urbaf2

PICRIC ACID ETHERS^549

It gives a lead block expansion equivalent to 84% of that produced by picric

acid. Its rate of detonation, however, is relatively high - its maximum value being

6880 m/sec.
Trinitrophenetole is prepared in a way similar in principle to that for trinitro-

anisole :

(5)

The greatest difficulty to overcome is the nitration of dinitrophenetole to trinitro-

phenetole, since it must be carried out within a narrow temperature range. Too high

a temperature may result in a decomposition of the product, while too low a tem-

perature causes a considerable part of the substance to remain unnitrated. Nitration

at 60°C gives the best results.

POLYNITRO DERIVATIVES OF DIPHENYL ETHER

Polynitrodiphenyl ethers (for example hexanitro-) cannot be obtained by the

direct nitration of diphenyl ether. Therefore attempts have been made to prepare

the polynitro compounds (beginning with the pentanitro compounds) by indirect

ways.

PENTANITRODIPHENYL ETHER

Two isomers of pentanitrodiphenyl ether are known:

I Il

Isomer I (2,4,6,2’,4’-, m. p. 210°C was obtained by Desvergnes [6] by reacting

picryl chloride with sodium o- nitrophenate, followed by the nitration: