urbaf2

318 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

the volumes of the two phases. The reaction occurs in both phases but the rate in

the mineral acid phase is much higher than in the organic oil phase. In the latter

it is relatively high only when the factor " Φ " is high.

This is because the organic oil phase contains only HNO 3 with practically no

H 2 SO 4. The rate of nitration of dinitrotoluene depends therefore largely on the

solubility of dinitrotoluene in the acid layer.

To some extent the organic phase has a negative action on nitration. It is a good

solvent of HNO 3 and considerably reduces the concentration of HNO 3 in the acid

phase.

The secondary reaction of oxidation occurs in both the organic and mineral

layers. It is likely that oxidation occurs strongly in the organic layer because of the

presence of HNO 3 free from H 2 SO 4.

The negative influence of the organic layer also consists in reducing the con-

centration of dinitrotoluene in the mineral acid phase. This occurs when the organic

phase is composed mainly of molten trinitrotoluene. The distribution coefficient

of dinitrotoluene between the two phases shifts the dinitrotoluene towards the

organic layer. This particular negative action of the trinitrotoluene layer is less

pronounced by the end of the nitration when very little dinitrotoluene is left unni-

trated. To favour the reaction it is necessary to raise the temperature. Therefore

the most favourable condition of heterogeneous nitration exists at the begin-

ning of the reaction when the organic layer is composed only of dinitrotoluene.

Therefore at this stage of the reaction it is possible to use less concentrated nitrating

mixtures and a lower nitration temperature.

Explosive properties of TNT...........................

Decomposition of TNT during detonation, dependent on a number of factors.
may be represented (Kast [57]) by the following equation:

16C 7 H 5 (NO 2 ) 3 = 20CO 2 + 47CO + CH 4 + H 2 O + 2C 2 H 2 + 2HCN + 14.5 H 2 + 21.5 N 2 +

+ 3NH 4 HCO + 29C

The heat of explosion of TNT is 950 kcal/kg, the volume of gases V 0 = 690 l/kg,

the temperature t = 2820°C.

Schmidt gave [111] a number of the equations for TNT decomposition; calcu-

lated on 1000 g (4.4 moles) of trinitrotoluene. Here are two of them, for the extreme
density of loadings d = 1.0 and 1.59 g/cm^3

(1) for A = 1.0 g/cm

3

4.4C 7 H 5 (NO 2 ) 3 = 2.84CO 2 + 17.0CO + 3.77H 2 O + 2.49H 2 + 0.1CmHn + 0.1CH 4 +

+ 2.85NH 3 + 0.47HCN + 0.2C 2 N 2 + 4.75N 2 + 10C

The heat of explosion = 910 kcal/kg, the volume of gases V 0 = 773 l./kg,

t = 3080°C.