THE MECHANISM COT LIQUID PHASE HITRATICW 07 ALIPHATIC Hnsocabboib

THE MECHANISM COT LIQUID PHASE HITRATICW 07 ALIPHATIC HnSOCABBOIB

DISSERTATICW

Preaented In Partial Pulflllnent of the Requireaenhe for the Degree Doctor of Fhiloeophj In the Graduate School of The Ohio State Ufaiveraity

DEVTN KLHG BRAIN, B.S., M.S. The Ohio 3-tate TMlrereity 195^

Approved hy: i

ACKHCMIJnxaMBnS

The author wishes to express his sincere appreciation to

Professor Harold Shechter for his suggestions, encouragement, and faith during the course of this investigation.

The author gives his undying gratitude to his wife for her sense of humor, assistance, and self-sacrifice without which the fulfillment of this degree would not have been possible.

The author extends his gratitude to Dr. Kenneth M. Greenlee who so willingly supplied several hydrocarbons which were used in this research.

* , ' U u H 5 li

TABLE OF CONTENTS

Page I. STATEMENT OF FRCBLEM ...... 1

II. INTRODOCTIOH...... 2

A. Historical of Nitration in the Liquid Ph a s e ...... 2

B. Mechanisms of Substitution Reactions ocf Saturated Hydrocarbons...... 9

III. DISCTSSIOH OF INVESTIGATIOH AMD R E S U L T S ...... 25

A. Nitration of (*) -3-Methylheptane and (f) — 3-Methylheptane 2 5

x». Nitration of Commercial, Cls , and Trans-Decalin 32

C. Nitration of Cls and Trans - Hydr indane 4c

D. Conclusions U6

IY. EXPERIMENTAL...... ^9

Resolution of (-)-2-Ethylhexanoic Acid ^9

Preparation of (-)-Ethyl 2-Ethylhexanoate 50

Preparation of (-)-2-Ethyl-1-hexanol from (-)-2-Ethyl 2-Ethylhexanoate 50

Preparation of (-)-2-Ethyl-1-hexanol from (-)-2-Ethylhexanoic Acid 51

Preparation of (-)-l-Brcmo-2-ethylhexane 52

Preparation of (-)-3-Methylheptane 52

Purification of (-)-2-Methyl- 1-butanol 53

Preparation of (»)-l-Bromo-2-methylbutane 54

Prepara tion of (•»■)-5 -Methyl-1-heptane from Allyl Magnesium Bromide and (*■) -l-Brcmo-2-me thy lb utane 55

Preparation of (♦)-5-Methyl-1-heptene from (♦ )-2-Methyl-l-butyl Magnesium Bromide and Allyl Bromide 57 i n

TABLE OF COWTHITS (Continued)

Page Preparation of (*■)-3-Methylheptane “ ■S

Nitration of (♦)-3-Hethylheptane 6l

Reduction of (I)-3-Methyl-3-nitroheptane Obtained from (i)-3-Methylheptane 63

Preparation of N-Phenyl-N,-3(3-E»et.hylheptyl)thiourea from (l)-3-Amino-3-methylheptane Obtained from (i) -3-Methylheptane 64

Nitration of (* )-3-Methylheptane 64

Deduction of S-'Methyl-S-nltroheptane Obtained from (♦)-3-Methylheptane 67

Preparation of N-Phenyl-N1 — 3(3—methylheptyl)thiourea from 3-Amino-3 -methylheptane Obtained from (+)-3-Methylheptane 68

Nitration of Commercial Decalln 69

Reduction of 9"®l'b*‘odecalin Obtained from Commercial Decalln 71

Preparation of N-9 -Decalylacetamlde from 9 -Amlnodeoalln Obtained from Commercial Decalln 72

Nitration of Cls-Decalln 73

Reduction of 9 -Nltrodecalin Obtained from Cls-Decalln 75

Preparation of N-9-Decalylacetamlde from 9 -AminodecalIn Obtained from Cls-Decalln 75

Nitration of Trans-Decalln 76

Reduction of 9-Nitrodecalln from Trans - Decalln 77

Preparation of N-Q-Decalylacetamlde from 9 “Aminodecalin Obtained from Trans-Decalln 78

Nitration of Cls- Hydrlndane 79

Reduct 1 on of 8 -Nltrohydrlndane Obtained from C 1s- Hydrlndane 8l It

TABLE OF CONTENTS (Continued)

Page Preparation of N-8 -Hydrindylacetami Ae from 8 -Amlnohydrlndane Obtained from Cls-Hydrlndane 82

Preparation of N-8 -Hydrindylbenzamide from 8 -Amlnohydrlndane Obtained from Cla-Hydrlndane 82

Nitration of Trans-Hydrlndane 83

Seduction of 8 -Nitrohydrindane containing ^--N1 trohydr 1 ndane as Impurity 85

Preparation of N-8 -Hydrlndylacetamlde from 8 -Amlnohydrlndane and N-4-Hydrindylacetamlde from U-Aminohydrindane Obtained from Trans-Hydrlndane 85

Preparation of N-8 -Hydrindylbenzamide from 8 -Amin ohydr indane and N-4-Hydr Indy lbenz amide from U-Amin ohydr Indane Obtained from Trans - Hydrlndane 86

Preparation of Pure 8 -N1 tr ohydr Indane from Trans - Hydrlndane 87

Reduction of 8-Nitrohydrindane Obtained from Trans- Hydrlndane 8 8

Preparation of N-8 -Hydr Indy lac etamlde from 8 -Amlnohydrlndane Obtained from Trans - Hydrlndane 8 9

Infrared Analysis of the Nitrate Ester Impurity 9°

V. S T M I A R Y ...... 92

VI. B I B L I O G R A P H Y ...... 9k v i i . A p p m r o i x ...... 97

Tables I through VII. 97

Infrared Spectra, Figs. 1 through 2k. 105 MECHANISM CT LIQUID PHASE NITRATION OF ALIPHATIC HYIROCARBORS

I. STATPCHT OF PRCBLP4.

A surrey of the present literature produced so little evidence con

coming the liquid phase nitration of aliphatic hydrocarbons that it

has been impossible to reach any conclusions as to the reaction mechan

ism. Since the substitution reaction Is an important one, the present

work was initiated in order to provide some experimental evidence upon

which a mechanism might be established.

The first approach to a solution of this problem involves the

liquid phase nitration of the optically active hydrocarbon,

(*■ )-3-methylheptane. An investigation of the stereochemistry of the

reaction (racemization, inversion, or retention) in which the tertiary

hydrogen of the asymmetric carbon atom is substituted by a nitro group will possibly provide considerable insight as to the path of nitration.

A study of the stereochemistry of the 9-nitrodecallns and 9,10-di-

nltrodecalins resulting from the nitration of commercial, cls and trans

decalins was also projected to provide information concerning the mech

anism of liquld-phase nitration. By comparison of the physical proper

ties and Infrared spectra of the products and by comparison of their derivatives, It might be possible to relate the stereochemistry of the products to each other and with the initial hydrocarbons.

An investigation of the stereochemlstxyr of nitration of cls and trans-hydrind* was also proposed. The relative configurations of the products obtained by nitration of the tertiary positions, 8 -nltro- 2 hydrindanes and 8,9~d ini trohydr indanes, can possibly be determined from their physical, chemical, and spectral properties and fran properties

of appropriate derivatives. It vas also anticipated that the stereo chemical results obtained from this system can be compared vith that obtained from (* )-3-me thylheptane and from cls and trans-decal Ins , and sufficient conclusions be dravn to establish a basis for a reaction mechanism.

II. IHTROPOCTION.

A. Historical Bexley of Nitration in the Liquid Phase.

The mechanism of nitration of saturated hydrocaxtoons in the liquid phase is, as yet, not clearly understood. The published material in this field has been inconclusive because of the lack of continuity

In the various approaches to the problem and because of the inaccurate evaluation of the structures and compositions of the nitration products.

At the present time there are a feu basic ideas vhich have been gener ally accepted that may be used for a foundation of a possible mechanism.

In 1895, Konovalov* nitrated various normal and branched chain saturated hydrocarbons vith dilute nitric acid (sp. gr. 1.075)• From the structure of the products Isolated he deduced that the tertiary hydrogen atoms vers more easily replaced than the secondary hydrogen atoms, and the secondary hydrogen atoms vere more readily removed than the primary atoms. For example, treatment of 2,7 -dimethyloctane vith dilute nitric acid at 1 2 0 -1 2 5 ° produced a mixture of nitrated products vhich vas claimed to be 60)6 tertiary moncnltroa 1 fcane even thougi the primary and the secondary hydrogens outnumbered the tertiary 3

(1 ° : 3° ■ 6:4:1). Furthermore , Kursanoff^ round that nitration, of

phenylcyclohexane vith 30% nitric acid gave 1 -phenyl-l-nitrocyclohexane

as the principal product. In this instance there vere ten secondary

hydrogens competing vith the one tertiary hydrogen; the tertiary hydro

gen atom, however, might have been activated by the substituted benzyl

group.

Markovnikcf f ^ obtained 2 ,2-dimethyl-3-nltrobutane upon nitration

of neohexane (2 ,2 -dimethylbutane) vith dilute nitric acid (sp. gr.

I.2 3 5 ) at 100°. Ho products vere detected vhich resulted from the

rearrangement of the carbon-skeleton of neohexane as might be predicted

if the reaction Involved a carbotnlum lan Intermediate; however, a

thorough investigation of the yield and by-products of nitration vas

not made.

Hametkin has reported that nitration of camphane ( I , isocamphane

(II)7 , and camph any lane (III) vith dilute nitric acid yields only the CM

CMCH

i n m respective secondary nltro derivatives along vith considerable quantities

of ketones some dibasic acids. In formation of the secondary nltro

compounds, no rearrangements of the Wagner-Meervein type vere observed.

Ho compounds could be Isolated In vhich the nltro group vas attached to a bridge-head position (a tertiary position). It is surprising however,

that nitration of is ocamphane does not form the tertiary nltro compound

in vhich the nltro group is not attached at the bridge-head positions. u

There hare been various mechanisms postulated In later work to 7 explain these and other pertinent experimental resultants. Ingold has proposed that the nitration of an alkane is an electrophillc substitu tion on carbon, S^2 , vhich occurs in the foilowing manner:

_ .,*i

: ? ----- ^ R:N02* ♦ H:OH ' : OH”

This mechanism Is based primarily on the reactivity of the hydrogen atoms and the electrophillc nature of nitric acid. Since, in the nitra tion reaction, the hydrogens react in the order 3°> 2°>1°, Ingold assumes that the greater the electron density at any single carbon atom

(also 30 > 2 °p-l°) the greater the attraction there is for the strongly electrophillc reagent, nitric acid, and thus the faster the reaction will be at that position. Although the differences of permanent polar ity between the carbon atoms must be very small, there may be a decid ing factor in that an Induced polarity may be set up by the entering

NOg* group. "Those atoms will become most negative on the approach of the electrophillc reagent vhich vould permanently have been the most negative atoms had they been attached to a negative substituent."

Q Stevens and Schlessler propose that there are three possibilities

(neglecting kinetic considerations for the over-all processes) for the mechanism of nitration of paraffins. The first Involves the removal of hydrogen as a hydride Ion; the second requires removal of a proton; and the last Is the removal of a hydrogen atom. 5

HNOq ^ ♦ 1 .-- K 3C-H ------> K 3C * H

HHO1} — i 2. » 3C-H ---— 3— > R 3C f H

HNOo 3 .-- B 3C-H ---— 3— > R 3C* ♦ H*

They Bulgest "that the failure of neohexane to rearrange during the ni tration reaction eliminates the idea of hydrogen remoral as a hydride a ion. According to the general results of Whitmore a neo structure will he expected to rearrange if a carbonlum ion is an intermediate In the reaction. A mechanism based on remoral of a proton did not seem likely since tertiary carbon atoms, the positions of greatest electron density, are the ones most easily attacked. In an attempt by these authors to obtain information on the mechanism of liquid-phase nitration,

(-)-3-methyl octane was nitrated at 1 3 0 ° in a sealed tube with 18£ nitric acid for 12 hour's, to yield (-)-3~n>ethyl-3 -nitrooctane,

-O.6 5 ? Even though the rotation of the nltro compound was quite small, and the experimental results did not allow any conclusions on the stereochemistry of displacement and the extent of racemlzatlon In the reaction, the optical activity of the product was assumed to elimin ate the mechanism involving alkyl free radicals. This conclusion was based on the fact that the intermediate would be predicted to have a planar configuration. In consideration of this data and the fact that oamphane could not be nitrated on the bridge-head position, Stevens and

S chi easier postulated that substitution occurs by a one-step acceptor- donor inversion mechanism (analogous to an 3^ Ionic displacement reac tion )of the homolytlc type In vhich the hydrogen Is replaced as an atom 6

and stereo-speclf iclty of the asynmetrlc center Is maintained:

R0 2 * * C — H — > H 02n _ ^ " r - H-

Hass and R i l e y ^ , reinterpreting the results of Stevens and

Schlessler, propose that the reaction does not Involve free alkyl radi

cals and suggest the Aisplacement of a positive group, the proton, ac

cording to the proposal of Ingold. In their analysis, Hass and Riley

do not consent an the possible stereochemical Implications (Inversion

or retention) of their displacement mechanism.

In 19331 Huclcel and Blohm^, as part of a study of the stereo

chemistry of substituted decallns, prepared "9 -nitroAecalin". From

the nitration of trans-decalln, a 9 -nitrodecalln vas obtained vhich vas

shovn to be homogeneous since only one derivative vas obtained from Its

reduction product, 9-aminodecalin. These authors assigned a trans -

structure to the Q-aminodecalin and to the 9 -nitrodecalin obtained from

nitration of cossaerclal decalln. Since commercial decalln contained

primarily cls - decalln (65^), and since trans -9 -nltrodecalln vas the major tertiary nitration product, Huckel and Blohm proposed that the

nitration of cls- decalln proceeded primarily by Walden Inversion to

give the trane- product. They believed that this conclusion vas substan

tiated by the fact that, during the course of their experiments, they

found that the recovered commercial decalln vas richer In trans-Isomer

than the starting material. They neglected to consider, hovever, the

possibility that the cls -decalln might be Isomerlzed under the conditions 7

of 'the nitration to the more stable trans-Isomer. Since the nitration

of pure cls-decalln was newer undertaken, there was no way of knowing which form was undergoing more rapid nitration. These authors did not continue their investigation any further; thus, no conclusions con cerning the mechanism of displacement could be made. 12 Titov , an the basis of the ease of nitration of some saturated hydrocarbons and the side chains of trlphenylmethane, diphenylmethane, and toluene, In the presence of nitric acid and nitrogen dlooclde, sug gests that nitration Is a radical reaction, Initiated by the attack of the nitrating agent, nitrogen dioxide, on the hydrogen atom:

R-H * *NOg - ■■ > R- HROg

The alkyl radical may then react with various other radicals produced by the decomposition of nitric acid and thus give the observed pro ducts :

R* «- *NGot --- ^ KNO2 R* ♦ *W02 > ROWO

R* «• *liO > RNO

This mechanism was extended to Include other reagents such as dinltrogen tetraxlde, dinltrogen trlaxlde, nitric acid, and otxygsn:

R* * IfgO^ —— ROlfO * *NOg

R* *• H 2 ° 3 ■■■ RNO ’**0 2

> ROWO - *NO

^ HROg ♦ -NO

R* * HOHOg > ROB ♦ *R0 2

R* * Og ^ R0 0 * 8

This mechanism is substantiated by several experimental facts; for In stance, almost no nitration of saturated hydrocarbons occurs In the ab sence of nitrogen dioxide. Also, a correlation between the rate of ni tration and the radical concentration (nitrogen dioxide) vas found:

Thus, nitric acid, a good nitrating agent

In the aromatic series, has no function in the nitration of aliphatic hydrocarbons other than to act as a source of nitrogen dioxide. Further more , the nitration proceeds In the hydrocarbon phase (rather than the acid phase) where It Is essentially independent of the polarity of the medium and the presence of strong acids. Further evidence to support this proposal Is that trlphenylmethyl radicals react vith nitrogen di oxide to yield trlphenylnltrcmethaae and trlphenylmethyl nitrite.1^

It may be noted that this concept proposed by Titov resembles the mech anism postulated for the slow oxidation of hydrocarbons In the liquid phase by oxygen.

From a consideration of the activation energies for the removal of hydrogen atoms on a saturated carbon, Titov proposed a resonance theory of the hyperconjugation type for the stabilization of the free radical to explain the difference in rates for the substitution of primary, secondary, and tertiary atoms. The decrease In the activation energy for formation of the alkyl radicals (e.g., CH^-CH^ — > CH^CH^ H*,

• CHg—CH^ CBg — CHg * H* 9

Involving partial localization of the uncoupled electron on the hydro gens. As the branching on the carbon atom Is Increased, the resonance possibilities are enhanced (Et-H; 3 ; IPr-H:6 ; t-but-H:9; etc.), and thus the stability of the alkyl radical increases.

From this discussion, It is apparent that the available experiment al data is insufficient for any conclusions to be drawn concerning a mechanism for this reaction. Therefore, xhe following research was conducted so that some information concerning the mechanism of the liquid phase nitration of aliphatic hydrocarbons might be obtained.

B . Mechanisms of Substitution Reactions of Saturated Hydrocarbans.

Since more intensive investigations have been made into the mechanisms of some of the substitution reactions of saturated hydrocar bons (other than liquid phase nitration), a study of the experimental facts and conclusions from these reactions may provide further basis for the construction of a workable mechanism for liquid phase nitration.

Therefore, a short discussion of the pertinent facts concerning the more important reactions of this type will be given in the following para graphs. Xt should be noted particularly that the mechanism involving free alkyl radicals was considered to be the most logical mechanism for most of the reactions.

The mechanism of vapor-phase nitration of hydrocarbons has become an Important Issue in recent years because of the wide commercial success of the process. However, since the nitration may be affected with nitric acid, with oxides of nitrogen, or with these & 1 bra ting agents in the 10 presence of oxygen or bromine, It has been impossible to determine the exact pattern of the various decomposition, oxidation, and nitration re actions that are Involved. As a result of a series of Investigations, lU the following generalizations have been made to describe vapor-phase nitration processes:

1 . Ho carban skeleton rearrangements occur If pyrolytic tempera tures are avoided.

2 . Simple paraffins yield mononltro products.

3- Any primary, secondary, or tertiary hydrogen atom may be sub stituted. The rates are tertiary >secondary > primary. At higher tem peratures, these rates tend to become equal!.

1+. The nltro group may substitute any alkyl group in a paraffin with the more highly branched hydrocarbons undergoing less fission durlig nitration.

5 . Nitrogen dioxide and nitric acid yield identical products, but the acid gives better yields and higher nitration rates.

6. Oxidation accompanies nitration.

7. Nitration producing hydrogen substitution has a high activa tion energy. Reaction rates are greatly accelerated at increased tem peratures and pressures.

8 . The fission reactions resulting in displacement of alkyl groups become more Important at hl^ier temperatures.

9 . Total yields of nltro compounds do not vary greatly If exposure time and reaction temperature are carefully matched. 11

10. Heterogeneous catalysts accelerate oxidation rather than nitration. Nitration may be induced by the action of either oxygen, bromine, or chlorine; the efficiency of nitration is greatly Increased by addition of the induction agents.

