Organic Syntheses, Coll. Vol. 2, p.7 (1943); Vol. 15, p.1 (1935).
In a 5-l. three-necked, round-bottomed flask
fitted with an efficient stirrer (Note 1)
, a separatory funnel
, and a thermometer in a well
is placed a solution of 500 g. (9.7 moles) of powdered 95 per cent sodium cyanide
in 1.2 l. of water and 900 cc. (713 g., 12.3 moles) of acetone
. The flask is surrounded by an ice bath
, and the solution is stirred vigorously. When the temperature falls to 15°, 2.1 l. (8.5 moles) of 40 per cent sulfuric acid (Note 2)
is added over a period of three hours, the temperature being kept between 10° and 20°. After all the acid has been added the stirring is continued for fifteen minutes and then the flask is set aside for the salt to settle. Usually a layer of acetone cyanohydrin
forms and is decanted and separated from the aqueous layer. The sodium bisulfate
is removed by filtration and washed with three 50-cc. portions of acetone
. The combined filtrate and acetone
washings are added to the aqueous solution, which is then extracted three times with 250-cc. portions of ether (Note 3)
. The extracts are combined with the cyanohydrin previously separated and dried with anhydrous sodium sulfate
. The ether
are removed by distillation from a water bath
, and the residue is distilled under reduced pressure. The low-boiling portion is discarded, and acetone cyanohydrin
is collected at 78–82°/15 mm.
The yield is 640–650 g.
per cent of the theoretical amount) (Note 4)
It is advantageous to use a heavy metal stirrer
because of the increased viscosity of the mixture toward the end of the reaction. Since some hydrogen cyanide
may escape from the reaction mixture, the stopper
carrying the stirrer should be fitted with a tube for leading off the gas or the reaction should be carried out under a hood
Extraction and distillation should be started as soon as possible after the completion of the reaction, and the distillation should be done as rapidly as possible to avoid decomposition.
This preparation is referenced from:
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved