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NITRO DERIVATIVES OF HIGHER BENZENE HOMOLOGUES 397

Nitro derivatives of xylene were first mentioned in a work by Bussenius and

Eisenstück [4], in 1860, on various products obtained from petroleum. The authors

investigated among others the Hannover oil fraction, boiling from 75°C to 180°C.

This fraction contains easily nitrated aromatic hydrocarbons. Among the products

obtained in nitration, there was a crystalline compound melting at 169°C of com-

position, corresponding to that of trinitroxylene, as confirmed by analysis. A similar

substance of higher purity, melting, at 177°C was obtained by Beilstein [5] in 1864

by nitration of xylene.

Systematic studies of the nitration of xylene and of the constitution of the

products obtained were carried out by Noelting and Fore1 [6] and Blanksma [7].

During World War I in Russia Solonina [8] and Filippov [8a] and in France

Marqueyrol and Loriette [9] developed methods of preparing nitroxylene in

an industrial scale.

Isomers of dinitro-m-xylene (DNX)........................

Three isomers of mononitro-m-xylene are known, viz.: 2-,4-, and 5-nitro-m-xy-

lenes :

b. p. 225.5°C m. p. 2°C m. p. 74°C

b. p. 246°C b. p. 273.7°C

All three isomers can be obtained by nitrating m-xylene using a nitrating mixture

of the composition:

HNO 3 25-28%

H 2 SO 4 56-59%

H 2 O 16%

The nitration temperature should not exceed 35-40°C.

The principle products are the 2- and 4-isomers in the proportion of 25:75,

while the 5- isomer is obtained only in an insignificant quantity.

The latter can be obtained from the 4- isomer (Wróblewski [46]):