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266 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

diagram which shows the influence of the composition of the nitrating mixtures

on the product obtained (Fig. 51).

As Gorst [2] points out, it is advisable to relate the nitration results to the

composition of the nitrating mixture at the moment when the organic substance

has ceased being nitrated. Gorst presented the corresponding results in a diagram

(Fig. 52).

FIG. 51. Nitration of toluene with HNO 3 -H 2 SO 4 -H 2 O mixtures (Kostevich and

Sapozhnikov [1]).

There is an important feature of nitrating toluene to nitrotoluenes, namely

the very low solubility of toluene and nitrotoluenes in nitrating mixtures. There-

fore the nitration proceeds in a two phase system and the rate of nitration depends

greatly on dispersion which in turn depends on keeping the two phases efficiently

stirred. Attention has previously been drawn to the importance of stirring on the

yield of nitrotoluene (Fig. 25, p. 153).

Orlova [2a] gives a similar but fuller figure depicting the change of yield of

nitrotoluene against the rate of stirring (Fig. 53). This relationship was established

when toluene was nitrated for 30 min with an acid mixture: 11% HNO 3 , 64%

H 2 SO 4 , 25% H 2 O (Φ = 69%) with a nitrating acid/toluene ratio of 3, at

30°C.

The ratio r = nitrating acid/toluene is also of importance and should be as

high as economic considerations permit. The ratio r is given in Fig. 54. Here toluene

was nitrated for 50 min with an acid mixture: 27% HNO 3 , 55% H 2 SO 3 , 18%

H 2 O (Φ = 68%) at 30°C.