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TNT MANUFACTURE^447

TABLE 81

Toluene from Toluene from

coal petroleum

Specific gravity at 15°C

Boiling range

Colouration with sulphuric acid

0.870±0.002 0.863-0.870

109-111°C 108.5-111°C

(95% distils within a range of 1°C)

(comparison with standard potassium di-

chromate solutions of concentrations

x grammes per 1 l. of 50% sulphuric

acid)

x 0.5 x 0.5

Bromine number (y grammes of bromine

decolourized by 100 ml. of toluene)

Sulphonation test with 5% oleum

y 0.8

y 0.8

not less than 96 vol. %

should be sulphonated

According to a German standard, toluene for nitration shall distil within a range

not wider than 0.8°C.

NITRATION OF TOLUENE TO TNT

General remarks................................

The nitration of toluene to TNT is carried out by successive introduction of

nitro groups. Such a method is justified from the points of view both of safety and

economy as it permits the most efficient use of acids and produces a final product

of high purity due to the purification of the intermediate products obtained in the

separate stages of the process.

Nitration is commonly carried out in three stages, and less often in two

Stages.

The principle of economical acid usage is simply achieved by using the spent

acid from a higher nitration stage for the lower stage, after it has been fortified to

the required concentration.

The diagram presented below illustrates the reactions occurring, and shows the

average composition of the products and heat effects of the reactions. Another

diagram (Gorst [4]) gives the yields of nitration of intermediate compounds.

THREE-STAGE PROCESS FOR MANUFACTURE OF TNT’

The three-stage nitration of toluene to TNT comprises the following processes:

I. C 6 H 5 .CH 3 -> C 6 H 4 .CH 3 .NO 2 (MNT)

II. C 6 H 4 .CH 3 .NO 2 -> C 6 H 3 .CH 3 .(NO 2 ) 2 (DNT)

III. C 6 H 3 .CH 3 .(NO 2 ) 2 -> C 6 H 2 .CH 3 .(NO 2 ) 3 (TNT)