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100 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

hexane and 2-nitrocyclohexyl nitrite, were not formed. Instead, the main products

were : 2-bromonitrocyclohexane and 2-bromochlorocyclohexane.

(Yield 20.6%) (Yield 31.5%)

These products derive from the interaction of the intermediate β− nitroalkyl radical

and the bromotrichloromethane e.g. :

The main reaction was accompanied by a number of secondary reactions.

Recently T. E. Stevens and Emmons [82] examined the reaction between N 2 O 4

and olefins in the presence of iodine in to order to trap the intermediate nitroalkyl

radical, and they have been able to isolate β− nitroalkyl iodides in good yield:

(24)

These experiments provide further proof of the radical nature of the N 2 O 4 -olefin

addition reaction.

The nitration of acetylene hydrocarbons proceeds in a more complex way than

that of olefins. The first member of the series-acetylene-undergoes various re-

actions, for example, with nitric acid (see p. 82 and p. 599) Tolane (diphenylacety-

lene) is nitrated with N 2 O 4 to form dinitrostilbene. Two products are formed which

are presumably α− and β− stereoisomers:

α m. p. 186-187°C β m. p. 105-107°C

When nitrating phenylacetylene, Wieland and Blümich [79] obtained phenyl-
dinitroethylene:

an unstable product which decomposes giving off benzonitrile, CO 2 and HNO 2 ,

probably according to the following scheme: