0.090 0.751 0.73U 0.26 0.180 0.751 1 . W 0.91 0.369 0.733 curvature 0.738 0.733 curvature cis

0. 0 0 0 15.6 0 .1 ÔU 0.503 16.3 — 0.329 0.503 15.7 0 . 8 2 3 0.530 31o9 (approx.) curvature

In an attSEpt to aeasura this offect the rate of isomerization of asohansan© "was measured in the prosoncG of anisolOj nitrobenzene and ths para and meto—nitrcazobensenes. The rates for the isomeriza®» ties of eis-azobenzene in the presence of these oxygenated compounds are shomi in Tabel VII b@l^@

Table V H

The Acid Catalysed ÎDomerisation of cis-Asobensen© in the Fresenee sf Oxygenated Compounds In Benzene Solvent at 39.60c. (Tables XXXIX , XIII)

%lllmolarity Rate constant XIO"

HClio Aaobensen© Oxygen. Oompd. Effeotivs HC1« catalytic

And 3 ole

0.58 0.675 0 .7 0 0 .6 0 5.iil 33

Table VII (contd«)

milimolarlty Rate consteat XIO*

HGl. Azobenzene Ozygan. Compd Effective HCl* (at&lytlc

Nitrobenzene

OM 0*675 2*20 0*30 2*66 trans—L-Nitroaaobenzene

0.18 0*358 0.550 0*08 0*73 0.72 0.358 0*550 0,3U 3.06 trans—3-Ni troa zobenzene

0.09 0.338 0.633 0 . 0 6 0,58 0.18 0.338 0.633 0.19 1.71 0.21 0.338 0.633 0.26 2.Û0 0.53 0.338 0.633 0.77 6.95

îbe effective concentration of hydrogen chloride -Ras obtained fron the ^^oa ta lytic (^thercml + oatalytiC=°°^%he rma 1 - ^catalytic) valueo in Figaro 18 for pure azobenzene at 39.6^0» Ejcamination of these values indicate that anisole in the presence of hydrogen chloride has no effect on ■Üie rate of Isomerization of cis—asobaasane * HoReverp in the case whore nitrobenzene is present in the isomerization reaction of cis-asobenzoEO the effective concentration of hydrogen chloride io reduced conparod to the initial amount© Experimants were performed to show that nitrobenzene had no effect on the rate in the absence of hydrogen chloride© Mien trans—p-nitroazobenzene was present the effect ive concentration of hydrogen chloride was only half tho stoichimetric value. Tnis factor was true for the tç?o different values of hydrogen chloride concentration; but calculation of equilibrium constants for a conç>lex bet?/een the nitro compound and hydrogen chloride showed n® 3U consistent behavior. The apparent strong coordination between the catalyst and the nitro confound agrees with the isomerization mechanism described earlier for para-nitroazobanzane in which one of the rason— ance hybrids has a formal negative charge on the nitro oxygens* Hie

Isomerization of cis-azobenzene in the presence of trans-mi-nitro-» azebenzene the effective hydrogen chlojride concentration was lower than the stoichimetric concentrations only at the lowest molarity of hydrogen chloride which was studied* At higher concentrations the surprising result was obtained that the effective hydrogen chloride concentration was greater than the stoichiometric concentration# The explanation of this result is not apparent except that with trans—m«nitro- asobenzsae (which has no effect without hydrogen chloride present) thers? exists a synergistic effect with hydrogon chloride© By inspection of

Table VI it is noted that curvature in the plot of the log porcont cis vso time begins to occur at about the same concentration where the synergistic effect is first observed# At higher concentrations of hydrogen chlorido this synergistic effect becomaa increasingly promin ent as correspondingly the curvature becomes more pronounced# The curvature in the rate plot for the isoaerisatigin of cio-»m=nitroazobenzene can be osiplained using this synergistic effect if it is assxüAêd tVuit the cis isomer provides a more highly catalytic hydrogen chloride than does the transp

The apparently mors stable ccmploz between tho p-ni troa zobenzene compared to the me ta compound explains in part the very much higher concentrations of hydrogen chloride which were required to obtain a 35 given catalytic rate in the isomérisation of their respective d a isomers (sea Table 71 J* !Rîis same effect appears in the very much higher concentrations of hydrogen chloride vhich must be used before curvature appears in the rate plot for the catalytic isomerization of cis^-nitroaaobenzane •

The catalytic effects on cis-azobenaene of hydrogen bromide in a

conç)arable concentration to that used in the hydrogen chlorido experi ments caused almost instantaneous isomerization* The purpose of this

experiment ■sras to determine the effects of different anions in the acid

catalysis* Since light and oxygen were present the rapid isomerization

is probably evidence for a free radical isomerization*

D* Absorption Spectra of the Aao Compoundse

1© ültraviolGt and Visible Absorption Spectra* All the

ultraviolet and visible absorption spectra T7sre determined vû-tii a Beck

mann Modol D©Ua ©oarts Spectrophtomater* The molecular extinction co

efficient^ where ^ = (l/cl^O.B* ( Csconcontration in moles liter^ Islongth

of tub© In era*,) is given in Table VIII® The solvent 'was 95%)Qrcent

Qthanol in all cases except for iijit'-dinitroaaobenzene -whore G©?© chloro=

fora, was used* The length of the qi3ârta cells were l&OO cm®

Absorption spectra for trans-3—ai troa sobs nasn e in chloroform^

n-heptane and 95-porcGnt ethanol (see Figure 32) showed no shift in tho

maximao For all cases of pairs of isomers, the cls-aso compounds have

stronger intensitite than the trans—isomers© The strong absorption 36

Tabla VIII

Molecular Extanction Coofflcienta and Wavelength of Maximum Absorption for Various Azo Conçounds in the Region of ItOO-^OO mu*

■e Number Azo Compound € cis Amu. € trans Am u .

19 3—Nitro— 1209/L27 9iO/hkO 20 3,3*-I>lnitro— IOI9/L2S 39k/UU^ 21 3,^Ifinitro- III4I/U29 kô9/kh9 22 U-Nitro- 1^15.'A38 5 7 1 A ? 8 23 3-Ni tr o-ii-me thyl*» iU i7 A 3 3 S 2 L A L 3 2h 3-Me thy 1-li-ni tro- A 5 9 A 3 5 6 1 8 A ^ ^ 2$ 3-Sulfaiaoyl- 1022A30 3 7 3 A h 8 26 U-Sulfamoyl- 1280A31 $ 6 o A ^ 27 3- ( Dime thylsul famoyl ) - 128i*A29 h7U/hh7 28 U- ( Dime thy Isulfaraoyl ) - li;10A33 S L 8 A ^ 1 29 3-(Piperidinosulfcnyl)- ll^lA29 505’M ^ 30 Ip-(Pip e ri dinosulf onyl ) li;35A31 ^ 9 8 A ^ 2 ( 3,ii'-Dinitro- — 52i A 5 o 31 < 3,4-Dinitro- 8 2 6 A 6 0 ’-Di ni tr o<=» 6UiiA72 band of these conçjounds in the region of U2O-U70 mu is ascribed to the

N=N linkagee In all cases the absorption maximum of the ci&^isomer was shifted sli^tly tov/ard lower wavelengths with respect to the trans - isomer* In the low ultraviolet region (22O-=350 mu), the spectra vary with the position of the substituent and the substituent itself© In general, these trans-aao compounds have an absorption maximum in the region of 31î?=>3iiO En© This is attributed to the conjugation between the 2î=N group and the aromatic nuclei* However, with the cis^lSomers the absorption nrnxina shor/ large shifts to shorter wavelengths©

The measurements in the region U00-Ji50 mu* were made with high accuracy because the analytical method used in following the rate of isomerization is based on those measurements © 37 2, Infra Red Absorption Spectra. The infra red absorption

spectra for eis and trans-isomers of azobenzene, 3—nitroazobenzene and U-nitroazobenzene are shown in Figure 33* The confounds were 26 27 dissolved in chloroform in preference to nujol mulls * in order to

eliminate any differences which result fTcan characteristics of the

crystal form» The spectra were determined with a Baird double beam

infra red recording spectrophotmetor using a compensating cell contain

ing chloroform* Since little is known of the absorption band frequenc

ies and vibrations of atomic groups in these conç>ler molecules, no

attenç>t is laada to interpret the characteristic absorption peaks. 38

IV, EXPERIMENTAL

A. Materials The adsorbent used in the chromatographic studies

•was a mixture of approximately three parts by weight of silicic acid

with two parts of Cell to a product of Johns-Manville Corpora tion.

In the early woric Merck reagent silicic acid was used. In later work

Mallinckrodt silicic acid (Prepared for chromatographic purposes accord

ing to the method of Ramsay and Patterson) was ground 6-8 hours in a

ball mill to obtain a satisfactoiy adsorbent. The silicic acid-celite 28 adsorbent -was activated according to Trueblood and Malaberg by hea-t=

ing in an oven at 160-200®G, for at least two hours o

The pS-psrcent ethanol, chlorofora and the benaens used in •tiie

rate studies and the spectra de'temainations was reagent grade. The

n=^hep-bane (Phillips Petroleum Ccspai^) "was redistilled in a packed

columno At J60 nan, the boiling point rras 98o^°C« All other reagents were obtained from the sources noted in the experimental 8eetion@

B, Synthesis of the Dasired Substituted Aaobensenes,

lo Preparation of Nitrosobanseno.^^ A solution of 1 ^ g,

ammoni'ün chloride in ^ la water was stirred -vigorously with 300 go

(2ahh mole) of nitrobenzene, The resulting heterogeneous mixture -was

treated slrawly with 3Sh g# \h&9 mole) of high grade sine duste The

reaction tenterature •wsis Eain-fcained at 60<=6S°C, by regulating the addi<=.

tion of ainc dust® After "the addition -cas complets, the tesçjera-fcure

decreased and the resulting ml^cture -was filtered© The sine oxide pre«

cipitats was -waahc 1 -with 3 1 . boiling-wa-tar and the combined yellow filtrates containing phenylhydroxylaiaine -were treated with icco Tho 39 solution at 0 to — 2°C* was treated Tilth 25Ü ml* cold sulfuric acid and cooled to ca* « 5®C* A cold solution of 170 g* sodium di chroma te in ca* 600 ml* water was rapidly poured into the reaction mixture with stirring,^ The brown solution containing straw colored needles was filtered immediately and the yellow crystalline residue was washed with water* The crude product was rapidly steam distilled in an all glass apparatus* The distillate was filtered and the nitrosobenzene which was obtained was recrystallized from ethanol, m*p* 6 8 °C*, yield liiO*l g*

(,Sh%) » (lit*^^ m*p* 66°C*)a (The m*p*’s reported throughout this thesis were taken on a calibrated thermometer and corrected for steam ©mergence).

2o Preparation of 3-Nitroazobenzene A hot solution of 27*6 g*

(0q20 mole) of 3-nitroaniline (Eastman Kodak Con^&ny, W»!-*) in 320 ml* glacial acetic acid was treated with 23*ü go (0 ® 2 2 mole) of nitroso— bsnzeno« After standing 63 hours at room tcnperature the oixturo was filtoredj the orange crystals of 3<=>nitroaa6bensen© which were obtained after charcoal treataaent and recrystallization from ethanol weighed l8o3 go (W&^) * A chrcnstographically purified sample malted at 9 5 © ^

96*7'^Co (lit*^^ m«,p© 96^0©) © Dilution of the acetic acid mother liquor by addition of ice yielded 12*9 g# (31^) of additional pro duct o

3* Preparation of L^Nltrcazobsnzsne A solution of 27*6 g*

(0«20 mole) of A~nitroaniline (Eastman Kodak Con^sny, W®L») and 2 3 g»

(0*22 mole) of nitrosobenzene in 280 ml* glacial acotic acid was heated

* On the suggestion of Dr* N*C* Deno the overall yield was improved when the sodium dichromate solution was added as rapidly as possible* This detail is inadequately described in Organic Synthesis* Uo

to ca* 6 0 °C* until all the material w e in solution* After 72 hours of

standing at room tenç»rature, the black solution iras cooled and filter

ed* "Die residue was recrystallized from ethanol after treatment with

charcoal to yield 3 © 5 g© (8 5 ^) of red crystals of U-nitroazobenzene*

With chrcma to graphic purification a sample melted at 133©7-13U.6®C*

(lit*^ m,p* 135®C*) The acetic acid mother liquor was diluted by-

addition of chipped ice; an additional yield of 2h©3 g* (^9^) was

ob-fcainedo i;* Synthesis of 3 ,U*~Dinitroazobenzene* 31 (a) Preparation of 3-Nitrosonitrobenzene* A solution of

20*0 go (0*12 mole) of m-dinitrobenzene in 200 ml* e-thanol and ml©

glacial acetic acid xjsls prepared* When this soli:tion was "warmed and

trea-tod with small portions of 1 2 *$ g* (l©8 mole) zinc dust, an axo=»

thermic reaction occurred and spontaneous rafluxing was observed* The

brown solution was cooled and poured over 8OO ml© of 10/5 ferric chloride

solution* The mixture was stsam distilled in 3 equal portions; the

yield was 3 @$ g* (19*0^) of white 3 -mtrosonitrobenzenoj, m*p* 8 9 *»9 0 °C*

(lit@^^ m*p. 89©5-90*$°C*). 32 (b) Alterna "be preparation of 3-ni trosoni trobenzene * A

suspension of 8*2 g* (0 * 0 6 mole) 3-nitroaniline in 1 0 0 nü.a water was

treated with a solution Carol's acid (prepared by grinding 3 6 * 0 g*

(0*12 mole) potassiuH persulfate (Merck reagent grade) -with 2? ml*

cone entra-ted sulfuric acid in an ice bath followed by addition of 2C0 g*

ic@=water) * Af-ber stirring for 20 minutes the solution was filtered

and yieldW a residue of 2*0 g« 3 ,3 ®-dinitroasoxybenzcne was recovered 1*1 and identified by its melting point. The green filtrate nas neutrali

zed irith ammonium carbonate and filtered again; 1, 9 g, (20$) yellowish oo 3—nitrosonitrobenzene, m,p, 9 0 «5 °C, was obtained (lit, m,p, 8 9 #5—

90.5®C.)* 32 (c) Preparation of It-Nitresonitrobenzene, A suspension of

20,6 g, (0 ,1 ^ mole) l*-nitroaniline in 1$00 ml, water was treated with

a solution of Caro’s acid (prepared by grinding 80,0 g, (0,30 mole) potasium persulfate in 6o ml* concentrated sulfuric acid in an ice

bath followed by addition of ^00 g, ice—water). After stirring for

hours the solution was filtered and the residue was steam distilled.

Filtration of fraction 1 of the distillate gai® 1,6 g, (7$) l*-nitros©nitro

benzene m,p® 116°Co (llt,^^ m,p, ll8«5-119^C»)o Fraction 2 gave 1,0 g,

of 3m te rial malting at 125-lUp^Cc, The residue obtained from fraction

3 was 2,5 g« l,U-dinitrobenzene, m,p, 17^®C« (litm,p, 173-»17^®C,),

Fae residue recovered from tte steam distillation flask was 13 g, ii'=

nitroaniline ,

(d) Coupling Reaction of 3—Uitrosonitrobenzene and h«=Nitroaniline,

A solution of 2,2 g, (0«0lU mole) 3-nitrosonitrobenzene in 10 ml, glacial

acetic acid was added to a warm solution of 2,0 g, (O.Olis. nolo) U—nitro—

aniline in 20 ml* glacial acetic acid. The resulting mixture was warm=

ed on Û steam bath and allowed to stand at room tennserature for l6,5

hours, #ien the mixture was filtered 2 ,U g, (6 3 $) red crystalline

3,1»’-dinitroazobenzene was obtained. With chromatographic purifica

tion and recrystallization from ethanol the saisie malted at l5 3 »0 -o

153,6®C, The acetic acid mother liquor was diluted by addition of chip

ped ice; an additional g, crude product was obtained. U2

Anal,

Caled. for C._H N 0, % C, $2,96; H, 2.96; N, 20.$8. o I4 Found: C, $3.30; H, 2,98; N, 20.68.

(o) Coupling Reaction of U-Nltrosonitrobenzene and 3-«Nitroanlllne

A solution of 0,30 g. (0,002 mole) U-nitrosonitrobenzene in 7 ml. glacial acetic acid was added to a solution of 0.28 g, (0.002 mol©)

3—nitrcard.line in 10 ml. glacial acetic acid. The resulting mixture

■was waimed on a steam bath and allowed to stand at room te opera ture for iUi hours. After filtering the solution 0,30 g, ($0«) of 3,U’-dinitroazobenzene melting at 1$2°C, was obtained. Mixed malting point with the product prepared by the reverse condensation "was 1$0-1$2®C.

$0 Preparation of 3,3'-Dinitroazobenzene. A solution of 2,2 g.

(O.OlU mola) of 3-nitrosonitrobenzene in 10 ml, glacial acetic acid was added to 2.0 g. (O.Olii mole) 3-nitroaniline in 20 ml. glacial acetic acido After 2 hours the solution -was filtered; ihe residue yielded

3.3 g. (9 0 ^) of 3j,3’“dinitroasobsnsGne. A sample •which -was chronato* graphically purified melted at 1$0-1$1^C. (I5.tc>~^ m«p® 1$0°G.).

6, Preparation of U.U^-I>iaitroazobenzene. A solution of 1.3 g.

(0 . 0 0 8 6 mole) of ii—nitrosonitrobenzono in 9 ml. glacial acetic acid was added to a -warm solution of l.lS g. (O0OO86 mole) of U—nitroaniline in

1$ nils glacial acetic add. The resulting mixture was warmed on a s-beam bath and allowed to stand 2 days at room temperature. The residue ob tained after filtration -was 1.6$ g. (71^) of Ujii*«>dinltr<^zobenz0ne.

A chroniatographically pure sample nelted at 221—222°G. Clit,^^ m.p, 22l"^GJ. k3

7» Synthesis of 3»$-Dinitroaaol3engenqo

(a) Preparation of 3*^.Dinitroaniline# A saiaple of 25#0 g*

(0*117 mole) of 1,3,5-trinitrabenzene (Eastman Kodak Ccoç»any, W«L«)

■was dissolved in k^O ml, of 95-p®rcent ethanol. The solution was re fluxed vigorously and treated dropwise with 72,? g, of aqueous ammonium sulfide (Coleman and Bell; 23,5^ by wei^t of ammonium sulfide) in 7^ ml,

95-percent ethanol. The mixture was further refluxed 1,5 hours after the addition. The resulting red-hrown solution was filtered free of sulfur and refluxed for an additional l5 minutes* After e'vaporation of the solvent 19,0 g, of crude crystals were ob-tained® The crude product -was didsol'ved in ether and filtered thru a mat of silicic acid- celite* On the addition of benzene lli.O g* (6^%) of 3^5=dinitroaniline was pracipi-fcated. Recrystallisation from-water yielded yellow crys-tals, n,po l5?*2-l6l*O^Co (FlurscheiEL^^ repor-tod m,p, 159°C * ^ Nicolet^^ reported m®p, l55»l56°Co)o

(b) Preparation of Sodium Formaldehyde B i s u l f i t e Forraalin

(100 go) (Bakers) containing 36*7 g* (1*21 mole) formaldehyde was treat ed -with 125 g« (1*21 mole) sodium bisulfite in 100 ml® warm water.

After standing 1/2 hour at room temperatui'e, the reaction mixture was filtered to remove any solid impurities* On addition of 95-p®rQeat ethanol to the filtrate ^ 128 g© (86,5^) -white sodium formaldehyde bisulfite -was precipi-tated®

Sulfonic Acide~ A suspension on 2U,9 g, (0,267 mole) of aniline

(Merck reagent grade) in l50 ml, water was added drcpwise with stirring Uk

to g« (0*267 mole) sodium formaldehyde bisulfite* The reaction mixture wa» warmed to 7 5 ®C* during the addition and for 10 minutes

after the addition was completed# The mixture was cooled and filtered;

the white crystalline product wei^èd 17*8 g» Evaporation of the aqueous solvent yielded 3U#8 g# additional pure product; the total yield was 87^*

(d) Coupling Reaction of 3,^-Dinltroaniline and AnilinG^(0«metliane 22 Sulfonic Acid*^ A solution of 10*0 g* (0#0^5 mole) 3,5-dinitroanilina

in 75 ml* 30^ hydrochloric acid was cooled to 0°C« and diaaotizod

slowly with 3*93 g« (0#05? mole) sodium nitrite in l5 ml* water* The resulting diazo solution was added with stirring to a cold suspension

of 12«1 g© (0#058 mole) sodium salt of anilina-^Xaethane sulfonic acid and 103 g# sodium acetate (hydrate) in 125 ml* Tratar# After stirring

the reaction mixture at O^C* for 5 minutes, the solution was filtered and the residue ©f rad 3i,5— dinitrc^-U’—atninomethane sulfonic acid azo* benzene was treated with dilute sodium hydroxide at 50-60®C* The

solution was cooled and filtered and the resulting residue was dissolved in ethanolo On evaporation of the solvent lU«0 g» of crude product was obtained» Continuous extraction in a Soîdilet extractor with benzene followed by evaporation of the solvent^ yielded ?»! go (U5^) 3,5—dlnitro—

U^-^minoaaobenaena * Chromatographic purification of a 2 mg* test

carrple in benzene was effected on a column (l5 x l55 es) of silicic

acids calite with a prewash of 10 ml# Skollysolvo B followed by 5 ml» benzene* Development with U5 ml# J.% ethyl ether in benzene gave tte

following: h$

Zone Cain») Color g^^aOH Streak Reagent

0-18 Brown Pink (Strongly adsorbed inpurities)

80-95 Weak Orange Pink

9^107 Owinge Brown (3 ,5-Dinitro«U*-aininoa2 oboaaene)

A large scale chrcHaatographic purification followed by i*8crystalliza-

tion from ethanol yielded cfeirk red crystals, m*p» 219#3—223#0°C.

Anal*

Calcd. for G H N 0 : C, $0*19; H, 3l6; N, 2U*39* 1'^ 10 5 h Found: G, 50,$7; H, 3*08; N, 2 h ^ h U

(e) Deamination of 3*5-r)initro-U*-»aminoaaobeng9ne* A solution

of 1*1$ go (0*00!i mole) of 3 ,5-dinitro-U’*-aBd.noazobanzen0 ■was dissolved 36 in 10 elL* of pyridine and added slowly to a cold mixture of 0*60 g*

(0*0087 mole) of scSium nitri'te in 17 ml* of concentrated sulfuric

acid and $ ml* of water* The reaction mixture was maintained at 10®C*

during the addition and for two hours afterwards* The col^^S-so

solution TOs then treated dropwise with 9©0 ml* of cold aqueous hypo* phosphorous acid (îJallinckrodt 30-percent solution) and "die reaction

mixture was stirred for 1$ minutes at O^C* Aftor two days at room

temperature, the brcrm solution was poured over chipped ice and neutral

ised with dilute base* The solution was then filtered and the residue

■was dissolved in benzene* The benzene extract was washed suceossivoly

with water, 5-percent sodium hydroxide solution, water, 5«parcont

hydrochloric acid solution and water* The solution was then filtered

through a mat of anhydrous sodium sulfate » The resulting benzene

solution was purified on a column (37 x 270 mm*) of silicic acid: celite ii6 with a prewash of 125 ml# benzene as a flowing cbromatogram# With a dovelapment of 1000 ml# l#5-3% ethyl ether in benzene, a major orange zone pasaed thru the column# A minor orange zone of 90-1U5 mm# frœa the top of the column turned red-brown with 25^ sodium hydroxide streak reagent (chromatographic behavior indicated this zone probably was the original amine)# A small sample of the major orange zone was chromato graphed on a column (l5 x 150 mm#) of silicic acid; cell te with a prewash of l5 ml# of Skellysolve B# Development with 25 ml# of 25^ ben zene in Skellysolve B folloimd by 70 ml# of 1% ethyl ether in Skelly solve B gave the following:

Zone fmnie) Color 25^ NaOH

1—lJi weak orange purple turning brown (fiia form)

78-110 orange purple truning brown (desired product) TKé A Solvent tTas evaporated from the major zone and recrystallisation of the residue from 95=parcent ethanol was o ffectad# A yield of 0*55 g®

(5l^) orange 3p5-»dinitroasobansene, s#p# lli2#3-lU2o6®Co was obtainedo

Analff,

Calcd# for V h ' 52#96; H, 2#96; N, 20#58#

Found: C, 53#W^; H, 2*96; II, 20#32#

8e Synthesis of 3 ^U-DLnitroasobensano # 37 (a) Preparation of 3,ü-Dinitroac0 tanilide* A suspension of

28oO go (0#203 molo) of a-nitroanilina in l50 nO.# benzene was warmed and treated with 21 #0 ml# ©f acetic anhydid.de* The resulting reaction was exothermic and a clear brown solution formad# A précipitât© was formed after a few minutes and thh mixture was cooled and filtered* A yield of U7 36*0 g. i99%) of grey crystalline 3-nitroacetanilide, m*p. l5l*5-1^3*0^0,

was obtained* (lit*^^ m*p# l5l«l53°C*)»

(b) Nitration of 3 .L-Dlnltro&eetanlllde A solution of

7$.0 g* (O.U20 mole) of 3-nitroacatanilide in L2$ ml# of 100$ sulfuric

acid was cooled and added dropwisa to a cold solution of llii*0 g* of

potassium nitrate in U2^ ml# of 100$ sulfuric acid* The temperature

was maintained below 5°C# during the addition# After 23 hours at room

temperature, the brown-black solution yielded a yellow precipitate

which was removed by filtration thru a mat of glass wool; U0#0 g# yellow

crystalline undàsired product melting at 212°C# was obtained# The

filtrate was poured into 6 liters of ice-water and allowed to stand at

rocffli tengjeratura for 1 hour© The solution was filtered and the yield

was 30*0 g© (32$) of 3^L-dinitroacQtanilids, m*pa l38-lU5®Co (lit©^®

map* lUU°C«)o Purification was effected by dissolving 2$©0 g© of im=

pure product in 150 ml« acetone^benzene and filtering the resulting

solution through a mat of silicic acid-celito© The solvent was evapor

ated and 23©1 g© of 3gL-dinitroacetanilid@ m©p# 1^2-115^0© (dec©) was

obtaiQsd©

(0#103 mole) of BjA-dinitroaee-teailide was dissolved in l50 ml© concsnt=

rated sulfuric acid and heated to 120°C© After the solution was filt*»

erad a yield of lU#0 g« (75$) of yellow 3,^dinitroaniline, m#p«

l5l®0»l5U©5°C© (dec©) (lit©^® QoP# l5^^C@) was obtained®

(d) Coupling of 3 ©U-Dinitroaniline and the Sodium Salt of Aniline— oCWsetiiaae Sulfonic Acid# (with Sulfuric Acid in the Diaaotising Solution©) 1*8

A solution of 3*0 g* (0.017 mole) of 3,U-dinitroaniline in l5 ml# con- contrated sulfuric acid iras cooled to 0®G« and dia*oti«ed slowly with

1.5 g. (0.022 mole) of sodium nitrite in S ml, water. The dlazo solu tion was then added wltdi stirring to a cold suspension of i*.0 g.

(0.019 mole) of the sodium salt of aniline-dvi-methane sulfonic acid and 30 g. of sodium acetate (hydrate) in 35 ml# water. After the reaction mixture had been stirred at 0°G* for 5 minutes, the solution was filtered and the resulting residue was hydrolyzed with 50 ml. of

30^ sodium hydroxide at rocan tençierature # (It was found that hydrolysis at high temperatui^s did not yield the desired product.) After l8 hours the solution was extracted three times with 200 ml. portions of benzene,

The combined benzene extracts were then washed successively with 5— percent sodium hydroxide solution, water, 5“‘P©î°cont hydrochloric acid solution, water, saturated sodium chloride soluttiicrio The benzene solu tion was then evâporatod to half its volume under reduced pressure, A small sample of the resulting solution tras chrcitat-ographod on a column

(l5 X l50 nam©) of silicic acid—cell to with a pr swash of l5 ml© Skellysolve

B was made* Development with l50 ml© 25^ ethyl ether in Skellysolve B gave the following:

Zoi^ (ism*) Color 25% ^’^aOH conc%H^SO,^

0—2 residue — —

11-16 tan blue yellow

35-53 red dark blue yellow

75-101 faint orange faint purple - k9 The zone corresponding to 35-53 mm. on a large scale chromatogram was eluted with ethyl ether. The solvent was evaporated and 0.7 go black crystals of 3 ,i4— dinitro-lt'-aminoaaobanzene, m.p. l83.2-l8U,0®C. was obtained.

Anal.

Calcd. for H N^O, : C, 50.18; H, 3.16; N, 2&.39. Ic 10 5 U Found; C, ^.05; H, 2.81;; N, 23.60.

(e) Coupling of 3 .U-Dinitroanlline and Aniline^O-methane Sulfonic

Acid, (with Hydrochloric Acid in the Dâagotiaing Solution.) A solution of 3.5 g. (0.019 mole) of 3gL-dinitroanilino in 30 ml, of 37^ hydro chloric acid was cooled and diaaotized with 1.05 g. (0.019 mole) of sodium nitrite in 10 ml. water. The resulting solution was treated with a suspension of 1&@2 g. (0.020 mole) of the sodium salt of &niline-^J=. methane sulfonic acid and 55 go sodium acetate (hydrate) in 70 ml.

Tfater. After 10 minutes of stirring the reaction mixture was filtered and the residue was hydrolyzed with dilute sodium hydroxide at 75^0.

The mixture was cooled and filtered; the residue was then extracted with hot benzene containing a small amount of acetone, The extract was washed successively with water, 57° sodium hydroxidQ, water, dilute hydro chloric acid, water, sstturated sodium chloride and further dried with anhydrous sodium sulfate, A small scale chromatogram was made on a column (l5 X lU5 mm.) of silicic acid-cell te with a prewash of l5 mlc

Skellysolve B and 1; ml. of benzene. Development wiüi 200 ml® of 1^ ethyl other in benzene; Skellysolve B (igl) gave the follOT.7ing; 50

Zone (mm*) Color 25?S NaOH

20-36 pink orange

W - 7 0 yellow pink

The zone corresponding to iiO-70 was separated on a large scale flowing chromatogram* "Oie solvent was evaporated and the residue was recrystal-

11 zed twice from ethanol* A yield of 0*65 g* (12^ 3-nitro-ii-chloro-

U *-aminoszohenzene, m#p* 200— 200*5^0* was obtained*

Anal*

Calcd* for C^^gH^N^OgCl: C, 52*09; H, 3*28; N, 20.25.

Found: C, 52*3U; H, 3.06; N, 20*01*

(f) Deamination of 3,L—Dlnitro-L'-aminoazobsnzene * A solution of 0*150 g* (*00052 mole) of 3yU-dinitrc=U'-aminoazob9nsene in 9©0 ml© concentrated sulltiric acid nas diasotized dropwiso in the cold with a solution of 300 mg* (*00U3 mole) sodium nitrite in 5*0 ml* water with vigorous stirring* After 10 minutes in the coldj the diaso solution was treated slowly with l5«0 ml* hypophosphorus acid (Mallinckrodt) and allowed to stand ovemite at room tençjerature* The suspension uas filtered and the resulting residue was washed with water and dissolvod in benzene* The benzene solution was chromatographed on a column (30 ::

200 fi®*) of silicic acid^celits vfith a prewash of 35 ml@ Skellysolve B followed by l5 ml* benzene® Development with l50 ml* 20^ ethyl ether in Skellysolve B=b©nzens (8:2) gave the following: 51

Zone (mm.) Color 25%KaOH Gone. HoSO^

0-10 broim blue purple

31-Wi orange purple red

6i4~68 orange - yellow

155-167 major orange orange yellow

eluted weak yellow - -

1 major zone was eluted with C«P« ethyl ether. The solvent was evaporated and a yield of «060 g« (h3%) of red 3,U-dinitroszobensene m.p. 82»3<«82«5®C. iras obtained©

Anal.

Calcda for ^2.96; H, 2.96; 20«58.

Found: C, 53.5l; H, 3.50; N, 20.50.

9. Synthesis of U-gSuIfaraoylasobenzene(p^Phenylasob8nzenesulfona~ mide.) A=Aminobenzenesulfonamide (Squibb’s sulfanilamide) (llo5 g.^

O.C67 mole) in 50 ml® of glacial acetic acid was reacted at o0-90°0a with 7.0 g© (0 o0 6 6 mole) of nitresobenzone dissolved in Lo ml® of glacial acetic acid for two hours® The reaction nixtui’c was poured over one liter of ice=r.Tater after standing ovemd. ^t the solution was filtered and (95.6^) of cruds U-=sulfamoyl asobensene was obtained. A l5oO go portion of crude product was dissolved in 750 ml. of Oe2 E sodium hydroJàdo j re fluxed with charcoal and filtered throu^ a celita mat. ‘Hie filtrate was then neutralised with dilute hydrochloric acid©

The resulting precipitate was filtered and recrystallized from ethanol.

A yield of 9.8 g. (63^) of U-sulfaraoyiasobensene was recovered; chromato graphic purification gave orange crystals m.p. 22^226®C. (lit.^^ m.p. 52

Anal» Calcd» for C, 55»l6j H, li.22. Found: C, 55»12; H, U»05* 10. Ssrnthesis of U~(DimethylsulfaTOoyl)azobenaeng(W,N--Dimethyl-p— phenylazo'benzenesulf onami de.)

(a) Préparation of U~(liimethyl3ulfamoyl)anlline. A mixture of 2 5 ml* of 25^ aqueous dimethylamine (Matheson) and l5®0 g» (O.O6U mol®) of ii-acetylaiainobenzenesulfonyl chloride (Easimian Kodak ConçÆny,

WoL.) in l5 ml» ethanol was refluxed Jor 30 minutes. The resulting solution "sras evaporated to dryness under reduced pressure and the re sidue ■was hydrolyzed with a V^% solution of hydrochloric acid. Neu't- ralisation of the resulting solution with sodium bicarbonate yielded

11*9 go (59^) of üi«(dime'thylsulfamoyl)aniline, melting at l6 9 °C. (lit.^^ mopo 170^0©) o (b) Condensation of U«^(PiEathylsulfamoyl)anilin9 and Mitro« sobangene© A solution of 7*0 go (0«035 mole) of U-(dimethyIsulfamoyl) aniline in hO ml© of glacial acetic acid was treated with UoO g» (0©037 mole) of nitrosobenzene in iiO ml» of glacial acetic acid and "warmed for two hours at 80-90^C » The brown solution aft-er cooling g was poured over chipped ice and filtered» Theresulting residue, after treatment with charcoal in hot ethanolj was filtered thru a cellte mat» Ihe solvent was evaporated and the residue was reciys-ballised from ethanol©

A yield of 7*2 g® (71^) of* orange L-(dimethiyl8ulfamoyl)azobenzene was obtained» Chromatographic purification followed by recryst-allization 53 frcMB eliianol, gave a product melting at l65*2*^C«

Anal#

Calcd, for 0, $8,12; H, $.23; N, lh,$2.

