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532 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Pentanitrophenol (m. p. 190°C) was obtained by Blanksma [21], who nitrated

3,5-dinitrophenol with an anhydrous mixture of nitric and sulphuric acids. The

product was precipitated, and could then be recrystallized from chloroform.

Both meta-nitro groups are reactive. With water, pentanitrophenol yields trinitro-

phloroglucinol, with alcoholic ammonia solutions it gives diaminodinitrophenol.

NITRO DERIVATIVES OF CRESOLS

Of the three isomeric cresols: ortho-, meta-, and para-, only m- cresol can be

used as the starting material for introducing three nitro groups, viz. in the 2,4,6-

positions. Ortho and p- cresols are able to form stable nitro group systems only

when no more than two nitro groups are introduced. Under the conditions of the

nitration of m- cresol to its trinitro derivative the o- and p- isomers are oxidized to

oxalic acid.

Cresol for nitration should contain a high proportion of the m- isomer. Commer-

cial “meta-cresol” usually contains about 60% of the m- isomer and 40% of p- cresol.

The preparation of a much more costly raw material, containing 90% of m- cresol

is also possible. It is clear that the yield of trinitro-m-cresol will correspond to the

m- cresol content in the starting product.

A methyl group present in the ring facilitates the introduction of nitro groups.

This is why m- cresol is more readily nitrated than phenol. On the other hand a methyl

group enhances oxidation processes. This accounts for the lower yield of trinitro-

cresol obtained, as compared with that of picric acid. Like picric acid, trinitrocresol

has the disadvantage of readily forming metallic salts which are sensitive to impact.

All these factors have limited the practical application of trinitrocresol. France

was the only country which used it, under the name of “Cresilite” mostly in

mixtures with other nitro compounds to lower their melting points (Vol. III).

Among nitro derivatives of cresols, dinitro-m-cresol (m. p. 86.5°C)

is of some practical importance, though not as an explosive but as a herbicide.

2,4,6-TRINITRO-m-CRESOL