"The preparation of Triacetone Hydrate"
JCS 1927, 2897
The following method was devised some years ago, but was not described at the time, since it was desired to investigate the other products of the
reaction and to increase materially the yield of the base.
Into a mixture of 2.5 kg acetone and 800 g fused calcium chloride in a large (no kidding) round bottomed flask provided with an efficient condenser,
ammonia is passed at intervals until the whole of the chloride has been converted into a liquid complex. After 3 days, the product is gently boiled on
a water bath until the liquid calcium chloride-ammonia compound has decomposed and resolidified, ammonia being evolved. The dark, strongly smelling
liquid is then decanted from the solid or pasty chloride, and distilled until a thermometer in the vapor registers 75 C; the distillate consists
chiefly of acetone. The residue is placed in a freezing mixture of ice and hydrochloric acid and when the temperature has fallen to 1-2 C an amount of
water is added, with vigorous stirring, corresponding to a yield of 28% of triacetoneamine calculated on the acetone used. i.e., the amount taken less
that distilled off. Triacetoneamine hydrate separarates in a crystalline condition as the temperature falls; after being pressed between filter paper
and recrystallized several times from undried ether, it is obtained in large, well-formed, slightly yellow crystals (yield, 20-26%, calculated on the
acetone used).
The conversion of the hydrate into the nitrosotriacetoneamine is carried out in the usual manner and the yield is quantitative. The extreme
ease with which this nitrosoamine is decomposed catalytically by alkalis, giving a nearly quantitative yield of phorone, renders this an elegant
method for the preparation of this unsaturated ketone. (JCS 1912, 2358). |
