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398 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Isomers of trinitro-m-xylene (TNX)........................

The following three isomers of dinitro-m-xylene are known:

m. p. 132°C m. p. 82-84°C m. p. 101°C

All three isomers can be obtained either by the nitration of m- xylene with a nitrating

mixture such as:

HNO 3 20%

H 2 SO 4 65%

H 2 O 15%

or by the nitration of mononitro-m-xylene with a mixture poorer in nitric acid

(e.g. HNO3 - 10-12%, H 2 O - 15%).

The 2- isomer predominates in the nitration product, while the 2,5- isomer

formed in the nitration of 5-nitro-m-xylene is obtained only in small quantity.

ISOMERS OF TRINITRO-m-XYLENE (TNX)

There are three isomeric trinitro-m-xylenes: 2,4,6-trinitro-m-xylene, 2,4,5-, and

4,5,6-trinitro-m-xylene :

m. p. 182°C m. p. 90°C m. p. 125°C

The 2,4,6- isomer is the principal component of the products of nitration of

m- xylene. It constitutes the largest part of the purified commercial product. The

4,5,6- isomer is formed only in an insignificant quantity.

The composition of the nitrating mixture depends on whether m- xylene, nitro-

or dinitro-m-xylene is to be nitrated. Usually more dilute mixtures are applied

than for the nitration of toluene to trinitrotoluene.

For example, for the conversion of dinitro- to trinitro-m-xylene, a mixture

containing 9-10% of water at a temperature up to 100°C is used.

m- Xylene can be nitrated to its trinitro derivative in one stage using a nitrating

mixture containing ca. 20% of HNO 3 and ca. 3% of H 2 O.