Found; G, $8.26; H, $.10; N, li^.U?#

11, Synthesis of 1*—CPiperidinosulfonyl)agobenzene. (l-(p-.

Phenylazophenyl sulfoiiyl)piperldine) »

(a) Preparation of U-(Piperldinosulfonyl)aniline. An 8,0 g,

(0,03U mole) portion of U-acetylaminobenzenesijlfonyl chloride was gr

ound in a mortar with a hO% aqueous solution of piperidine (excess^.

The resulting precipitate, after standing overnight, was washed free

of piperidine and hydrolysed with a 20^ solution of hydrochloric acido

The solution was then neutralized with sodium bicarbonate and filtered,

A yield of 6.2 g, (76%) of white U-(piperidin©sulfonyl)aniline, n.p®

1 6 3 °C@ was obtained, (lit.^^ m.p, 16L°C@)@

(b) Condensation of i4°»^-^iperldinosulfonyl)aniline and Nitro°

sobonsene, A 10.0 g. (OaOU2 mole) sample of is.—(piporidinoS'alfonyl)aIi- ilin0 in U$ ml, glacial acetic acid was reacted with $.0 g. (0 ©0 U6 mole) of nitrosobsnsGne at 80-90°C. for two hours. The resulting brown solution was poured over chipped ico and filtered. The re si duo xTas racryetallisQd from ethanol twice, a yield of ?©1 g. (52 ^) of product, melting at 187-190°C. was obtainsdo Chromatographic purifica=

tion, foil ewe d by recrystallisation from ethanol, jrielded orange

crystals of h— (piperidinosulfonyl)azdbensene, which molted at 193.6 ^0 , sa

Anal»

Calcd. for C ^ ^ ^ N ^ O g S ; C, 61,99; H, ^.8 l; N, 12.76.

Foundî G, 62.01; H, 6.05; N, 12.90, 12.U6, 12.60.

12. Synthesis of 3-Sulfamoylaaobengene,(in-PhenylazobengeneBulfon- amida). (a) Préparation of m-Snlfamoylnitrobenzene. A 1 0 * 0 g. (O.OUS mole) sample of m-nitrobenzenesulfonyl chloride (Easianan Kodak Conçjany,

¥.L») was dissolved in 50 ml. of benzene. The solution was re fluxed

and treated with 10 ml. of annnonium hydroxide (28^). The reaction mixture was re fluxed for one hour; it was then cooled and the aqueous

fraction was removed. The benzene fraction washed with water, dried with anhydrous sodium sulfate and evaporated; a yield of 5* 1 g. (5 6 ^)

of ra—snlfamoylnitrobonzene, m.p. l59-i6 0 ®C, ime obtained, (litm.p.

l6 0 °Co)o

(b) Reduction of E^ulfamoylnitrobenzenGo A solution of 3.0 g.

(OoOl5 mois) of s=-3ulfamoylnitrobsnsene in 50 ml, of eüianol vms re fluxed

and treated with tliree 5 ml. portions of 2 3 .5 ^ aqueous ammonium sulfido

(Coleman and Bell) @ The mixture was re.flujced ovemi^t, cooled and

filtered to remove the suspended sulfer. The solvent was then evapora«

tod and the resulting residue was rocryetallized from ethanol. A yield

of 1.8 go (7 0 ^) of m-sulfamoylaniline m. l38«lLo°C, was recovered,

(lit.^ m.p. lU2®Co)®

A solution of 1.5 g, (0.0087 mole) of s^sulfamoylaniline in 10 ml. of

glacial acetic acid was reacted at 8 0 -9 0 °C. with 1.0 g. (0,0093 molo)

of nitrosobaaizene in 10 ml, of glacial acetic acj.d. The reaction mix« ture, after standing overnight at room tempearature, was poured over ice—water* The resulting suspension was filtered, and the residue was

dissolved in $0 ml* of 0.2 N sodium hydroxide. This solution was treat ed with charcoal, filtered through a celite mat and the filtrate was neutralized with dilute hydrochloric acid. The resulting precipitate was filtered and a yield of 1*7 g* {7h%) of 3-sulfamoylazobenzene was

obtained* A chromatographically purified sample melted at 168—169°C,

(lit,^^ m*p* l69°Ce).

13, Synthesis of 3-(Dlmethylsulfamoyl)azobenzene gCN^N^Xdmethyl- m-phenylagobenzenesulfonamida),

(a) Preparation of m—(Dimethylaulfamoyl)nitrobenzene, A

l5oO go (0 , 0 6 7 mole) sample of m-n5.trobenzen©sulfonyl chloride and

36 ml, of 2$% aqueous dimethylamine was refluxod for U hours. The

resulting precipitate was filtered and washed with water; a yield of

10,8 go (82^) of (dimethylsulfamoyl)nitrobensene^ Ssp, l21eO-l21s5°Ce was oblmned©

Anal,

Calcd* for CgH^QN^O, S: C, Ll,7^; it,38; N, 12,1?*

Founds C . ill.7 6 ; Hj, iu2$; N, 12*05o

(b) Reduction of m^(Dimethyl3ulfamoyl)nitrobsn^ene6 A solu

tion of ii,0 g, (O0O 20 mole) of m-(dimethylsulfamoyl)nitrobenzone in

^0 ml, of ethanol was refluxed and treated with four 5 ml* portions of

2 3 ,5^ aqueous ammonuim sulfide. After 3 hours of refluxing the nûxturo was cooled and filtered to remove suspended sulfur. The solvsit was

evaporated, and a residue of 2*9 g, (86^) m-(dimethylsulfamoylianiline 56 melting at l55*3-l56#3^C. was recovered.

(c) Coupling Reaction of m-(13iinethylsulfamoyl)aniline and Nitro» sobenzene, A solution of 1,5 g, (0,0089 mole) of 3-(dimethylsulfamoyl) aniline in 10 ml, of glacial acetic acid was reacted at 80-90®C, with

1,0 g, (0 , 0 0 9 3 mole) of nitrosobenzene in 10 ml* of glacial acetic acid.

After 5 hours at room tenç)erature the mixture was treated with ice-water; a black oil was obtained. The aqueous fraction ■>vas decanted and the oil was taken up in benzene and chromatographed. Evaporation of the solvent gave a red oil which on long standing yielded 1 *2 g, (h7%) of orange crystalline 3 -.(dimsthylsulfamoyl)azob9 nzene melting at 6 6 ,1-

67®0°C,

Analo

Calcd, for 58,12; 5.23; ÎÎ, 1Ü.52.

Pound: c, 58,00; 5oU2; 13, lU,U9®

lli.. Synthesis of 3=(?iperidinosulfonyl)a2obenzene. l-(m-Phenylaso= phenyl Sulfonyl)Piperidine*

(a) Preparation of si-(Piperidinosulfonyl)nitrobenseneo A 10*0 g,

(0»0A5 mole) sample of m-nltrobensenesulfonyl chloride was dissolved in

50 ml® benzene, Tiie solution was rea.U2tod and treated with 30 ml® of

50,v- aqueous piperidine solution* After U hours of re fluxing the reaction

mixture was cooled and the aqueous layer was removed. The benzene frac-=

tion was wa^ed with water and dried with anhydrous sodium sulShte, ,

Evaporation of the solvent yielded 10,8 g, (89^) of white crysta.lline m«.(pip9ridinosulfonyl)nitrob0nzene, m,p, I2li.,2;-125»5°C, ?7

Anal,

Calcd. for C n % ^ N 201tS: C, U8.87? H, $.22; N, 10.36.

Found: 0, U8.87j H, $.29; N, 1 0 .0 6 .

(b) Réduction of ni—(Piperldinosulfonyl)nitrob9n2ane, A. solution of 1 0 . 0 g. (0.037 mole) m-(plperldlnosulfonyl)nitrobenzene in 200 ml. of ethanol was re fluxed and treated with three 20 ml. portions of 23*$% aqueous ammonium sulfide. After 8 hours of re fluxing, the mixture was cooled and filtered to remove suspended sulfur. The solvent was evapor ated and a yield of 6 , 7 g. (71%) of m-(piperidinosulfonyl)aniline m.p, 11$.U-117'^C. was obtained.

Analo

Calcd. for $U»98; H, 6.71) N, llo6 $.

Found: C, $a.$2; H, 7.03; W, 11.81.

(c) Condensation of ra-(Piperidinosulfonyl)aniline and Nitro— sobangenoa A 2,$ g. (0.010 mole) sample of m-(pipsridinosulfonyl> aniline in 10 ml. of glacial acetic acid was treated with 1.2 go

(OoOll mole) of nitrosobenzene in 10 nO.® glacial acetic acid. The reaction mixture after standing overnight was poured over ice^water.

T^ie water was decanted from the resulting oil and the oil was talma up in benzene and chrciîfâ to graphically purified. Re crystallisation from ethanol yielded l.U g. (iil%) of 3 -(plperidinosulfonyl)asobens0nep melt«. ing at 79 0)4-8 1 .3^0.

Anal,

Calcd. for ; C, 61.99; H, $.81; N, 12.76,

Found: C, 62.11; H, $.93; N, 12,61. 58

10, Synthesis of 3»Nitro»UH^iMnethylagobengene,

(a) Preparation of 3-»Nitro-U.^ethylanilln9 A 50*0 g, (0 J468 mole) sample of £-toluidine (Eastman Kodak Cai^any, W, L,) was dissolved in 5U5 ml. of concentrated sulfuric acid with cooling. The solution was then cooled to O^C. and treated drqpwise with a mixture of 82 ml, of concentrated sulfuid.c acid and 27 ml. of concentrated nitric acid

(Specific gravity l,ii2). The reaction mixture after standing overnight at l5-20°C, was poured over U liters of ice-water. The resulting pre cipitate was filtered, and a yield of 13,2 g, white imter soluble c013- pound the salt of the nitrategAamine was recovered. The filtrate was diluted with 8-10 liters of ice-water and neutralized in the cold with sodium carbonate. Filtration of the yellow precipitate yielded 36.? g.

(5l«) 3-nitro-U-mathylaniline, After recrystallization from ethanol the product melted at 78-8 0 %. (lit. m.p. 8l.5% e ) @

(b) Goupling Reaction of 3=Nitro«>Wmethylagiliaa and Nitro- sobsnzens.^^ A mixture of UoO g. (0o037 mole) of nitrosobenzene in loO mlo of glacial acetic acid and $.8 g. (0.038 mole) of 3=>nitrc=° ii—mathyianiline in 60 ml* of glacial acetic acid was allowed to s-band at room tançjeraturo for l5 hours. The resulting solution was diluted with ice-water and later filtered* A yield of bresn crystals m.p. 90=

95°Oo was recovered. After re crystallisation from eüianol of the pro duct U.7 g® (5l^) of 3-nitro-ii-mathylazobenzene was obtained. Chromato graphic purd.fication yielded orange crystals melting at 1 0 1 .0 - 1 0 1 *5°G.

(litj^"^ m.p. 103-10U°C*)e 59 l6. Synthesis of 3-Methyl»U»nitroagobeazene»

(a) Preparation of 3-Methyl-it-nitroaniline A 32*0 g*

(0*30 mole) sample of m-toluidine (Eastman Kodak Congjany, W*L*) was

dissolved in 6 5 ml* of glacial acetic acid and 60 0 g* of concentrated

snlfpric acid and treated in the cold with a mixture of 25 ml* 6 3 ^ nitric acid and 33 ml* concentrated sulfuric acid* After 30 minutes

the mixture wae poured over 2000 g* chipped ice and neutralized with

sodium carbonate and sodium hydroxide. The solution was then filtered and the residue was steam distilled. The distillate yielded a mixture

of 7*8 g* (17^) 2=nitro-3-methylaniline and 2«nitro-5-methylaniline®

The residue solution of the steam distillation was filtered while hot;

the filtrate was cooled and filtered* A yield of 8*3 g. (13^) 3-

msthyl-!^<=nitroanilino was obtained® After two recrystallisationc from water, the product melted at 1 3 0 - 1 3 ( lit m*p* 133=135°C*)*

(b) Coupling Reaction of 3-Methyl-li-nitroaniIine and Nitroso»

benaeng* A solution of 1*0 go (0 * 0 0 6 6 mole) of 3-m0thyl-U-nitroaniline

in 10 mlo of glacial acetic acid was reacted with 0,75 g* (OoOO? mole)

of nitrosobenssne in 10 ml® of glacial acetic acid. The reaction mix«.

tura after standing ovorni^t was poured over ice-water. The solution was then filtered and the brown resicluo was taken up in benzene* Chromato

graphic purification of a test sample was effected on a column (l5 x

l55 nmio) of silicic acid;celite with a prewash of l5 ml* of Skellysolve

B* Development with 50 mlo of 1.% ethyl ether in benzene gave the follow

ing; 6o

Zone (mm.) Color 2$% NaOH Streak Reagent

0 - 7 brown (residue) red-orange

10-U7 brown —

55-8 0 weak-yellow yellow

1 0 8 — 113 orange brown

eluted weak-yellow —

The benzene solution of the mixture was purified on a (30 x 230 mm*) column by a flowing chromatogram# The solvent was evaporated for the orange zone (corresponding to 10 8 - 1 1 3 mm®) and the residue was re- crystallised from ethanol g a yield of 0 « 2 5 g® (l6 ^) of orange 3-methyl- ii—nitrcazobanzene, melting at 1 0 0 @5 °C® was obtained®

Anal*

Calcdo for C H N 0 : C„ 6^*73; H, L*60; N, l7o-U3o XX i 2 Found : ôLulUj H, U®6U; W, 17o70o

After evaporation of the solvent the brown zone (corresponding to l5- hi iffiHo) yielded 0 * 6 7 g® ( W % ) brown crystalline material, m»po 171-

172°C@

Anal c

Calcd* for C, 61*75; Hp he^9*, w? 16*35»

Fouads Op 59*53; 5, L@55; Np 16*35; Ash, 1*525«

Correction of the analysis 6r ash gives the follov/ingî

C, 60oUiij H, It.62; N, l6 .6 o

C. Synthesis of niphenylketone

1© Preparation of Benzil Monohydrazone^^ A hot solution of 80*0 g* (Oo38 mole) benzil (Eastman Kodak, f7.L«) in l5o ml* of 61 ethanol was treated dropwlee with a 23*0 g* (0*38 mole) of hydrazine

(Matheson, B^^soluticn^ • The solution was stift^ed throughout the addition* After the addition was conqjleted, the reaction mixture was refluxed for 5 minutes* The solution was then cooled and filtered*

After the residue was washed with cold ethanol a yield of 80*5 g* {9h%) of white crystalline benzil monohydrazone was obtained. The product melted at with decomposition, (lit*^^ m.p* l!t9-lSl°C. ded.)

2* Oxidation of Benzil Monohydrazone^ A 22,0 g, (0,10 mole) sample of benzil monohydrazone, was mixed in a mortar with 32,0 g.

(o,l$ mole) of yellow mercuric oxides and 1^,0 g« of anhydrous calcium sulfateo After the mixture was ground to a fine powder, it was placed in a flask equipped with a stirrer, a condenser, and a thermometer.

After stirring was initiated 100 ml® of C,p, benzene was added. At this point in the preparation the temperature of the orange suspension

■was carefully observado Wtien the mixture showed a slight exothesic reaction the flask was immediately immersed in an ice«bath, and the temperature of the reaction -was maintained at 30-=Â0"G@ After the suspension turned gray the temperature remainsd at 2^=.3 ^°C, for one hour, Tha reaction mixtare was thon filtered and the residue was wa.sh ed wi-th ÿ) mlo of Go?® ben sane e The combined benzene solutions were

'"fExtreme care must be -taken -with respect to the "^yellow" merùuric oxide^ ■EThich is required In the preparation* It was found that yellow mercuric oxide (Mallinckrodt) which had been standing in the stockroom for some time gave no reaction. Freshly precipi-bated mercuric oxide (made by the addition of base to a solution of mercuric nitrate) -was found to be much too reactive. The beet results ware obtained when Mallinckrodt mercuric oxido and freshly procipatated mercuric oxide were used in a 1:1 ratio. 62 flash distilled into a modified Claiseij^ask, Under these conditions, the benzene solvent was removed by distillation and the diaae congsound was converted to diphenylketena* The residue was distilled under an atmosphere of CO2# A yield of 8*5 g» (Ultî?) of orange diphenylketene was obtained. The product bailed at 121-125°C* at U*0 mm* (lit,^ b. 119-121®C. at 3.5 mm.)