It is generally believed^ that nitration resulting in replacement

of hydrogen atoms involves formation of intermediate alkyl radicals by hemolytic reaction of the hydrocarbon with hydroxyl radicals, nitrogen dioxide, nitric acid or any of the various oxidizing agents that are present In the nitrating mixture. If itroalkanes result from electron pairing of alkyl radicals with ’NOg or from exchange with nitric acid:

HCN02 < > HO* ♦ *N02

CH^-CH^ *■ * OH ■■ ■ ■ i CH^-CHg* *• HpO

CH^-CHg* ♦ *HOe (or H0NO2 ) ---- > CH-j-CHg-NOg ( * -OH)

The mechanism involving alkyl radicals is compatible with the generaliza tions that have been made and with the facts that: (a) reaction of tetraethyllead and nitric acid gives n i t roe thane and ethyl nitrate^;

(b) thermal decomposition of alkyl radicals results In olefins^ identi cal with those Isolated from nitration reactions; (c) tertiary alkyl radicals are formed more readily than secondary, and secondary more readily than primary^®; and (d) low nitration yields are obtained In the presence of nitric o x i d e ^ (nitric oxide reacts rapidly with alkyl radi cals; its function as an inhibitor for reactions involving chain sequences has been widely demonstrated). lV Nitration resulting in replacement of alkyl groups is believed to

Involve alkoxy radicals derived from (a) thermal decomposition of alkyl 12

nitrites and alkyl nitrates that are presumed to he formed and (h) com bination of alkyl radicals with oxygen and subsequent exchange vith the

parent alteane to yield alkyl hydroperoxides and additional alkyl radi

cals20:

CH^CHgCWOg uil ^CEgO * * *NOg

CH^CEgCWO - > CH^CHgO* * -NO

* * Og CE^CEgOO*

CHjCHgOO' * CH^CH^ Uii^CH^OOH * CH^CE^ * 21 The hydroperoxides decompose to form alkoxy and hydroxyl radicals :

CE^CHgOCH CH^CHgO* ♦ * OE

Lover alkyl radicals and carbonyl compounds are formed from the alkoxy radicals 22 :

CBjCBgO* --- > CB3* ♦ CEgO Ik* The corresponding lover nltroalkanes may then be produced by combina tion of the alkyl radicals with nitrogen dioxide or by exchange reactions of the alkyl radicals vith nitric acid. HROi •NOg — — 3-> CE^NOg CE3 Thus it has been shown that a free radical mechanism can account for the high percentage (2 0 j6) of nltromethane formed In the nitration of ethane^?

The mechanism is substantiated by the facts that: (a) nitration of toluene yields phenylnitrcsne thane, nitrobenzene and benzaldehyde > but pL no nltromethane ; (b) high yields of formaldehyde are obtained from the nitration of me thane2 (c) oxygen plays such an important role in the vapor-phase nitration processes; and (d) substitution of bromine for oxygen In the nitration mixture decreases the relative yields of 13

products derived from alkyl flssl anS5.

Oxidation of alkanes In either the liquid or gas phase Is Inti mately related to liquid or vapor-phase nitration of these hydrocarbons.

Since It has been found that arygen plays an Important role In nitra

tion of saturated hydrocarbons, the salient features of controlled oxi dation of hydrocarbons In the liquid or gas phase will be outlined; it

is much beyond the scope of this presentation to review or to discuss

the entire significant work In this field. At present the oxidation of hydrocarbons is believed to Involve hemolytic chain processes embodying principles of peroxidation . It has been proposed that Initial attack

of oxygen on a tertiary allcane occurs preferentially at tertiary C-H positions (3°> 2 ° > 1 °) and results in formation of a tertiary alkyl- hydroperoxide. The mechanistic sequence which is presumed to account for foxmatlon of the tertiary hydroperoxide involves hemolytic removal 27 of a hydrogen atom from the hydrocarbon by the action of oxygen ; sub sequent additlon of oxygen to the tertiary alkyl free radical yields the tertiary peroxy radical. Formation of the tertiary hydroperoxide

Is completed and the chain sequence is continued upon exchange of the tertiary peroxy radical with the parent hydrocarbon to give the tertiary alkylhydroperoxlde and the subsequent tertiary alkyl free radical. Ex tent! on of the peroxidation sequences to primary and secondary C-H bonds

CH^—C-CHg—CH-CH^ ♦ Og > ch3 -c-ch2 -c-ch3 * ho2 - CH^ ch3 ch3 ch3 Ih

CH0 I 3 ?h 3 ?a CH -C -C H o -C -C H _ * 0 G CH-C-CH0 -C-CH 0 3 ) ^ 1 3 2 3 ( 2 , 3 CH. CH, ch3 ch3

CH-. i 3 ?H3 CH^-C-CHg-C-CH^ ♦ CH^-C-CHg-CH-CH^ CH. CH, CH- CH- CH CoH i 3 i ^ ?R3 CH„-C--C-CHo -C-CH, * CH-j-C-CHo-C-CH- 3 I *=■ t 3 t ^ I 3 CH,CH, CH. CH-

leads to the formation of primary and secondary alkylhydroperoxides. In most oxidations, however, the peroxides are formed at such temperatures

that their survival is unlikely, and thus, they are not isolated in

quantity except when special methods are used

Additional evidences which support the belief that hydrocarbon

oxidation involves a free-radical sequence and chain-propagation are:

(l) induction periods are usually realized, resulting in formation of active centers2^’ (2) addition of substances which undergo free 2 9 31 32 33 radical decomposition sensitizes oxidation, * 7 7 , (3 ) certain foreign gases or solids may accelerate or inhibit reaction, depending on whether their action is to prevent chain breaking at the vails or to end the chains by direct collisian2^* ^ ^ ^ ^■ - oxi dation may be initiated at relatively low temperatures by hydrogen hi . bromide , (5 ) tertiary alkyl radicals are formed more readily than secondary, and secondary more readily than primary, and (6 ) the complex kinetic results can be accomodated using accepted principles for chain reaction.

The reactions of nitrosyl chloride an paraffin hydrocarbons in the 15 presence of sunlight or ultra-violet light result In fomation of nitroeo compounds, chloronltroe o compounds, and ax lines of the hydro- lf.2 carbon The general reaction Is described as follows;

^7®l6 * lfOCl ^ C-^H^NO *■ HC1

Ct H15HO ^ C^H^HQH

The chemistry involved in these reactions has not been studied In any great detail and the mechanisms of these reactions are subject to con jecture. The effect of sunlight Indicates a free radical mechanism.

The fact that chlorination and oxidation occur at the same time also indicates that a chain reaction may be occurring.

The direct halogenation of aliphatic hydrocarbons is one of the most Important reactions in organic chemistry. Since in general chlori nation seems to have been the moet widely studied, the mechanism of this reaction will be discussed first. The experimental evidence for the mechanism of chlorination strongly suggests free radical attack by chlorine atoms. For example, a mixture of hydrocarbon and chlorine re main unchanged for an indefinite period if it is kept in the dark and at room temperature. Any change that produces free radicals, however, will initiate chlorination. Heat or 11 ght, either of which are known to dissociate molecular chlorine into atoms^ may Induce substitution; addl- LL tion of a free radical such as ethyl also has similar effects The inhibitory actions of oxygen also support the belief that chlorination occurs by a free radical process. An induction period and the depend ence of the reaction upon the type of surf ace and the surface area of the reactor*^ further indicate that a chain mechanism is involved. The 16

complex kinetic data of Schumacher and Wolff ^ may also he interpreted

In terms of a homo lytic chain process.

The mechanism of chlorination has been postulated to proceed as

f o IIowb ;

Cl2 * hv> ---> 2C1 *

(a) Cl* ♦ HH --- > RC1 *■ H*

H* ♦ Clg --- > HC1 «■ e l

(b) Cl* RH --- > s ’ ♦ HC1

* Clg ----> RC1 * Cl*

Route (b) is considered to be the correct mechanism since the chlorina tion of optically active l-chloro-2 -methylbutane results in the forma tion of inactive l,2-dichloro-2-methylbutane^^). Route (a) should in volve displacement via a path of the Walden Inversion type to give an optically active product; however, the second route yields a free radi cal R* which should have a planar configuration, and consequently result

In a racemic product. A consideration of the heats of reaction Involved in each step of these two mechanisms indicates also that route (b) is kft the more probable . Since there is such a great resemblance between liquid and gas-phase chlorination of hydrocarbons, it is generally be lieved that both substitution processes occur by analogous chain processes .

Hass, McBee, and WBber^^'^'^ have reported the foilcsring general izations for chlorination of hydrocarbons; these generalizations may be adequately rationalized in terns of the free radical sequences (route b) that have been postulated for chlorination:

1. No carbon skeleton rearrangement occurs during either photo- 17

chemical or thermal chlorination If pyrolysis temperatures are

av oided51b #

2. The relative rates of substitution are primary > secondary ;>

tertiary, but the rates approach 1:1:1 at Increasing temperatures.

3. The relative rates of 1°, 2°, and 3° substitution are not af

fected by moisture, carbon surfaces, or li^it.

**■. Excessive temperatures or reaction times result in appreciable

pyrolysis of the chlorides in the order 3°> 2°> 1°.

5. A molar excess of alkane over halogen diminishes the amount of

polychlorinati on.

6. Oxygen and alkenes inhibit the chlorination of alkanes.

7- 3)1chlorination proceeds by two mechanisms; by dehydrohalo-

genatian and addition, and by progressive substitution. The presence of

one chlorine atom on a carbon hinders the entry of a second atom.

The chlorination of a hydrocarbon by sulphuryl chloride is also believed to occur by a free radical mechanism. The reaction is cata

lyzed by light, peroxides, or any substance capable of producing free

radicals^. Substances that destroy atomic chlorine inhibit the reac- J^7 to c2 tion. Kharasch and Brown J suggest the following mechanism for

chlorination of hydrocarbons vith sulphuryl chloride in the presence of

peroxides:

B* * S02 C12 --- > B-Cl ♦ *SOgCl 18

This mechanism accounts readily for the various chlorination products

that are obtained and also is very similar to the mechanisms of chlori nation that were discussed previously. Schumacher and Stauff-^ con sider It unnecessary to postulate the existence of the ’SOgCl radical, since they believe that the reversible molecular dissociation of sul phuryl chloride to sulfur dioxide and chlorine proceeds so rapidly that reaction mixtures always contain free molecular chlorine. The mechanism

of chlorination with sulfuryl chloride then becomes almost completely

identical with that postulated previously for chlorination of hydrocar bon.

SO^Clg ^ SOg *■ Clg

Clg 2C1-

Cl* ♦ HR --- > R* ♦ HC1

The mechanisms of halogenation of hydrocarbons with iodine, bromine, or fluorine are not nearly as well defined as chlorination.

First of all, alkyl halides of these types are seldom prepared by the direct method; in general, the reactions are too difficult to control.

Fluorine reacts too rapidly and results either in explosions or at best perfluorination. Iodlnatlon occurs in such poor yields that the reverse reaction (HI ♦ HI ■■■■) HH » I2 ) Is considered to be the more useful.

Direct bromlnation is possible but not very practical because of the unusual experimental conditions that are necessary.

Aliphatic bromination is believed to occur mainly by a free radical mechanism^®, however, kinetic studies have indicated the possibility of an Ionic route in polar solvents of hl($i dielectric constant. The reaction may be initiated by irradiation, by heat, or by sources of

free radicals . Substances which destroy bromine atoms inhibit

b rami nation*^. The facts described plus the kinetic results-^ are in

accord with the following mechanism:

Br2 * hv ^ ^ 2Br*

Br' * CgH^-CH^ —> C^H^-CHg• * HBr

CgHej-CHg* ♦ Br2 > C^H^-CH^Br * Br*

Direct fluorlnation of aliphatic hydrocarbons, although difficult

to control, is possible if the fluorine is diluted with a solvent or

an Inert gas. Fluorlnation of methane yields not only the expected

methyl fluoride, difluoromethane, fluoroform, and carbon tetrafluoride, but also hexafluoroethane and octafluoropropane; it 1b of interest that

a carbon chain may be built up as well as broken down by the action of

fluorine on a hydrocarbon. A chain mechanism resembling that for

chlorination has been postulated to account for the formation of the various derivatives obtained by fluorlnation of methane.

Finally: Kharasch and Eberly ‘b’l have re ported that hydrocarbons undergo re action with carbon disulfide in the presence of light and chlorine. It seems logical from their results that the following mechanism is in operation. h V Cl2 ^ """> 2C1-

EH * Cl* ---- > E * t HC1

B* ♦ CS2 > (RSCS ) •

R* ♦ Cl^ ---- > RC1 *• Cl*

(BSCS)* ♦ Cl0 --- > R-S-C* *■ Cl* «? ^ HS-C? * CLp --- > R-S-C-SC1 'Cl ^

Kharasch and Brown hare found that aliphatic hydrocarbons react with phosgene or with aralyl chloride to yield substituted acid chlorides.

The substitution reactions are initiated by actinic radiation or by peroxides and are believed to occur by chain mechanisms involving *COCl and *C0-C0C1 radicals. The existence of *C0C1 has also been reported in other reactions^. The mechanism which has been proposed for reaction of phosgene or oxalyl chloride with allcanes

(a) COCXr, - •C0C1 * Cl*

0>) (C0C1)2 •COCOC1 «• Cl*

(a) •C0C1 - CO ♦ Cl*

(e) •C0C0C1 > 2C0 ♦ Cl*

(f) RH * Cl* ■» R* *• HC1

(e) R* ♦ (C0C1)2 --- > RC0C1 * • 21

Aliphatic hydrocarbons react with sulfur dioxide and chlorine or

with sulfuryl chloride to give alkylsulfanyl chlorides along with

alkyl chlorides. Hass, McBee, and H atch^ have proposed the following

hemolytic sequence to account for the formation of sulfonyl chlorides

from alkanes, sulfur dioxide, and chlorine. h v v Cl2 ^ > 2C1 *

HH t- Cl* --- > B- •- HC1

B ■ * S a, > BS 02 *

BS02 * «• Cl? ' --- > BSOgCl * Cl*

The mechanisms of reactions of hydrocarbons with sulfuryl chloride are believed to he of the radlcal-chaln type and very similar to those of

reactions of hydrocarbons with sulfur dioxide and chlorine. Evidence which implies that simultaneous chlorination and chloroeulfonylation

occurs by free radical processes are: (1 ) both reactions are initiated by peroxides and by irradiation, (2 ) oxygen inhibits both chlorination and ehlorosulf onylat ion, and (3 ) temperature increases retard the

chloroeulf onylat! an reaction. The following mechanism has been pro

posed for reaction ofalkanes with sulfuryl chloride^; there is still question at present of the possible importance of the *S02C1 radical in the over-all substitution sequences:

(a) 3O2CI2 < > SOg ♦ 0X3 h V s. (b) CI2 xz ...> 2C1 •

(d) R* * s o 2 < ^ bso2 *

(e) B* * Cl2 --- > BC1 * Cl-

(f) rso2 * ♦ Cl2 --- > BS02C1 ♦ Cl* 2?

The increase in yield of sulfonatian product when excess SO2 is added

can be explained by equation (d). Higher temperatures reduce the

stability of the HSOg* radical, thus decreasing the yield of alkyl -

sulfanyl chloride. Since equation (c) is the same as that for chlori

nation of alkanes, it can be expected that the ratio of primary to

secondary to tertiary substitution is the same for chlorination as for

chiorosuIf onylation; this has been found to be experimentally true.

Sulfuric acid reacts slowly at room temperature or in the cold with aliphatic hydrocarbons that contain tertiary hydrogens^. No re

action occurs between sulfuric acid and n-paraffin hydrocarbons under

these conditions. Fuming sulfuric acid and chlorosulfonic acid react with paraffins and cycloparaffins, however, the tertiary position ap

pears to be the main point of attack^. The extent of sulfonatian by

these three reagents is bo small and the overall reaction is so complex

that direct sulfanation is impractical, both from the standpoint of

syntheses and mechanism studies. fiil Tngold, Raisin, and Wilson report that aliphatic hydrocarbons exchange hydrogen in the presence of d2-sulfuric acid. Tertiary hydro gens exchange most rapidly, but the number of exchangeable hydrogens exceeds one. The mechanism of exchange that has been postulated is of

the electrophilic type: \ \ . "s. -C-H ♦ DC6O0H ---- ^ -C. X) S O ^ ---- ^ — CD ♦ H^Oi, ^ y T> 5 . H 3H ♦ DBSO^

Burwell and Gordon^ have found in reaction of (*■) -3-methylheptane with 23 d^-eulfuric acid that: (a) the hydrogen atom at the tertiary poeitlon

is not the only one which exchanges; the number of exchangeable hydro gen atoms exceeds 8; (b) branched chain octanes exchange much more rapidly than does normal octane; and (c) for every molecule rncemized, about 15 atoms of hydrogen are exchanged. As a result of these observa

tions, they postulated the following mechanism:

CH 3

dl - Cq H7Di :l * C^H^-CsCE-C^

It is believed that the rates are inconsistent with any mechanism in which the sulfuric acid, acting as a strong proton donor, displaces the hydrogen atoms from hydrocarbons with accompanying Inversion of configuration. In a subsequent study Gordon and Burwell 66 reported the rates of hydrogen exchange for several different hydrocarb one with buI- furic acid-dg, ethanesulfonic acid, chloroeulfonlc acid, or mixtures of these; their res tilts appear consistent with the mechanism Just discussed.

Many investigations have been devoted to the reaction of hydrocarbcns with sulfur, but they have been largely of a qualitative nature and little Information is available concerning the mechanisms. The princi pal reaction is dehydrogenation rather than substitution. Nellensteyn 2 k and Thoenes observed that in the reaction of hydrocarbons with free sulfur aimoet all of the sulfur appeared as hydrogen sulfide; there were only minor traces of organic sulfur compounds. Bryce and 68 Hlnshelvood have postulated a chain sequence for reaction of sulfur and aliphatic hydrocarbons. Although the concentration of sulfur in this form is low, kinetic studied indicate that the sulfur atom is the attacking species. The reaction is believed to follow this course;

(a) CH HgCH^CH^ ♦ S --- > CH^HgCH^Hg * «■ H3 *

It is assinned that the relative substituticn rates for hydrogens fall in the order 3° > 2°>'l0. The BS• radical then continues the chain;

(b) CH3CH2CH2CH3 t > CH^CHgCHCH^ ♦ H^S

The radicals formed in (a) and (b) now decompose to give olefins and lower radicals:

CH-^CH^HCH-j --- > CH3* ♦ CK3CH=CH2

> CH^Hg* ♦ CH2=CH2

CHjCHg* --- > CHg'CHg ♦ H*

This mechanism results in formation of approximately three olefin molecules to one of hydrogen sulfide; this is in agreement with the ex- pevimental results. The hydrogen atom and the lcwer alkyl radicals con tinue the chain sequence.

H* ♦ Sx --- ^ ®x-l *■ HS * Continues chain

alkyl radical* ♦- Sx --- > Tar (mercaptans, sulfides, disul fides , and polysulfurated alkanes) 25

III. DISCUSSION car INVESTIGATION and RB3 ULI3 .

The experimental work carried out in this investigation consisted of three principal parts; namely, (I) the nitration of (Z) -3-methylheptane and of (*)-3-methylheptane; (II) the nitration of commercial, els, and trans-decalin; and (Til) the nitration of els and trans-hydrindane.

A. Nitration of (♦)-3-Methylheptane and (t)-3-Mo thylheptane.

The substitution of a nitro group for the tertiary hydrogen atom on an asymmetric center of an optically active hydrocarbon provides an Important method for Btudying the mechanism of the nitration reaction.

By relating the configuration of the tertiary nltro product through its optical properties to that of its parent hydrocarbon, it is possible to determine by various methods whether racemization, inversion, or re ten- a tion occurs during nitration. Stevens and Schiessler have excluded a nitration mechanism involving free alkyl radicals from the fact that

3-metnyi-3-ni trooc tane, obtained from nitration of ( -) - 3-methyl octane

( -6.5O0 , J? - 1) in a sealed tube at 130°, rotated polarized light

( -O.650, 3 1 ). The tertiary nitrcnonane was separated from the primary and secondary nitro products by three-fold extraction with

15 per cent aqueous alcoholic (3 :1 ) potassium hydroxide. These authors did not study the reaction other than to determine the rotations of the initial hydrocarbon and the tertiary nitration product; there were no conclusions as to the stereochemistry and the extent of racemization of the substitution reaction or the extent of racemization of the initial hydrocarbon. When the optical rotation failed to change after a second series of 3 extractions with base, Stevens and Schiessler con- 2 6

s ldered the compound "bo be pure and tha rotati cn to ba due to the opti

cal activity of the 3-metbyl-3-nitrooctane.

Since tha optical rotation of tha 3-m«thyl-3-nitrooctane obtained a by Stevena and Schiessler was so small, and tha stereochemistry of

the displacement was not determined, it was believed that more decisive

information could be obtained from a thorough investigation of the sub stitution of a nitro group for the hydrogen at cm on an asymmetric car bon atom. (*•)-3-Methylheptane ♦9*2 5°) was thus prepared (see

Experimental) and nitrated with 5OJ6 nitric acid at 1 0o°.

