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194 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

and, hence of relatively low reactivity, may also be substituted. Thus, for example,

from sym-trinitrobenzene, 3,5-dinitrophenol or its ethers may be obtained

(p. 251).
An interesting example of the replacement of a nitro group in the meta po-
sition by a bromine atom can be observed in the case of the pyridine derivatives
(Koenigs, Gerdes and Sirot [8]):

(6)

Also the nitro group in 4-nitropyridine-N-oxide is very mobile (den Hertog

and Combé [8a]).

The nitro group itself exhibits a certain reactivity which is not confined to the

liability to reduction or to the formation of addition products.

Thus, Backer [9] explained that in certain cases an aliphatic nitro group could

react with such a typical methylating agent as diazomethane. For example, bis-

(methylsulphonyl)nitromethane (I), when reacted with diazomethane, formed a

crystalline product which was found to be an oxime (IV). Simultaneously formal-

dehyde was formed, doubtless from the methylene group of diazomethane.

Backer explained the reaction assuming the following mechanism:

(7)

The observation that a nitro group of an aliphatic character in an aromatic

molecule could react with diazomethane was confirmed by Edwards [10] for

nitroanthrone, which reacted with diazomethane to form anthraquinone oxime

(VI):