The Chemistry of Powder and Explosives - Sciencemadness Dot Org

TRINITROTOLUENE 145
with a corresponding improvement in the melting point and appearance
of the material, by washing the crystals with a solvent.
On a plant scale, alcohol, benzene, solvent naphtha (mixed
xylenes), carbon tetrachloride, and concentrated sulfuric acid
have all been used. Among these, sulfuric acid removes dinitrotoluene
most readily, and organic solvents the /?- and y-TNT,
FIGURE 47. Commercial Sample of Purified TNT (25X).
but all of them dissolve away a portion of the a-TNT with resulting
loss. The material dissolved by the sulfuric acid is recovered
by diluting with water. The organic solvents are recovered by
distillation, and the residues, dark brown liquids known as "TNT
oil," are used in the manufacture of non-freezing dynamite. The
best process of purification is that in which the crude TNT is
agitated with a warm solution of sodium sulfite. A 5 per cent
solution is used, as much by weight of the solution as there is of
the crude TNT. The sulfite leaves the a-TNT (and any TNB,
TNX, and 2,4-dinitrotoluene) unaffected, but reacts rapidly and
completely with the /3- and y-TNT to form red-colored materials