CH„ i j CH^-CHg-CHg-CHg-C-CHg-CH^ ♦ HNO^ ---- > H CH, I -5 CH^-CI^-CHg-CHg-C-CHg-CH^ ♦ HgO fco2

The unreacted hydrocarbon which was recovered exhibited virtually no racemization under the conditions of nitration. The two fractions of crude nitration products which distilled in the range predicted for

3-methyl-3-nitroheptane had very pronounced rotations: (1) b.p. 35"

7 5°/8 mm. , *9.8 3° ( $ - 2), and (2) b.p. 75"90°/8 mm., ♦7*5 7°

{ $ ~ 2). Since any compound produced in the nitration reaction which resulted from an attack on any part of the molecule except the asym metric carbon atom would poesess optical activity regardless of the mechanism, It was not surprising to find many products which did rotate polarized light.

The method that was used for separating 3-methyl-3-nitroheptane from its acidic primary and secondary isomers was based on its unre 27 activity toward alkaline reagents; conversion of primary and secondary nltroalkanes to their corresponding salts allowe a separation hased on their solubilities in aqueous or alcoholic solvents. During the present investigation it was found that the technique involving extraction with g alcoholic potassium hydroxide that was used by Stevens and Schiessler for separating 3“®®thyl-3-nitrooctane from its isomers was Inadequate for removing all of the acidic products from nitration of 3-methylheptane. In order to Insure that the 3-methyl-3-nitroheptane obtained from nitration of (♦)-3-methylheptane was completely free of primary and secondary nitro impurities, it was necessary to treat the crude nitrated product many times in homogeneous solution in methanol with equivalent amounts of sodium methoxide. Negative tests for primary and secondary nitro compounds in the reaction product were finally obtained after a series of the drastic treatments.

Polarimetric analysis of the 3-methyl-3-nitroheptane, even though freed of alkali-soluble materials and purified by rectification, re vealed that it exhibited rotations ranging from *0.73 to

(see footnotes d through k, Table II). It was noted, however, in further purification of the tertiary reaction product that there was no trend in its slight positive or negative rotations. Efforts to purify the

3-methyl-3-nitroheptane in concentrated sulfuric acid were unsuccessful because of excessive decomposition of the tertiary nltroalkane. Examina tion of the infrared spectra of the many samples of 3-methyl-3-nitro heptane revealed weak nitrate and hydroxyl absorption (see Appendix,

Fig. 4 ); it was impossible to remove these impurities completely by 28

treatment of the product many tinea with methanollc sodium math oxide or

by repeated fractional distillations. Upon comparison of the infrared

spectra of the samples of 3-methyl-3-nitroheptane with that of a 5^

solution of amyl nitrate in 4 -nitroheptane (see Appendix, Fig. 5), it was apparent from the relative sizes of the nitrate peaks at 6.10/ui

that the concentration of the nitrate impurity in the 3~methyl-3-nitroheptane was at maximum 1^.

At this stage in the present research, It was unknown whether the slight rotations of 'the many preparations of 3-methyl-3-nitroheptane were real or due to the presence of optically active impurities (alco hols, nitrates, nltro-nitrates, etc.). It was then discovered, however, that, contrary to general belief, the position of the 2dm. semimicro tube in the polarimeter rack affected a rotation reading by as much as

-0,50 . Only by placing the polarimeter tube as close to the source as possible was a reliable and reproducible reading obtainable. In the initial determinations the polarimeter tube had been placed compara tively near the eyepiece without regard to its exact position. The improper positioning of the tube could easily account (and was believed to be the reason) for the minor rotations of the different samples of

3-methyl-3-nltroheptarnc obtained from, the many nitration experiments.

The nitration of ( O - 3-methylheptane and subsequent purification of 3-methyl-3-nltroheptane was repeated (Exp. No. 1 7). When the optic al activity of the 3-methyl-3-nltroheptane was determined with the

2dm. aemlmlcro tube placed properly in the polarimeter, its rotation was practically zero; there was little change in the observed rotations 2 9

when the determi nations were made at various wavelengths. In order

that any errors derived from the polarimeter or the polarimeter tube

might be obviated, and also as an independent method of synthesis and

structural confirmation, (t)-3 -methyl-3 -nltroheptane was prepared from

(i)-3 -methylheptane by a procedure identical with that used with

(♦}-3-methylheptane. Since the racemlc 3-methyl-3-nltroheptane pre

pared front (1 )-3 -methylheptane had optical properties which were identi

cal with that of the 3 -methyl-3-nltroheptane obtained from (*•)-3~methyl-

heptane, the latter nitration product was considered to be a racemate.

It is possible, however, that since such small rotations are in

volved, there might be enough optically active impurities in the pro

duct with rotations of opposite signs in sufficient strength to cancel

any real rotation inherent in the 3-methyl-3 -nitroheptane derived from

(*)-3 -methylheptane. The quantitative analyses of the 3 -methyl-

3-nitroheptane (of negligible rotation) obtained from (*)-3-methyl heptane were not completely satisfactory; its infrared spectrum (as described previously) and its physical constants indicated the presence

of alcohol and nitrate impurities. It is possible to obtain excellent analytical data for (I)-3-methyl-3-nitroheptane obtained from

(±)-3-methylheptane; hc*rever, it Is believed that quantitative analysis

is not totally Indicative of the purity of the tertiary nitro products

obtained from either (i) or (♦ )-3-methylheptanes since analytically pure (i)-3-methyl-3-nitroheptane also exhibited absorption character istic of alcohols and of nitrate esters.

In order to eliminate the possibility that minor contaminants might 30

be obviating any real rotation of 3~®©thyl-3-nitroheptane derived from

(*)-3-raothylheptane, the 3-®©thyl-3 -nitroheptane was hydrogenated

catalytically to 3-amino-3-methylhept&ne. A 30 per cent solution of

the tertiary aailne (crude) in absolute ethanol exhibited no rotation

over a series of 4 wavelengths. It seems highly improbable that a mix

ture of compounds, if the **3 -methyl-3-nitroheptane” is such, which has

no rotation as a result of cancellation compensation would also give

reduction products in which the zero rotation is due to cancellation

characteristics. It is conceivably possible, however, that the rota

tion of the product is too small to be detected under the circum

stances under which the reading was made; i.e., 30 P©r cent solution.

As a final proof of the racemlc properties of the 3-amino-3-methyl

heptane derived from (♦)-3 -methylheptane, the amine was converted in

63 per cent yield to the solid derivative, H-phenyl-W-3 -(3-methyl-

heptyl)-thiourea, by reaction with phenyl isothiocyanate. Solutions

(1^ per cent in ethyl alcohol) of the crude, unrecrystalllzed

N-phenyl-N*-3-(3-methylheptyl) thiourea (m.p. 7^-76°) or of the puri

fied derivative (m.p. 79°) exhibited no rotation over a series of wave lengths. (It might be predicted that attachment of a large

polarlzable group to an asymmetric center would result in enhanced 67 rotation; Mann and Porter have found that the rotation of ( )-2 -amino

octane, M i 7 -8.53°? Is greatly increased upon conversion to Its benzanlde, [aJ^7°-6S.l°, [a] ^ x -7 3-5 °, ^ 3 ^ 8 "125 0)* Th® I"®11- titative analysis of the derivative was excellent.

In order that the identities of 3-amino-3-methylheptane and 31

N-phenyl-Tl1-3-(3-methylheptyl)-thiourea derived from 3-methyl-3-nitro heptane ctotalned from (♦>)-3-methylheptane might be conf 1 rmed, analytic ally pure (I )-3-methyl-3-nitroheptane derived from (1)-3-methylheptane was hydrogenated over Raney nickel to (t)-3-amino-3-methylheptane.

(!)-3-Amino-3-methylheptane vas then converted by reaction with phenyl is othi ocyanate to N - phenyl-N *-3-( 3-ms'thylheptyl)-thiourea, m.p. 79°, in 60 per cent yield. The melting point of the K-phenyl-W-3-(3-methylheptyl)-thiourea obtained from (i)-3-amino-3-methylheptane derived from

(1)-3-methylheptane did not depress that of the analogous derivative derived from (*)-3-methylheptane. The physical constants of the nitra tion products and the derivatives obtained from (♦)-3-methylheptane and (1)-3-methylheptane are summarized for comparison:

Physical Constants of Products Derived from (l)-3-Ms thylhe ptane

V & 3-Methyl-3 -nitroheptane 82°/l0 mu. 1 .1*319 0 .9 2 8

3-Amino-3-methylheptane 6 3-6 5 ° /2 8 m . 1 .4 2 2 3 --

N-Phenyl-N*-3- m.p. 7 9° (3-methylheptyl)thiourea (6Ot yield from the amine) 32

Physical Constanta of Products Deri rad f ron (♦)-3-Methylheptane 25 b.p. D 3-Me thyl-3-nltr oheptane 8l-8 2°/l0 arm.. 1 .^ 3 3 0 0 .9 3 6

3-Amino-3-methylheptane 63-6^°/27 mm. 1.U223

N-Phenyl-N’-3- (3-me thy lhepty 1)thlourea m. p. 7 9° (5^6 yield from the amine)

It is therefore concluded, an the basis of the lack of optical proper

ties of the 3-methyl-3-nitroheptane, 3-amiuo-3-methylheptane, and

R -phenyl-N'-3-(3-methylheptyl)-thiourea derived from (♦)-3-methylheptane,

that the steric Identity of the asymmetric center of ( O - 3-methylheptane

is lost In Its conversion to 3 -methyl-3-nitroheptane by the action of

50 per cent nitric acid.

B . Nitration of Coiinei clal, Cls, and Trans -Decalins.

In order to obtain additional information concerning the mechanism of liquid phase nitration of saturated hydrocarbons, the stereochemistry of the substitution of nitro groups for the tertiary hydrogen a tens of cls t trans , and ccaenerclal-decal Ins vas studied.

The orer-all stereochemical possibilities for conversion of the decallns

to cls- or/and traps-9-nltrodecallns and cls- or/and trans-9,1 0-dlnltro- decallns are outlined by the following sequences: HHO- (3) C©*G©

and/or

HNO. (b)

and/or

For this purpoee, cls-decalln (l) trans-docalln (2 ) , and conmercial-decalIn (3) (approximately 65^ cls and 35^ trans) were reacted with 5056 nitric acid for 5 hours at 1 0 0°. It was found that neither cls- nor trans -decal in undergoes detectable isomerization under the nitration conditions; the refractive indices and the infrared spectra 3^

of the decalins recovered after nitration were essentially unchanged

from that of the Initial pure cls and trans-isomers. It was observed,

Physical Properties and Infrared Spectra of Cls-Decalin

n ^ Infrared Abs orpti on

Initial 1 .4 7 9 0 ? 3 .40/t , 6.9O/X V 1 0 .32- , 11.72/* , Recovered 1 .4 8 0 1 I 1 2.0 0/*

Physical Properties and Infrared Spectra of Trans-Decalin

Infrared Absorption

Initial 1.4671 ? 3 *^0p , 6. 9 0 m , 1 0.30/* , f 10.52m , 11 .90H , 12.20m Recovered 1 .4 6 7 2 J

however, that cls-decalln undergoes nitration at a faster rate than does

trans-decalln. It vas also found in nitration of conmercial decalln,

on the basis of refractive indices and infrared spectra, that the re-

Physlcal Properties and Infrared Spectra of Commercial Decalin 25 njj Infrared Absorption

Initial 1 .4 7 5 1 ) 3.kO)jLt 6.9 0m , > 10.81/* , 11.72/*, Recovered 1 .4 7 2 3 J 1 1.92/*, 12.12/4

covered decalln contained a higher percentage of trans-decalin than the

initial conmercial decalin. Huckel^ has reported similar results in

the course of nitration of commercial decalln in that the recovered decalln was always richer in trans-decalln than the initial mixture of decalins. In view of the fact that cis- and trans-decalins are not 35

isomerIzed during nitration, the enrichment of the trans-*isomer in com mercial decalin Indicates further that cls-decs31 r. is undergoing nitra

tion at a greater rate than does the trans-iscaner. It cannot be con cluded, however, from this data that cls-decalin undergoes nitration at

tertiary positions faster than does trans-decalln since the over-all reactivities of cig and trans-decalins may result from nitration at the various secondary positions as well as from substitution of the tertiary position.

The tertiary nltrodecaline obtained from commercial, cls, and trans decalins, respectively, were separated from their secondary nitro

isomers and purified by prolonged treatment with methanolic sodium methaxlde. The alkaline extractions were continued until the insoluble nitration product no longer gave a positive pseudonitrole test for secondary nitro compounds. Upon careful rectification of each of the reaction products, three samples of "Q-nitrodecalln" were obtained as colorless liquids which possessed almost identical physical properties;

I.e., infrared spectra (see Appendix, Jigs. 1 2, 1 3, and 1*0 , analyses, boiling points, refractive Indices, and densities; the physical proper ties of the "9"n,itrodecallnM are in agreement with those reported by

Huckel 11 and Name tkin68 . The yield of pure "9~ni trod ©call n" obtained from nitration of either commercial, trans , or cls -decalln vas approxi mately 4 per cent. 36

Physical Constants and Infrared Spectra of

Parent Decalin 25 825 b.p. V 4 Infrared Absorption

Commercial 0 7.8°/l.3 mm. 1.4925 1.081 C-H 3.38/* , 6. 90/a , 7.25/*

Cls 85~86°/l no. 1.4933 1 .0 8 4 N02 6.1+0/* , 7. 35/*

Trans 79-8l°/o. 8 mm. 1.4919 1.082. Trans ring structure: 7 10.70/* , 11.90/* 1 2 .10/1

Conmercial 20 (lit.68) 96-97°/2 mu. 1 .4 9 2 4 1 .0 8 4 7 11 25.4 Trans (lit. ) 1 2 2-1 2 5 / 1 8 mm. 1.49221

1.0803

In order to develop a rigorous structural proof and to relate their

stereochemical configurations, each of the three reaction products of

’9-nitrodecalin** vas reduced vith hydrogen and Raney nickel. The reduc

tion of each ^-nitrodecalin** occurred rapidly to give ^-aminodecalin";

the yield of amine from each reduction vas at minimum 98 per cent. The

physical properties of each sample of "9-aminodecalin" vere almost iden- 13 66 tlcal and agreed satisfactorily vith those previously reported '*

Physical Properties of 9-Aminodecalins

Parent Li terature Decalln 25 b .p. Ref.Ind. H20 V d4 4 Conmercial 1.4923 0 .9 4 5 5 9 8°/l5 n^°l.4932 0 .9 4 3 5

Trans 1 .4 9 2 7 0 .9 4 5 2 2 2.6 ° /7 5 7 mo. nj^*91 .4 9 2 1 0 -9 3 9 1

Cls 1 .4 9 2 2 0.947 2 2 7 ° /7 5 7mn. n|**°1 .4 9 8 2 0.9508 37

The stereochemistry of the "9-nitrodecalins" was related upon con

version of their amines to their corresponding N-9-decalylacetamides.

Reaction of each sample of ^ “SJBlnodecalin" occurred readily with

acetic anhydride and 20 per cent sodium hydroxide to give N-9-decalyl-

acetamide, m.p. I830; the over-all yields for conversion of the "Q-nltro~

decalin" to "N-9-decalylacetamide" were excellent, ranging at minimum

from 77 to 86.5 per cent. Since there was no depression in melting

point upon mixing the various samples of N-9-decalylacetamide, it was

concluded that the derivatives had identical structures. It also may

Conversion of 9-NItrodecalin to N -9-Decalylacetamide

Parent Over-all m.p. of Decalln Yield Derivative

Conmercial 85.0^ 183°

Cls 86.5* 1 8 3°

Trans 7 7.0* 183° be concluded that nitration of commercial, cls , or trans decalins yields

identical 9-nitrodecalin. Huckel^ reports that trans-N-9-decalyl-

HNO-> r p**0* ] HRO, '-Bgo* I H J J *• -fi^o

ace tamide obtained from 9-aminodecalln (via 9-ni trodecalin prepared by nitration of commercial decalin) melts at l83°j this is in excellent agreement with the melting point of the product from the present research,

Huckel also reports a second N-9-decalylacetamide (presumably cls , no 38 yields were given), m.p. 127°, from the 9~&mlnodec&lln (derived from the 9-nitrodecalin obtained by nitration of conmercial decalin); there vas no evidence for the formation of the isomeric (lower melting)

N-9-decaly lace tamide in the present Investigation. If the 9-ni tro decalin obtained in the present research had contained any isomeric

9-nl trodecalin, the maximum, percentage (and presumably much less) of the isomer could only be 23 per cent (see previous Table).

The Infrared spectra of cls and trans -decal ins and of the 9-nitrodecalin allow certain conclusions as to the stereochemistry of the

9-nitrodecalin. Cls and trans-decalIns differ in their spectra to such an extent that infrared analysis may be used for quantitative determination of the ccaposltlon of mixtures of decalins^. The Infra red spectrum of trans -decalln contains three strong characteristic ab sorptions at 1 0.7 0^* , 1 1.90^u, and 1 2.10^ (see Appendix, Fig. 1 0); these absorptions do not occur In the spectrum of cls -decalln (see

Appendix, Fig. 8). The Infrared spectra of the 9_nitrodecalin (from either commercial, cls, or trans-decalins) exhibits even stronger ab sorptions at 1 0.70yu , ll.aO/A, and 1 2.10^u. These absorption maxima are entirely analogous to those exhibited by trans -decalln; It also appears that the intensities of the absorptions at these wavelengths are greatly accentuated by replacing one of the tertiary hydrogen atoms by a nitro group in a trans -decalln structure (see Appendix, Figs. 1 2, 1 3 , and 1 4 ). On the basis of infrared assignments characteristic of trans - decalln ring systems, it may be concluded that the 9“*1itrodecalin c^}~ talned from either comaercial, trans, or cis-decalln is trans-9-nltro- 39 decalln. The structural assignment to the 9-nltrodecalin Is In agree ment with that arbitrarily chosen by Huckel11 and with that which mlght be predicted on the basis of ring strain and sterlc effects.

The nitration products from either commercial, cls, or trans- decalln contain identical 9 ,10-dinitrodecalins (m.p. 169°; mixed melt ing points, no depression). The dinitrodecalin may be readily Isolated as large transparent crystals; its chemical properties and melting point agree with reported by Huckel^. The 9 > 1 0-dini trodecalin was assigned the trans structure on the basis of its strong absorption

(apparently characteristic of trans-decalin ring systems, see previous discussion) at 10.62^1 , 1 1.80^jl , and 1 2.1^ (see Appendix, FlgB .

16 and 17).

The Isolation of 9,1 0-dlnltrodecalin of Identical structure from nitration of either cls or trans-decalln further confirms the belief that the stereochemistry of substitution of nitro groups for tertiary hydrogen atoms Is Independent of the stereochemistry of the Initial decalin; the trans-9,10-dlnltrodecalin Is presumed to have been derived from nitration of trans-9-nltrodecalin. It Is of interest that the

trans-structure of the 9,10-dlnltrodecalin that was isolated is in agree ment with that which might be predicted on the bases of ring strain and s teric c cnsIderatlons. 40

C . ffltratlon of Cls and Trans Hydrlndanes

Tha nitrati on of cls and trans hydrlndanes In the liquid phase

has been investigated in order to obtain information concerning the

stereochemistries of substitution at the tertiary positions resulting

in formation of 8-nitrohydrindanes. In general, the procedures for

nitration and the methods for relating the structures of the 8-nitro-

hydrindanes are identical with thoee used in the studies of nitration

of the decal ins. It was observed that cls hydrindane undergoes nitra

tion more rapidly than does trans hydrindane (the same order was ob

served with cls and trans decalins); because of the complexities of

the many competing reactions, however, it cannot be concluded that nitra

tion of the tertiary positions of cls hydrindane occurs more rapidly

than nitration of the tertiary positions of trans hydrindane.