D# Reaction of Diphenylket.ene and cis Azo Compounds » A solu tion of 0.30 g. (0,0015 mole) cis-aaobenzene in Skellysolve B was treat ed with 0,30 g. (0 , 0 0 1 6 mole) of diphenylketene. After 5 minutes at room tençierature, the solution was completely decolorized and a w h i ^ precipitate was formed, Ibe solutionnas filtered and tte residue was washed with Skellysolve F, A yield of OoUO g, (6 7 ^) ii-keto-l,2,3^3 tetraphenyldiaethylene-1 j,2»di-irain® was obtained. The product melted at l?ij-175^Ce (lit,^ m,p, 175*^0.)o A chrcTiiatographic study of this coiipound showed it to be much more strongly adsorbed than the parent cis azo compound*

The reaction of diphenylketene and nitro-substituted cis—azo com« pounds \7as found to be very complex, A chromatographic study of the rec action products indicated several reactions were occurring simultané-. ou sly thus discouraging any further study.

Eo Preparation of the cis Isomers, A sacç>l© of chroma to graphic ally pure trans azo eongsound was placed in a quartz flask and dissolved in a suitable amount of chlorofomo The flask was then placed in an ice- bath and irradiated with a Hanovia ultraviolet light source. After 3-ii hours of irradiation the photochemical steady state of roughly one-fifth of cis isomer was present and the solution was chromatographed. The 63 cis and trans isomers were separated easily, by«Lrtue of the strong

adsorption of the cis isomer# In the cases where only small amounts of

trans isaner were available the trans isomer was recovered and the pro

cedure was repeated several times to obtain sufficient cis isomer# The

cis isomer was then eluted with cold C*P# ethyl ether and the solvent was evaporated, under reduced pressure* The residue was then washed with cold Skellysolve ? and dried under reduced pressure. The entire procedure after the irradiation was parried out in the dark as much as possible. In each case a small sample of d s isomer was chromato

graphed to chock whether any isomerization had occurred during the preparation*

To confirm the identity of this new product as the cis isomer,

the cis zone was eluted with C,P* ethyl ether. The solvent was evapor

ated, the residue was dissolved in benzene and the solution was refluxed

overnight* vJhen the solution was chromatographed, tha chromatogram

showed a complete conversion of the cis isomer to the trans form®

The cis isomers were characterized by their malting points, but

the value of this measurement is doubtful because of the difficulty in

accurate measurementso The melting points were detezmned by rapidly

introducing the sample tube containing the ci£ compound into an oil

bath in the temperature range at which a preceeding sample had melted®

The best melting points for the various cis isomers by this method of

successi-"-e approximations are shcKm in Table II® Tabla IX Melting Points of cis and trans-Isomers

Compound m*p« trans isomer (^C*) m.p. isoner (°C*)

Asobensene 68 oO (68.0)^ 71.0 ( 7 1 . W ^

3“Nitroazobenzan0 9^.^»96,7 (96 71.0 (70

troa s obanzene 133*7-131.6 (135 125.0 (128

3 p 3 ‘ «Diniti'oazobenzena 150-1^1 (150 1U3.0 (i5b

3 s^-Dini troasobenzeno ll42»3-lU2.8 135.0

3«Methyl«Ji-=nitroazobenzenQ 100,5 6o.O

3=Nitro=li'4d8thyl8zobanzen8 ioioO«ioio5 (103-loU)^'^ oil

3«(Dimethylsulfamoyl)asob0nzan0 66*1-67.0 97.0

U«(Dime thylsulfamoyl)azob8nzene 165.2 117.0

3-.(Piperidinosulfonyl)azobeii2ane 7 9 . W 1 . 3 121.0

U«(Pip0ridinosulfonyl)azob0nzon9 193 *U 138.0

3«^ulfamoylazobanzene 168-169 — ii^tSulfamoylazobenzona 225-226 -

3pl| ’ “Dini troazobenzene 153.0-153.6 -

3 ,U~3)initroazobsnzeiia 82.3-82.5 —

U jli ' -Dinitroazobenzane 221-222 (221)^^ - Nota: The values in parenthesis are literature values* 65 F. Measurement of the Rates of Isomerization# 'Hie aceurately weighed sample of cis aao coHçjound(lO-l5 mg*) was dissolved in solvent contained in an amber volumetric flask (100 ml) The resulting solu tion was then poured into the reaction on vessel shovm in Figure 1#

To prevent any photochemical conversion the reaction vessel was covered with black enamel* The tube was then placed in the constant temperature bath containing tthylene glycol solvent. At given time intervale a steam of dried air was passed into the top of the tube and the stopcock was opened. The first 6-8 ml» of sample was dis carded; the solution following was collected in a Beckmann cell and cooled in an ice bath, Ttie optical density was then determined on a Beckmann BU Zuartz Spectrophotometer®

G« Calculations for Dotermining Rate of Isomerizationa During the isomerization the optical density^ D, at a given wasolength in the region of the maxima for the ci^ isomer decreases as the trans isomer io forme do After the isomerization to the trans f o m is completed the D value remains constant. All intermedia te D values are directly proportional to the cis/trans ratio» The wavelength at which the optical density readings were made was at the point in the maxima where tha difference between the D values was greatss. In order to determine the composition of the mixture of cis and trans azo confounds the optical density for the sample of unknown composition was subtracted from the optical density of the puia cis sample® 6 6

D pure cis, -_D-unknown con^oeition (optical density directly proportional to the amount of cis irhlch has isomerized)

The resulting optical density, D^, was then divided by the dif ference in optical density between the pure cis and the final reading at infinite time for the trans coi^ound» The value obtained was equal to the percent trans in the unknown saspla,

cis - D trans = Fraction trans.

To obtain the percent cis the value obtained for the percent trans

T7as subtracted from 100-percent » A plot of the log percent cis against the time, t, at which the sample was withdrawn gave a strai^t line, the slope of which, when multiplied by 2,303 gate the first order rate constant, k*

Î: = 2,303 z » log t C where Co is the concentration of cis at the beginning of the isomeriza-a tion T^en the time is zero and C is the concentration of cis after time, t, has elapsed.

Ho Calculation of the Activation Energies and Frequency Factors,

According to the Arrhenius equation.

k s A e-^/RT or log k g - — E 1^0 O 2,303H T

where A « frequency factor E a heat of activation k = rate constant T 5 absolute testerature R - gas constant C s constant 67 Hîhen the log of ttie rate constant is plotted against the recipro cal of the absolute temperature a straight line is obtained. The slope of this line, irtien multiplied by 2,303 R is equal to the activation energy. The value for the log of the frequency factor was obtained from the Arrhenius plot intercept of the ordinate. 68 V, SUMMART

A series of mono— and di- substituted azo confounds In tha me ta and paira positions h u b prepared by conventional methods»

1# 3-Nitroaaobenzene 2 • it-Nltroazobenzene 3. 3,3*-Dlnitpoazobeneene U* 3-Nltro-lMsethylazobenzena 5 • 3-Me thyl-ii-ni troasobenzane-» 6, 3«-(Diaethylsulfamoyl)azobenzene-K- 7» L—( Dime thylsulfamoyl ) a z obenzene* 8, 3— ( Pipe ridinosulf onyl ) az obenzene* 9* li—(Piperidinosulfonyl)azob®nseno-R^ 10* 3^ulfsaoylazobenzens 11 « ii-Sulfamoylaz obensene 12* 3,U*—Dinitroazobenzene^j 13* it^U'-Dinitroazobenaaa®

-M-Now.' compounds

A nen general method of synthesis iras dovsloped for xinsymmetrical aao compounds urtiich contain strongly electronegative groups. The follovYing neiT c omp ounds we re prepared by this method;

iho 3 g S-Di nl tr oa zobensene l5e Dinitroaaobsnsene

The cis isomers of compounds ii-11 and lU trere prepared for the first tiraoo

The rates of cis to trans isomerization for coirçounds 1-9 and lii laas measured at three different ten^eratures and in polar and non polar solvents o

The activation energies for the isomerization of this series of compounds varied from 22 to 25 kcal® per mole. The frequency factors X 2 X^ "*X calculated from the Arzhenius plots varied from 10 to 10 sec*"* * 69 The experimental results were reviewed with respect to the ïÿring

treatment of gecmietric isomerization and it was concluded that the

singlet mechanism is operating in the case of these azo cospounds*

The relative rates of isomerization are not correlated by the

Hammett "sigma-rho*^ treatment; a study of the catalytic effect of hydrogen chloride in benzene was made in order to obtain further information on the electrical characteristics of the molecules*

The experimental results of the studies of the thermal and catalytic isomerizations are interpreted with the us© of the molecular orbital picture of the azobenaen© systoma 70 PART II, A Study of Certain Derivatives of Carbonyl Confounds.

I . INTRODUCTION

A large number of derivatives of carbonyl conçiounds are known which are in general used for qualitative purposes. Some of the

reagents are also used for quantitative determination of carbonyl

coîTOounds as a class but with no differentiation of individual com pounds. 2,ii-Dinitroph0nylhydrasine gives quantitative precipitation

of the derivatives and individual conç)ounds can be determined to a

certain extent by chromtographic methods. However^ ttese derivatives have in general unsatisfactory melting points, exhibit polymorphism

to a very unde si re able extent, and in the range are not separated by chromatographyo

The ideal carbonyl reagent is one which is satisfactory for sep

aration, identification and quantitative estimation of mixtures of

small amounts of carbonyl compounds, The choice of an ideal reagent

is dependent on five basic factors.

(1) The reagent should form a derivative which is precipitated

quantitatively frcm various media.

(2) The derivative should have no isomerism or polymorphism,

since this would complicate separation and identification. For example,

acetaldehyde 2,ii—dinitrophenylhydrasons exists in two polymorphic

forms each having a different melting point and infra^rod spectrum

(I'lujol mull ) •

(3) Since the separation is to be effected by chromatographic 71 techniques^ it is desireable to have a derivative ■which is strongly adsorbed* This characteristic would facilitate the separation of closely relathd confounds such as a series of homologues in the car bonyl conçjounds* For exançle, a satisfactory separation on a column of silicic acid-celite was obtained by Malmberg and coworkers^^ on for a mixture of hexahydro l,3,^ti*initrc-s-triazine (RDX) and 1-ace- tylhexahydro-3,5-dinitro-s-triazina (TA.X)* These separations of very closely similar molecules -were obtained because the compounds -were very strongly adsoibed,

(ii) Ano'ther quality which facilitates sepaiation by chromato graphic techniques is as follows: the group on the derivative which holds the ccm^ound to the adsorbent should be close to the point at

■crhich the carbonyl compound couples with the reagent* Thus, any slight difference in structure of the carbonyl component -will have a ma:cimum effect in changing the adsorptive strength* For example a separation of methyl-e-(iiyl ketone and n-butyraldohyda derivatives could be ol>= taincdo

($) Colored compounds are more desirable for two reasons* First* the separation of colored derivatives on a chromatographic column may be easily observed@ Second, estimation of milligram quantities of derivative can be made more accurately spectrcphotomotrically "when absorption is in the visible région* A reagent -which exemplifies several of these good qualitiès is p-aaobenaenasulfonyl chlorido reagent for alcohols developed in this laboratory for the study of oxidation of hydrocarbons* Illustrating (3) and (U), the chromato- 72 graphie separation between asters of the various alcohols was strongly enhanced by virtue of the strongly adsorbed sulfonyl group-SO^-* The

R. group (alkyl group of the corresponding alcohols) being adjacent to this strong hydrogen bonding center, would exact different degrees of shielding, depending on the size of the R group. Experimentally, it was shown that this derivative for alcohols afford a clear cut sep aration of the derivatives of n- and isopropyl alcohol, a result which cannot be achieved with conventional reagents such as the 3,5— dinitrobenzoate esters© 73

II, STATEMENT 0? THE PROBLEM.

Prom a survey of the chemical literature on carbonyl derivatives, it was decided that a U- substituted sendcarbazide would he a favorable reagent, substituent should contain a Amotional group which would tend to make the derivative of the carbonyl conç>ound extremely insoluble, colored, and weakly held to the chromatographic adsorbent.

The relative adsorptive strength of the hydrazine portion of the semi— carbazide would be high and would vary greatly with the steric character of the carbonyl component^ It was for these properties that the U-

(o-nitrophenyl) semicarbazide dazivatives were investigated. The U-p- ni trophenyl derivatives wara also studied as modal conpounds when difficulties were encountered in the o-nitro series, 7U III. DISCUSSION OF RESULTS.

There are isolated cases in the literature^ nhere +wo isomeric

forms of a samicarbazone derivative are reported, Nef reported two

such geometiric isomers for propionaldéhyde sendoarbazone « "When this

îTork was repeated and the two forms isolated, further study indicated

that the two forms were polymorphic rather than geometric isomers*

Chromatography of samples of both forms gives identical zones; a

property which would be unusual for isomers. Elution from the chromato

graphic adsorbent gave the lowers melting form regardless of the

original sample » Tlie insolubility of the higher melting form made it

difficult t) obtain satisfactory infra red spectra in solution. Spectra

obtained with Nujol mulls would not differentiate between isomers and 26 polymorphs. Regardless of what the case may be, the single chromoto«

graphic zone which is found shows that compounds of this 'lypo wouldp

be suitable for chromatographic work,

Tlie ortho and para nitro substituted à-phenylsenri.carbazidos wore

preparod by analogous methods. Tlie corresponding substituted pneriylis®.

ocyanates, ccramericalLy available, ware converted to the urea and then

reacted with hydrazine hydrate to fora the respective semicarbasideso

The derivatives were prepared by the conventional method of reacting tho

semicarbazi de hydrochloride with the carbonyl compound in a buffer

Solution. TfieTburêihvatives preparedrdirthi^Tïanner-âreîBrtWTJoriçrDunds^

and the analyses aro in good agreement with calculated values. An

attempt to separata a mixture of the n—butyraldéhyde and methylethyl

ketone derivatives of the ii-Co-nitrophenyl) semicarbazide or the U-Cp- 7S iîitroph9nyl)3emicarbazid« by the u s m l chromatogrsçjhic methods was unsuccessful* The methylethyl ketone and n-bmtyraIdebyde derivatives were chosen because they do not give a satisfactory separation as dinitrophenylhydrazones* Part of the reason why the separation was not realized was because the conçjounds were more weakly adsorbed than was hoped; however, the almost equal adsorption of the ortho and para derivatives shows that most of the adsorption was at the —CO—NH—N - structure as was desired*

In earlier work it was believed that a molecule in which tho ii-hydrogen atom in )o-nitrophenyl)semicarbazide was replaced by a phenyl group should facilitate quantitative recovery* Attempts to convert 2-=nltrodiphonylamine to the carbamyl chloride with phosgene or to the corresponding urethane with ethylchlorocarbonata were un successful*

The reaction of N-ethyl-N-(o-nitrcphonyl) carbamoyl chloridej, a kno'kTn compound, iTlth hydrazine hydrate yi.eld@d a product for 'iThich the elementary composition corresponded exactly with that expected for h-e thyl-L°=( o—nitrophenyl) semicarbazi de ; however, attempts to prepare the hydrochloride or derivatives of this compound v/era unsuccessfulo

The exact bature of this product is therefore, not clear* 76

IV. EXPERIMENTAL

1# SyntbeslB of U-»Co»nltroph9nyl)samicarbazide.

(a) Preparation of o~Nitrophenylm‘ea. A stream of ammonia

was bubbled throng a clear solution of 20.0 g. (0.12 mole) o-nitrophenylisocyanate (Eastman Kodak, W.L.) in 250 ml. of ethyl ether.

After the precipitatito was completed, the solution was filtered. A yield of 5.0 g. (,23%) white crystalline 2-nitrophenylurea, malting at l8l°Co was obtained (lit.^^ m.o* l8l®G.) The resulting ether solu tion was treated with 28,o ammonium hydroxide solution; an additional yield of 10@1 g, (hl%) was obtained. The product after re crystalliza tion from ethanol melted at 1 7 9 -1 8 1 ^0 *

(b) Preparation of L-( o-Ni trophenyl) semicarbazi de . A solution of 6 . 0 go («.03Ù mole) o-nitrophonylurc-a in 75 ml. of 95“»percont ethanol was treated with 8.0 go (©125 mole) 50^ hydrazine hydrate (Matheson,

Coleman and Bell) and re fluxed for 63 hours. The reaction was then cooled and poured over ice-water. A yield of 5©5 g« (85^) yellow

2-nitrophenyl) semlcarbazlde was obtained. Racrystallisation from

95-percent ethanol gave a product melting at 1 9 0 'C.

Calcdo for C^H^îî^O^î 0, k2.$7; H, h.ll; N, 28.57.

Found: C, Ij3oOO; H, ii©2l; H, 28.^5©

A solution of 3*0 g. (.195 mole) of ( o-«ni trophenyl) semicarbazi de in

50 mlo absolute alcohol was heated to reflux and treated with 10 ml® of concentrated hydrochloric acid» 77 The resulting solution after standing o v e mi^t was cooled in an

ice bath and filtered, yielded 1*3 g. (3^^) “idiite crystalline li—(o-nitro- pheiQTl)88micarbazide molting at 183-I8i+®C*

(d) Synthesis of iWButyraldehyje and Methylethyl Ketone

Derivatives of U— (o-«Ni trophenyl) semicarbazi de* A solution of 0.2$ g*

(0*0011 mole) of ii-(o-nitrophenyl) semicarbazi de hydrochloride was dis

solved in 10 ml* of water and $ ml, of ethanol and treated with 0«$0 g.

(0 * 0 0 6 9 mole) of carbonyl COTçjound* The mixture was warmed and 1 ml,

of saturated aqueous sodium acétate solution was added* The solution after standing overnight, was filtered and the resulting precipitate was raczystallizad from ethanol® In the reaction with methylethyl-» ketone a yield of 0*20 g* (73%) of yellow crystalline l->(sec«butyl)-

ü«(o-nitrophenyl)aemicarbasid09 melting at lyS^Co was obtainedo

Anal®

Calcdo for 52.80; H, $*6k; 22.39.

Found; C, $2®69; H, 6o02; ÎT, 22*UUo

In the readtion with n-butjrrodehyde a yield of 0.18 g® (6h^) o? yellow

crystâiiino -i^-.(o-naTropnenyj.; scnn.caroaziaû , coxting a

129o5“130oO°Co was obtainedo

Anal®

Galcde for C, $2,80; H, $.6U; N, 22.39.

Found: C„ $2,90; H, $®77; N, 22.28.

2o Synthesis of h-»(p-Nitropheayl)s8micarbazido®

(a) Preparation of p-Nitrophonylurea. A stream of ammonia

gas was bubbled through a clear solution of 8.0 g® (0.0$ mole) of 78 p-nitrophenylisocyanate (Eastman Kodak, W*l.) in 300 ml, of cartoon tetrachloride. After minutes, precipitation appeared completed and tiie solution was filtered, A yield of 8,1 g* (85^) pwiitro- pher^lurea was obtained. The product was recrystallized from ethanol; the yellcnr crystals m,p, 2ii7,5-2U8,6®C, (dec.) (lit,^^ m,p, 2U2®G,), B3 (to) Preparation of U«-(p-Nitrophenyl)samicarbazide, A solution of 6,0 g, (,03U mole) p-nitrophenylurea in 75 ml, 95-percent ethanol was treated with 8,0 g, (0,12$ mole) $0^ hydrazine hydrate and refluxed

60 hours, Ihe reaction was then cooled and poured over ice—water* The yellow L-(p-nitrophenyl)semicarbazi de ob'bained in this manner dis solved in a m-inimnm of hot 95-parcont ethanol and treated with 5 ml, concentrated hydrochloric acid. After cooling the solution was filt ered, A yield of 3,5 g, (L5%) yellow U-(p«-nitrophenyl)semicarbazido hydrochloride, 26U«=266®C, with decomposition, (lit,^^ m@pe> 265^0,dec,)

Dsrivatives of (p-Mitrophenyl)semicarbasido, A soluti.on c£ 0,2$ g,

(OoCOll mole^ of i*-«(p-nitrophezîyl)Eon3icarbasid0 hydrochloride was dis™ solved in 10 mlo of vfater and 5 ml, of o'thsmol and treated with 0,50 g,

(0 . 0 0 6 9 mole) of carbonyl compound* The mixture was wanaed and 1 ml, of saturated aqueous sodium acetate solution -was added. The solution after standing overnight was f iltered and the lesuiting precipitate was rocrystallized from ethanol.

In the reaction with methylethyl ketone a yield of 0,15 gc (53^) of white crystalline l«,(sec-butyl) Jj«.(p-nitrophenyl)semicartoaside, melting at 210—212°C, (dec.,) was obtainedo 79 Anal*

Calcd, for C, S2.80; H, S.6k; N, 22.39.

Fcmnd: C, $2.50; H, 5.68; N, 21.86; ash 0.7%.

Correction of the analysis for ash gives the following:

C, 52.85; H, 5.72; N, 22.01*

In the reaction with n-butyraldehyde a yield of 0.19 g. (69%) of white crystalline l-(n-.butyl)—U-«(U-nitrophenyl)semicarbazide; melting at 191*6—193*6®C. (dec.) was obtained*

Anal*

Calcd. for G, 52.80; H, 5.6U; N, 22.39.

Found: C, 52.93; H, 6*o6; N, 22.38.

3» Chromatographic Properties of 1 (n-Butyl)!&-.(2-nitrophenyl) oemicarbazides. l-(sGC-Butyl)— (2-nitrophenyl)semlcarbasidGs, 1-

( n-Butyl ) It-nitrophenyl ) semicarbazi da and 1- ( sec-Butyl ) —U— ( U-nl tro— phenyl) seaicarbasi de @ A l-mg. sample of the semicarbazi de in 1 ralo of CoPo chloroform was chronKitographed on a column (l5 >' l50 mm*) of silicic acid—oolite * Tne column was prowashed with 10 ml. Skellysolvo

B followed by 10 ml* C*?. chloroform. After development with 50 rsl* of 10-percent ethyl ether in benzene the adsorbent was extruded and the column was streaked with & 2$^ercent sodium hydroxide solution or a 10-percent alcoholic sodium raethoxide solution; a yellow (for NaOH) and an orange (for h'aOMe) zone was. observed. 00

Compormd Zone (mm*)

4— ( o—ni trophenyl) semicarbazi das n-butyrald«hyde 100-122 methylethyl ketone 98-120 Ik-ip-ni trophenyl) seiricarba aides n-hutyraldohyde 88-105 methylethyl ketono 8 8 -10)4

ll. Synthesis of ü— ( o-ni trophenyl—N-ethyl) semicarbazi de .

(a) Preparation of p-Tolnenesnlfonyl-o-nitroanilide. A

solution of 52*0 g, (0*375 mole) of o-nitroaniline (Eastman Kodak, W.L.) and 95«0 g» (0*5 mole) p-toluenesulfonyl chloride (Eastman Kodak, W,L.) in 1 2 5 mlo of CoPo pyridine (J.T, Baker Company) nas heated on a steam bath for U hours* The solution was then cooled to about hO^C* and poured slowly into h liters of ice-water with vigorous stirring* The resulting solution, after standing 18 hours at room temperature,

filtered* The residue obtained was recrj^stallized from ethanol» A yield of 81*6 g* (71%) of yellcv; crystals of p-toluenesulfonyl-o-nitro- anilids which melted at lll-113a5°Co wa.s obtained» (lit*"^ m@p» 111—

113°G*)*

(b) Preparation of p—Toluenesulfonyl—o-nijbro-K-ethylanilide'^^

A sample of 79©5 g* (0*27 mole) of p-toluenesulfonyl-o—ni troanilide was suspended in 66 ml* of UH» sodium hydroxide, and 28 ml* (0»2lL mol©) of diethyl sulfate was added* The mixture was then heated on a steam bath; an exothermic reaction followed* Alkalinity to phenolthalein was maintained by the addition of 1-2 N sodium hydroxide as necessary*

A second sample of diethylsulfate (28 ml* , *2lL mole) was added after the reaction from the first portion was complete* Alkalinity was again maintained by the addition of sodium hydroxide* ihe mixture was then 81 cooled and filtered* The residue was recyrstallized from èthanol and a yield of 52,g. (àO%) of p-toluenesnlfonyl-o-nitro-N-ethylanilide was obtained* The product melted at 102-105°C. (lit*^^ 103—105^C,),

55*0 g. (0*17 mole) sanple of p-toluenesulfonyl-o—nitro-N-ethylanilide was heated on a steam bath for 1 hour with a mixture of 30 mlo of glac

ial acetic acid and 70 ml* of concentrated sulfuric acid. The result ing mixture was poured into 1 1 , of cold water; a rod oil separated.

The oil was then taken up in ethyl ether, washed successively with an aqueous solution of sodium bicarbonate and a saturated sodium chloride

soluti-ono The ether solution was then dried with anhydrous sodium

sulfate and evaporated. The resulting red oil was distilled in a modified Claisen flask under reduced pressure, A yield of 22,0 g*

(7 8 ^) of o-nitro-N-ethylaniline boiling at 122^0, at 2 miae, (lit,^^ b,

111-112 C,/lnai©) was obtaineds

( Preparation of iT«Ethyl«.rJ«( o^nitrophenyl) carbamoyl Chloride^^

A 22*0 go (O0I3 mole) sample of N-ethyl-2-nitroaniline and lh*7 go

(Oo35 mole) of redistilled triethylaiaine (festman Kodak, YTolo) ware dissolved in UOO ml, od dry benzene, Phosgene (Matheson) was passed into the solution at O^C, for l5 minutes at a steady rate at the end

of this time g the ice-bath was removed and the reaction mi:-:ture was allowed to warm to room temperature* The temperature of the reaction raised spontaneously to ii2®Go The reaction, after standing 75 minutes was heated to 50°Co for 20 minutes. The mixture, after standing ovor- night, was filtered to remove the tin. e thy lamine hydrochloride. The 82

resulting benzene solution -was -washed, successively, with three 200-al* portions of 6 N hydrochloric acid and with four 2 0 0 - ^ , portions of

■water. The yellow solution was then dried over calcium chloride and evaporated to an oil. The residue oil was taken up with a small amount

of e-bhyl ether and Skellysolve P, The solution was then cooled and

filtared. A yield of 2^,0 g, (63%) yellow crystalline N-e-thyl-N-(o- nitrophenyl)carbamoyl chloride -was ob'bained. The product melted at b7-L8,5°C. Clit,"^ U6,5-57«5°C,),

(g) Preparation of li~Ethyl-U«.( o-ni trophenyl) semicarbazide, A

7*0 go (OeOii mole ) sample of N-ethyl-N—(o—ni trophenyl) carbamoyl chloride

-fras dissolved in ^ 0 ml, of ethanol and added to 1 0 ml, of hydrazine

(Matheson, 6$% solution) in 1 $ ml* of ethanol* ihe reaction flask was stirred and a spontaneous exothemic reaction occurred» The mixture was refluxed for U hours and thon allowed to stand ova might. The yello-i? solution -was pourod over ice~-water and a heavy yellow precipi-tate formed* The solution -nas filtered and a yield of 5o2 g. (75%) of

Uraothyl—U-(o-rjitrGphQnyl)somicarba3 id® was obtained* A 300 mg. sample

■was dissolved in 1 2 0 ml* of benzene and chromatographed on a column

(30 X 175 EEio) of silicic acid-colite with a prewash of 50 ml* of

Skellysolve B and 50 ml, of benzene. Development with 200 ml* of U0% ethyl ether in dry chloroform gave a yellow zone 75-150 mm, from the top of the col-uian. With a 25^ sodium hydroxide streak reagent, the zone tSïTied blue* Ti-ie colorless portion above the zone gave a weak blue coloration -with this reagent. The yellow zone (75-l50 mm*) was eluted with ethyl ether and the solvent was evaporated. The sample rras re— 83 crystRllize

Anal.

Calcd. for C, U8.20; H, 5,39; N, 2it.99.

Found: G, U8.6O; H, 5.5%; H, 2i+.62.

5. Preparation of Propionaldéhyde Semicarbazone^^ A warm solu

tion of 30.0 g, semlcarbazlde hydrochloride (Eastman Kodak, W.L.) and ii^ . 5 g. sodium acetate (hydrate) was treated with 1 5 . 0 g. propional

déhyde (Eastman Kodak, T7.L,). The resulting solution was shaken and

the flask was placed in a beaker of hot water. The yellow solution, after standing overnight was extracted three times with benzene. The

solution was then dried by filtration through a mat of anhydrous sodium

sulfate and evaporated to a volume of 100 mlo Skellysolve B was added and the resulting solution was cooled and filteredo The white crystals

obtained in this manner were recrystalliaod four times from benzene<>

In each case a high melting residue which was insoluble in benzene was obtained. The filtrate, whan treated with Skellysolve B, yielded a low melting isomsro The two pure foims of propionaldéhyde secil- carbazide melted at 1^9-l50°C. and 90«92°C. ( l i t r a . p o l5U°C, and

8 8 «9 0 ^C«, respectively.)*

A 100 ngo sample of the two forms were separately chromatographed on a column of silicic acid-celite (20 x I9 0 mm*). A prewash of l5 ml. of Skellysolve B, 10 ml. of benzene and 10 ml, of developer was used.

The zone was developed with 90 ml. of 20^ acetone and ethyl ether in C.Po chloroform* The zones were detected by streaking the column Sh with acid permanganate solution. After detection the zone iras eluted with actone-other, the propionaldéhyde semicarbazide was recovered by evaporation of the solvent, and the particular form present was characterized by the melting point,

m,p, of Form Sample Solvent Zone (mm,) Recovered material

High melting O.P. chloroform 80-170 Low melting benzene 8O-IS0 90^0, 8^

Vc s u m m r t

The two geometric isomers for propionaldéhyde seraicarbazone reported by Nef^^ are probably polymorphic rather than geometric isomers.

The ortho and para nitro substituted ii—phenylsemicarbazidas were prepared together with their respective n-butyraldehyde and methyl ethyl ketone derivatives in order to investigate the possiblity of chromatographic separation of this type of derivative. There was no inprovemenb in the separation over the presently used dinitrophenyl*» hydrazine derivatives* APPEMDIX 8?

S to pcock

7.0 cm. Spring fastener

20.0 cm

Sample solution

FIGURE I REACTION VESSEL-SAMPUNG APPARATUS USED IN RATE STUDY 2.00

1.80

L60 •SI

S' 1.40

1.20

2000 4000 6000 8000 Time (min.)

FIGURE 2

RATES OF ISOMERIZATION OF çis - 3-NITROAZOBENZENE IN 95 PERCENT ETHANOL AT DIFFERENT TEMPERATURES

CS 2.00

.80

.60 ol

O' ° 1.40

.20

39.5X.

0 900 1800 2700 3600 4500 Time (min.)

FIGURE 3 RATES OF ISOMERIZATION OF çis “3- NITROAZOBENZENE IN BENZENE AT DIFFERENT TEMPERATURES C» 2.00

.80

.60 o

1.40

.20

0 1000 2000 3000 4000 Time (min.)

FIGURE 4

RATES OF ISOMERIZATION OF çis -3- NITROAZOBENZENE IN n - HEPTANE AT DIFFERENT TEMPERATURES 2 0 0

.80

■si

0» o 1.40

.20

n-heptane Benzene

0 2000 4 0 0 0 6 0 0 0 8 0 0 0 Time (min.)

FIGURE 5

RATES OF ISOMERIZATION OF çis - 3- NITROAZOBENZENE AT 39.5°C. IN ethanol, n -HEPTANE, AND BENZENE 2.00

1.80

(fli 1.60 ôl

O' o 1.40

.20

n-heptane Benzene 95 per cent ^ ethanol

0 6 0 0 900 1200 1500 1800 Time (min.)

FIGURE 6

RATES OF ISOMERIZATION OF ds - 3 - NITROAZOBENZENE AT ^9.2°C. IN ETHANOL, n-HEPTANE AND BENZENE 2. 00,

.80

1.60 o en o

1.20

Benzene- heptane Benzene-

0 200 400 600 800 Time (min.)

FIGURE 7

RATES OF ISOMERIZATION OF çis - 3- NITROAZOBENZENE AT 6 0 “G. IN ETHANOL, n - HEPTANE, AND BENZENE 9ii

9.2

Et hanoI Benzenev N ITROAZOBENZENE 8.8 n- heptanev NITROAZOBENZENE

8.4

8.0

6.8

vo -heptone 6.4 Benzen e Ethano

3.00 3 .0 8 3.16 3 .2 4 3 3 2 3 .4 0 '/j X 10-3 FIGURE 8 ARRHENIUS PLOT FOR THE RATE OF ISOMERIZATION OF MONO- NITROAZOBENZENES 95

8.8

o 3,5 - dinitroazobenzene O 3,3 - dinitroozobenzene 8.4

8.0

7 6 o> o

7.2

Benzene

6.8 Ethano

6.4 Benzene

thonol

6.0 2.92 3.00 3.08 3.16 3 .2 4 3.32 j/p X 10'3

FIGURE 9

ARRHENIUS PLOT FOR THE RATE OF ISOMERIZATION OF DINITROAZOBENZENES 96

8.8 o 3 “ nitro - 4- methyl azobenzene □ 3~ methyl-4 - nitro azobenzene

8.4

7.6

O’ o Ethano 7.2

Benzene

6.8

Benzene6.4

Ethanol

6.0 2 9 6 3 .0 4 3.12 3 .2 0 3.28 3 .3 6 l/y - 10“^ FIGURE 10 ARREHNIUS PLOTS FOR RATES OF ISOMERIZATION OF m eth yl SUBSTITUTED NITROAZOBENZENES IN ETHANOL AND BENZENE 97

9,2

O 4 - { piperidine sulfonyl) azobenzene 8.8 - □ 3 ~ ( pi per idino sulfonyl) azobenzene A 3- (dimethyl sulfamoyl) azobenzene # 4 - (dimethyl sulfamoyl) azobenzene 8.4

8.0

^ Benzene 6.8 Benzene Ethanol Ethanol

6.4 \N Benzene ^ Benzene Ethanol Ethanol 6.0 2.92 3 .0 0 3.08 3.16 3.24 3.32 X 10“ 3

FIGURE II ARRHEN I US PLOT FOR th e r a t e OF ISOMERIZATION OF N-SUBSTITUTED SULFAMOYL AZOBENZENES Cone, of HCI (m molarity) 2.0 o 0.00 A 5.3 X I0"3 □ 9.3 X 10'^ o 2.2 X I0"2 X 2.3 X 10-'

•-! ÔI

O' o _l

600 1200 2400 30001800 Time (min.) FIGURE 12 RATES OF ACID CATALYZED SOMERIZATION OF cis-AZOBENZENE IN BENZENE AT VARIOUS CONCENTRATIONS OF HCI AT 39.6"C. 5.0

4.0

3.0

2.0

Rate of unc< ed reaction

0 5 10 15 20 25 30 35 40 45 Cone, of HCI (m molarity x IO"î) FIGURE 13 RATES OF ACID CATALYZED ISOMERIZATION OF cjs - AZOBENZENE IN BENZENE AT DIFFERENT CONCENTRATIONS OF HCI AT 396*0. 5.0

4.0

ro 3.0 I O

2.0

Rate of uncatalyzed reaction

0 5 !0 15 20 25 30 35 40 45 Cone, of HCI (m molarity x 10'®^)

FIGURE 14

RATES OF ACID CATALYZED ISOMERIZATION OF cis - AZOBENZENE IN BENZENE AT DIFFERENT CONCENTRATIONS OF HCI AT 39.6®C. ( X - AZOBENZENE CONCENTRATION 1/5 MOLARITY OF OTHER POINTS) Cone, of HCI (m molarity) • 0.0009 Xlo 2.0

A 0.037 □ 0.074 X I ^

O' o _i

400 800 1200 1600 Time (min.) FIGURE 15

RATES OF ACID CATALYZED ISOMERIZATION OF cis-] - NITROAZOBENZENE IN BENZENE AT VARIOUS CONCENTRATIONS OF HCI AT 39.6 I 2.0 Cone, of HCI (in molarity)0.0Z2)\\O

t/)\

O' o _i

0 200 4 0 0 600 Time (min.)

FIGURE 16

RATE OF ACID CATALYZED ISOMERIZATION OF cis - AZOBENZENE IN n-HEPTANE AT 39.6 * C. g -2 Cone, of HCI (m m olarity)Xfo 2.0 O 0.00164 • 0.00329 A 0.00823

u 0 o> o _I

40 100 120 140 16060 Time (min.)

FIGURE 17 RATES OF ACID CATALYZED ISOMERIZATION OF cis-4 -NITROAZOBENZENE AT VARIOUS CONCENTRATIONS OF HCI AT 39.6*C. Thermal t catalytic at 49.3®C. 8.0

Thermal + catalytic at 39.6*C. '' Catalytic o at 39.6®C. 6.0 # at 49.3®C. rO I O 4.0 y

2.0

6.0 Gone, of HCI (m molarity x IO"â)

FIGURE 18

RATES CI- ACID CATALYZED ISOMERIZATION OF çis - AZOBENZENE AT DIFFERENT CONCENTRATIONS OF HCI I .20 Cone. (mg./lOOml.) Isomer cis 0.88 22.0 Irons 0.88 22.0 .00

0.80

g 0 . 6 0

Q. 0.40

020

O.OOL 6 0 0 200 3 0 0 4 0 0 500 Wavelength (m/a)

FIGURE 19

ABSORPTION SPECTRUM OF 3 - NITROAZOBENZENE IN 95 PERCENT ETHANOL Cone, (mg. /to o ml.) 1.00 isomer CIS 0.65 20.5 trons 0.81 48.6

0.80

0.60

z 0.40

0.20

000 200 300 400 500 6 0 0 Wavelength (m^)

FIGURE 20

ABSORPTION SPECTRUM OF 3,3 - DINITROAZOBENZENE IN 95 PER CENT ETHANOL Cone. (mg./ 100ml. ) Isomer cis 1.05 13.6 trons 0.82 42.0

0.80

c 0.60

a 0.40

0.20

0.00 200 300 400 5 0 0 600 Wavelength (m^u.) FIGURE 21

ABSORPTION SPECTRUM OF 3,5-DINITROAZO0ENZEr\)E IN 95 PER CENT ETHANOL Cone. ( mg./100 ml.) Isomer 1.00 - CIS 1.44 trons 0.47 23.4

0.80

0.60

y 0.40 fJ

0.20

O.OOl 200 300 400 500 600 Wavelength (mju-)

FIGURE 22 ABSORPTION SPECTRUM OF 4 - NITROAZOBENZENE IN 95 PER CENT ETHANOL Cone. (mg./lOO ml.) Isomer

CIS 0.30 1.00 trons 0.89 44.7

0.80

0 6 0

0.40

020

000 200 300 500400 600 Wavelength ( myu.)

FIGURE 23 3- NITRO-4 methyl AZOBENZENE IN 95 PERCENT ETHANOL I Cone. ( mg./lOOml.) Isomer n r 0.46 11.6 1.00 trons 0. 58 29.0

0 8 0

m 0.60

0.40

0.20

0.00 200 3 0 0 400 500 6 0 0 Wavelength (m^) FIGURE 24

3-METHYL-4-NITROAZOBENZENE IN 95 PERCENT ETHANOL Cone. (mg./ 100ml.) isomer 1.00 ds 1.45 14.5 trons 2.14 53.6

0.80

0.60

0.40

0.20

0.00 200 300 4 0 0 0 6 0 050 Wavelength (m ^)

FIGURE 25

ABSORPTION SPECTRUM OF 3~SULFAM0YL AZOBENZENE IN 95 PERCENT ETHANOL 1.00 Cone. ( mg./IOOrnl.) Isomer CIS 2.10 10.5 trons 0.94 23.5 0.80

s 0.60

0.40

0.20

0.00 200 3 0 0 4 0 0 5 0 0 6 0 0 Wavelength (mp)

FIGURE 26

ABSORPTION SPECTRUM OF 4 -SULFAMOYL AZOBENZENE IN 95 PER CENT ETHANOL LOO Cone, (mg./100ml.) Isomer CIS 1.37 16.3 trons 0.72 36.2 0.80

w 0.60

0.40

020

0.00 200 3 0 0 4 0 0 5 0 0 6 0 0 Wavelength (m/a.)

FIGURE 27

ABSORPTION SPECTRUM OF 3 - (DIMETHY SULFAMOYL) AZOBENZENE IN 95 PERCENT ETHANOL 5 1.00 Cone, (mg./100ml.) Isomer 2.18 16.8 trons 27.8

0.80

« 0.60

0.40

0.20

0.00 200 3 0 0 4 0 0 5 0 0 6 0 0 Wavelength (m^)

FIGURE 28

ABSORPTION SPECTRUM OF 4-( UIMETHYLSULFAMONO,) AZOBENZENE IN 95 PER CENT ETHANOL Cone. (mg./IOOml.) Isomer 1.00 CIS 5.72 14.3 trons 0.78 39.1

0.80

3 0.60

•E 0.40

020

000 200 3 0 0 400 5 0 0 6 0 0 Wavelength (m/a )

FIGURE 29

absorption s p e c t r u m of 3 -(PIPERIDINO SULFONYL) AZOBENZENE IN 95 PER CENT ETHANOL Cone. (mg./IOOml.) .00 Isomer — CIS 2.24 — Irons 1.25 31.2

0.80

0.60

0.20 -

0.00 200 0 4 0 030 5 0 0 6 0 0 Wavelength {mfi)

FIGURE 30

ABSORPTION SPECTRUM OF 4 - (PIPERIDINO SULFONYL) AZOBENZENE IN 95 PER CENT ETHANOL Cone. {'^VlOOml. A B I.OOr- I 0.60 30.0 E 0.63 31.5 0.90- m 0.48 24.2

0.705-

ü 0.40

O 0.30

0 .20 -

200 250 300 350 400 450 500 550 600 Wavelength (

FIGURE 31

ABSORPTION SPECTRA OF r trons 3,4 - DINITRQAZOBENZENE IN 95 PERCENT ETHANOL E Irons 4,4'-DINITROAZOBENZENE IN O.P. CHLOROFORM m trons 3,4-DIN ITROAZOBENZENE IN 95 PERCENT ETHANOL S Cone. (mg./IOOmL)

.00 Solvent B ----- Chloroform 0.89 22,2 n- heptane 0.89 222 95% ethanol 0.89 222

0.80

^ 0.60

0.20

0.00 200 3 0 0 0 5 0 0 6 0 040 Wavelength (m^)

FIGURE 32

ABSORPTION SPECTRA OF Irons - 5~ NITROAZOBENZENE IN CHLOROFORM, n-HEPTANE AND 95 PERCENT ETHANOL g 100

60 (T trons - 40 AZOBENZENE c[s — AZOBENZENE 20

CONCENTRATION; l.5g./5ml. CCI4 u 0-100 o z Ê 80 S in 2 60 CC4 I- 40 trons-3-NITROAZOBENZENE - cis -3- NITROAZOBENZENE lijz Ü 20 CONCENTRATION: 227mg./5ml. CC IT O.LJ 0-100

40 trans-4-NITROAZOBEN- ---- ZENE ds-4-NITROAZOBENZENE __ 20 CONCENTRATION: 227mg./5ml. CCI4

WAVELENGTH IN MICRONS FIGURE 33 INFRA-RED ABSORPTION SPECTRA OF ds AND trons AZO COMPOUNDS. NoCI SAMPLE CELL: 0.2mm. R E F E R E N C E CELL: 0.2mm. Table X 120

Rate of Isom erization of 3-Nitroazobenzene in Benzene at 60.30, L9.20, and 39.5°.

Time (min.) P.P. (U30m.u) Fraction cis k X 10 -3

Te mo . 60.3i.05°C, Gone, 0.73U millimolar. — 0 .830 O.9UO 70 .693 0 .6 9 1 3.13 130 .3^0 0.302 3 . 2 3 190 .3Ï8 0 . 3 7 2 3.13 2 S0 .U60 0.263 3 . 2 9 310 .U22 0 .1 9 L 3 . 2 6 370 .391 0.137 3.33 .316 0.000

Average 3 .2U Graphically 3.31

Temp. It9.2°0.t.05°G., Cone. O.7UI millimolar.

0 .820 O.9LO 710 .L92 O.3L1 i.UU 830 .L39 0 . 2 8 1 1 .U6 1010 ,iil7 O.20U 1 . 3 2 1130 .Loo O.I7 L 1 .I19 1U30 .363 0.110 1 . 3 0 0 ^ .303 0.000

Average l.Lo Graphically 1.3U

Punlicate, Cone. O 0 8 0 8 millimolar®

0 .879 O.9L0 270 .693 0.628 1 .L9 L 20 .620 0 . 3 0 3 1 .U8 6 9 0 .323 0.3L3 1 cU6 139S .391 0.120 1 .U7 o o .320 0.000

Average 1.LS Graphically 1,u 8 Table X (contd.) 121 Temp. 39«5°C»t:.05°G«Cono. 0.733 millimolar

0 .799 O.9 U0 1030 .613 0.583 U .67 1Ü30 .566 0.U80 a.8U 1715 .515 0.395 5.07 2ii65 .152 0 .2 7 a 5.02 2765 .1x29 0 . 2 2 9 5.11 3200 .U03 0 . 1 8 0 5.18 hoL5 .367 0.111 5.25 Oo .310 0.000 Average 5.02 Graphically 5.21 Tabla XI 122 Rate of Isomerization of U-Nitroazobenzene in n-Hentane at L9.20, 39.S*, and 2k.9°.

Time (min.) O.D. (l4-50ntu) Fraction cis

Temp. U9.2 Cone. 0*357 millimolar.

0 .532 0.950 5 .530 0.752 11 .U60 0.656 15 .U26 0.558 20 .391 0 .U30 28 .3U5 0.315 38 .30U 0.23U US .275 0.123 00 .191 0.000

'.Graphically determined k = 3 elU

Temp. 39.3db.05oc., Cone. 0.520 millimolara

0 .805 0.950 30 .67U 0,710 61 .580 0.539 96 .U83 0 «361 131 .U12 0.231 196 .351 0.120 CX» .2SU 0.000

Graphically determined k= 1.06 10' .2

Temp. 2 U . 9 ± o05°0,^ cone* Oo556 millimolara 0 *662 0.950 155 .737 O . 7UO 3U0 .610 0.525 525 .516 0 .368 800 .U31 O . 22U 1000 *351 0.155 0 0 .300 OoOOO

Graphically determined k-lo?U x 10 Table XII 1 2 3

Rate of Isom erization of 3-Nitroazobenzene in 95-Percent Ethanol a t 6 0 . 6 °, and 39.5°

Time (min.) O.D. (L30mu) Fraction cis k X 10"-3

Temp. 60.6 t.05°C.. Cone, O.7U5 millimolar.

0 1.017 0.950 105 .8L 8 0.700 3.22 210 ,713 0.500 3.20 315 .618 0.358 3.24 1|20 .560 0.273 3.04 525 .k99 0.180 3.23 660 .162 0.127 3.09 0 0 .376 0.000

Average 3.17 Graphically 3.18

Temp. ii9.2 ±" .05°C., Cone, 0.696 millimolar,

0 .993 O.9LO 275 ,860 0.755 8.5l 1:25 .80^ 0.672 8.25 695 .712 0.534 8.32 l U o o .559 0.307 8.10 1835 .^57 0.215 6.14 0 0 .353 0.000 Average 8,26 Graphically 8,05

Duplicate , Cone, 0,622 millimolar,

0 .900 0 .9U0 705 0638 0.520 8.^0 1005 .570 0 oUli 8.21 i i U o .5L5 0.371 B.lU 1U 25 .U96 0.292 8.20 2580 .387 0.118 8.06 0 0 ,3lU 0.000

Average 8.20 Graphically nr Tabla XII (contd») 12li Temp, 39»5°C»^ .05^0., Gonc» 0»U89 millimolar»

0 .638 O.9U0 lOilO .3U? O.69U 2.93 iUi5 .317 0.623 2.91 1725 .U96 O.37U 2.88 2hlS .LU 2 0 .UU7 3.01 3803 .U27 0 .U n 2.96 3210 . U n 0.373 2.88 U055 .370 0.278 3.01 3593 .321 0.163 3.08 00 .232 0.000

Average 2.96 Graphically 2.97 Tabla XIII 125

Rate of Isomerization of 3—Nitroazobenzene in n-Heptane at 60.3°, U9.0°, and 39.5°.

Time (min.) O.D. (U30mu) Fraction cis

0 .780 0,9h0 70 .5 9 0 0 .5 9 0 130 .U77 0.38U 190 .U05 0 .2 5 1 250 .358 0 .1 6 5 310 .326 0 .1 0 6 0 0 .268 0.000

Graphically determined k ^7.11 .-3

Temp. U9.O tr.05°C., Cone* 0 ,7 0 1 millimolar*

0 .738 O. 9U0 30 .715 0.883 100 . 6I43 0.7U5 175 .588 0.639 2L5 .5L8 0.562 39S Ji7G 0 „UiU 65o .379 0.2Ü0 900 .331 0 oiU5 0 0 .255 0 .0 0 0

Graphically determined ]c 2 .07 10

Temn. 39.5dz.05°C . , Cone. 0*7^6 millimolar.

0 .76I1 O. 9UO 1025 .510 0.558 1I1I 5 .Ii5U 0.355 1725 .^19 0 .2 8 7 2h65 .356 0 .1 7 0 2765 .337 0.133 00 .265 0.000

Graphically determined Ic - 6,98 Tabla XIV 126

Rate of Isomerization of U-Mitroazobenzene in Benzene at 39.5°, and 2U.9°. Time (min.) 0,D. (U50mu) Fraction cis

0 .793 0.975 12 .628 0 ,626 20 .552 0.1467 25 .U99 0.356 30 .U69 0.293 i+0 .U20 0.190 50 .387 0.120 to .330 0.000

Graphically determined k jr Ü ,Ul

Temp. 39.5±.05°C., Cone. 0,5ll millimolar.

0 .79L 0.950 7 .765 0.890 3h .62a 0.609 6h .510 0.383 95 .L39 O . 2U1 l5l .368 0.100 oo .318 0.000

Graohically determined k - 1 . 5 l ,-2

Temp. 2k.9 .05°C., Cone, 0.)i9U millimolar. 0 .780 0 .89b 70 .675 0.778 130 .628 0.679 220 .562 0.539 310 .513 O 0U36 395 .U71 O.3U 7 1^90 .LLo 0.282 oo .306 0.000

G raphically determined k= 2.Ü6 x lO""^ Table XV 127

Rate of Isom erization of It-Nitroazobenzens in 9^-Percent Ethanol at U9.2°, 39.5Ô, and 2ii.9°.

Time (min. ) O.D. (U50inu) Fraction cis + Temp, U9 .2 ,o 5 °c•, Cono,, 0.626 millimolar. 0 ,820 0 .9 5 0 5 .697 0 ,7 0 2 10 ,59h 0 ,4 9 3 18 .483 0.270 36 ,422 0.147 00 .350 0.000 -2 Graphically determined 7.5 1 X 10'

+ Temp. 3 9 .S .o9°c •, Gone, 0,5dO millimolar. 0 .740 0.950 10 .647 0,742 Uo .457 0.319 55 .418 0 .2 3 1 75 .375 0,136 00 .314 0.000

-2 Graphically determined k f 2.58 X 10

Temp , 2L .9 ± .o9°c », Cone. 0 ,5 3 l milliritolar0 0 .740 0.902 70 .642 0.687 130 ,572 0 .5 3 5 220 .492 0.361 310 .438 0 .2 3 5 395 .407 0.176 L90 .381 0,120 CO .326 0 .0 0 0

-.Graphically determined k^l+.l? x 10“^ Table XVI 128

Rate of Isomerization of 3,3'-Dinitroazobenzene in 95-Percent Ethanol at 62.30, U9 .OO, and 39,5°,

Time (min.) O.D. (U35nni) Fraction cis

Temp. 62.3 ‘fc.05°C,, Cone. 0.725 millimolar. 0 .691 1.000 130 .592 0.756 230 .523 0 .586 330 .U70 0.456 U 90 .U09 0.306 725 .349 0.160 CO .285 0.000

Grapiiically determined k = 2 .4!

