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292 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

(3) Water and volatile matters-no more than 0.075%.

(4) Acidity (as H 2 SO 4 ) - no more than 0.01%.

(5) Substances insoluble in benzene - no more than 0.15%.

(6) Content of ash - no more than 0.1%.

(7) Content of oily products - lower than in the standard substance.

The low melting point of α− trinitrotoluene is due mainly to the presence of

trinitrotoluene isomers, and to a lesser degree, to the presence of other impurities,

such as trinitrobenzene, trinitrocresol, dinitrotoluene.

Since the trinitrotoluene isomers are formed as a result of the nitration of m- ni-

trotoluene, W. W. Jones and Russel [9] undertook the task of determining to what

extent the presence of m- nitrotoluene in mononitrotoluene lowers the melting

point of α− nitrotoluene. The authors nitrated mixtures of m- and p- nitrotoluenes

(Table 61).

TABLE 61

RELATIONSHIP BETWEEN LOWERING THE MELTING POINT OF TNT AND THE

CONTENT OF m- NITROTOLUENE IN MONONITROTOLUENE

m- Nitrotoluene

content, %

0

Melting point °C

Found experimentally 80.78

Calculated from formula (12) 80.80

2.11 3.22 4.58

79.87 79.26 78.70

79.82 79.30 78.67

5.75

78.13

78.13

Pure 2,4-dinitrotoluene was also nitrated for comparison and, as a result tri-

nitrotoluene melting at 80.80°C was obtained.

Jones and Russel propose the following empirical formula for the calculation

of the melting point of TNT, depending on the m- nitrotoluene content in mono-

nitrotoluene:

m. p. = 80.80-0.465c (12)

where c is the percentage of m- nitrotoluene.

Solubility. a- Trinitrotoluene is rather insoluble in water. It dissolves in con-

centrated sulphuric or nitric acids and is precipitated from the solutions on adding
water.

The solubility data for α− trinitrotoluene in sulphuric acid of various concen-

trations are tabulated in Table 62 (Belenkii [39]).

TNT dissolves with difficulty in nitrating mixtures. Its solubility may how-

ever be fairly high when the content of HNO 3 in the nitrating mixture falls to a
few per cent, as in waste acid.

Solubility data for α− trinitrotoluene in various mixtures at 20°, 50° and 70°C
are shown in Table 63.