The cls and trans hydrlndanes recovered from the nitration experi ments were Identical with the initial hydrocarbons. It thus can be con

cluded that the stereochemical identity of the "8-nitrohydrindanes** may be related to nitration of the parent hydrocarbon rather than to any complexities arising from Isomerization of the cls and trans hydrindanes and subsequent nitration. 41

Fhyaleal Constants of Cis and Trana Hydrlndanes Roc or ©rod after Nitration

Refractive Indices Infrared Absorption

Cis Trans Cls Trans

Initial 1.I4.700 1.4616 3.40/*, 6.90/u l , 3.45^t, 6.9Q m , 7.35/x, 10 .30/*, 7 . 6 3 m > 7 -75/*, Recovered nfp 1 .469? 1.4616 11.7T u , 12-35/* 8.50/,, 10.30/c, 11.68px , 11.9^/*, 12.35/*

The crude nitration products obtained from cls and trans hydrln danes, respectively, vere treated with methanollc sodium methoxide until the "8-nitrohydrindanes" were obtained as colorless liquids of analytic al purity; the reaction products did not give any tests that are charac teristic of secondary nitro compounds. The physical properties and the

Infrared spectra of the "8-nitrohydrindanes" prepared from cls and trans hydrlndanes were practically identical:

Physical Constants and Infrared Spectra of "8-N1trohydrlndaneB" Prepared from Cls and Trans Hydrlndanes, Respectively

Initial 29 Hydrindane b.p. V djj5 Infrared Absorption Cls 68-6q °/0.8 mm. 1.4880 1.0892 C-H (3.38/u, 6 .90/*)

Trans 68-69°/O.Q mm. 1.4875 1.0892 NO2 (6 .40/u , 7 .32/* , 11 .50/*.1 1 -75/*, 1 1 .42/i)

In order to effect proofs and to relate the structures of the

"3-nitrohydrindanea", the nltrohydrlndanes were reduced with hydrogen and Raney nickel to give the 8-aminohydrindanes and then converted to the corresponding N-8-hydrindylacetamides. Hydrogenation of the 42

NO. NM

8-nitrohydrindanes occurred rapidly and In near quantitative yields to

give 8-aminohydrindane; the physical properties of the 8-aminohydrIn-

danes are practically Identical:

Physical Properties of "S-Amlnohydrlndane" Obtained fran "8-N1trohydrlndano"

Initial 2s Hydrindane n^ ^-4 Infrared Absorption

Cis I.U923 O.943 1 NH (3.00yu , 6.20/* > 9-10H , 9-50/* 5 Trans 1 .4 9 2 5 0 .9 4 0 j C-H (3.40/* , 6.90fA )

The 8-aaInohydrindanes were converted to their corresponding

Iv-8-hydrindylace tamldes by reaction with acetic anhydride and 20 per

cent sodium hydrctrlde. The over-all yields for conversion of each sample of w8-nitrodecallnw to N-8-hydrindylacetamide were excellent:

83 per cent for the cls-series, 73 per cent for the traps-series.

The two derivatives gave excellent analyses for IT-8-hydrindylacetamide and melted at 88°; no depression In melting points was effected upon mixing the two derivatives. The homogeneity and similarity of the

8-aminohydrindane derived from either cls or trans hydrlndanes was demonstrated further upon preparation of their N -8-hydrindylbenzamides

the derivatives melted at 98° and on the bases of their quantitative analyses and mixed melting points were Identical. It Is thus con- *3

eluded ‘that nitration of either cls or traps hydrindane yields Identi

cal 8-nltrohydrlndanes.

A stereochemical assignment vas attempted for the 8-ni trohydr in-

dane prepared In this research. Cls and trans hydrlndanes (see Appendix

Fi^. 18, 19) have very definite differences In their Infrared spectra;

absorption differences which are characteristic of cis hydrindane occur

at 11.77ym , whereas In trans hydrindane these differences occur at

7.6*yj , 8.50jjl , 11.68^4., and 1 1.9^t*. From the fact that trans decalln

gave enhanced trans -aba orpti on when nitro groups were substituted for

tertiary hydrogen atoms, It might be expected that similar results would be obtained for the hydrlndanes. It was found that the 8-nltrohydrlndane exhibited marked absorption at 11.75^1; this absorption also was characteristic of cls hydrindane. The absorption at 1 1.7*5j-*. of

8-nltrohydrindane appears enhanced over that exhibited by cls-hydrindane. On the other hand, peaks at 8.50^1 and 1 1.9 5^* which are charac

teristic of trans -hydrindane were not present In the absorption spectra

of the 8-ni trohydr lndane. On the basis of the limited Infrared data it might be concluded that 8-nitrohydrindan© prepared from either cls or trans-h y d r i i s of the cle-structure. If the structure of the

8-nltrohydrindane is actually cls, this stereochemical result will be somewhat surprising since trans hydrindane Is slightly more stable than cls -hydrindane and it is difficult to see any steric or strain factors which allcar formation of cis -8-nl trohydr lndane at a much greater rate than of trans-8-nltrohydrlndane.

In the initial nitration studies of trans-hydrindane, a secondary nl trohydr lndane was carried through as a contaminant of the (cis)- h k

8-nitrohydrindan®; the reaction products had not been treated vith suf

ficient sodium math oxide in methanol. The presence of the impurity

was not detected until the nitration product had been reduced to its

amines and then converted into its substituted acetamides and benz-

amldes . Along with the major derivatives obtained from (c is )-8-nitro-

hydrindane (N-8-hydrindylacetamide and N -8-hydrindylbenzamide), there

was obtained in low yields a N-hydr indy lace tamide , m.p. 160. f>-l6l. 5°,

and a N-hydr indy lb enzamide, m.p. 1 7 1.5 -1 7 2-5 °. The melting points

and the quantitative- analyses of these two minor derivatives compare

favorably with the melting points of the acetamide, m.p. 163°, and the

benzamlde, m.p. 167-168°, prepared by Huckel^0 from U - amino-trans -

hydrindane. It vas thus believed that the minor impurity in incom

pletely neutralized (cis)-8-nitrohydrindane is h-nltro-trans-hydrindane.

It is of importance that the infrared spectrum of (cis)-8-nltro

hydrindane containing minor proportions of ** -nitro-trans -hydrindane

exhibits definite trans absorption at 8.50^ , weak trans absorption at

1 1.95^* , and unidentified absorption at 13.50^t . The infrared data

further corroborates the structural assignment of the impurity as

t-nl tro-trans-hydrindane, but, even more importantly points out the

possible value of the spectrophotaraetrlc method for assigning cls and

trans-struetures to various derivatives of hydrindane. The Infrared

data that is diagnostic of the presence of secondary nitro-trans- hydrlndanes also allow greater credence to the belief that the 8-nltro

hydr Indane obtained by nitration of either cls or trans-hydrindane is

of the cis-structure. Crude 8,9-d ini trohydr indane vas isolated as a white waxy solid

(m.p. 50-60°) from the polynitratian products derived from either cls or trans -hydrindane. The infrared spectra of this product Is very similar to that of the (cis) -8-ni trohydr indane in that a cls configura

tion is indicated; the spectra vas somewhat obscure, however, and thus no absolute conclusion can be drawn. he

D. Conclusions.

The liquid phase nitration of aliphatic hydrocarbons may pos sibly occur by one or a combination of three general mechanisms Involv ing either hemolytic or heterolytic displacement. In principle, these displacements may be of the carbonium, carbanlon, or free radical types.

In each of these three classifications, differentiated either by pro cesses In which the nitro group is Introduced directly (single stage) by a react!on of the bImolecular type, or whether hydrogen is removed as a hydride ion (l)> as a proton (2 ), or as an atom (3 ) (two stage), any number of reactions may be written: HNO (1 ) (a) R-H 3— > H"

(b) R-H * n o 2* R* ♦ HNO.

f RffO, HgO HNO, (2 ) (a) R-H ---- ♦ H*

(b) R-H * N02* -> R-NO,2 H*

(d) R-/( H * HO-r - > H N O , Ho0 etc. HNO^ (3) (a) R-H 3— > R* f H>

(b) R-H ♦ N02 * — > R* HNO,

As a result of the work in the present research concerning the nitra tion of the tertiary position of an optically active hydrocarbon, of c- 8 , trans , and commercial decalln, and of els and trans hydrindan©,

It has been established that the nitration of hydrocarbons involves the loss In stereochemical Identity of the center undergoing reaction.

These facts Immediately eliminate all mechanism of a blmolecular type

in which a nitro group is substituted directly on the hydrocarbon.

Therefore, the substitution reaction must take place through one or more of the three paths which involve the formation of a free radical or ion, I.e., the carbonlum ion, the carbanion, or the free radical.

The carbonlum ion mechanism Is compatible with the results ob tained in the present research, however, the evidence presented by

MarkovnikoffJ Indicates that if the carbonium ion is an intermediate, then a second competing mechanism must also be operating. Since

2 ,2 -dimethyl-3-nitrobutane was Isolated from the nitration of neo hexane and no indication was found for products resulting from a re arranged molecule, it may be assumed that, at least in part, the ni tration mechanism involves an Intermediate other than the carbonlum ion, e.g., the free radical. Further evidence which does not fit in to the scheme of a carbonlum ion intermediate is: (l) the independ ence of the reaction with respect to the dielectric constant of the solvent* (2 ) the absence of any rate acceleration in the presence of strong acids; (3 ) the effect of concentration of nitrogen dioxide on the rate of nitration; and (U) the failure of the nitration to occur on the bridge-head position.

The formation of the carbanion intermediate by the removal of a proton also provides a m © * ™ by which the hydrocarbon molecule may lose ke

Its stereochemical Identity. Therefore, the experimental data from this research does not eliminate this type of mechanism. However, since other workers have shown that the relative reactivities of the hydrogens are 3°> *?1°, It Is not logical that the removal of the proton (the rate-determining step) will be faster from the tertiary carbon, the center of greatest electron density and Bteric hindrance.

Other evidence which discredits this mechanism is (l) the reaction takes place in solvents of lew dielectric constants; (2 ) the absence of any effect by the presence of strong acids; and (3 ) "the dependence of the rate of reaction upon the concentration of nitrogen dioxide monomer. 12 The mechanism as proposed by Titov , In which the nitrogen di oxide molecule extracts a hydrogen atom from the hydrocarbon to give a free alkyl radical, Is substantiated by the available experimental data. The free radical may be of symmetrical structure, and therefore be capable of explaining the products obtained from the nitration of an asymmetric cartoon atom, commercial, els , and trans -decal ins , and the els and trans-hydrlndanes. Further experimental evidence which substantiates this mechanism is; (1 ) the reaction proceeds readily in solvents of lew dielectric constants; (2 ) the effect of strong acids is negligible; and (3 ) the concentration of the nitrogen dioxide has a definite kinetic relationship to the rate of nitration. TV. EXPERIMENTAL

(1) -2-Ethylhexanoic Acid.

(- ) -2-Ethylhexanoic acid was ob tained from Cart Ida and Carbon Chem-

Icals Corporation (b.p. 226.9°/760 na., ^20 ^•^^7” ; minimum purity,

9*=^ by weight)77.

Resolutlcan of (♦ )-g-Ethylhexanolc Acid; (-)-2-Ethylhexanolc Acid.

Quinine (656 g. , 2 moles) was dissolved In a hot solution of

(Z}- 2 -ethylhexanoic acid (288 g. , 2 moles, b.p. 8 *+°/l.5 mm., 11^ 2 .1*2 2 6 , lit., b.p. 119-121 /lU mm., 1. U2557 ) In 1800 ml. of acetone. Water

(on 1200 ml.) was added until the mixture became slightly turbid. The cloudiness was removed from the mixture upon addition of approximately

1C ml. of acetone; the solution was then allowed to cool gradually to room temperature. The quinine salt which separated upon refrigeration overnight was collected on a Buchner funnel and pressed free of all liquid. After 6 recinstall5zatIans by this method, the salt was decom posed upon steam distillation from dilute hydrochloric acid. The steam distillate was separated and the aqueous layer was extracted h times with ether. The extracts and the carboxylic acid layer were combined and dried over Drierlte. Upon distillation 57.1 g. (0.397 moles) of

(- )-2 -ethylhexanoic acid was obtained (b.p. 8 2 .5 -83 °/! mm., n^pl. 1+2 3 1 ,

<*5 O.8 9 8 7 , 0*3p -8 .30°, 20«£ of a possible 50^ levo form (Uc^t yield), lit., b.p. 218-220°, d^° 0 .906if, M ^ 1 *00 ♦8 .8 9 °71; b.p. 228-229°/755 nm n|5 1 .U22972; b.p. 2 2 6 .9 ° / 7 6 o nn., d^° 0.9°7777 ; b.p. 120°/13 mu.,

l.lf2 2 9 , d|5 O.903I, -if.2 0 086. 50

Bb terlflcatlon of (-)-2-Bthylhexanolc Acid with Ethanol; (-)-Bthyl 2-Ethylhexanoate.

(-)-2-Ethylhexanolc acid (72 g. , 0.5 mole, -7 .60°) was re

fluxed fear 3 days with ethanol (100 g., 2.17 moles), benzene (150 g.,

1.93 moles) and concentrated sulfuric acid (2 ml.). The distilling

head of the column, was so designed that the lower boiling azeotrope

(64.9 ) of water, alcohol, and benzene was collected and removed; the

other camp orients of the ref luring vapor were separated and returned to

the es terif i cat ion. When the tertiary azeotrope no longer appeared and

the boiling point rose to 6 8 .2 °, the mixture was cooled and washed with

10& s o d i m bicarbonate solution and saturated sodium chloride solution.

After the mixture had been dried over anhydrous sodium sulfate, the

solvents were removed under reduced pressure and the residue was dis

tilled to give 82.5 g. of (-)-ethyl 2 -ethyIhexanoate (0.48 moles, 96^

yield): b.p. 8 7 -8 8 °/20 an., n^5 1.4128, d25 0 .8 5 9 , -6.04°,

lit., b.p. 96-97°/35 am-, nj3°1.4l85, dj7 0.8641, £ > j£7 -6.79°;71

b.p. l89-191°/766 am., n£° 1.4128, d^° 0 .862^ 2; b.p. 9 0 -91°/25 mm.,

nj*5 1.4179, ac£0 °-2.47O ( « * 2)7 6 ; b.p. 90°/28 mm., 1.4123,

d25 0 .8 5 8 6 , M 25 -3 .38086.

82 Reduction of (-)-Ethyl 2-Bthylhexanoate with Lithium Aluminum Hydride; (-)-2 -Bthyl-l-hexanol.

Lithium aluminum hydride (8.0 g., 0.209 moles) was dissolved in

125 ml. of dry ethyl ether in a 1 -liter, 3-necked flash equipped with

a stirrer, a thermometer, a reflux condenser, and a dropping funnel.

While the solution was being stirred and cooled with an ice-water bath

(5 -IO0), (-)-ethyl 2 -ethylhexanoate (49.2 g., 0.286 moles, -^.04°) 51

In. 75 ml. of ether was added slowly. Thirty minutes after the addition was completed, 75 ml. of water, then 300 ml. of 10% sulfuric acid solu tion were added gradually to the cooled reaction mixture. The reaction mixture was separated, and the aqueous layer was extracted 3 times with ether. The ether solutions were combined and dried over Drier!te. Dis tillation of this material gave (- )-2 -ethyl-l-hexanol in 92% yield

(b.p. 90°/l8 m . , 3^.25 6 * t 0 .2 6 k moles, n^p 1 .1*2 9 0 , d{J° 0 .8 6 1 ,

W j °'2 -3 .O5 0 ), lit., b.p. 92 -9l*°/22 ms., n^ 7 1 .1*3 2 5 , d^° 0 .8 6 1 1 ,

[aj|° *1*.03°;71 b.p.-I8 l-1 8 3 °/T*3 mm., n?° I.U3 2 8 , d^° 0 .8328^; b.p. 79 90°/26 am., n|° 1.4278 j b.p. 110°/55 1.4292, djj5 0 .8 2 9 3 ,

-1 .5 3 °7^. The ccaiblned yield from the acid to the alcohol was 88%.

Reduction of (- )-2-Ethylhexanolc Acid with Lithium Aluminum H y d r i d e ^ . ( - ) -2-Ethyl-l-hexanol.

A solution of lithium aluminum hydride (25.2 g. , 0.66 moles) in

250 ml. of dry ether was cooled to 0 -5 °, and (-)-2 -ethylhexanoic acid

(1*6.0 g. , 0.32 moles, [ -8 .5O0 ) in 100 ml. of ether was added dropwlse. Stirring and cooling were continued for 30 minutes after com plete addition. Approximately 25 ml. of water was necessary to destroy the excess llthlw aluminum hydride, and 280 ml. of 10% sulfuric acid was required to hydrolyze the product. The ether layer was removed, and the aqueous layer was washed 1* times with ether. After the comblned extracts and ether layer were dried over Drierite, the solvent was re moved and the residue was distilled. (-)-2-Ethyl-l-hexanol was obtained in 90% yield (37-15 6 -, O .285 moles, b.p. 9l**93°/20 mm., n^p l.J*286, 52 o d ^ 0 .8^7 , -3*^°)* This yield represented an Increase of 2*£

over the yield obtained by the preparation and reduction of the ester.

Rii Reaction of (- )-2-Ethyl-1-haxanol with Phosphorus Trlbro™

( -)-2 -Ethyl-1-haxanol (37-15 g ., 0.285 moles, [^J* 9 *3 -3 *^°)

was placed In a 5OO ml. 3~necked flask equipped with a stirrer, a drop

ping funnel and a thermometer. Stirring was begun and the alcohol was

cooled to -10°. Phosphorus trlbrcmide (77 8 -, 0.285 moles) was added

dropwlse. After 15 minutes of stirring at -10°, the solution was heated

to 100° for one hour. The flask was cooled and the excess phosphorus

trlbrcaulde was destroyed with water. The alkyl bromide layer was re

moved, and the aqueous portion was washed 3 times with ether. The

ether extracts and alkyl bromide layer were combined and washed with 10^

sodium bicarbonate solution until basic and dried over calcium chloride.

Removal of the solvent and distillation of the residue gave 32.3 g. (6 V<>)

of (-)-l-bromo-2 -ethylhexane (b.p. 1 0 6 .5 -1 0 8 .0 °/5h am., n^5 1 .^5 1 6 ,

d^ 1 .1 2 1 , -5 .3^ {CftXc ^d • } ^6 ■ 09 j (f ound ) ^ # y b... 72-750/10 ”■*•, i2 0 1.08<> °j b.p. 80°/l8 m . ® 1; b.p. Ii0-ll8°/71 m .

n^ 5 1.4526, d25 1.1197, W l 5 -2.59° 86 •

gc- Reduction of (-)-l-Bromo-2-ethylhexane; (-)-3-Methylheptane.

A solution of lithium aluminum hydride (7.6 g., 0.20 mol^s) in

purified tetrahydrofuran (100 ml.) was prepared at 0 ° in a 1 -liter

3-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel. The stirred solution was heated to reflux tem

perature and (-)-l-bromo-2 -ethylhexane (32.30 g., O .167 moles, 53

-5*3^°) in 50 ®1. of tetrahydrofuran was added at a rate so as

to maintain the reflux without external heating. The mixture was

stirred and heated for one hour and then cooled In an Ice bath. A mix

ture of 50 ml. of water/tetrahydrofuran (U0/60 by volume) was dropped

In very cautiously In order to destroy any excess lithium aluminum

hydride. Hydrolysis was brought about upon addition of 10io sulfuric

acid (300 ml.). The ether layer was removed; the aqueous layer was

extracted 3 times with ether. The extracts were washed with water

(4 x 2 5 O ml. ) and added to the hydrocarban layer. The combined aolu-

tlons were dried over calcium chloride and rectified in a small helix

packed column. A 9056 yield of ( - )-3-methylheptane (17-3 g. , b.p.

117-117.2 °, n^ 5 1.3971, d^ 5 0 .7 0 2 ,-7.93°) vas obtained, lit

b.p. 11 5 -11 8 °, n ^ 1.4000, dj8 0.7075, [<*] J8 ♦6 .7 0 °71; b.p.

120-122°/755 w m ., n^° 1 .3 9 6 0 , d^° 0.7O6972; to.p. ll8 .9°/760 mm.,

n£° 1.3905,

( - ) -2 -Methyl-l-butanol.

Fermentation amyl alcohol (United States Industrial Chemical Co.)

(see footnote 1) was distilled 3 times on a Fodblelnlak Heligrid column

at a reflux ratio of 60:1 until (-)-2 -methyl-l-butanol was produced in

approximately 9 7 .5% purity, see footnote 2 , (b.p. 129°, 1.4107,

2-methyl-1-butanol with optical purity of 97^ ( "5*72°). Dr. Theodore Burton of the University of Utah provided *500 g. of alcohol 54

\ ' 0 .8 1 9 , M i 5 -5 .76°), n t . , b.p. 128-129°A 60 mm., n|° I.JH0 9 , d^° 0 .8 1 8 9 , a®7'5 O.8 1 3 , [a]I7-5 -5 .66 ° (95# optical purity)87;

b.p. 130°/760 k . , dj8 0 .8 1 6 , [oc]p° -5 .90° (optically pure)8 8 ; b.p.

129°/760 — ., n£° 1 .M 0 2 , djj5 0 .8 1 9 , [«]-5 .05 °°°; b.p.

128°/V60 >b ., d|° 0 .8 1 6 , [oc] |° -5 .90089.

Raactlcc of (- )-2-Hethyl-l-butanol vlth Fhcaphorw Tritar ^ 1 da;' ’' ■ (» )-l-Brosu>-2-netliylbutane.

(-)-2-Methyl-1-butanol (442 g. , 5.02 moles, [ p O ^ 0 -5*76°) vas

cooled to -3O0 In a -flask equipped with a Hers Kb erg stirrer, a low tem

perature thermometer, and a dropping funnel. Phosphorus trlbrced.de

(542 g., 2 moles) was added dropwlse orer a period of 5 hours while the

temperature was maintained between -25 and -35°* The mixture was stirred for 2 days at a temperature of approximately -30°. Since a constant temperature of -30° could not be maintained readily at night, stirring was stopped, and the flask was cooled to -7 0 °. After 48 hours an escape went with a ga* trap was substituted for the dropping funnel, and the solution was allowed to gradually warm up to room temperature.

Upon allowing the mixture to stand for 6 weeks, 2 layers became evident.

The layer of alkyl bromide (top) was cooled, washed 3 times with Ice water, once with brine, and filtered through anhydrous sodium sulfate into a 1 -llter, 3-necked flask equipped with dropping funnel, stirrer, and thermometer. The bromide was cooled to -8 to -10° with an Ice-salt bath, and Ice-cold concentrated sulfuric acid (2^0 ml.) was added slowly.

Stirring was continued for 30 minutes, and the mixture was separated.

The amyl bromide was washed progressively with ice-cold concentrated 55 sulfuric acid (lx), ice water (3x), 10^ sodium bicarbonate solution (lx),

ice water (lx), and saturated sodium chloride solution (lx). Since heat or hydrogen brosd.de might effect Its isomerization or racemlza-

tion, the bromide was stored, without distillation, in a refrigerator

over anhydrous potassium carbonate. The product, (♦)-l-bromo-2-methylbutane, was obtained in 89^ yield (673 g. , 4.46 moles, n 1.4430, d^5 1 .2 1 2 , M b *'3 H t . , fa] Jp + k t0 5 olk >9 ] b.p. 6 9 .6 °

/l40 mm., 4 ° 1.4450, d®° 1 .2 2 3 9 , ♦3.75°87J t.p. 71.04-71.7°

/150 mm., n£° 1 .4 4 5 5 , d®° I.2 2 5 , 4 ° f2 .94o9°; b.p. 7 1 .7 °/l50 mm.,

4 ° 1.4451, 4 ° 1.283*, W j 0 '6 »4.043o8iib.

Reaction of Allyl Magneeluxa Bromide with ( ♦ ) - 1-Brcmo-2-methylbutane; (♦)-5-Methyl-lHbepteneTv* >93

Powdered magnesium (382 g., I5.9 moles) was placed in a 5-liter

3-necked flask fitted with a reflux condenser, a Hershberg stirrer, and a dropping funnel. As soon as the reaction was started by the ad dition of a small amount (10 ml. ) of allyl broodde in ether (50/50 ty volume), liters of dry ether was added rapidly. Stirring was com menced and allyl brootide (642 g., 5.3 moles) in one liter of dry ether vslb added dropwlse at such a rate as to produce gentle reflux without external heating or cooling. The mixture was stirred for 6 hours at roan temperature end then refluxed for one hour. The excess magnesium was removed by filtering the solution through glass wool into a similar3y equipped 5-liter flask. The yield of Grlgnard reagent (4.50 moles, 85^) was determined by first hydrolyzing 10 ml. of the reagent with standard acid and then by titrating the excess acid with standard base The yield of Grlgnard reagent varied from 85^ to 100^6 during the course of 56

numerous runs j nevertheless, a 1C«£ excess of Grlgnard reagent, over

amyl b ratal do vas used In every run.

Stirring vas eomenoed and (O-l-bramo-2-methylbutane (623 g . ,

4.13 molee, Jofj ^ *4.00°) vas added to the Grlgnard reagent over a

period of 30 minutes. The solution vas refluxed for 2 weeks. At the

end of this time, the reaction mixture vas cooled with an ice bath and hydrolyzed upon si car addition of 4^0 ml. of 30£ sulfuric acid. The aqueous layer vas removed, and extracted 3 times vlth ether. The com bined extracts and ether layer vere vashed vlth water (lx), saturated sodium chloride (lx), and dried over calcium chloride. The solvent vas rem oved, and the residue vas rectified In a column. (■*■)-5 -Methyl-l- heptene vas obtained in 97^6 crude yield (b.p. 110-114°, 448.0 g., 4.0 moles) .

Since this material gave a positive test for bromide vhen treated with alcoholic sliver nitrate, it vas stirred at room temperature vlth saturated aqueous silver nitrate (25O ml.) for 5O hours. The precipi tate vas collected on a Buchner funnel and vashed thoroughly vlth ether.

The ether layer of the filtrate vas separated, vashed vlth vater (4x), vashed vlth saturated sodium chloride, and dried over calcium chloride.

After stripping off the solvent, the residue vas rectified In a helix packed coltmm to produce 3^0 grams of pure (♦)-5-methyl-l-heptene

(3.39 moles, 83* yield, b.p. 112°, n§5 1.4088, d^5 O.7 U 8 , M d 5*9 .37°, lit., [

The final yield of pure olefin ranged from 70f> to In the various runs that vere made. 57

Reaction of Optically Active 2»M»thyl-l-butyl Magnesium Bromide vlth Allyl Bromide; ( » )-5-Methyl-1-heptane .*95

A solution of (* )-l-brcmo-2-methylbutan© (75 g., 0.5 mole,

jP ♦4.00°) la 330 ml. of Ory ether was dropped slowly onto powdered magnesium (27 6 - , 1.1 mole) In a 1 -liter 3“J&e

reflux condenser, a Hershberg stirrer, and a dropping funnel. The mix

ture was stirred for an hour after the addition vas completed. Hie reagent vas then filtered through glass wool Into a similarly equipped

1-liter flask and cooled vlth an Ice hath. After allyl bromide (80 g.,

0.66 mole) In 80 ml. of dry ether vas added oxer a period of 30 minutes, the mixture was gently refluxed for 20 hours. The reaction mixture was then cooled and treated with 20f> sulfuric acid (25O ml.). The aqueous layer vas removed and extracted 3 times with ether. The coentblned ether layer and extracts were dried oxer calcium chloride and distilled to yield 41.0 g. ( 7 3 of crude (*)-5 -methyl-l-heptene (b.r. 101-118°)

The olefin vas stirred overnight at room temperature vlth saturated aqueous silver nitrate solution. The ether solution vas filtered clear of the white precipitate, washed with water (3x), vashed vlth brine (lx), and dried oxer calcium chloride. Removal of the ether and rectification of the residue In a small column produced 30.85 g. of (*)-5-methyl-1 - heptmj. tn 55# jimlA (b.r. 110-112°, l.b058, dj5 0.710,

[ * ] „ *8 .50°).

This procedure did not seem as effective as the preparation by means of the allyl Grlgnard reagent, so the latter vas used exclusively.

Tetrahydrofuran was tried In one experiment as the solvent; however, It vas eliminated for use because of difficulties Involved vlth excessive 58 foaming during the reaction and formation of azeotropes during distil* la t ion.

Catalytic Hydrogenation of (»)-5-Methjirl-l-hepteiie: (♦)-3-Methylheptane^ F 1

Because of the size of the hydrogenator available, and the large amount of heat evolved during reaction, the reduction vas conducted in a series of small-scale experiments. (f)-5-Methyl-l-heptene (0.7 mole, A.° 7 8 .O g., d ♦9-37°) w placed in a Parr hydrogenator with 150 ml. of ether and 0.8 g. of Adams catalyst, (platinum oocide). A pressure of

50 psl of hydrogen vas applied and the shaker vas started. Reduction vas complete in 12-15 minutes; however, agitation of the mixture vas continued for another 45 minutes.

After each reduction, the catalyst vas removed by filtration and vashed thoroughly vlth ether. The filtrate vas concentrated and recti fied in a helix packed column. Methanol and glacial acetic acid vere used as solvents for this reduction, however, ether vas the most practical. Methanol formed an azeotrope vlth the hydrocarbon, and the acetic acid had to be extracted vlth base vhereas the ether vas easily removed by distillation.

Three hundred and fifty grams (3*12 moles) of (*)-5 -methyl-l- heptene vas reduced in 5 portions to yield upon rectification in a helix packed coltasn the following fractions: (1) 20 g., b.p. 100-115°

(760 mu.), n^° 1.3951; (2 ) 280 g., 2.50 moles, b.p. 117° (?60 mm.), n£° 1.3995, dip 0 .7 0 1 8 , W f *9.25°, n|51 .3962, dg5 O.70 I9 ,

M l 6 *9.3fc°7 ; t.p. 118.9°, n|° 1.39849, d20° 0.70583 3; (3) 15 g., residue, n§° 1.4041. 59

The Infrared spec trim of fraction (2) contains C-H bands (3*30

6 .9O , 7*50>O> See Appendix, Fig. 2 . No Indication vaa found for a

carbon-carbon double bond. Fraction (2) represents an 80% yield of

pure (♦)-3-»ethylheptane. The yield of hydrocarbon varied from 7516 to

9e% depending upon the purity of the olefin and the size of the run.

Hydrocarbons.

Coanerclal decalln, b.p. 8l-83°/20 m . , n ^ 1.4751, d ^ O.8 8 5 7 , O OK ca 65% els and 351& trans; els decalln, b.p. 195.7 , rtf 1.4790,

d*° O.8968, 9 9 -3* purity, lit., b.p. 19b.6 °, n^° 1.48113, dj° 0 .896373,]e

trans decalln, b.p. 1 87 .2 5 °, n ^ 1.4671, d^° O.8698, 99.816 purity,

lit., b.p. 1 8 5 .5 , 1 .^6 9 6 8 , 4^® 0 .8 6 9 9 ?^ els hydrlndane, b.p. 1 6 7 .8 °,

n^° 1.4720, d®° 0.8846, 99-916 purity, lit., b.p. 1 6 7 .8 6 °, n£° 1.4721,

plied by the American Petroleum Institute, Project # 3 1 , at Coluabus,

Ohio. 6o nitration of Hydrocarb onn > ^8

The nltntlotts vsro earrlod out. according to the coodltioni gifcn in. Tables I through VII. The conditions vere varied vlth eaeh separate hydrocarbon at first In order to determine the best method; upon adopt ing the most sat 1bfactory procedure far each hydrocarbon, experimental variables such as time, temperature, and hydrocarbon/nitric acid ratio, etc. vere kept constant. In tvo experiments the heterogeneous system

(Table II) vas stirred during nitration, but the technique vas diffi cult and not productive.

In each nitration one part (molar) of hydrocarbon and 6 parte (mol ar) of nitric acid, diluted vlth vater to vere placed in a 1 -necked round bottom flask fitted vlth a reflux condenser and a thermometer.

The flask vas chosen such that the liquid did not fill more them one- third of the flask, since all the hydrocarbons foamed considerably at the temperature of nitration. The thermometer vas dropped down the con denser and held In position with the bulb In the hydrocarbon layer.

When the mixture of saturated hydrocarbon and nitric acid vas heated to 95°, large quantities of nitrogen dioacide appeared. The heat of reaction carried the temperature up to 108-112° and held It there for approximately 30 minutes without the benefit of external heat. As soon as the temperature of the mixture fell to 95 °* heat vas applied so that the temperature vas held constant throughout the nitration.

The nitration vas stopped after a certain length of time by cool ing the reaction mixture vlth an Ice vater bath. The aqueous layer vas removed vashed 3 times vlth ether. The extracts and the organic 6l

layer vere cosdjined and vashed eons ecutively vlth vater (3x ) , 204,

sodium bicarbonate (2x), vater (lx), and saturated sodium chloride

solution. After the extracts had been dried over Drlerlte, the sol

vent vas removed on a steam bath. The unreacted hydrocarbon vas re

covered by dlstIllation under reduced pressure. The nltro compound

residue vas distilled at a much lover pressure. The nitrated product vas dissolved in 3 S sodium methoxlde In methanol (approximately 1 mole base/2rale ultra compound) and allowed to stand for 2 days. The alka

line solution vas dissolved In large amounts of ether and vashed twice vlth vater. The aqueous vas hinge vere combined, saturated vlth sodlvmi

chloride and extracted 5 times vlth ether. All the ether solutions vere cosfelned, vashed vlth brine, and dried over Drlerlte. The nitro- nltauie vas distilled and treated again vlth base. The base/nltro com pound mole ratio vas approximately 1:1 In the second treatment and 2*1

in -he third and fourth. After the U treatments, there vas no evi dence of base-soluble material in the product and negative red and blue

tests for primary and secondary nltro cosqpounds vere obtained. The material vas distilled roughly In a Clalsen distillation apparatus and

then rectified In a small helix packed column (1.5 * 13 cm.) to give vater-vhite liquids.

Nitration of (*)-3-Methylheptane; (i)-3-Msthyl-3-nltroheptane.

(♦)-3-Methylheptane (lit g. , 1.0 rale, n^5 1 .3970, djp 0.702, pro cured from the American Petroleum Institute, for Infrared see Appendix,

Fig. 1) and 532 ml. of 50jt nitric acid (375 m l • of 71^ nitric acid and

157 ml. of vater) vere placed in a 1 -liter round bottom flask equipped 62 with a reflux condenser and a thermosaeter, See Appendix, Table I. The mixture was refluxed slowly at 100° for 13 hours. The crude product was separated, neutralised, and dried according to the procedure out lined previously and distilled Into 4 fractions: (1 ) 46.0 g. (41* recovery of (±)-3-methylheptane), b.p. 47°/55 am., n^^ 1.3945, lit.,

1.396^7^ (2) 14.80 g. of crude nitro-octane, b.p. 68-87°/8 mm.,

1.4278; (3 ) IO.5O g. of crude nitro-octane, b.p. 87-±06°/8 am., tOjp 1.4450; (4) 19.47 g. of crude nitro-octane, 1 0 6 - 1 1 2 ° /2 am., n| 5 1.4531. Fractions (2), (3) and (4) £44.77 g., 0.282 moles, 28*

crude c our era ion assuming molecular weight of product of 159} were com bined with 49.3 g. (0.312 moles) of nitro-octanes obtained from nitra tion of 1.54 moles of (1 )-3-methylheptene. The nitration products were treated 4 times vlth base as described previously, worked up, and dis tilled to give: (1 ) I .25 g., b.p. 55-63°/lO am., n^° 1 .4238; (2 )

2.00 g., b.p. 63-73°/lO mm., n^° 1 .4254; (3 ) 3-06 g., b.p. 73-85°

/10 am., n^° 1.4332, d25 O.9285; (4) 3.10 g., b.p. 82°/l0 mm., 20 njj 1.4364* (5 ) 5.2 g., residue.

The infrared spectra of fractions (1) and (2) contain strong car bonyl bands and weak nitro bands. Strong nitro and weak carbonyl bands are present in the spectra of fractions (3 ) and (4). The spectrum of the residue has strong mononltro and dlnitro peaks.

Fractions (3 ) and (4) vere combined and distilled into four frac tions: (1) 0.81 g., b.p. 65-7O0/10 mm., n§° 1.4226; (2) 1.10 g., b.p.

70-74°/lO n§° 1.4302; (3 ) 0.20 g., b.p. 74°/l0 am., n£° I.4309;

(4) 2.40 g., b.p. 8l.8-82°/l0 » . , ng° 1.4339, O.928O; (5 ) 1.60 g., residue, n^° 1.4359. Fraction (4) represents a 1* yield. 63

The Infrared spectrum of fraction (t), identified as (i) - 3 - me thy 1-

3-nitroheptane, contains strong nltro hands (6 .top., 7 . 3 2 p and 1 1 .6 5 / 0 and C-H hands (3*38p , 6.85/l, and 7.20p), see Appendix, Fig. 3.

Small hydroxy (3 .00/ ) and nitrate peaks (6 .1 0 /i) indicate these im purities are present in very small concentration, however, the analysis is well within experimental error for the pure 3 -methyl-3-nitroheptane.

Pure (i)-3-methyl-3-nitroheptane has the following properties: b.p.

8 2 °/l0 mu., n§° 1 .V339 , 0 .9 2 8 0 ; (calc'd) tt .8 t; MR^j (found) k k . 37.

Anal. Calc’d for CqH17N02 : C, 6 0 .38; H, 10.6 9 ; N, 8.80

Found: C, 60.t-9; H, 10.73; N, 8 .81

98 99 Reduction of (1)-3-Methyl-3~nltroheptane; (i)-3-Amlno-3-»othylheptane. ’

(±)-3-Methyl-3-nltroheptane (3.21 g., 0.0202 moles) in tO ml. of ether vas placed In a Parr hydrogenator vlth a teaspoonful of Raney nickel. Hydrogen at 50 pel was added and the mixture was shaken for

3 hours. After the catalyst had been removed by filtration and the sol vent stripped off on a steam bath, the residue vas distilled to give:

(1) 0.70 g., b.p. 27-3‘?°/25 n*pi.Ul29; (2) 0 .5^ g. , b.p. 62-63°/28 mm., n^ 5 1 .U2 1 0 ; (3 ) O .97 g., b.p. 63 -65°/28 mm., n| 5 I.U2 2 3 .

Fraction (3 ) was identified as crude (i)-3-amino-3-methylheptane.

Fractions (2) and (3) represent a SOf> yield of reduction product.

The Infrared spectrum of fraction (3) exhibits peaks for H-H

(3.00//, 6 . 2 0 9 *1 0 /1, and 9 .5 0 ^1 ) and for C-H (3-38>*» 6 .85/1 , and 7 .2 5 /t) bonds; there vas no absorption that can be attributed to nitro groups. 64

Reaction of (1 )-3-Amlno-3-me thylheptane vlth Phenyl Iaothlocy»n**ta^; W-Phenyl-N * - 3( 3-methylheptyl) thlourea.

A solution of phenyl isothiocyanate (O.55 g.) and (i)-3-amlno-

3-methylheptane (0*5 8 * f O.OO388 moles) was heated on a steam hath for

3 minutes. The oil gradually crystallized upon standing at 10°. The hard white solid was broken up on a filter paper, washed with cold ligroin (2 ml.), and air dried. The crude derivative vas obtained in a yield of 70^ (0.72 g., 0.00281 moles, m.p. 72-74°). After recrystal- lizatioo from hOfa aqueous ethanol, N-phenyl-5’-3 (3-methylheptyl) thiourea was obtained as a pure white powder: m.p. 79°, 0 .6l g., 0.00234 moles,

60^ yield. The melting point of this derivative when mixed with

5-phenyl-5'-3(3-methylheptyl)thiourea, prepared from (i)-3-amino-

3-methylheptane obtained from (i)-3-methyl-3-nitroheptane derived from

(i)-3-me thylheptane, was not depressed.

Nitration of (»)-3-Methylheptane; 3-Methy 1-3-nltroheptane.

