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268 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

The reaction most probably occurs on the surface dividing the two reacting

layers. The rate of nitration is therefore determined by the concentration of reactants

on the surface. This in turn is determined by the rate of diffusion of two phases.

The rate of nitration is plotted against temperature of nitration in Fig. 55 (nitra-

tion mixture with Φ = 70.9%, r = 7.9, time 30 min) and the rate of nitration

against the factor Φ, - in Fig. 56. Here two curves are given: one for a homogeneous

FIG. 55. change of the rate of nitration of

toluene with temperature (Orlova [2a]).

FIG. 56. Influence of the factor @ (nitrating

activity) on the rate of nitration of toluene:

I - in a homogeneous system, II - in a he-

terogeneous system (Orlova [2a]).

system (nitrating mixture of low H 2 SO 4 and HNO 3 content) and another one for

a heterogeneous system (the usual nitrating mixture with a high H 2 SO 4 content).

The change in the rate of nitration with Φ is particularly significant in the homo-

geneous system.

MONONITROTOLUENES

Three isomers of mononitrotoluene, ortho-, meta-, and para-, are known.

PHYSICAL PROPERTIES

The ortho-isomer can exist in the α -form, melting at -10.5°C, and in the β -form,

melting at -4.l°C. The melting point of the meta-isomer is 16°C, and that of

the para- isomer 52°C. The boiling points of the ortho-, meta-, and para- isomers
are 222, 230 and 238°C respectively.