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200 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

amine and with OH

• in dioxane-water (50/50). The results suggest that the
  reaction with the amine is catalysed by both n-butylamine and OH


• 
  

  ions.
  Plazek and L. Kuczyriski [31] investigated the reactivity towards ammonia of
  bromine atoms in o-, m- and p- bromonitrobenzene. The bromine atom in a position
  ortho to the nitro group is the most reactive, while the bromine atom in the meta
  position is the least so. However, in the presence of copper catalyst (CuSO 4 .5H 2 O)
  there is not much difference between the reactivity of meta- and para- bromine

  
  

atoms. The bromine atom in the ortho position remains the most reactive in the

presence of a catalyst.

Hawthorne [31a] arrived at a similar conclusion when investigating the rate

of reaction of o- and p- chloronitrobenzene with piperidine. The displacement of

the chlorine atom from the ortho compound by piperidine at 116°C proceeds 80

times more rapidly than the similar reaction of the para compound. He also ob-

served that substitution of D for H in the amino group in the nucleophile (piperid-

ine) did not alter these rates of reaction.

Recently Reinheimer and his co-workers [31b] found that a number of salts

have a marked effect on the rate of reaction of chloro-2,4-dinitrobenzene with

sodium methoxide to yield 2,4-dinitroanisole. Thus, lithium salts slowed the re-

action, sodium salts did not change the rate of reaction while potassium salts

increased the reaction rate. These results were interpreted on the basis of the

ion pairing of Na

+

and OCH 3

• ions in solution. Addition of another M

+

from

added salt would affect the equilibrium

M+ + OCH 3 - <-> M-OCH 3

The carboxyl group of trinitrobenzoic acid is also mobile and can readily be

liberated as CO 2 simply by heating.

The fact that nitro groups attached to an aromatic ring increase the reactivity

of the hydrogen atoms of a methyl group, can also be explained by the induction

effect strengthening the effect of hyperconjugation of the molecule of toluene.

According to the concept of hyperconjugation, the ionized states of toluene can

be written as II, III and IV:

(see for instance Waters [32], E. Müller [33]).

This would explain a number of reactions of the methyl group in nitro deriva-

tives of toluene, particularly in trinitrotoluene. For example, formaldehyde can