(♦)-3-MethyIheptane (228 g., 2.0 moles, n^5 I.3975, djp 0 .7018,

L°0 *9 *25°, see Appendix, Table II; for infrared spectrum see Append!^,

Pig. 2) was heated to 100° for 13 hours with 12 moles of 5°^ nitric acid (750 ml. of 71^ nitric acid and 314 ml. of water). The layer con taining the hydrocarbon and nitrated products vas removed and washed with vater (3x), 20jb sodium bicarbonate solution (2 x), and saturated sodium chloride solution (lx). After the mixture was dried over Drlerlte the solvent was removed on a steam bath, and the residue was distilled to give the following fractions: (1 ) 101 g. of (♦)-3-methylheptane representing 4?£ recovery, b.p. 45-5l°/*37 m . , n^5 1 .3967, 65

(2 ) 17*23 g. of crude nltro-octanes, b.p. 35-75°/B am., n§ 5 1.4320,

*-9*83°; (3) 19.32 g* of crude nitrooctanes, b.p. 7 5 -90°/8 m . ,

1.4384, *7*57°; (4) 11.46 g. of crude nano and polynitro-

octanes, b.p. 73-83°/l am. , nj^ 1.4450; (5 ) 52.57 g., residue, r^> 1.4633*

Fractions (2), (3), and (4) were treated with methanollc sodium methodide (see general directions) until negative tests were obtained for primary and secondary nitro groups. The product that was Insoluble

in s odium methoxide was worked up and distilled to give the following fractions: (i) I .23 g., b.p. 37-7 2 °/lO m b . , n§ 5 I.438I; (20 2.11 g., b.p. 72-8l°/l0 mm., n| 5 1.4324; (^) I .95 g. , b.p. 8l-82°/l0 ann. ,

1.4330, d| 5 O.9 3 6 , MRjj (calc'd) 44.84, (found) 44.05; (*') 0-75 g-, b.p. 8 2 -8 3 °/l0 mm., n ^ 1 .4 3 3 6 ; (^) residue.

Fraction (3*) was identified as 3-“®thyl-3-nitraheptane; it was

Isolated in 1^ yield. The infrared spectrum of this compound contains strong peaks indicating the presence of mononitro group (6.40j* , 7 -37>4 , and 11.85;*) and C-H (3-38^ , 6 .8 5 ^1 , and 7.20;*) bonda (See Appendix,

Fig. 4). Hiere are also small peaks which indicate that some nitrate

(6.10;*) euid hydroxy (3.00^i) compounds sure present. These impurities were in sufficient quantity to lower the elemental analysis.

Anal. Calc * d for C^H^HOg: C, 6O.3 8 ; H, 10.6 9 ; H, 8.80

Found: C, 5 6 .6 2 ; H, 9-73; N, 7.86

The elemental analyses for other nitrations (See Appendix, Table IX) gave similar results: 66

Anal. Calc*d tarCqH 17H02 * C, 6 0 .38 ; H, 10.6 9 * H , 8 .8l

Found for Exp. Ho. 1 5 : C, 5^.07; H, 9-97; H, 8.13

Ho. 16 : C, 57.12; H, 10.1 3 ; H, 8 .C*

Ho. Iks C, 5 6 .31; H, 10.62; H, 8.05

The polarise ter reading for 3-methyl-3-nl troheptane (fraction (3 ))

prepared from («-)-3-me thylheptane were taken at four ware lengths . The

rotations were corrected for errors In the tube Instrument by using

(t)-3-methyl-3-nitroheptane In the same tube as a blank. The readings were as follows:

Obserred Rotation For Observed Rotation For 3-Methyl-3-nitroheptane (i)-3-Methyl-3-nltro- Corrected Wavelength ______at 26° heptane at 26° Rotation

623k X -0.07° -0.03° -O.OU°

5893 A -0.08 -0.03 -0.05

5^61 A -0.11 -0.05 -0.06

5160 A -0.14 -0.07 -0.07

In the numerous nitrations of (*■)-3-methylheptane listed In

Table II, the 3-methyl-3-nltroheptane varied in final rotation from

*0.33° to 0CD -O.2 5 0. Other than for the last rotation ( -0 .0 U ) the correction was made without the (1 )-3-®ethyl-3 -nitroheptane blank.

The zero reading usually was taken without any tube In the polarlmeter.

It was believed that the alcohol and nitrate impurities In the compound, as Indicated by the infrared and the elemental analysis, were the reason for this rotation. Most of the attempts to purify the nitrooctane resulted In a severe loss of tertiary nltro compound, e.g., dis tillation, chromatography, concentrated sulfuric acid t r e a t m e n t * a n d 6? dilute acid treatment. After a comparatively large amount of 3-nethyl-3-

3-nitroheptane vas lost, it vas decided it vould be more advantageous

to reduce the crude nltrooctane to 3-amino-3-methylheptane convert the amine to the phenyl thiourea, rather than to continue the purification of the parent nitro compound.

Recently the position of the tube in the polarlmeter rack vas dis covered to be a critical factor in the reading of small rotations vlth a 2dm semlmlcro tube. B y moving the tube from one end of the rack to the other, the rotation vould change as much as ±0.5°. This error is believed to be a major reason for the rotations observed In the earlier runs. Therefore, the nitration and purification procedure vas carried out as described above. By using the new method, the reading of

O t ^ -0. Oh° vas obtained. All of the rotations recorded from this point vere determined according to the Improved technique.

Reduction of 3-Methyl-3-nltroheptane Obtained from (»)-3-Methylheptane; (i ) - 3-Amino- 3-me thylheptane. ^ ^

3-Methyl-3-nltroheptane (b.p. 8l-82°/l0 mm., n^^ 1.^330, dj^ 0.936,

2 6 ° O-p -0.0h°) from (♦)-3-methylheptane vas reduced in a Parr hydrogenator.

The 3-methyl-3-nitroheptane (5*71 6*, 0.0359 moles) vas dissolved in ho ml. of ether and reduced vlth Raney nickel teaspoon) and hydrogen

(starting pressure of 50 psl). When the reduction vas complete, the solution vas filtered to remove the catalyst and then concentrated on a steam bath. Distillation of the residue gave a colorless liquid: (1)

2.90 g., b.p. 26-h7°/27 ng? 1 .^987; (2) O.hO g., b.p. k7-50°/27 m . , n|5 i.hl2 3 s (3 ) 0.20 g., b.p. 63°/27 l.h2 1 2 ; (h) l.lh g., 68

b.p. 63 -65°/27 mm., njj^ 1 .1*2 2 3 ; (5 ) 0.60 g., residue.

The Infrared spec trim of fraction (3 ) contains characteristic ab

sorption for tf-H bonds ( 3 . 0 0 / a , 6.20/* , 9 .10/1 , and 9 .5O / O »nfl C-H

bonds ( 3 , 6 .9 O/A , and 7 .2 5 /1 ). There was no absorption character

istic of a nltro group. Fraction (3 ) was analyzed as follows:

Anal. Calc * d for C, 7 4 -4 5 ; H, 14.72; N, 10.86

Found: C, 7 2 .94; H, 14.66; N, 9.71

A 30^ solution (0.64 g. of amine in I .50 g. of ethanol) of frac

tion (4) exhibited no rotation at 6 2 3 4 A , 5 8 9 3 X , 546l X , or 5160 X.

(i * 2dm).

Fran the physical constants, odor, chemical properties, and Infra

red analysis, fractions (3 ) and (4) were Identified as 3 -amino-3-methyl-

heptane (33)6 yield). The yield was tinderstandably lower than that for

the (*) compound since the original 3-methyl-3-nitroheptane frcm

(♦) -3-methylheptane was Impure. Comparison of the properties of this

compound with the (1 )-3-amino-3-methylheptane indicated that they were

Identical. Although the analysis for this 3-amino-3-methylheptane was

low, It was considered more advantageous to convert the small amount available to a derivative rather than to attempt to purify the amine further.

Keactloo. of Phenyl Isothlocyanate with (±)-3 -Amlno-3 -methylheptane Prepared fro«* (»)-3-Methylheptane; N-Fhenyl-N* -3 (3-methylheptyl) thiourea.96

3-Amino-3-methylheptane (0.5 g., O.OO38 moles) was mixed with

9*?? 8 * (0.0040 moles) of phenyl Is othlocyanate and heated for 3 minutes on a steam bath. The colorless oil solidified on standing over- 69

night In a refrigerator. The white solid vas crushed on a filter paper

and washed with a few drops of cold 11 groin to restore excess reagent.

The crude derivative (0.64 g., 0.096 moles, 6yf> yield, m.p. 74-76°)

vas dissolved In absolute ethanol (0.64 g. of solid in 3.56 g. of

ethanol, 15*3 g./lOO g. of solution), filtered, and placed in a 2dm

semi-micro polarlmeter tube. Ho detectable rotation could be found at

the following wavelengths; 6234 A, 5893 X, 5461 X, 5160 X.

The derivative which vas identified as N-phenyl-N’-3( 3-methylheptyl)

thiourea, vas re crystallized from 40$ aqueous ethanol and dried in a

drying pistol for several hours to give 0.59 8 * (0.00224 moles, 58#

yield) melting at 79°* This recrystallized material exhibited zero

rotation, also. There vas no depression of melting point vhen this

derivative vas mixed vith the N-phenyl-N' -3(3-methylheptyl)thiourea

prepared from (i)-3-amino-3-methylheptane.

Anal. Calc*d for C, 68.17; H, 9 .O9 ; N , 10.62

Found: C, 68.15; H, 8.91; N , 10.60

C, 68.32; H, 9.22; N, 10.51

a ^ Nitration of C ™ —»rclal Decalln; 9 -Nltrodecalin. *

In the following experimental work, the designation of commercial, els, or trans in parentheees after the decalln and the hydrlndane will not be the configuration of the compound Itself, but will indicate the configuration of the hydrocarbon from which the compound vas prepared.

Commercial decalln (138 &•, 1*0 mole, b.p. 8l-83°/20 mm., n ^ I.475I, df5aU0B57, for infrared spectrum see Appendix, Fig. 6 ) vas refluxed for 4 hours vith 6 moles of 50^ nitric acid (375 of 71^ 70 nitric acid and 1?7 ml. of water), see Appendix, Table i n . The aqueous layer was remcrred and extracted 3 ttoms with ether. The ether extracts and the layer containing the nitro hydrocarbon were combined and washed with water (3*)> 20$ sodium bicarbonate solution (2x), water (lx), and brine (lx). The mixture was dried over Drlerlte, and the solvent was removed. Distillation of the residue gave the following: (l) 3U .0 g. ,

50^ recovery of decalln, b.p. 3 6 .?-39°/2 rmn. , njp 1 .^7 2 3 ; (2 ) 3 .21 g. of crude nltrodecalins, b.p. 8 8 -98°/2 mm., n^p l.k9 32 ; (3 ) 3.55 g. of crude nltrodecalins > b.p. 9 8 -lo8°/2 ami,, n ^ I.496O; (4) 7.22 g. of crude mono and polynltrodecallns, b.p. 108 -122°/2 b i d . , n^p 1 . ?02 l ;

(?) 13.0 g., black tar residue.

The refractive index of the recovered hydrocarbon (fraction (1), n^' 1 .1*7 2 3 ) is 6 lightly lower than that of the starting material

(njp 1.1*751). This fact would indicate that the percentage of trans decalln has increased as a result of the nitration. Comparison of the infrared spectrum of the starting material (Appendix, Fig. 6 ) with the spectrum of the recovered material (Appendix, Fig. 7) shews qualitatively that a mixture of els and trans forms is present in both; however, no quantitative conclusions can be made. The peaks are as follows: regular

C-H, 3-^0f*> 6 .9O jj , and 10.30jji; trans configurational peaks, 10.8lyi ,

H. 9 2 ^1, and 12.12pi; and els configurational peaks, 1 1 .7 2 ^i, and

12.00 p* .

Fractions (2), (3 ), and (k) were caatoined, and treated with sodium methorlde (kx) until a negative secondary nitro group test was obtained.

Eectif1cation in a helix packed column gave a colorless liquid: 71

(I1) 1.75 g-, b.p. 70.0-8 l.9 °/l.3 m . , ng5 1 .489**; (2*) I .67 g. , b.p.

81.9-87.8°/l. 3 « . , n|5 1A917; (3‘) 5*16 g. , b.p. 87.8°/l.3 nm.,

n|5 1.1*925, 1 .061.

Pure 9-nitrodecalin (fraction ( ^) ), which w&s obtained in **4>

yield frcB commercial decalin, had the following physical properties:

b.p. 87 .8 °/l. 3 mm., n^ 5 1 .1*925, d^ 5 1 .08l, MR^ (calc'd) 1*9 .8 0 , MJ^

(found) I*9.l5* The infrared spectrum contained strong nitro peaks

(6.U0p and 7 .35^1), strong C-H peaks (3 .38^1, 6.90/4, and 7 .25^ ) ,

very strong trans configurational peaks (1 0 .7 0 /ji, 11 .90 ^1, and 1 2 .10 /u),

and weak nitrate (6.10/j ) and nitrite (5 .80/ji ) bands. (See Appendix,

Fig. ll* for spectran.)

Fran the liquid phase nitration of commercial decalin, Name tk in 68

obtained a 9 -nitrodecalin with the following properties: b.p. 9^*7°

/2 mm., 1.1*91*1*, d^° 1.081*7 . Huckel11 prepared from both pure

trans and ccaxmercial decalin a 9 -n^trodecalin which he designated as

trans. b.p. 122-125°/l8 an., ng-* 1 .1*9221, djp'2 I.O80 3 .

Reduction of 9 -N1 trodecalin (Cosnerclal); 9 -Amlnodecalln.^*^?

9-Ritrodecalin (5.0 g., O .0278 moles) prepared by the nitration of

commercial decalin was dissolved in 1*0 ml. of 95^ ethanol and placed in

a Parr hydrogenation apparatus with \ teaspoon of Raney nickel. Hydro

gen was added at 50 psi and shaking of the hydrogenator was initiated.

When the reduction was complete, the catalyst was filtered off and the

alcohol was removed under reduced pressure. Crude 9 -aminodecalin (com

mercial) was obtained as a light yellow liquid in 95^ yield; **.0 g. , 72

0.0262 molds, n|5 1.4923, d^5 O.9455, MR^ (calc'd) 47.^2, MR^ (found)

47.16. 68 Nametkln reported the following physical properties for the

9-aminodecalin prepared from commercial decalin: b.p. 98°/l^ n«n.,

Or> 2 0 1 1 1.4932, dj^ O.9435. Huckel reported similar properties (b.p.

222.6 /757 mm., n ^ 1.4921, dj^0*2 O.939I) for the 9-aminodecalin pre

pared from either caumercial or trans decalin.

The infrared spectrum of 9-&minodecalln (commercial) exhibited

N-H peaks (3.00>j and 6.20/-t) and C-H peaks (3.38^1 and 6.90>i). The

bands attributed to the nitro group vere not present.

Reaction, of Acetic Anhydride and Sodium Hydroxide with 9-Amlnodecalln TC ccaaerc ial) ; W-9-Pecaiylacetamlde. ^

9-Aminodecalin (commercial, 2.0 g., O.OI39 moles) was placed in a

large test tube with 3 ml* of 20^ sodluu hydroxide. Acetic anhydride was added a few drops at a time until the amine was completely con

verted to a white solid* The test tube was stoppered and shaken vigorously after each addition. The precipitate was broken up on a

filter paper and washed several times with water to remove excess re agent. Crude lf-9-decalylacetamide (commercial) was obtained in 95^ yield, 2.42 g., 0.0124 moles, m.p. I5I-I650. One and one-half grams of

this derivative was recrystallized from acetone to give 0.84 g. of pure white crystals, m.p. 183°. The filtrate was concentrated, and the pre cipitate was recrystall 1 zed twice to give 0.50 g. of additional material with m.p. 183°. The total of 1.34 g. of pure H-9-decalylacetamide

(m.p. I830) represents an 85^ yield calculated from the 9~nitrodecalin. 73

the cis and trans series (nixed melting points).

Huckel^ reports that the N-9“decalylacetamide with melting point

of 183° has the trans configuration.

T 1 /"ft Nitration of Cis Decalin; 9-Nltrodecalln. J

Cis decalin (71*4 g., 0*517 moles, b.p. 19if.6 °, 1.4808, 20 d^ 0 .8963, 99*2^, see Appendix^Fig. 8 for infrared spectrum) was re

fluxed for 3 hours with 3 moles of 50^ nitric acid (187.5 ml. of 7l£

nitric acid and 78 ml. of water), see Appendix, Table TV. The aqueous

layer was removed and extracted 3 times with ether. The extracts and

nltrodecalin layer were ccmbined, dried over Drierite, and concentrated

on a steam bath. Distillation of the residue gave the following frac

tions; (1 ) 22.5 g. , 32^ recovery of cis decalin, b.p. 36-4l°/2 ntc.,

1.1*801; (2 ) 1.1*6 g. of crude nitrodecalins, b.p. 41-51°/2 mm.,

n^p 1.4780; (3 ) H .58 g. of crude nitrodecalins, b.p. 79-ld5°/2 nnn. ,

A c 1 A 923; (4) 3*61 g. of crude mono and polynitrodecalins, b.p.

H5-125°/2 mm., n ^ I.5OO8 ; (5 ) 20.10 g., black tar residue.

The physical properties and infrared analysis (compare Fig. 8

and 9 in Appendix) of the recovered decalin (fraction (1)) show that it

is identical with the starting material. The infrared spectrum of frac

tion (l) contains C-H peaks (3-40^1 , S.^Oyx , and 10.32/j ) and the cis

configurational peaks (11.72 p and 12.0 0 /j ).

The nitrodecalin (fractions (3 ) and (4)) was combined with the pro ducts from three other nitrations and treated with sodium methoxide in 71+

methanol until a negative test for secondary nitro groups vas obtained

(4x). From a total of 1.1+9 moles of decalin (recovered material ex

cluded) there vas produced 22.53 g- cf yellow liquid. This vas recti

fied on a small helix packed column to give: (l') 2.72 g., b.p.

72-8l°/l nan., 1.1+875; (21) 3.91 g., b.p. 8l-85°/l mm., r^-1.1+920;

( A 10.07 g*, b.p. 85-86°A I.I+933, d£5 1 .084; (4f) 2.46 g.,

b.p. 86-90°/l mm., nj^ 1.4941.

Pure 9-ni trodecalin (fraction (3)), which vas obtained in 4%

yield from cis decalin, has the following physical properties: b.p.

85-86°/l ma., njp 1.4933, djp 1.084, MR^ (calc'd) 49 .80, MT^ (found)

4 0 .0 9 . The infrared spectrum (see Appendix, Fig. 12) contained strong

nitro peaks (6.40)4. and 7 *38)4 ), strong C-H peaks (3 -38)4 , 6.90)4, and

7.25y* ), very strong trans configurational peakB (10.70)4 , 11.90>4 , and

12.10)4 ), and a weak nitrate peak (6 .10)4 ). This compound exhibited

identical physical properties and infrared spectrum as the 9-nitro-

decallns prepared from commercial and trans decallns.

Anal. Calc * d for C10H17N02 : C, 6 5 .55 ; H, 9*29; ^*65

Found: C, 65.76; H, 9*24; N, 7-52

C, 65.71; H, 9*19; N, 7.1+6

Reduction of g-Hlbrodecalln (cis); 9~Aminodecalln.98,99

9 -1?itrodecalin (2.0 g., 0.0274 moles) from cis decalin in 50 ml.

of 95

gen at 50 pel and Raney nickel (J teaspoon). Reduction was complete after 3 hours. The catalyst was filtered off, and the solvent vas re moved under reduced pressure. The light yellcw oil (4.05 g*) was 75

identified as 9-aminodecalin (cis) in 97# crude yield. The physical

properties of this 9-aminodecalin ( n 1.4922, d^5 0 .947, MR^ (calc*d)

47.52, MRjj (found) 46.89) and the infrared spectrum (N-H peaks (3.00^4 and 6.20/x ) and the C-H peaks (3.38>* and 6 .90^1 )) were identical with

those of the 9-ami nodecal ins prepared from commercial end trans

decalins . There was no absorption for nitro groups in the reaction

product.

Reaction of 9-Amlnodecalln (Cis) with Acetic Anhydride and Sodium Hydroxide;1 W-9-Da~caljrlacetanide. ^

9-Aminodecalin (1.95 g.» 0.0127 moles) from cis decalin was shaken vigorously in a stoppered test tube with 3 ml. of 20)6 sodium hydroxide and a few drops of acetic anhydride. Additional acetic anhydride was added several times until the reaction was complete. The precipitate was crushed on a filter paper, washed with water, and dried to give

2.36 g. of a white solid (951& crude yield) melting at 17I-I760. Re crystallization of I .50 g. of this material from acetone produced

1.20 g. of pure white crystals, m.p. 183°. The filtrate was concentrated, and the precipitate was recrystallized twice to give an additional 0.13 g. of the acetamlde, m.p. 183°. The total of 1.33 g* of pure N-9-decalylacetamlde (m.p. I830 ) represents a yield of 8 6 .5^ calculated from the

9-nitrodecalin (cis). The mixed melting point of this compound with the N-9-decalylacetaaide prepared in either the commercial or the trans series vas not depressed. 76 nitration of Trans Decalin; 9-NI trodecalin.

Trans decalin (138 g., 1.0 mole, b.p. I85.50, 1.4671,

4^° O.8699, 99*9^, for Its Infrared spectrum see Appendix, Fig. 10) was refluxed for 5 hours with 6 moles of 504 nitric acid (375 ml. of

714 nitric acid and 157 ml. of water), see Appendix, Table V. The aqueous layer was removed and extracted 3 times with ether. The extracts and the hydrocarban-nitrohydrocarbon layer were combined, and succes sively washed with water (3*)> 20^ sodium bicarbonate (2x), water (lx), and saturated sodium chloride solution (lx). After the mixture was dried over Brierite, the solvent was removed and the residue was dis tilled: (1 ) 70 g., representing 514 recovery of trans decalin, b.p.

65°/l2 ram., n ^ 1.4672; (2 ) 13.46 g. of crude nitrodecalins, b.p.

72-ll9°/2 on., r^p 1.4921; (3) 10*10 g. of crude mono and polynltrodecallns, b.p. ll5-131°/2 in., n!^p 1.4973; (4) 20.0 g., black tar resi due .

The physical properties and the infrared spectrum of the recovered decalin (fraction (1 )) indicate that It is unchanged from the starting material. The infrared spectrum of the recovered decalin contains C-H peaks (3*40>x, 6 .9 0 |j, and 10.30>4 ) and trans configurational peaks

(10.82pi , U . 90^4 , and 12.20p). Compare Figs. 10 and 11 in the Appen dix.

Fractions (2) and (3) were combined with the products obtained from two similar nitrations and treated with sodium methocclde In methanol.

A total of 1.26 moles of trans decalin (excluding recovered material) was nitrated to give 27.36 g. of 9 -ni trodecalin after 4 treatments with 77

base. This material gave a negative test for secondary nitro groups.

Rectification in a small helix packed column gave the following frac

tions: (f) 8.30 g. , b.p. 60-70°/0.8 imn., n^5 1 .4869; (2*) 3.40 g.,

b.p. 70-79°/0.8 mm., n^5 1.4893; (3*) 9.05 g., b.p. 79-8l°/0.8 nm.,

r^p 1 .4Q19, d£5 1 .082; (4') 3.61 g., b.p. 81-82%). 8 sm., n£5 1 .4927.

Fraction (3f)> vhich was identified as 9-1*! trodecalin (trans),

represented a Uffc yield. The physical properties of this pure product

(b.p. 79-8l°/0.8 mm., n|5 1.4919, d^5 1 .082, MRjj (calc'd) 49.00, MR^

(found) 49.66) were identical with the properties described earlier for the 9-nitrodecalins prepared from ccmaercial and cis decal ins.

Anal. Calc'd for ClQHl7H02 : C, 65.55; H, 9*29; H, 7.65

Found: C, 65.69; H, 9.52; N, 7.33

The infrared spectrum of the 9-ni trodecalin (Appendix, Fig. 12) was identical with the spectra of the other two 9-nitrodecalins (cis,

Fig. 12; conmerclal, Fig. 14) and contained C-H peaks (3 .38 ^4, 6.90>* , and 7 .2 5 ^*), strong nitro peaks (6.40p and 7 .3 2 ^), strong trans con figurational bands (1 0 .7 0 ja, H . 90^4 , and 1 2 .1 0 p), and weak nitrite

(5 .80^ 1) and nitrate (6 .1 0 ^*) bands.

Reduction of 9- W l trodecalin (Trans); 9-Amlnodecalln.9^>99

9-Nitrodecalin (5 .O g., 0.0273 moles) prepared from trans decalin was dissolved in 50 ml. of 95^ ethanol and placed in a Parr hydro genation apparatus with \ teaspoon of Raney nickel. Hydrogen was added at 50 psi ay>d shaking of the hydrogenator was initiated. When the re duction was complete (3 hours), the catalyst was filtered off, and the 78

solvents vere removed under reduced pressure. The residue of 4.13 g-

(98% yield) was identified as crude 9-aminodecalin 1 .4927, d^5 0 .945, MRjj (calc'd) 47.52 , (found) 47.03). The Infrared spectrum

contained W-H peaks (3 .00)u and 6 .20^), *r\A c-H peaks (3 .38/n and

6.Q0^j); the peaks for a nitro group were absent. The physical proper ties and Infrared spectrum of this 9~a.m.1 nodecal In (trans) were almost

identical with those of the 9-aminodecalin (commercial) and 9-aminodecalin (cis) prepared previously.

Reaction of 9-Amlnodecalln with Acetic Anhydride and Sodium Hydroxide; H-9-Decalylacetamide. 9^

9-Aminodecalin (2.0 g., O.OI309 moles) prepared from trans decalin was shaken in a stoppered test tube with 3 ml. of 20% sodium hydroxide and a few drops of acetic anhydride. Additional acetic anhydride was added until all of the amine had reacted. The precipitate was col lected on a filter paper, washed with water and dried to give 2.44 g. of a white powder (m.p. 130-143°). A portion (I.50 g.) of this deri vative was dissolved in hot acetone, filtered, and allowed to crystal lize. The pure white crystals were filtered and dried to give 0.75 g* melting at 183°. An additional 0.4^ g. of the same acetamide (m.p. I830) was obtained by further treatment of the filtrate. The white crystals were identified as N-9-decalylacetamide; the derivative is Identical with that isolated in the cis and in the commercial decalin series, since the mixed melting points were not depressed. The 1.20 g. of

N-9-decalylacetamide (trans) represents a yield of 77% based on the

Q-nitrodecalin. 79

Anal. Calc*d fear C, 74.20; H, 10.32; N, 7.22

Found: C, 74,32; H, 10.50; N, 7.12

9 ,10-Dlnltrodecalin.

A crystalline solid was Isolated from the distillation residues of

the base insoluble material from each of the 9-nitrodecalin preparations,

i.e., from the commercial decalin, cis decalin, and trans decalin. This

solid was recrystallized from ether to give large, clear rhombic crys-

tala, m.p. 169°; lit., 9 ,10-dinltrodecalin, m.p. 164° m.p. 169° 11.

The rate of heating apparently determined whether the melting point was

164° or 169°.

The mixed melting points for the three compounds (from the conmer-

cial, els, and trans decal ins) were not depressed. The infrared spectra

of the three were identical. The peaks for C-H bonds (3*38p, 6.90p,

and 7.40^u), nitro group (6.40^t , and 7 .52 /u), and trans configuration

(I0 .62^u , U.QOjj, and 12.15yu) were present in all three samples (see

Appendix, FigB. 15, 16 , and 17).

Hltratlon of Cis Hydrlndane; 8 -Nltrohydrlndane.100

Cis hydrlndane (124 g., 1.0 mole, b.p. 167.8 °, n ^ 1.4700, 20 d^ 0.8846, 99*9^6, for infrared spectrum see Appendix, Fig. 18) was re

fluxed for 5 hours with 6 moles of nitric acid (375 ■ of 71$ nitric acid 157 ml. of water); see Appendix, Table VI. The aqueous

layer was removed extracted 3 times with ether. The ether extracts and the hydrocarbon layer were combined and washed with water (3x), 20$ 80 sodium bicarbonate (2x), water (lxv and saturated sodium chloride (lx), and dried ewer I>rierite. The ether was removed on a steam bath and the residue was dlBtilled to give: (1) 34.0 g., representing a 28$ re covery of cis hydrlndane, b.p. 62°/20 nm., n|5 1 .U697; (2 ) 17-54 g. of crude nitrohydrlndanes, b.p. 93-120°/l ran., 1 .4953.

The recovered hydrlndane (fraction (1)) was unchanged from the starting cis hydrlndane since the physical properties end the infrared spectra were the same. The infrared spectrum of the recovered hydrlndane (Appendix, Fig. 20) contains C-H peaks (3.40p , 6.90>* , 7.35jjl , and 10.30yj), and the cis configurational peaks (11 .11 )j and 12.35^4 ).

Fraction (2) was comb in od with the nitrohydrlndanes from two simi lar nitrations and treated with equivalent amounts of 3 N sodium msth- axlde in methanol (4x) until a negative test for secondary nitro groups was obtained. From 1,80 moles (excluding recovered material) of cis hydrlndane, 2 1 .1+3 g. of nitrated hydrlndane was obtained as a colorless liquid which has a camphor-like odor. Rectification of this material in a helix packed column gave the following fractions: (l‘) 3 -0° 6 * > b.p.

66-68°/0.8 ms., n^p 1.4876; (t/) 3-70 g., b.p. 68-69°/o.8 mm., n^5 1.1.880, a^ 5 1 .0892; (i ) 3-31 6 ., b.p. 69-69 .8°/0.8 mm.,

4 ? 1.M83S (H) 9.25 g., residue. Fractions (21) and (3) represent a

3$ yield of 8-nitrohydrindane.

Fraction (2*) was identified as 8-nitr ohydr indane (cis). The physi- ^ 2 c cal properties for the pure compound (b.p. 68-69 /0.8 mm., n^ 1.4880, d^5 I.O892, MRjj (calc'd) 45 .ll, MRjj (found) 44.87) and the infrared spectrum (C-H peaks: 3*42jjl and 6.90p ; nitro peakB; 6.4op , 7*35^* an& 81

11.55ft ; the els configurational peaks : 11.77ft and 12.42jjl , see

Appendix, Fig. 22) matched the properties and spectrum found for the

S-nitrohydrindane (trans). Small nitrite (5 .9 p ) and nitrate (6.10fi )

peaks indicated the presence of impurities.

Anal. Calc’d for C^ff^NO^ C, 63.91; H, 8 .88; H, 8.28

Found: C, 64.57; H, 8.94; N, 7.90

C, 64.55; H, 8 .89; N , 7.82 100 Nametkln obtained an 8-nitr ohydr Indane from the nitration of

coomerclal hydrlndane with the following physical properties: b.p.

9Q.5-101°/4 am., n£° 1.4888, d^° 1 .0857.

Reduction of 8 -Nltr ohydr indane (Cis); 8 -Amin ohydr Indane. ^

8-Hitrohydrindane (5.0 g., 0.0296 moles) prepared from cis hy dr in dane was dissolved in 40 ml. of ether and placed in a hydrogenator.

Raney nickel (^ teaspoon) and hydrogen at 50 pel were added and the shaker was started. At the end of 3 hours the reduction was complete.

The catalyst was removed by filtration »nd the solvent was distilled .

The residue (4.0 g. ) was Identified as crude 8 -aminohydrindane (cis) in

98^ yield. The physical properties of_this compound 1-4923, d^5 O.943, MRjj (calc’d) 42.83, MRjj (found) 42.79) and the infrared spectrum (N-H peaks: 3.00ft, 6.20ft, and 9-5°f* J a^id C-H peaks: 3.40/-* and 6 .90f* ) were identical with those found for 8-aminohydrindane (trans).

There vas no absorption characteristic of nitro groups.

Nametkln 100 reported an 8-aminohydrindane with the properties: b.p.

86.5-87°/20 an., n£° 1.489*, df° 0.9396. 82

Reaction of 8-Aminahydi'indane (Cis) with Acetic Anhydride Sodium Hydroxide; ff-fi-Hjdrlndylacet*™***- 9o

One gram (0.0072 moles) of 8-aminbhydrindane prepared from cis hydrlndane was shaken in a test tube with 3 ml. of sodium hydroxide and a few drops of acetic anhydride. Additional acetic anhydride was added until a slight excess was present. The heavy oil solidified upon stand ing overnight at 10°. The cake was broken up on a filter paper, washed with water, and dried. The derivative was dissolved in hot acetone, filtered and crystallized at 0° to give 0 .71* g. of pure white crystals, m.p. 88°. The filtrate was concentrated, and the precipitate was worked up to give an additional 0.35 6 * of the acetamide, m.p. 88°. The I .09 g. of white crystals was identified as H-8 -hydrindylacetamide in 83^ yield

(calculated from the 8 -nltrohydrlnrtane). The melting point of this derivative when mixed with the acetamide from 8-aminohydrindane (trans ) was also 88°.

Anal. Calc * d for C ^ H ^ O ; C, 72.93; H, 10.50; H, 7.73

Found: C, 72.97; H, 10.51; N, 1.6h

Reaction of 8-Amlnohydr Indane (Cis) with Benzoyl Chloride and Sodium Hydr oxide; W-8 -Hydrindylbenzamide.

8 -Aminohydr indane (1.0 g., 0.0072 moles) prepared from cis hydr in dane was shaken In a stoppered test tube with 3 ml. of 2(Jf> sodium hydrox ide and a few drops of benzoyl chloride. Benzoyl chloride was added gradually until the reaction was complete. The heavy oil solidified on standing overnight at 10° to give 1.70 g. of crude derivative, m.p. 79-

85°. After 2 re crystallizations from acetone, 0.78 g. of R-8 -hydrindyl- 83 benzamide vas obtained, m.p. 97-5-98°. This derivative was identical with the N-8 -hydr 1 ndylbenz amide isolated in the tr»«« series. Their mixed melting point was not depressed.

Anal. Calc'd for H°: C, 79*01; H, 8.64; N, 5.76

Found: C, 79-16; H, 8 .83; N , 5 .80

Nitration of Trans Hydrlndane; 8 -Witrohydrindarw.

Trans hydrlndane (124 g., 1.0 mole), b.p. 161°, 1.4616, 2o dj, 0 .8625, 9 9 .J#; for its infrared spectrum see Appendix, Fig. 19) was ref 1 axed with 6 moles of 50# nitric acid (375 *1 - of 71# nitric acid and 157 ml. of water), see Appendix, Table VII. The aqueous layer vas extracted with ether (3*) end combined with the hydrocarbon layer. The solution was washed with water (3x), 20# sodium bicarbonate (2x) , water

(lx), brine (lx), and dried over Drierlte. The solvent was removed on a steam bath, and the residue was distilled to give: (1 ) 54 g. of trans hydrlndane, 44# recovery, b.p. 6o°/24 mn., n ^ 1.4616; (2 ) 10.50 g. of crude nitrohydrlndanes, b.p. 80-100°/l ma., 1 ,1*909; (3) 3.65 g. of crude mono and polynitrohydrindanes, 100-112°/l mm., n ^ 1-4973; (4)

13*0 g., black tar residue.

The refractive Index (n^^ 1.4616) and infrared spectrum of fraction

(1) identify this material as unchanged trans hydrlndane. Its infrared spectrum (see Appendix, Fig. 21) contains C-H peaks; , 6 .90^1 ,

7 .63^1 , and 10 .30 ^ , and trans configurational peaks: 8 .50^1 , 11.68^4. ,

11.95p > «»d 1 2 .35 yjk.

Fractions (2) and (3) were comblned with the nitration products from two similar reactions and treated with sodium math oxide in methanol 84

(kx). A total of 1.16 mol os of hydrocarbon reacted to giro 13.05 g. of nitr ohydr indane. Rectification of this material in a simiII helix packed column gave the following fractions; (l‘) 4.57 g., b.p. 59.5-6 6 .5°

/0.8 mm., njp 1.4857; (&) 3.22 g. , b.p. 66.5-67°/0.8 mm., n^5 1.4875, d^5 1 .0892, MRp (calc*d) 45.ll, MRjj (found) 44.71; (3*) 3-12 g. , b.p.

67-69°/o.8 mm., n ^ 1.4884; (4*) residue.

Anal, of fraction (2*) Calcfd for C^Hl5R02 : C, 63.91; H, 8 .88; N, 8.28

Found; C, 64.61; H, 9-07; N, 8 .O9

C, 64.57; H, 8.95; N, 8.20

Fractions (2*) and (3O were considered to be 8 -nltrohydrindane (3^ yield) since the physical properties and the analysis were identical with those of 8 -nltrohydrindane (cis). The infrared spectrum, however, in dicated that possibly taro isomers were present. The infrared spectrum

(see Appendix, Fig. 23 ) contains strong C-H peaks (3*38>a and 6.90/*), strong nitro peaks (6.40/* , 7 .32/4 , and II.5O/4 ), cis configurational peaks (1 1 .75/1 and 11.42/t), and weak nitrate (6 .10/jl) and nitrite (5.9QM) bands. The spectrum does not entirely match the spectrum for 8 -nitrohydrlndane (cis) for there was a small amount of material present which produced weak trans peaks (8 .5C/A , 11.95/1 , and 13.50/-*) in the 8 -nitro- hy dr indane (trans ).

When this nitrohydrindane was reduced to the aminohydrlndane, and the acetami&e benzamide were prepared, two derivatives were isolated from each preparation. One acetamide and one benzamide were Identical to the corresponding derivatives from 8 -aminohydr indane (cis), but the others were unknown. The original nitro compound was checked again for 85 secondary nitro groups, and since a positive test was obtained, the nitration and purification were repeated In later experiments.

Reduction of 8-B1 trobjdrIndane (Trans) Containing Secon*«ry Hltro- hy dr Indane as an Impurity; Amlnohydrlndtnes .9&,99

8-N1 trohydrlndane (trans . 5.0 g., O.0296 moles) which was later found to contain some secondary nitro groups was dissolved in 3^ ml. of

95<$ ethanol and placed In a hydrogen*tor. Raney nickel catalyst

teaspoon) and hydrogen at 50 pel were added and the mixture was shaken mechanically 'for 3 hours. The catalyst was removed by filtra tion and the solvent was distilled off under reduced pressure to give

4.10 g. of crude aminohydrindane In 99$ yield. The physical properties of the 6 -aminohydrIndane (n^^ 1.4925, d£ 5 0 .9*0 , MRjj (calc'd) 42.83,

MRjj (found) 42.94) and the Infrared spectrum (C-H peaks: 3 • 40ju. and

6 .90^1 , and R-H peaks: 3 .00^*. , 6.20^ , 9-10yu, and 9 .50^*) were the same as for the 8 -aminohydrIndane (cis) In spite of the Impurity of secondary aminohydr Indane. The nitro peaks were not In evidence in the

Infrared spectrum.

Reaction of 8-Anlnohydrlndane and the Secondary Amin ohydrlndane with Acetic Anhydride said Sodium Hydr'cg'lde'; W-8'-Hydrlndylacet*ml'de~ and N - V-Hydrlndylace tamlde .90

8 -AminohydrIndane (trans, 1.0 g., 0.0072 moles) which contains some secondary nltrohydrlndane was shaken In a test tube with 3 of 20$ sodium hydroxide and a few drops of acetic anhydride. Additional acetic anhydride was added from time to time until the reaction was complete. The solid which formed when the oily product was cooled to

0° for 2 days was collected on a filter paper and dried to give 1.25 g. 86

of "the acetamide derivatives, m.p. 75*65 • One r e c r y s tallization of

over a range 138-IU50. Further purification produced O.27 g. of white needles, m.p. 160.5-I6I.50.

Anal. Calc'd for CjjHj^O: C, 72.93; H, 10.5O; H, 7-73

Found: C, 73-06; H, 10.77; N, 7.69

The acetamide was identified as trans-W-h-hydrindylacetamide since

this is the only acetamide of an aminohydr indane reported by Huckel which had a similar melting point. Reported value - 163°.^®

The filtrate from the recrystallization of the 1.2^ g. of crude derivative was concentrated and cooled until a precipitate appeared.

The solid vas filtered and recrystallized twice to give O .65 g. of o white crystals, m.p. 80 . This material vas Identified as the same

N-8-hydr Indy lacetamide which was obtained in the cis hydrlndane series.

A total yield of 71^ (50.5*16 of low melting and 2 0 .5^6 of high melt

ing) of the If-hydr indy lacetamide was obtained. This yield vas calcu

lated on the basis of nitr ohydr indane.

