In a
16-l. earthenware jar are placed
250 g. (4.7 moles) of technical ammonium chloride, 8 l. of water, and
500 g. (416 cc., 4.1 moles) of nitrobenzene. The mixture is stirred vigorously by means of a
mechanical stirrer, and
620 g. (8.1 atoms) of zinc dust of 85 per cent purity is added (Note
1) during the course of fifteen to twenty minutes (Note
2). As the reduction proceeds, the temperature rises to 60–65°. Stirring is continued for fifteen minutes after all the
zinc dust has been added, at the end of which time the reaction is complete, as indicated by the fact that the temperature of the mixture ceases to rise.
While still hot, the solution is filtered with suction in order to remove the
zinc oxide, which is washed with 1 l. of hot water. The filtrate is placed in an
enameled pan, saturated with salt, about 3 kg. being required, and cooled to 0° by being placed in an ice-salt mixture. The
phenylhydroxylamine, which crystallizes out in long, light yellow needles (Note
3), is filtered by suction. The yield of crude product varies considerably, depending upon the amount of salt solution present, but averages
350–400 g. This corresponds to
275–300 g. (
62–68 per cent of the theoretical amount) of actual
phenylhydroxylamine, as determined by its separation from inorganic materials by solution in
ether (Note
4).