NITRO DERIVATIVES OF HALOGENOBENZENES 465pyridinium picrate. The same salt was obtained by Okon when subjecting picryl-
pyridinium chloride to hydrolysis by means of an aqueous solution of pyridine.
1-Chloro-2,4,5-trinitrobenzene
By the nitration of 1-chloro-3,4-dinitrobenzene with nitric acid in the presence
of 40% oleum, at a temperature of 140-150°C a picryl chloride isomer, 1-chloro-
2,4,5-trinitrobenzene, is formed.
A nitro group in the position ortho and para to other nitro groups exhibits higher
reactivity than a chlorine atom. That is why by the action of, for example, ammonia,
chlorodinitroaniline can be formed:
(13)The chlorine atom in 1-chloro-2,4,5-trinitrobenzene becomes reactive only at
higher temperatures.
Diagram of the nitration of chlorobenzene
The following diagram represents the complete process of nitration of chloro-
benzene to trinitro derivatives :