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440 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Then the vessel is charged with 1000-2000 1. of water and 100 kg of sodium car-

bonate and the whole is heated with live steam until the nitronaphthalene becomes

molten. This requires about 2 hr. The water should remain alkaline towards phenol-

phthalein. The contents of the vessel are pumped to one of three washing tanks.

The tank are made of sheet iron and equipped with a steam heater and with a stirrer

(40 r. p. m). After 2 hr of agitation the lower layer (molten nitronaphthalene) is

pumped into the next tank charged with a solution of 50 kg of sodium carbonate

in 3000 1. of water and heated up to 85-95°C.

The molten nitronaphthalene is pumped to the last tank and is washed there

with 3000 1. of water having a temperature of 85-95°C during 2-3 hr. The separation

of the nitro compound from water requires 2 hr. The washed, molten nitronaphtha-

lene is transferred to a drying kettle, where after being heated up to 95-105°C

it is allowed to remain for 4 hr under reduced pressure (about 200 mm Hg), while

constantly stirred (28 r. p. m).

Pure nitronaphthalene is sent, while still molten, for the preparation of α− naph-

thylamine by reduction.

If α− nitronaphthalene is to be used for preparing explosive compositions, it

is poured off from the drying kettle into pans for solidification and then broken

up into lumps.

From the quantities of raw materials given above, 2920 kg of nitronaphthalene

(m. p. 52-52.5°C) are obtained. This corresponds to a yield of 132.5 kg of nitro-

naphthalene from 100 kg of naphthalene, i.e. 98% of the theoretical.

French method

The nitration of naphthalene to nitronaphthalene, according to Pascal [20a],

is effected in a nitrator of the type shown in Fig. 108. The nitrator (1.16 m in diameter,

1.0 m high) is made of cast iron. The lower, conical part is provided with an outlet

5 cm in diameter, closed by a valve. The sheet iron jacket on the cylindrical part

of the nitrator may serve a double purpose: cooling the nitrator contents by water

or heating by steam.

The lid is provided with a rectangular opening (1) (35 x 20 cm) for feeding in the

naphthalene. After the nitrator has been charged the opening is closed with a sheet

iron lid. The nitrator lid is also equipped with pipe (2), connected with a ventilator

by means of a stoneware pipe; the ventilator itself is connected with an absorption

tower for absorption of nitrogen dioxide in water. In addition the nitrator is equipped

with stirrer (3) (85-90 r. p. m) and with two baffles (4) located opposite to each

other to increase the stirring effect.

In the nitrator described 300 kg of naphthalene can be nitrated in one batch.

The nitrator is charged with 1100 kg of a nitrating mixture of the com-

position :

HNO 3 12-14%

H 2 SO 4 40-50%

H 2 O 36-48%