,05°C,, Gone, 0,850 millimolar.

0 .334 1.000 210 .779 0.893 390 .725 0.788 660 ,669 0.680 1330 ,559 0.466 1600 ,509- C .369 2635 ,425 0.207 3255 ,4co 0.158

= - - JL'^

Temp. 39,5 -»05"^,. Cone. 0,75^ izLllimolar,

0 .739 1.000 1150 .65? 0.820 1575 .626 0.752 2355 ,554 0.594 43S5 .480 0 ,U32 5335 ,442 0.349 00 .260 O.CCO

Graphically determined h =1,6à 10 ~ Table XVII 129

Rate of Isomerization of 3,3’—Dinitroazobenzene in Benzene at 6 2 .3 0 , 49.0°, and 39.5°.

Fraction cis

Temp. 6 2 .3 ± . 050c.. Cone. 0.770 millimolar.

0 .772 1 .0 0 0 130 .2U2 0 .2 2 8 230 Mhl 0 .32U 330 .379 0.198 2:90 .326 0.090 00 ,281 0 .0 0 0

Graphically determined k% a .9 '

Temp. L 9 .O1 .OS°c., Cone, 0 ,3 2 ^ millimolar. 0 .8 0 6 1 .0 0 0 210 .7 0 6 0.802 390 .630 0 .6 2 1 660 .238 0 J470 1380 J4OI 0 .1 9 9 1800 .361 0 .1 1 8 0 0 .301 0 .0 0 0

Graphically determined k = lolc

Temp. 39.^:f:.0^°0.^ Gonc » Og719 millimolaro 0 .692 1 .0 0 0 3Ü0 .622 0 .90L 1292 .236 0.632 17^0 .L89 0.223 2712 .hl3 0.3L7 3192 .388 0.290 L 292 .3L4 0.189 00 .263 0.000

Graphically determined k-ii»09 x 1 0 " ^ Table XVIII 130

Rate of Isomerization of 3,S-Dinitroazobenzene in 9^-Percent Ethanol at 62.10, U9.3°, and 39.6o.

Time (min.) O.D. (ii38mu) Fraction cis

Temp . 62 .1 zt ,0^®G « , Cone . 0*5l2 millimolar. 0 .519 1.000 35 .^37 0.646 50 .397 0.521 6 5 .369 0.433 85 .335 0.325 107 .311 0.250 1Ù0 .283 0.161 00 .232 0.000

Graphically determined k jr 1.3]

Temp. ^9.3 ^«05 0.^ Gonc. 0.500 millimolar. 0 .572 1.000 30 .539 0.905 135 .1:53 0.658 180 .429 0.586 355 .342 0.339 L83 .306 0.235 CO .224 0.000

Graphically determined 2.95 10-3

Temp. 39o6± .05°C 0.479 millimolar. 0 .542 1.000 220 ,471 0.790 U 75 .401 0.581 955 .326 0.359 1185 .303 0.289 1300 .266 0.151 00 .205 0.000

Graphically determined k=l,OU x 10 - 3 Table XIX I31 Rate of Isomerization of 3,5-Dinitroazobenzene in Benzene at 62.30, L9 .OO, and 39.6°.

Time (min.) O.D. (L38mu) Fraction cis

1., Cone. 0.5l5 millimolar.

0 .525 1.000 10 .^88 0.875 20 .U29 0.675 31 .386 0.529 Uo .359 0.437 50 .334 0.353 66 .299 0.234 00 .230 0.000

Graphically determined k= 2,28 x 10“^

Temp o L 9.O ±.0$OC.'C. , Cone, 0,475 millimolar.

0 .484 1.000 30 .449 0.374 100 .383 0.635 175 .330 0.442 245 .290 0,299 450 .245 0.107 CO .207 0.000

Gr^ hie ally determined x 10 ^

Temp. 39.6 ± .O^OÇ Cone, 0.574 millimolar.

0 .575 1.000 55 .550 0.920 155 .508 0.731 295 .463 0.633 4 io .432 0.530 690 .372 0.335 1000 .332 0,204 00 .270 0,000

Graphically determined k = 1.^9 % 10~^ Table XX 132

Rate of Isomerization of 3-Methyl-L-nitroazobenzene in 9^-Percent Ethanol at U9.0°, 39.6°, and 2U.9°.

Time (min.) O.D. (liUOmu) Fraction cis

:.y Gonc, 0.U6O millimolar.

0 ,670 1.000 6 .605 0.8L2 12 .5^0 0.685 22 ,h^0 0 .^66 30 ,Uo8 0,36ii 39 . 36U 0.255 6o .308 0.120 oo .258 0.000

Graphically determined k= 3.62 x 10“^

Tenro. 39*6 t »03°0.. Cone. 0.U96* millimolar.

0 .705 1.000 30 .587 0.712 50 .522 0.553 70 0U69 0.525 100 .513 0,286 135 .370 0.181 eO .295 0,000

Graphically determined k r 1.30 x 10 ^

Temp. 2U.9 A .O S ' ^ C Gone. 0,U05^ millimolar.

' 0 .590 1.000 30 .552 0.863 105 .599 0.750 230 .532 0.558 360 .385 o.5i5 570 .350 0,285 800 .295 0.155 OO .250 OoOOO

G raphically determined k = 2.2U x 10“^ Tabla XXI 133

Rate of Isomerization of 3-Methyl-ii-nitroazobenzene in Benzene at 3 9 .60 , a nd 2i|.9®.

Time (min.) 0,D« (WiOmn) Fraction cis

Temp, L 9 .Ot.030c.. Cone, 0,ii88 millimolar.

0 .750 1.000 6 .675 0.358 12 .628 0.755 30 .501 0.575 39 .558 0.381 55 .505 0.266 75 .356 0.158 00 .285 0.000

Graphically determined kc 2,55 %

Temp, 39..6 ± ,05°C.. Cone, 0.555 millimolar. 0 .682 1.000 30 .601 0.305 60 .527 0,625 105 . w 0 .520 iU5 .393 0.300 200 .356 0.186 .269 OoOOO

Graphically determined k =8.65 X

Temp 0 250 9 £,05°C Cone „ 0,550 millimolar.

0 .639 loOOO 105 .577 0.835 230 .523 0 ,6 8 8 360 .582 0.580 570 .527 0.531 1000 .356 0.250 00 ,266 0 .0 0 0

Graphically detemained k = 1.38 X . - 3 Table XXII 13^

Rate of Isomerization of i;-(Piperidino sulfonyl) Azobenzene in 95-P3rcent Ethanol at 62,1°, and 39*6°

Time (min. ) O.D. (UUOmu) Fraction cis

Temp. 62.1 + . 05° c .. Cone, 0 ,338 millimolar.

0 ,ii?l 1,000 35 .367 O.62U 5o ,333 0 ,5 0 2 65 .310 0 ,hl9 85 .27U 0.239 107 .251 0,216 Où .194 0.000

Graphically de te rmined k^l.Ul x 10"^

Temp. U9.3 ^ . 05OC.. Gonc. 0 ,3 6 8 millimolar. 0 .510 1,000 61 0.810 120 ,Ul2 0 .6 7 3 216 .358 O.L92 28=^ . 32L 0.380 350 .300 0 ,2 9 9 00 .211 0,000

Graphically dete rmined k ^3.L6 x 10-3

Temp, 39.63: .o 5 ° c .. Cone 0 O.U9O millimolar.

0 .671 1.000 220 .595 0.805 L?5 .5 1 6 0 .6 0 2 1135 .kP9 0.379 1555 .395 0 ,2 9 2 20 .353 0.000

Graphically determined k =1,01 x 10“^ 13^ Table XXIII

Rate of Isomerization of li-(Piperidine sulfopyl) Azobenzene in Benzene at 62.3°, U9.3°, 39.6°, and 3k.3°.

Tjpie (min.) O.D. (lUtOmn) Fraction cis

Temp. 62»3±.o5°C.. Cone. 0*3UU millimolar.

0 J*96 1.000 10 .459 0.873 20 .Ui4 0.720 31 .369 0.505 iiO .339 0.463 So .311 0.366 66 .279 0,257 81 .254 0,170 PO .204 0,000

Graphically determined k .-2

Temp. U9.3d: .05°G.« Gone* 0.4ll millimolar.

0 .596 1.000 35 .549 0,869 60 .511 0.763 120 .443 0.573 216 .366 0.359 285 .330 0.259 350 .305 0.190 CO .237 0,000

Graphically determined k % 10-3

O Tarap* 39.6 ±. 0.5 C«., Cone, 0,390 millimolar.

0 .559 i.o n o 115 .513 0.796 205 .)i85 0 .668 285 ,465 0.582 Uo5 .439 0.474 5oo .425 0.322 6 3 5 .400 0,316 oo .225 0,000

Graphically determined ktl.61 x 10 Table XXIII (contd.) 136 Temp. 3 1 : . 3 ± .05°g., Cono. O.U^D millimolar.

0 ,6U 8 1.000 2hS .579 0.822 1000 .U27 0.U30 1135 . i m 0.390 lU77 .37k 0 .29k cO ,260 0,000

Graphically determined k=- 8.30 x 10 Table XXIV 137

Rate of Isomerization of It-(Dimethylsnlfamoyl)azobenzene in Benzene at 62,1°, U9.3°, and 39.6°,

Time (min,) 0,D, (I&38mn.) Fraction cis

Temp, 62.ij: ,0^dc.. Cone, 0.391 millimolar.

0 1,000 10 .2ip 0,912 20 ,U39 0 , 6 7 7 .337 0 , 3 6 3 6 0 .297 0,2U0 80 ,262 O.llil oo .219 0.000

Graphically determined k - 2,6f

Temp , U9 .3 * „05°G , ^ Cone . 0 .h6ii millimolar.

0 .612 1.000 6p .227 0.779 100 .201 0,637 l60 .133 0,263 220 ,371 0.308 3l0 .320 0.180 .2L9 0.000

Graphically determined k = 2 .2;

Tempo 39 .6 ± ,05°Go , Cone. 0 . 3 9 2 millimolar.

0 .260 1.000 120 .211 0 . 7 9 2 210 ,b80 0.629 290 ,U6i 0.279 Ulo oL32 0 .U68 ^0^ 0U 21 0.318 6ItO .399 0.312 .322 0.000

Graphically determined k ^1,69 x 10 Table XXV 138

Bate of Isoraerization of U-(Dimethylsulfamoyl)azobenzene in 95-Percent Ethanol at 6 2 .2 ° , 6o.l°, U9.3°,and 39.6 0.

Time (min.) O.D. (U38mu) Fraction

Temp. 62.2 t.05°C. . Cone. 0,382 milHmolar,

0 .5 2 5 1.000 20 .U58 0.79k 30 .Ul5 0.661 U5 .366 0.511 75 .301 0.310 105 .258 0.179 <30 .200 0.000

Graphically determined k - 1 .91

Temp. 60.1 ± . 0 5 ° C . ^ Conco 0,1|U3 millimolar. 0 .597 1.000 20 .523 0 .79k 50 ,k29 0.532 70 .382 O.kOl 105 .330 0.255 00 .238 OoOOO

Graphically determined k = 1 .3,

Temp. L9.3 ±.05°C. Gone. O.U16 millimolar. 0 .580 1.000 65 .509 0.803 160 .LJO 0.583 285 .351 0.363 365 .320 0.279 525 .276 0.155 00 .221 0.000

Graphically determined k = 3,56 x 10 ^ Table XXV (contd*) 139

Temp* 39.6 ± .OS°C. ^ Conc, 0«U6l millimolar.

0 .b6o 0.000 l 60 .b39 0.881 6o5 .377 0.531 130b .325 0.235 1715 .310 0.152 oo .283 0.000

Graohically determined k =l.lU x 10 ^ Table XXVI li^O

Rate of Isomerization of 3-(Piperidinosnlfonyl)azobenzene in 95-Percent Ethanol at 6 o . l ° , L9.3°, and 39-6°.

Time (min,) O.D. (I)-38mu) Fraction cis.

Temp. 6 0 . 1 -j: . 0 5 ° C Cono. 0 . 6 8 8 millimolar.

0 . 7 6 9 1 . 0 0 0 155 . 6 7 7 0 . 7 9 0 2 5 0 . 6 2 4 0 , 6 6 8 3 6 0 .567 0.537 5L2 .505 0.395 CO .333 0 . 0 0 0

Graphically determined k= 1,8C

Temp. 49.3 ± .05°C. . Cono. 0 . 5 9 6 millimolar.

0 . 7 0 1 1 . 0 0 0 735 .575 0 . 6 9 4 1 2 0 0 .512 0.540 IU8 O .487 0 . 4 8 0 2 1 9 5 . 4 2 1 0 . 3 2 0 3400 . 3 6 1 0.174 cO . 2 9 0 0 . 0 0 0

Graphically determined k- 5 .2 c

Temp. 39.6dL.05°C.. Cone. 0 , 6 3 3 millimolaro

0 .738 1 . 0 0 0 330 . 7 1 2 0.940 1305 .653 0 . 8 0 3 1 7 1 6 . 6 2 4 0.736 3 1 9 0 . 5 6 1 0 . 5 9 0 4 5 5 0 . 5 0 8 0.466 6185 .459 0.353 7 0 9 2 .437 0 . 3 0 2 0 0 .307 0 . 0 0 0

Graphically determined k= 1,71 x 10“^ Tabla XXVII lUl

Rate of Isomerization of 3-(Piperidinos-ulfonyl)azobenzene in Benzene at 6 0 . U9.3'^, and 39.60.

Time (min.) O.D. (U38m~u) Fraction cis

Temp. 6 0 . 1 ±.0$OC.. Cone. 0,609 millimolar.

0 . 7 U1 1.000 80 .636 0.759 155 .552 0.568 2$0 M 72 0.365 310 .hko 0.311 360 ,hl3 0 .2 5 0 00 . 30U 0.000

Graphically determined k =3.9'

Temp 0 h9.3 i- .0 5 °C . 0,58ij. millimolar. 0 .7 1 3 1.000 300 .613 0 .7 6 2 735 .L83 0.b56 loUo .L 23 0.315 1200 eh06 0 .2 7 5 1380 .382 0.219 lb80 .368 0.185 CO .28b 0.000

Graphically determined 1.1!

Temp. 39.6 —.OhOC <> ^ Omnc. 0 .5 7 5 millimolar. 0 .7 2 0 1.000 338 .6 6 9 0.913 1293 .568 0.659 1737 .515 Oo5bo 27 L6 .bb3 0.380 3 1 9 6 .U19 0 .3 2 6 4296 .3 7 2 0.220 0 0 . 27 b 0.000

-U G raphically determined k = 3.56 x 10' Table XXVIII lU2

Rate of Isomerization of 3-(DimethyIsulfamoyl)azobenzene in Benzene at 6 2 .3 0 , U9 .3 0 , and 39,60.

Time (min.) O.D. (Ij.38mii) Fraction cis

Temp. 6 2 .3 Cone. 0 , 5 9 2 millimolar.

0 .707 1 ,0 0 0 60 .606 0 .7 6 6 130 .509 0 . 5U1 180 .L56 0.1/19 2iiO M il 0 . 31U 330 .362 0.201 00 .276 0.000

Graphically determined k = 5 .Of

Temp. U9.3 -.o3°0«. Cono. 0 ,5 1 6 millimolar. 0 .616 1.000 30 .607 0 ,9 7 6 735 .U08 0.L53 880 .377 0 .3 7 1 ioU 5 .351 0 .3 0 2 1186 .331 0 .2 5 0 .306 0 . 18L 0 0 .236 0 .0 0 0

-3 Graphically determined k -1 .1 5

Temp. 3 9 0 6^ . 0 5^0 0 . Gone 0 Oo53Umillimolar.

0 ,639 1 .0 0 0 10b2 0 .6 9 8 IU 70 IC72 0 .5 8 0 25o5 .Loo 0 .Loo 2920 .368 0 ,319 U500 .312 0 .1 7 8 CO . 2L1 0.000

G raphically determined k =z3.9L x 1 0 ” ^ Tabla XXIX lU3

Rate of Isomerization of 3-(Dimethylsuifamoyl)azobenzene in 95-Percent Ethanol at 62.1°, U9*3°, and 39.6°.

Time (min.) O.D. (L38mu.) Fraction cis.

Temp. 62.1±.o5°C.« Gone, 0,565 millimolar.

0 . 6 9 5 1.000 35 .66U 0.928 95 . 6 1 6 0 . 8 1 6 lU5 .562 0 . 6 9 0 2U0 . 5 0 2 0.591 350 .iiU6 0 . 5 2 0 oo .265 0.000

Graphically determined Ic =2,5U x ■>— 3

Temp. U9.3±.05°C„^ Gone. O 0U8 9 millimolar. 0 .595 1.000 735 .573 0.658 880 .550 0 . 5 9 5 ioU5 .530 0.538 1187 .507 . 0.575 lii35 .393 0 .535 2200 .331 0 . 2 6 0 26L5 . 3 0 9 0.199 00 .238 0.000

Graphically determined k = 6.25 X ~h

Temp. 39o6±.05°C.. Cone» 0.579 millimolar. 0 .712 1.000 10U2 . 6 3 6 0.825 1U?0 . 6 0 8 0.759 25o5 .559 0 . 6 2 2 U200 .570 0.550 5^15 .529 0.356 o o .280 0.000

Graphically determined k - 2.00 X Ihk Table XXX

Rate of Isomerization of 3-Nitro-ü-methylazobenzene in at 62.1°, U9.3®, and 39.6°.

