NITRO DERIVATIVES OF HIGHER BENZENE HOMOLOGUES 419occurs in the 4- and 2,4-positions of the benzene ring. Hence one can infer that
during the nitration of polystyrene the first nitro groups take the position para
to the vinyl group and then part of the rings undergoes further nitration, the next
nitro groups taking the ortho position.
During the nitration, polystyrene undergoes partial degradation to an extent
which depends on the nitration conditions and is greatest at the beginning of the
reaction.
Nitropolystyrene is soluble in 90% nitric acid, nitroglycerine, nitrobenzene and
cyclohexanone. It burns without melting. Zenftman and MacLean [42] suggested
taking advantage of this by using the product as a combustible binder for explo-
sive mixtures instead of nitrocellulose.
Médard [43] has examined the explosive properties of nitropolystyrene contain-
ing 13.9% of N, i.e. consisting of about 90% of the dinitro and 10% of the
mononitro compound. In his investigations he compared nitropolystyrene with
dinitrotoluene and found the former to be a less powerful explosive and less sensitive
to impact.
The rate of detonation of nitropolystyrene of density 0.25 in a steel pipe 36-42 mm
in diameter is only 1510 m/sec.
The density of nitropolystyrene is very low, due to its “fluffiness”. Médard
suggested its use in the manufacture of ammonium nitrate mining explosives of
low density, hence of a relatively low power. The following figures give some idea
of such mixtures:
Nitropolystyrene 15% 12.75%
Ammonium nitrate 85% 72.75%
Sodium chloride - 15%
Density 0.6 0.72
Lead block expansion test 120
(picric acid = 100)
Rate of detonation - 2720 m/sec
Attempts to prepare nitropolystyrene by the nitration of styrene followed by
polymerization of the nitro derivatives, have failed.
Although it was possible to obtain the monomer 2,4,6-trinitrostyrene (Wiley
and Behr [44]) every attempt to polymerize it has proved useless. This is under-
standable in the light of the fact that aromatic nitro compounds inhibit polymeri-
zation processes (p. 214). Similarly 2,4-dinitrostyrene has not been polymerized.
2,4,6-Trinitrostyrene has been prepared by these authors from trinitrotoluene
in the following series of reactions: