urbaf2

PICRIC ACID ETHERS 551

It may be prepared by a method described in the patent filed by Westfälisch-

Anhaltische Sprengstoffe [10], namely :

IV

(9)

The authors state that the substance is less sensitive and more powerful than

picric acid.

This was not confirmed by van Duin and van Lennep [8] who found the sensi-

tivity of hexanitrodiphenyl ether to be higher than that of tetryl. The same authors

determined the initiation temperature to be 318°C. Neither is the stability of the

product satisfactory, since after 8 hr heating at 95°C the evolution of nitrogen

oxides may be observed.

According to data reported in the literature, sym-hexanitrodiphenyl ether should

be considered as an unstable compound and it is to this fact, that the failure to

obtain it is usually ascribed.

Recently Okori and Grabowski [ll] have proved that the whole system can be

stabilized by the presence of a methyl group on one of the benzene rings, in the

meta position to the ether bond. The stable compound VI can be obtained by

nitrating m- cresylpicric ether (V) with pure (100%) nitric acid:

(10)

V VI

m. p. 220-222°C

NlTRO DERIVATIVES OF VARIOUS PHENOLIC ETHERS

Polynitro derivatives of the simplest cyclic ether of pyrocatechol-1,2-ethylene-

dioxybenzene are interesting because of the position of the nitro groups (Vor-

Kinder [12]).