MECHANISM OF THE NITRATION AND OXIDATION OF CYCLOHEXANE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000700100309-6
• Release Decision: RIPPUB
• Original Classification: R
• Document Page Count: 4
• Document Creation Date: December 22, 2016
• Document Release Date: October 21, 2011
• Sequence Number: 309
• Publication Date: January 28, 1953
• Content Type: REPORT

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PUBLISHED Moscow .e /CL$SIFIE]
7-- R-]
DATE PUBLISHED Mar 1952
WHERE
FDA
FILE
COPY
DATE DIST..21 Jan 1953
NO. OF PAGES 4
SUPPLEMENT TO
REPORT NO.
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS
COUNTRY UssR
SUBJECT Scientific - Chemistry, nitro compounds
HOW
PUBLISHED Thrice-monthly periodical
I FEB 7 i9 F L4 44IF
FOR OFFICIAL USE ONLY
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Doklady Academia Nauk, SSSR, Vol L7XXITI No 1, 1952, pp 101-104.
MECHANISM OF THE NITRATION AND OXIDATION OF CYCLOHEXANE
From the standpoint of classical organic chemistry, the nitration of cyclo-
hexane with nitric acid was investigated by V.V. M rkavnikov (1), Aschan (2),
and in more detail by S.S. Nemetkin (3). The chief products of the reaction
were nitrocyclohexane and adipic acid.
Our theory of nitrating the paraffin chain (4) explained the mechanism of
the reaction between cyclohexane and nitric acid, permitted us to establish
that nitrogen dioxide is a more effective nitrating and oxidizing agent than
nitric aci7, and uncovered a series of other chemical phenomena in this fi21d.
On the btais of our theory, the chemical processes in the nitration of
cyclohexane under ordinery conditions may be formulated 'briefly as follows:
Nitric acid by itself does not react with cyclohexane but serves only as
a source for the formation of oxides of nitrogen from lower oxides by the
equations:
2HN03 - N0f'-3N02 + H2O, HNO3 + HNO2 , 2NO2 + H2O (1)
Just as with oxides of nitrogen and nitric acid, the first stage of the re-
action with cyyclohexane is an attack by a monomer of nitrogen dioxide in the
form of a.radical on the hydrocarbon, leading to the formation of free cyclo-
hexyl; this is shown as follows:
C6 Ell- H + NOo_,C6Hli ...H...N02-e C6H11. 4 dNO`
(2)
Cyclohexyl immediately reacts with nitrogen dioxide, giving a mixture of
the nitre compound and the nitrite, as follows:
l C61111- NO2
C6H11.
+ O==N--O,\1
(3)
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Under special conditions, the interaction of cyclohexyl with NO, N2O4, and
HNO3 can play a significant role.
Nitrocyclohexsne, formed by equation is almost entirely preserved in
the ind products of the reaction, Cyc.lohexyl nitrite rapidly enters into an
equilibrium reaction with water;
06H110N0 4 HaO *-.z-'6H110H + M102
The cyclohexanol that is formed oxidizes quite readily into adipic acid and
then is esterified by the latter, i.e., into acid and neutral cyclohexyl adipates;
oyclohexyl nitrate is formed in an analogous fachlon. rn accordance with theory
and chemical experiments, eaters of cyclohexaaol are more stable to the action
of oxidizing agents than the free alcohol,
nitricnaca des these iofrnitrceen, establishednotre react, for experimentally tat
purposes, with cyclohexane under any of the moat diverse conditions. The re-
action between cyclohexane and nitrogen dioxide takes place to a noticeable
extent even at room temperature and is almost completed after 2 months' stand ;
to carry out the reaction at 10,00, one hoar of heating is sufficient. The re-
action with nitrogen dioxide yields the name products as the one with nitric acid.
Heating cyclohexane at 1000 with a large excess; of nitrogen dioxide can lead to
an explosion. This is probably due to the chain reaction C011 t H + N02 - C6H1?;
C6H11? + N204-- C6H110N0 + NO2 etc. and to the development of subsequent oxidation
processes.
Nitration and oxidation of cyclohexane with nitric acid took place only in
the presence of nitrogen dioxide, and to an extent proportional to the quantity
of the latter. It is interesting that addition of nitric acid, even of a specific
gravity of 1.3, to nitrogen dioxide rsduced the nitrating and oxidizing activities
of nitrogen dioxide.