Reaction of 6-Amin oh ydrl ndane (Trans) and U-Aminohydr Indane (Trans) with Benzoyl Chloride and' Sodium Hydroxide; N-8-Hydrlndylbenzamlde and B-fr-Hyftrlndylbenzamlde .9^

8 -Aminohydrindane (trans, 1.0 g., 0.0072 moles) was shaken In a stoppered test tube with 3 oil. of 20)6 sodium hydroxide and a few drops of benzoyl chloride. Additional benzoyl chloride vas dropped in gradual ly until no further reaction occurred. After 2 days at 0° the heavy oil formed a brown gummy material (1.69 g.). The derivative was dis solved In acetone, refluxed with Darco for 10 minutes, and filtered. 87

The precipitate which formed when the solution, was concentrated and

cooled to 0° for 2 k hours, was filtered and dried to give 0.50 g. of

derivative, m.p. 125-145°. Two recrys tallizations of this solid yielded 0.21 g. of a pure white powder, m.p. I7I.5-172.50.

Anal. Calc'd for Cl6H21N0: C, 79*01; H, 8.64; N, 5.76

Found: C, 79*02; H, 8 .5O; N, 5*75

This derivative, identified as N-U-hydrindylbenzamid©, further substantiated the structure of the amino compound from which it was pre pared, since the only hydr indy lb enzamide reported by Huckel*^ which melted in this range was trans-N-k-hydrlndylbenzamlde, m.p. I67-1680.

The filtrate from the first crystallization outlined above was concentrated and cooled at 0° until a precipitate appeared. After two recrys talliz at Ions of this solid, 0 .2k g. of white crystals were ob tained, m.p. 97-980* This derivative was identified as N -8-hydrindy1- acetamide; the derivative was identical with that prepared from

8 -aminohydrlndane (cis) (no depression in mixed melting point).

Nitration of Trans Hydrlndane; 8 -Kltr ohydr Indane.

Trans hydrlndane (190 6 *, 1*53 moles, 99*3#) refluxed with

9*6 moles of 5056 nitric acid (575 al- of 71# nitric acid and 2 kl ml. of water) at 100° for k hours. The unreacted hydrlndane (93*0 g.,

O.75 moles) was removed and again exposed to the conditions of nitration.

The combined yields of crude nitrated product were combined, washed with water (3x), 20# sodlw bicarbonate (2x ) , water (lx), and brine (lx), and dried over Drierite. The solvent and the unreacted hydrlndane were re moved under reduced pressure and the residue (85 g.) was treated with an 88 equivalent amount (166 m l . ) of 3 H sodium methaxlde in methanol. Water vas added and the solution vas continuously ether extracted for 24 hours. The ether extract was dried over Drierite and distilled to give: (1 ) 15*78 g. of crude nitrohydrlndanes, h.p. 79-93°/l mm., ng^ 1.4889* (2 ) 2.00 g. of crude nitrohydrlndanes, h.p. 93-97°/l m b ., ng*^ 1.49*53* Both fractions were treated vlth base (3x) until a very definite negative test for secondary nitro groups vas obtained. Recti fication of the tertiary nltr ohydr Indane gave the following fractions:

(1*) 1.66 g., h.p. 60-63°/0.6 mm., ng5 1.4863; (2) 3-97 g*, h.p.

63-64°/0.6 mm., ng5 1.4873; (3) l .*2 g., h.p. 64-65°/°. 6 mu., ng5 1 .4875, d25 1 .089; (41) 2.50 g., h.p. 65-75°/o*6 mm., ng5 1 .4919.

The Infrared spectrum of fraction (3) contains strong nitro peaks

(6.40j* , 7.32f* , and 11.52^1 ), C-H hands (3*38^. , and 6 .90^1 }, and only cis configuration hands (11.77p, and 12.42^*). Weak nitrate (6.10/* ) and nitrite (5 .85/4 ) hands vere present. The trans peaks vere not ap parent, see Appendix, 71g. 24.

Fraction (3*) vas Identified as 8-nltrohydrindane (trans); Its physical properties (h.p. 64-65°/o,6 mm., ng^ 1.4875, d2^ 1 .089, MR^

(calc’d) 4 5 . U , MRjj (found) 44.6l) and Infrared spectrum are almost identical with those observed for 8 -nitrohydrindane (cis).

Reduction of 8 -Wltrohydrlndane from Trans Hydrlndane; 8-Amin ohydrlndane^^

8 -Nitrohydrindane (trans . 5.00 g., 0.0296 moles) in 40 ml. of ether vas reduced vlth hydrogen at 50 pel and Raney nickel teaspoon)

In a Parr hydrogenation apparatus. The reduction vas complete after

3 hours. The catalyst vas filtered and the ether vas removed on a steam 3o

bath to give 4.06 g. (O.OG92 moles) of crude 8-aminohydrIndane in 0 6 .yH

yield. The physical propart,lee ; n ^ 1.4qi8, dj^ 0.941, MR^ (calc'd)

42.83, (Tound) 43-00) were essentially the same as that of the

3-aminohydrindane (cis).

The infrared spectrum of the crude 8 -aminohydrlndane contains ab sorption for the N-E band (3 -OOp. , 6.20^ , o.lO^jt , and and

C-E bonds (3-38/-* , end 6 .90^.), but no nitro peahB were observed.

Beactlan of 6 -AminohytLrlndene (Traimt) with Acetic Anhydride and Sodlimt Hydraride; E-B-HydrlndylacetaJilde.

8 -AminohydrIndane (2.00 g. , 0.0144 moles, from trans hydrlndane) was treated with 3 “1. of 2Crt> aqueous sodium hydroxide and a few drops

of acetic anhydride, and shaken vigorously. Additional acetic anhydride vas dropped in until the reaction was complete. The heavy oil did not solidify on standing at 0° for 12 hours; it was thus dissolved in ether, removed frcm the aqueous layer, and filtered. When the ether was stripped off, and the residue was cooled to 0°, large white crystals were produced, m.p. 68-78°, O .76 g. Recrys tall iz at i an of this material frcm acetone yielded 0.64 g. of the pure acetamide, m.p. 87-88°. Treat ment of the comb in. ed filtrates produced an additional 0.30 g. of the same derivative, m.p. 87-88°. The total 0.94 g. of white crystals rep resents a 73*£ yield calculated from the 8 -nitr ohydr indane. This deriva tive, since its melting point was not depressed when mixed with

N-8-hydr indy lacetamide (cis ) , vas identified as the same R-8 -hydrindylacetamide (trans ). 89

bath to give 4.06 g. (0.02 9^ moles) of crude 8-aminohydrindane in 98.516

yield. The physical properties (n^ 5 I.U9I8 , dj^ O.9IH, MR^ (calc'd)

42.83, (found) 43.00) were essentially the same as that of the

8 -aminohydrIndane (cis).

The infrared spectrum of the crude 8 -aminohydrindane contains ab

sorption for the N-H bond (3-00^., 6.20jj. , 9.10jji, and 9 .5O/J.) arui

C-H bonds (3.38^* , and 6 .90^* ), but no nitro peaks were observed.

Reaction of 8-Amin ohydrlndane (Trans ) with Acetic Anhydride and Sodium Hydroxide; W-B-Hydrlndylacetamlde.

8 -AminohydrIndane (2.00 g., 0.0144 moles , from trans hydrlndane)

was treated with 3 ml. of 20$ aqueous sodium hydroxide and a few drops

of acetic anhydride, and shaken vigorously. Additional acetic anhydride was dropped in until the reaction was complete. The heavy oil did not

solidify on standing at 0° for 12 hours; it was thus dissolved in ether,

removed from the aqueous layer, and filtered. When the ether was

stripped off, and the residue was cooled to 0°, large white crystals

were produced, m.p. 68-75°, O.76 g. Recrystallization of this material

from acetone yielded 0.64 g. of the pure acetamide, m.p. 87-88°. Treat

ment of the combined filtrates produced an additional O .30 g. of the

same derivative, m.p. 87-88°. The total 0.94 g. of white crystals rep

resents a 73$ yield calculated from the 8-nitr ohydr indane. This deriva

tive, since Its melting point was not depressed when mixed with

N-8-hydr indy lacetamide (cis ), vas identified as the same H-8-hydrindyl-

acetamide (trans ). 90

8 ,9-Pin Itr ohydrlndane*

The nitration of cle and trans hydrlndane produced sons 8,9-dinltro- hydrindane. The compound was a white, waxy material melting at 50-60°.

Since the dlnitrohydrlndanes were contaminated with mononltrohydrlndane, the dinitro compounds did not give sharp melting points. The presence of this impurity was substantiated by the nitrogen analyses.

Axial. Calc’d for 13*12

Found for 8,9-dinltr ohydr Indane (cis): N, 8.87

Found for 8 ,9-di nitr ohydr indane (trans ) ; N , 11.33

The Infrared spectra were not strongly Indicative of either the cis or trans configuration. Since the peaks (nitro peaks: 6.^0/u.,

7.32p , and II.5O1* ; C-H peaks: 3-38/j. , snd 6 .90^ ; and others 8.70/* >

11.7 5 t e^nd 1 2 .U5 p ) were similar to those of the moncnltro compounds, it may be that these compounds have a cis configuration.

Infrared Analysis of the Hltrate Ester Impurity.

The existence of alkyl nitrite and alkyl nitrate compounds In the products has been noticed in all of the nitrations. In order to re move these impurities, the sulfuric acid treatment^was tried on the optically active nltrooctane; however, this apparently decomposed the tertiary nitro-alkane faster than the impurities. On the basis of infra red spectra, distillation removed the nitrite esters but the nitrate ester vas still present In trace amounts. In most cases the elemental and Infrared analyses eliminated the w orry of these impurities; however,

It vas desired to discover by an Infrared technique how much nitrate was present. Therefore, an Infrared spectrum of a ^ solution of amyl 91 nitrate In l*--nitr©heptane (Appendix, Fig. 5) was taken and compared with the spectrum ocf 3-nitro-3-methylheptane (Appendix, Fig. 4). Even in cons ide rati on of the many errors involved, this analysis indicates that the concent rat ion of nitrate esters in the 3“®®'fckyl-3-nitroheptane is less than one per cent. This fact became obvious in most cases when the amino compound end its derivative were prepared. 9 2

V. StMMARY

1. The optically active hydrocarbon (*)-3-methylheptane, vaa nitrated at the asymmetric carbon atom to give optically inactive

(♦ )-3-methyl-3-nitrobeptane. The racemlc nature of the 3-methyl-3- nitroheptane was substantiated by the facts that 3 ~ ami no- 3~niethyl- heptane and N-piienyl-N'-3 (3-methylheptyl)thiourea, prepared by reduc tion of the nitroalkane and subsequent treatment of the amine vlth phenyl laothiocyanate, vere also optically inactive. The 3-methyl-

3-ni troheptane, the ‘ 3-amino- 3-methylheptane and the R-phenyl-N * - 3-

(3-iaethylheptyl)thiourea vere Identical with the corresponding com pounds prepared from (I)- 3-mothylheptane. Since the ( O -3-methy1- heptane does not undergo racemization under the conditions of liquid- phase nitration, it may be concluded that liquid phase nitration of saturated hydrocarbons proceeds through an intermediate which loses Its asymmetric identity.

2 . Cossmercial decalin, cis decalin, and trans decalin vere nitrated at the Q-position to give n9~n 3. trodecalin 7 Reduction of the 9-nitrodecalin to 9 -aminodecalln end subsequent preparation of N-9-decalylacetamide gave the exact same derivative in high yield. Tt may thus be concluded that nitration of commercial, cis , or trans decallns gives an identical 9-nltrodecalin. The infrared spectra of the 9-nitrodecalin and the physical properties of its derivative, N-9-decalylacetamide, In dicate that the 9-nitrodecalin is of a trans-structure.

3* The 9 ,10-dlnitrodecalins Isolated from polynitration of either camnerclal, cis, or trans-decalin, are identical. The infrared spectra 93 of the Q,10-dinitrodecalin Indicates that It Is of a trans-8trueture.

The formation of the single 9 ,10-dinitrodecalin is not controlled by the stereochemical relationships involving cis and trans-decalins.

U. Cis and trans hydrlndanes were nitrated In the liquid phase to give (a single and) Identical 8-nitrohydrindanes. The similarity of the 8 -nitrohydrlndanes vas established upon preparation of the acetamldes and benzamldes of the 8-aminohydr indane a obtained from reduction of the 8-nitrohydrlndanes. The infrared studies of the

8-nitrohydrlndane indicate that It is of a cis-structure.

5 . It is proposed that the experimental data obtained in this research and the reliable data in the literature Indicate that the mechanism of liquid phase nitration of saturated hydrocarbons in volves free alley1 radicals; the reaction is believed to be initiated by removal of a hydrogen atom from the hydrocarbon by the nitrating agent (presumably, nitrogen dioxide). 94

VI. BIBLIOGRAPHY.

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TABLE I

NITRATION dr (1) - 3-METHYT HEPTANE

4 Re * covery Crude Moles of * Moles of of Yield* Exp. Hydro Nitric Nitric Temp., Time, Hydro Mol.Vt No. carbon Acid Acid °C. Hours carbon 159

1 0.30 21 0.91 95-100 26 93 0

2 0.30 30 0.91 95-100 9 76 0

3 0.254 •50 0.76 85 24 60 --

4 0.175 50 0-37 90 48 20 31.7

5 1.00 50 6.0 100 12 44 34.6

6 1.00 50 6.0 100 13 4l 47.2

7 0.544 50 3.3 100 14 35 31.0

8 0.30 60 0.91 85 22 -- 17.6

Q 0.30 71 0.91 95-100 12 34 17.0

^Yields were calculated from the moles of hydrocarbon used up In the nitration reaction. 98

TABLE II

NITRATION OF (♦ )- 3-METHYLHKPTANB WITH 50* NITRIC ACID

* Re- $ covery Crude. Moles of Moles of of Yield Exp. Hydro NS/trlc Time, Hydro Mol .Wt. a t No. carbon Acid Hours carbon 159 (* - 2 )°

1 0.319* O .96 90 30 30 --

2 0 .10* 0.86 90 32 29 -- *

3 0.446 1.3* 105 2lf if9 --

if 0.25 0.75 90 2lf lf5 38.0 -

5 0.343 2.0 108-110 if 67 23.0

6 0.190 0.57 90 15 28 -- -

7 0.361 1.08 90 12 ifO --

8 0.237 0.711 90 15 38 -- ♦0.73d4

9 0.320 0.96 90 15 ifO -- ♦0 .23°® 10 0.214 1.28 100 18 32 37.8

11 0.4l4 3-0 95 16 37 40.8 ♦0 .61^

12 O.63O 3-78 95 16 18 25-3 ♦0 .21°®

13 1.0 6.0 90 12 5* 20.2 -0 .26°^ o1 lh 1.0 6.0 100 16 37 18.0 -0.17

15 2.0 12.0 100 12 ifO 21.2 -0.if5°*^ 99

TABLE II (Continued)

NITRATION OF (*• )-3-MBTHYLHZPTAlTK WITH 50* NITRIC ACID

4 Re * covery Crude Moles of Moles of of Yield Exp. Hydro- Nitric Temp., Time, Hydro Mol.Wt. a D No. carbon Acid °C. Hours carbon 159 (I - 2 )c

16 1.0 6.0 100 12.5 37 32.0 -0 .28o*

17 2.0 12.0 100 13 45 27.0 -o.ouo1

^The heterogeneous mixture v m stirred during the nitration reaction. ^Yields were calculated from the moles of hydrocarbon used up In the nitration reaction. °TheBe rotations were observed for the purified material, I.e., after h treatments with base and rectification. ^j.p. 62.5-63.0°/l.5 mm., n|5l.*31*, d^°0.925, *0.73° (1-2). ®b.p. 78 .5-7 9 .1°/10 m . , 01 g° *0.23 (1*2). fb.p. 86-87.5°/l5 m . , n§51.^9*i, atP°#*0 .6lo (1 -2 ). «b.p. 85-86°/l5 a n ., n§5i.^321, a | ^ *0 .21° (1 *2 ). ^.p. 78-8l°/lO m b ., n|5i.U335, aj° -0.26° (1=2). S>.p. 80-8l°/l0 mb., ngl.43^2, .p. 8l-82°/l0 mu., n§5l. 1*330, d|p0 .936, 0f§6 -0 .0^° (1 *2 ). loo

TABLE III

NITRATION OF COMMERCIAL DEC ALIN

i> Crude $ Re Yield covery of Nltro- Moles of * Moles of of decalln, Exp. Hydro- Nitric Nitric Temp., Time, Hydro Mol. Wt. No. carb an Acid Acid °C. Hours carbon 1S-3 _

1 0.65 •21 3.35 IOO 2-5 19.5 2.3

2 0.5 21 2.5 100 3.0 62 2.3

3 0.32 35.5 1.24 100 3.0 85 3.0

4 0.5 4o 3.0 100 3.0 47.5 20.0

5 1.0 50 6.0 95 4.0 30 22.0

6 0.5 50 3.0 100 3.0 50 30.0

a Yields were calculated from the moles of hydrocarbon used up in the nitration reaction. 101

TABUS IV

NITRATION OP CIS SBC ALIN WITH 5 0* NITRIC ACID

^ Crude Yield*1 % of NItro Moles of Recovery decalln Exp. Moles of Nitric Temp., Time, of Mol. Wt. No. Decalln Acid °C . Hours Decalln 183.

1 0.162 i.oa 95 6 34.0 15

2 0.517 3.0 90 3 32.0 22.8

3 0.519 3.0 90 7 26 22.7

4 0.840 5.04 100 3 31 23.4

=j 0.246 1.47 95 5 31 22.4

®71* HNO^. b Yields were calculated from the moles of hydrocarbon used up in the nitration reaction. 102

TABLE V

NITRATION CF TRAJ6 DEC ALIN

Crude Yield® £ Re of Nltro- % Moles of covery decalin, Erp. Moles of Nitric Nitric Temp., Time, of Mol. Wt. No. Decalln Acid Acid °C. Hours Decalln 183

1 O .65 28.5 3.35 IOO 3 81 7.0

2 0.53 41 2.72 95 2.5 33*5 6.0

3 0.5 bo 3.0 IOO 3.0 52 28.5

J* 0.5 50 3.0 95 4.0 48 28.0

5 0.4 50 3*0 100 7.0 39 28.5

6 i.o4 50 6.0 105 6.0 49 25.5

7 1.0 50 6.0 100 5.0 51 26.2

8 0.507 50 3.04 100 5.0 49 24.4

a Yi elds wore calculated from the moles of hydrocarbon used up In the nitration reaction. 103

TABLE VI

NITRATION OP CIS EYIRINIANT£ WITH 50^ NITRIC ACID

Crude * Yield* Moles of Recovery Product Exp. Moles of Nitric Time, Temp., oT Mol. Wt No. Hydrlndane Acid Hours °C. Hydrlndane 169

1 0.5 3-0 6 100 20 11.2

2 1.0 6.0 5 IOO 33-5 15.0

3 1.0 6.0 5 IOO 28 15.0

Yields vere calculated from the moles of hydrocarton used up in the nitration reaction. 104

TABLE VII

NITRATION QP TRAJB HYDRINDANE WITH 5C# NITRIC ACID

Crude * Yield Moles of Rec ©very Product, Exp. Moles of Nitric Time, Temp., of Mol. Vt. No. Hydrlndane Acid Hours C. Hydrlndane 169

1 0.5 3 6 100 44 16.3 2 1.0 6 6 IOO 44 15.4

3 0.53 3.2 7 IOO 4l 15.0

4 1.53 9.6 4 IOO 49 42.5b

5 0.75 4.5 5 100 41 38b

a Yields were calculated from the moles of hydrocarbon, used up in the nitration reaction. b Before distillation. PERCENT TRANSMITTANCE

PERCENT TRANSMITTANCE PERCENT TRANSMITTANCE

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; Fig. 2U / AtTTCBIOGRAFHY

I, Devin King Brain„ was barn in Mt. Vernon, Ohio,

January 7, 1926. I received by secondary school educa tion in the public schools of the city of Springfield,

Ohio. One year of undergraduate wor?r was completed at

Kenyon College in Gambler, Ohio before I entered military service. The remainder of my undergraduate training was

obtained at the University of Arizona, Tucson, from which f I received the degree Bachelor of Science in 19*^8. From the University of Arizona, T received the degree Master

of Science in 19^9* While completing the requirements for the degree Doctor of Philosophy, at the Ohio State

University, I was employed as research assistant by the

Ohio State University Research Foundation for one year under an Arthur D. Little project, and for two years under an Office of Naval Research project.