Tima (min.) O.D. (L35imi) Fraction cis

Temp. 62.1i.O^°G,. Cone* 0*638 millimolar (calcd.).

0 .792 1.000 $0 .6 U9 0.791* 100 .570 0 * 5 2 5 ISS *U76 0*322 2 1 5 *U2l 0 * 2 0 5 290 .377 0*111 oa ,326 0.000

Grî.phically determined S.!

Temp. U9e3 a:.0S°C.. Gone, Go588 millimolar (calcd.)*

0 *7^6 1*000 1 2 5 .652 0.798 250 .597 0 *662 U90 .U92 0 .1*27 ^ 6 0 0U6U 0 . 3 6 3 700 .Ü31 0.288 800 *Uli 0.2Ü3 i o5o .373 0.158 op .303 0.000

Graphically datcrmined k =lo78 k 10“

Tamp a 39c6- iOS c », Conco Oo5?ii millimolar (calcd«) o?20 1 oOOO 2$0 .637 0.805 700 .605 0 * 7 2 9 1000 .563 0.631 1700 f.a35 0 a'41*7 2200 .I4U 2- 0 .31*7 32^0 o38U 0 . 2 0 9 ii500 .31*3 0.112 cQ .295 0.000

G raphically daternrlned k- I1088 x 10"^^ Table XXXI

Rate of Isomerization of 3*Nitro-ü*-m0tbylazobanzene in 9$-Percent Ethanol at 62.1°, U9.3°, and 39.6°.

Time (min.) O.P. (h3$imi) Fraction cis

Temp. 62.1-^.o5°C.« Cone, 0.^17 millimolar (calcd,).

0 .697 1.000 So .633 0.851 155 ,U35 0.503 215 .h3k 0.389 290 .33ii 0.273 iiW .322- 0.13U 09 .267 , 0.000

Graphically determined k - <

Temp. ii9.3:£ .05°C,, Gone. O 0U19 millimolar (calcd.)•

0 .5UU 1.000 220 0^72 0.792 U75 oij-OU 0.580 955 .328 0.360 1185 .305 0.292 1800 .266 0 0 1 5 1 op .220 OoOOO

- Graphicall.y determined k ^ ; 3

Tempo 39,6 ± .05^0.g Gone o OaUl5 millmolar (calcd.).

0 .560 1.000 85o .ii?8 0. 7 6 2 2250 .385 0 .U91 30U0 .335 0.3U? Uooo .305 0. 2 6 0 5000 .280 0.188 7125 .250 0=100 PO .215 0.000

G raphically do te m ined k iz 3.2)j % 10 1U6

Tâbid XXXIX

Rate of Isœnerization of ii»-Sulfamoylazobenaene in P^-Peroent Ethanol at 39.6®t.o5®C,

Cone» O.ijoU millimolar.

Time (min») O.P. (UitOnm) Fraction eia

0 •U89 1.000 »as6 0.876 10^ ,UU6 0.839 32^ »U22 0.7U9 610 .386 0 . 6 1 3 lUl^ »31U 0 .3UI 17^0 .292 0 . 2 5 9 oo .223 0.000

Graphically detormined k=7»05 x 1 0 " ^ lU7

Table XXXIII

Rato of Isomerization of 3-Snlfamoylazobenzena in 95-Parcant Ethanol at 39.6 ® i .05°C.

Cone. 0.5S6 millimolar.

Time (min*) O.D. (iUUOnm) Fraction cis

0 .5ii5 1.000 ll6 0 0 . 6 9 0 liil5 .1:20 0.632 2ii30 .361 0.1:59 30kS .333 0.377 3955 .299 0 . 2 7 6 5000 .273 0, 2 0 0 GO .205 0 . 0 0 0

Graphically determined k 3 «,22 x 10"'^ Table XXXIV ifiS

Rate of Acid Catalyzed Isomerization of cls-Azobenzene in Benzene at Different Concentrations of Hydrogen Chloride at 39*6®C. (ci^-Azobenzene cone* 0 * 6 7 5 millimolar)

Time (min.) O.D. (liUOrau) Fraction cis

Cone, of hydrogen chloride O.OU? millimolar.

0 ,775 0,913 120 .723 0.3U2 315 ,61;U 0,702 5 6 5 .609 0.622 625 .570 0,531} 1305 .152 0.266 1575 oUl9 0,190 00 .335 0,000

Graphically determined k = 1.03

Gone, of hydrogen chloride 0*053 millimolar.

0 .795 1.000 hi .780 0 . 9 6 7 170 .10k 0 . 8 0 3 350 .660 0,608 537 .581} 0 . 5 Ü 2 lU02 .1}30 0.210 1690 oh03 0 . 1 5 1 00 ,33U 0,000

Graphically determined k= 1.12 10=

Cone, of hydrogen chloride 0,093 millimolar,

0 .818 1,000 Ù5 .799 0.950 90 .769 0,381 16 0 .715 0,771 320 .655 0,61*9 Il6 0 J}35 O.20 U 1395 al}10 0.151 Où o33ù 0.000

Graphically determined k -lo37 x 1 0 ” ^ 1Ù9 Table XXXIV (contd.)

Time (min.) O.P. (hhOma) Fraction fils

Cone, of hydrogen chloride 0*222 millimolar.

0 .806 1.000 125 .675 0 .8 6 0 278 .568 0.697 505 .U6l O .W l 800 .398 0 .1 3 0 00 .33U 0.000 Graphically determined k= 2.58 x 10 -3

Jonc, of hydrogen chloride 0.U66 millimolar.

0 .80U 0.957 30 .7Ul 0,8 3 0 U5 .699 0.738 65 . 6 7 U 0.687 90 0632 0 .6 0 2 126 .586 O.51U l6 o .537 o .U io 190 .5 2 0 0 .3 7 6 320 ,hhl 0.215 •oo calcd. .3 3 6 0.000

Graphically determined k = ii.BÇ? x

GonCe of hydrogen chloride 0.93 railliinola.r„

0 .7 9 6 0 .9 3 5 15 ^7h3 0.826 30 .6 8 0 0 .7 0 0 U5 .631 0 .6 0 0 65 .581 0 .5 0 0 90 .531 o.Uoo 126 .182 0 .3 0 0 160 .U35 0 . 20U 00 .335 0 .0 0 0 - 3 G raphically determined k-zL 9.65 x 1C 1^0

Table XXXIV (contd»)

Time (min*) O.D. (UltOniu) Fraction cis

Conc* of hydrogen chloride 2,30 millimolar*

0 .788 0.913 21 .637 0.600 31 .566 0 .L9 L hS .511 0.339 60 .U6l 0 . 2 3 5 81 .U20 0.150 oo .3ii8 0.000

Graphically determined k >-2

1 chloride U .60 millimolar.*

0 .738 0.810 21 .530 0.377 31 oU6 l 0. 2 3 5 hS .L0 2 0.112 oo „3h6 0,000 —2 Graphically determined k ^Uo8l x 10“

Conc, of cis-Azobenzene Oo702 milliniolar I5i Table XXXV

Rate of Acid Catalyzed Isomerization of cis-Azobenzene in Benzene at Different Concentrations of Hydrogen Chloride at 1a9«3®C, (cis-Azobenzene conc. 0.720 millimolar)

Time (min,) O.D. (UitOmu) Fraction cis

Conc, of hydrogen chloride 0*C66 millimolar.

0 .687 1,000 5^ .823 0.881 23 < .672 0.600 385 •570 O.klO 6Uo .i»8l o.eUit 850 ,i42? o.iii5 oo .350 0,000 Graphically determined k = 2,29 % 10“’’^

Conc, of hydrogen chloride 0,096 millimolar,.

0 .870 1,000 Uo .795 0 .8 5 5 105 .719 0 .7 0 8 230 .6o8 0»k9h L35 .500 0 .2 8 5 6 i5 oli38 0 . 1 6 5 CO .352 r\ r\r\r\

Graphically dat-ermined Ic = 2,

Conc, 1 Ohio rids 0.38U millimolar.

0 .880 1,000 ho .770 0.791 65 .720 0,696 ].25 .619 0 .5 0 5 200 o53U 0 , 3 h 3 375 eU23 0 ,1 3 0 CO .353 0,000

Graphically determined k = 5 , - 3 152

Tabla XXXV (contd.)

Time (min.) O.D. (itUOafu) Fraction cis

Gone, of hydrogen chloride 0.6^9 millimolar.

0 .880 1.000 37 .710 0. 6 7 7 78 .619 0 . 5 0 5 122 .51+0 0 . 3 5 6 1 9 7 .ii59 0.2 0 0 o o .351+ 0,000

Graphically determined k=:7o70 x 10'-3 153

Table XXXVI

Rate of Acid Catalyzed Isomerization of cis-Azobenzene in n-Heptane at 39*6°C.

Time (m3.n,) O.D. (UigOimi) Fraction cis

Conc. of hydrogen chloride 0,22 millimolar, Conc. of cis-Asobenzane 0.733 millimolare

0 .6U5 0.853 10 .588 0.701 19 .550 0.600 36 .515 o.5c6 56 .1(85 0.1(26 7k Ji71 0,387 15U .1(36 0.295 35Ü .399 0.198 oo .325 0.000 Table XXXVII iSk Bate of Acid Catalyzed Isomerization of cis—3—Nltroazobenzene Benzene at Different Concentrations of Hydrogen Chloride at 39

Time (min.) O.D. (iiiiOnm) Fraction cis

Conc* of hydrogen chloride 0.09 millimolar. Gone, of cis»3—Nitroazobenzene 0,75 millimolar.

0 .828 1 ,0 0 0 70 .7 8 8 0.917 130 .? 6U 0 ,8 6 8 25o .719 O.77I4 Ul5' .688 0 ,6 6 8 580 .633 0 , 5 9 6 1260 ,519 0 ,3 6 0 1530 .1:93 0 ,3 0 6 1700 .1:7^ 0.268 2100 ,1436 0 . 1 9 0 oo ,3kk 0.000

Graphically determined k = 7,814 x ]

Gone, of hydrogen chloride 0,18 millimolar. Gone, of cis«3~NitroaaobsRzene 0,75 millimolar,

0 .825 1.000 70 o 7 6 3 0 . 8 7 1 130 .7 2 5 0 .7 9 2 185 .691 0 . 7 2 2 250 ,668 0.6714 a i5 .596 0 ,5 2 5 580 o5l4l 0 ,M o 1260 .1:21 0.161 1530 .395 0 .1 0 8 CO .3 I4I4 0.000

Graphieally d@terminée k=.lo^3 z: 10”^ 1^5 Table XXXVII (c ontd•)

Time (min,) O.D. (WiOimi) FracldLon cis

Conc. of hydrogen chloride 0,37 millimolar, conc, of cis—3—Nj-broazobenzene 0,73 millimolar.

0 .762 1,000 20 .720 0,90U IS .680 0.813 70 .65U 0.753 110 .610 0,652 18S ,560 0,538 250 ,520 0.UU5 310 .U90 ' 0.378 Ul7 ,U6o 0,309 600 ,U23 O.22U oo ,325 0,000

Gone, i chloride 0,7^ millimolar, conc .troazobenzen 0,b73 millimolar.

0 .795 1,000 20 .725 0.850 US .665 0.720 70 ,625 0.63U 110 ,56U 0.503 135 0U90 o,3UU 250 .USo 0.257 310 0U29 0.21U Ul7 ,U02 0.155 CO ,335 0,000 1$6

Table XXXVIII

Rat© of Acid Catalyzed Isomerization of cis—U—Nitreazobenzene in Benzene at Different Concentrations of Hydrogen Chloride at 39*6°C,

Tinte (min») O.D. (UiiOma) Fraction els

Conc, of hydrogen chloride 0,16 millimolar, conc, cis-U~Nitroazobenzene 0 . ^ 0 millimolar.

0 .721 1.000 15 .630 0.79ii 35 .538 0. 5 8 5 55 ,ii69 O.iilé 65 .U3U O.3U9 90 .39a 0.237 120 .3Uli 0.lii6 OO ,280 0.000

Graphically determined k ^ 1,63 x 10 -2

Conca of hydrogen chloride 0,33 mil]imolar, conc, of cis-ii—Nitroasobensene OaSO milliraolar.

0 ,721 1.000 15 .623 0.778 35 .533 0,573 55 aii6l O.llll 6? ck28 0 . 3 3 6 9 0 .365 0.250 oO> .280 0.000

Graphically dctormin■ed k =-1

;en chloride 0,82 millimolar. conc a .Nitrcasobenzens 0.53 millimolar,

0 .770 1.000 12 ,66ii 0.770 33 .552 0 , 5 2 6 53 ,189 0, 3 9 0 79 .Ü37 0. 2 7 8 103 ,Ul3 0,226 oO .309 0.000 15? Table XXXIX

Rate of Acid Catalyzed Isomerization of cis-A zobenzene (0.6?5 millimolar) in Benzene at 39*6®C. in the Presence of Anisole (0.70 millimolar).

Time (min.) O.D. (l^iiOmu) Fraction cis

Conc, of hydrogen chloride 0*58 millimolar.

0 .760 1,000 20 ,6U5 0 .7U1 85 .538 0,500 175 .iUtO 0,281 290 .380 oaU 5 350 ,358 0.100 oO ,315 0,000

Graphically dotermined^6.05 x 10~ 108

Table XL

Rate of Acid Catalyzed Isomerization of cia-Azobenzene in Benzene in the Presence of Nitrobenzene at 3?,6^0,

Time (mine) O.D. (lUiOmu) Fraction cis

Conc* of hydrogen chloride 0,h9h millimolar, conc, of cis-Azobenzene 0,720 nriLlUmôlar, conc, of Nitrobenzene 1,90 millimolar*

0 .733 0.811 80 .628 0 . 0 8 1 170 .07U O 0I46U 200 .022 0.300 0ii0 .iiUl 0.173 oo .361 0*000

Graphically deternD.ned k = 3,00 1^9 Rate of Acid Catalyzed Isomerization of cis-Azobenzene (0*338 millimolar) in Benzene at 39*6^0. in the Presence of trane-m-Nitroazobenzene (0,633 millimolar)

Time (min.) O.D. (iiUOmu) Fraction cis

Conc. of hydrogen chloride 0.09 millimolar.

0 .671 1.000 .653 0 . 9 1 5 120 .636 0.836 31< .591 0.638 .571 0.530 62^ .55h 0.U50 130 ? .U99 0 . 1 9 2 OO ,U58 0.000

Graphically de te mined k = 1.23

hydrogen chlord.de 0 .18 laillimolar

0 .670 1.000 hS .6140 0.851 120 .609 0.698 2iiO .57I4 0 . 5 2 5 31^ .560 0 .555 Ù05 .533 0 . 3 2 0 625 ,510 0 . 2 0 6 CÂ ohSh OoCOO

Graphically determined k =. 2,36

Conc a hydrogen chloride 0.21 millimolar.

0 .680 loOOO 27 .659 0 . 9 1 0 52 .6 U0 0.828 115 .608 0 . 6 9 0 170 o58l 0.575 212 .567 0.512 290 .5)i5 0.519 537 .i'-98 0 , 2 1 6 oO 0,000

Table X U (contd*)

Tima (min.) Q.P. (IdiOmu) Fraction ois

Conc* of hydrogen chlorido 0*53 millimolar.

0 ,680 1 . 0 0 0 27 .638 0*819 52 .601 0 , 6 6 0 115 *5U2 0.);05 170 *512 0 . 2 7 5 212 •h9^ 0*201 290 Ji79 0 . 1 2 7 00 0,000

.3 Graphically de te r m ne d k = 7 *59 10 ' l6l Tabl.e XLII

Rate of Acid Catalyzed Isomerization of cis-^aobenaene (0,358 millimolar) in Benzene at 39«6"C. in the Praaence of trans-p-Nitroazobonzene (0.550 millimolar) .

Time (min.) O.D. (UUObiu) Fraction cis

Conc. of hydrogen chloride O.lBO millimolar,

0 ,730 1 ,0 0 0 30 .710 0.916 30 .6 9 9 0 .8 7 1 lUo .6 7 7 0 ,7 7 9 265 06Û9 0 . 6 6 2 UÔ5 .6 1 0 0 ,5 0 0 6 5 5 .588 0,U07 1000 ,5 5 0 0 ,2 5 1 00 .U90 0 ,0 0 0

Graphically doterridned k = ls3? :c 10*“"'

Gonco of hydrogen chlo'cide 0,725. luillimolar.

0 .731 1.000 30 .687 0.821 8 0 .659 0.665 lUo 061.9 0 ,5 5 2 265 .570 0o353 565 .526 0 .1 6 2 00 .586 OoOOO

Graphically de terrai ne d k -3 : 0 “ -> 162

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AUTOBIOGRA.PHT

I, Melvin Kaplan, was b o m in Brooklyn, New York, November 11,

1 9 2 7 * I received my secondary school education in the public schools of New York City, I attended Brooklyn College for one year before I was drafted into the United States Array Air Force. After one year of diversified duty in service Ï returned to Brooklyn College, where I received my Bachelor of Science in Chemistry in 1950, I was admitted to the Graduate School at The Ohio State University in the summer of

19pO® While congèle ting the requirements for the Degree of Doctor of

Philosophy, X held appointments as Research Fellow under Research

Foundation Grants (19?1~1952« 1953-195U) and an Alumni Association

Development Fund Grant (19^2-1953)*