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PICRIC ACID ETHERS 541

MANUFACTURE OF TRINITROANISOLE

In industrial practice a process based on the following reaction:

(4)

is used.

In a Japanese factory at Maizuru a two stage process was used for the manufac-

ture of trinitroanisole, namely: alcoholysis of 1-chloro-2,4-dinitroberuene to

2,4-dinitroanisole and subsequently nitration of di- to tri-nitroanisole.

Alcoholysis of 1-chloro-2,4-dinitrobenzene to 2,4-dinitroanisole. To 800 kg of

methyl alcohol in the reactor 196 kg of sodium hydroxide and 600 kg of chloro-

dinitrobenzene are added in 10 equal portions. The reagents are added alternately.

During this operation, which requires 7 hr, a temperature at 40-45°C is maintained.

Then the temperature is raised to 50°C by heating the reactor jacket and kept there

for 30 min, before cooling the whole mixture to 35°C (which takes 3 hr). The crys-

tals of the product together with the mother liquor are then transferred to a vacuum

filter for separation. The product obtained is washed four times with water, centri-

fuged and finally transferred to the nitration plant.

Some 550 kg of dinitroanisole can be obtained, i.e. the yield is 95% of the

theoretical.

Nitration of di- to tri-nitroanisole. A conventional type of a nitrator, with

a jacket for cooling or heating, but without a coil is used. 3200 kg of a mixture of

acids :

HNO 3 17%

H 2 SO 4 77%

H 2 O 6%

is charged into the nitrator. The mixture is prepared by fortifying the spent acid.

550 kg of dinitroanisole is hand-fed to the nitrator, which requires 6 hr. The

temperature is allowed to rise to 50-55°C and is maintained there during the opera-

tion. The nitrator contents are then heated to 60-68°C and kept at this temperature

for half an hour before being cooled to 35°C. This takes another 4 hr. The trinitro-

anisole formed is separated from the acid on a filter. The spent acid is fortified

with nitric acid (sp. gr. 1.50) and is m- used for nitration. The product is washed

five times with water which is subsequently removed by centrifuging. In this way

615-620 kg of trinitroanisole is obtained, which is 93% of the theoretical yield.

Purification of trinitroanisole. In the past trinitroanisole was purified by dis-

solving in methyl alcohol. The solution was filtered and the product precipitated

by introducing the solution into water. Later the purification process was sim-
plified, the crude trinitroanisole being agitated with hot water, the water decanted