The explanation of the role of oxides Of nitrogen permitted understanding
the advantages o= the nitration of cyyclohexane in sealed tube; by the Konovaloc-
Nametkin method and led us to a aeries of rew c(".clusion- which were confirmed
by experivent. Consideration of the role of diffusion of nitrogen oxides from
the hydrocarbon layer into the acid layer and of nitrogen dioxide in the oppo-
site direction led us to the idea of the importa;ce of the dimensions of the
interface between the acid and hydrocarbon p'.,aees and of the height of the
layers to the rate and direction of the reaction. in accordance with this, it
developed that the total yield of the reaction when, the tubes were placed in a
horizontal position was c-3 times greater than when they were placed in a
vertical position, and that the difference between the yields was greatest
when the amount of nitrogen dioxide rir,;t added was least. The yield of adipic
acid, i:, agr-~rment with theory, increases ',ore than that of the nitro compound;
in some experiments, its yield was almost five timca frester. The effect of
factors of this kind had not been noted by previous investigators; in the liter-
ature there are even direct statemeLtein regard to carrying out the nitration
by Konovalcv's method in vertically placed t?iaei.
The rauical-molecular character of the reac'r'on was additionally confirmed
by establishing that the reaction took place in the hydrocarbon and not in the
acid phase and by the absence of any accelerating action of additions of protonic
and aprotonic acids (H230Z, AlCl3) and mercury ralte.
The experimental proof of our hypotheses of the mechanism of formation of
oxidation producto was begun by clarifying the chemical behavior of the previously
unknown cyciohexyl nitrite. It developed that this rite decomposed merely on
standing into a mixture -if cyclohexar.ol, adipic acid, and the previously unde-
scribed mono and dicyclohexyl. adipates, pre amably cyclohexanone, dicyclohexyl
ether, and esters of lover dicarboxylic. acids v>re also present in the mixture.
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We then succeeded in establishing the formation of cycl?hexyl nitrite and
the above-mentioned products of its decomposition during the reaction between
cyclohexane and nitrogen dioxide under mild conditions produced by heating for
one hour in'the presence of a large excess of the hydrocarbon. For the quali-
tative and quantitative determination of cyclohexyl nitrite in the products of
the reaction and the separated fractions, its capacity to diazotize sulfanilic
acid was utilized. With the aid of this reaction, the formation of nitrites
was similarly established in the analogous case with n-pentane, in the reaction
between cyclohexane and nitric acid, and finally, in the case when the reaction
was carried out in the gaseous phase.
Invcotigation of the neutral portion of the reaction products of one of the
experiments on nitrati-g cyciohexane with nitrogen dioxides at mild conditions,
showed that this portion consists of roughly 50 mot % of nitrocyclohexane, 8% of
cyclohexyl nitrite and 8% of cyclohexanol, 20% of adipic acid, and 149 of various
esters of cyclohexanol. One fraction ccntained about 30% of cyclohexyl nitrite
and 60% of cyclohexanol, judging from the combined results of diazotization with
sulfanilic acid, oxidation under mild .onditions into adipic acid, and isolation
of cyclohexyl-3,5-dinitrobenzoate (melting 112?) resulting from the action
of 3,5-dinitrobenzoyl chloride, Di?_yclohexy.l adipate was isolated in this experi-
ment in the crystalline state from the 3ast fraction obtained by distilling the
reaction product freed of the acids.
Except for nitrocyclohexane, which is stable to oxidation, all the other
fractions of the neutral part of the reaction, products were easily converted to
adipic'acid with nitric acid. This explains the formation of almost equimolecular
quantities of nitrocyclohexane and adipic acid in addition to lower homologues
under ordinary, rather severe nitrating conditions. These.experimentel results
also agree with the observed similarity of the composition of acids formed during
the oxidation of cyclohexarol with nitric acid (5) on the one hand and the oxi-
dation of cyclohexane (3) on the other hand.
All of these experimental data leave no doubt as to the accuracy of the
basic aspects of our theory of nitrating cyclohexane ana its applicability to
the mechanism of the formation of oxidation products. We also found experimental
confirmation of other aspects of our theory. For example, it was found that when
the total concentration of nitrogen dioxide is increased, the yie:id of oxidation
prciucts is increased and the yield of nitroc,-rclohe:;ape is reduced, since the
probability of collisions between cyclohexane and dieters of nitrogen dioxide in
increased wean this happens, leading to the formation of cyclohexyl nitrite, only.
In nitration experiments with N207+ at 600, a small quantity of cyclohexyl nitrate
was isolated. it had a boiling point of 96 - 98? at 40 mm.
We will give a short description of =aye of the experiments that clarify
the formation mechanism of oxidation prod its of cyclohexane. (For the re-
maining experimental data, see (6).)
1. Cyclohexyl nitrite and Its spontaneous decomposition. Cyclohexyl
nitrite was synthesized from cyclohexanol in the usual manner. It formed a
slightly yellowish liquid with a boiling point of 40 - 54?. From 69.8 g of
the nitrite, 2.6 g of pure adipic acid were isolated after 60 days of standing.
Extraction with a soda solution yielded an additional 0.3 g of the acid and
with 5% caustic alkali, nearly 7 g of crude acid, i.e., cyclohexyl adipate
were obtained. Distilling the :esidue at 40 mm yielded the following fractions:
I, 53 - 550, 27.4 g; 11, 55 - 77?, 1.4 g; III, 77 - 99?, 5.1 g (cyclohexanol);
at 5 mm; IV, 70 - 1000, 6.9 g; i, 130 - 170?, 1.2 g; and YI, 205?, 1.5 g. The
last fraction yielded crystals melting at 36? identical with dicyclohexyl adipate
obtained synthetically by heating 5 g of adini-c acid with 5.2 g of cyclchersnol
at 135? for 10 hours (yield of acid, i.e., ester, 3.1 g; neutral ester, 3.5 g).
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2. Evidences of the formation of cyclohexyl nitrite and the products of its
decomposition in the nitration of cyelohexane. Eighty milliliters of cyclohexane
and 12 ml of nitrogen dioxide were heated for one hour at 1000 in four sealed
tubes, each having a volume of 90 ml. On cooling, 3.6 g of adipic acid were iso-
lated from the reaction ni:ture. After acidifying the soda extract, a little
more of a mixture of crystalline acids was removed, and with a caustic alkali
extraction, an oil having the properties of acid, i.e., cyclohexyl adipate was
removed. Distillation of the neutral residue yielded 52 m?. of cyclohexene
(fraction I), fraction II and III at 40 an, and the following fractions at 5 mm:
II, 45 - 700, 1.5 g; III, 100 - 1100, 8.5 g; IV, 110 - 140?, 1.7 g; V, 2000, 0.3 g.
Fraction II consisted chiefly of cyclohexyl nitrite and cyclohexanol. Of this
fraction 0.382 g was mixed with 10 ml of 0.25 N solution of sulfanilic acid;
after acidification and agitation for one half hour, 6.4 ml jf a standard so-
lutio7 were spent on the back titration, which corresponds to 30.4% nitrite.
An amount of 0.302 g of the same fraction reacted rapidly with 5 ml HR03 of e.g.
1.2. Here, 0.08 g of pure, 0.26 g of crude adipic acid, and 0.07 g of nitro-
,cyclohexane were obtained, which corresponds to 52.4% of cyclohexanol, after
allowing for the nitrite; the latter wao also isolated as 3,5-dinitrobenzoate of
a melting point of 112?. The total cortent of cyclohexyl nitrite in all the
fractions, as determined by the diazo method, was 1 g, or 7% of the spent hydro-
carbon.
According to tae data on oxidation with nitric acid, fraction III contained
about 14% of cyclohexanol and cyclohexyl nitrate and 85%'of nitrocyclohexane.
Fraction IV consisted chiefly of dicyclohexyl ether. The latter fraction yielded
crystals of dicyclohexyl adipate, melting point 36?, identical with the product
of known constitution. After -ttration under milder conditions, fraction III
yielded cyclohexyl nitrate, with a boiling point of 99? at 30 zcs.subsequently
to removing the nitrocyclohexane with a caustic solution.
Bibliography
V. V. Markovnikov, Zhur.Russ.K;him.Obshch., Vol XXX, 157 (1898)
Aschan, Ber., Vcl X;{XII, 1771 (1899)
S. S. Nametkin, The Actior. of Nitric Acid on Hydrocarbons of
a Saturated Character, M. , 1911; Zhur. Russ, 12-in. Obshch, Vol XL
184, 1570 (1908); Vol XLI, ,.45 (1909) ' '
A. I. Titov, Zhur.Obshch.Khimy Vol XVI 1897 (1946); Vol XVIII,
465, 473, 534 (1948)
L. Bouveault et R. Locquin, Bull., (4), Vol Iil 437, 1908
M. K. Matveyeva, The t4echanism and the Method of Oxidation of
Cye_lohexane, Dissertation, 1948
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