Organic Syntheses, Coll. Vol. 1, p.445 (1941); Vol. 4, p.57 (1925).
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.
per cent of the theoretical amount) of actual phenylhydroxylamine
, as determined by its separation from inorganic materials by solution in ether (Note 4)
dust must be analyzed (Gattermann, "Practical Methods of Organic Chemistry," 3rd ed., p. 390
), and a proportional quantity used if the zinc
content is not 85 per cent. Technical nitrobenzene
is satisfactory if it distils over a range of not more than 5° and is not acid in reaction.
When the reaction is run more slowly, the temperature does not reach 60–65° and the yield is poorer. At 50–55°, the yield is about 55
It is important that the phenylhydroxylamine
solution be kept at 0° for at least one-half hour or considerable material will be lost in the solution. The use of an enameled pail
saves a great deal of time at this step.
is soluble in saturated salt solution at 0° to the extent of about 9 g. per liter, but this amount is not included in the yields given. Occasional yields of 300–310 g.
of dry phenylhydroxylamine
have been obtained.
β-Phenylhydroxylamine can be prepared by the reduction of nitrobenzene
a method in which various solvents and catalysts have been used, and in which copper-coated and amalgamated zinc
, as well as aluminum amalgam
have been substituted for the zinc
dust; by ammonium sufide
by sodium in liquid ammonia
and by the oxidation of anilinomagnesium bromide
with an ether
solution of hydrogen peroxide
The procedure described is like an earlier method,6
but it has been found7
that cooling is not essential. The preparation of the oxalate has been described.8
This preparation is referenced from:
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