The Chemistry of Powder and Explosives - Sciencemadness Dot Org

MONO- AND DI-NITROBENZENE 133
Trinitrobenzene 480 cc.
Trinitrotoluene 452 cc.
Picric acid 470 cc.
Trinitrocresol 384 cc.
Trinitronaphthalene 166 cc.
Mono- and Di-Nitrobenzene
Nitrobenzene is a pale yellow liquid, b.p. 208.0°, which is
poisonous and has an almondlike odor closely resembling that of
benzaldehyde (which is not poisonous). It is used as a component
of certain Sprengel explosives and as a raw material for the
preparation of aniline and of intermediates for the manufacture
of dyestuffs and medicinals. Its preparation, familiar to every
student of organic chemistry, is described here in order that the
conditions for the substitution of one nitro group in benzene may
serve us more conveniently as a standard for judging the relative
ease and difficulty of the nitration of other substances.
Preparation of Nitrobenzene. One hundred and fifty grams of concentrated
sulfuric acid (d. 1.84) and 100 grams of nitric acid (d. 1.42)
are mixed in a 500-cc. flask and cooled to room temperature, and 51
grams of benzene is added in small portions at a time with frequent
shaking. Shaking at this point is especially necessary lest the reaction
suddenly become violent. If the temperature of the mixture rises above
50-60°, the addition of the benzene is interrupted and the mixture is
cooled at the tap. After all the benzene has been added, an air condenser
is attached to the flask and the material is heated in the water
bath for an hour at 60° (thermometer in the water). After cooling, the
nitrobenzene (upper layer) is separated from the spent acid, washed
once with water (the nitrobenzene is now the lower layer), then several
times with dilute sodium carbonate solution until it is free from acid,
then once more with water, dried with calcium chloride, and distilled
(not quite to dryness). The portion boiling at 206-208° is taken as
nitrobenzene.
m-Dinitrobenzene, in accordance with the rule of Crum Brown
and Gibson, is the only product which results ordinarily from the
nitration of nitrobenzene. Small amounts of the ortho and para
compounds have been procured, along with the meta, from the
nitration of benzene in the presence of mercuric nitrate. 2 Dinitrobenzene
has been used in high explosives for shells in mixtures
with more powerful explosives or with ammonium nitrate. Its use
2 Davis, /. Am. Chem. Soc, 43, 598 (1921).