Org. Synth. 1931, 11, 92
[Thiocyanic acid, isopropyl ester]
Submitted by R. L. Shriner
Checked by C. R. Noller
In a 3-l. round-bottomed flask
, fitted with a very efficient mechanical stirrer (Note 1)
, a reflux condenser
, and a 500-cc. separatory funnel
, are placed 445 g. (5.5 moles) of sodium thiocyanate (Note 2)
and 1250 cc. of 90 per cent ethyl alcohol
. The stirrer is started and the mixture is heated to boiling. Then 615 g. (5 moles) of isopropyl bromide
; Org. Syn. Coll. Vol. I, 1941, 37
) is added slowly during the course of one hour. The mixture is refluxed with stirring for six hours. At the end of this time the precipitated sodium bromide
is removed by filtration and washed with 250 cc. of 95 per cent alcohol
. As much of the alcohol as possible is then removed by distillation on the steam bath. To the residue in the flask is added 500 cc. of water, and the upper layer of isopropyl thiocyanate
is separated. The aqueous layer is extracted with two 100-cc. portions of ether (Note 3)
. The ether
extracts are added to the crude thiocyanate, and the combined product is dried over anhydrous sodium sulfate (Note 4)
. The dried material is fractionated twice from a modified Claisen flask with a 25-cm. fractionating column
. The following fractions are collected: up to 60°; 60–100°; 100–130°; 130–146°; and 146–151°. The last fraction contains the pure product. The yield is 320–345 g.
per cent of the theoretical amount). By redistilling the alcohol that was removed on the steam bath through an efficient fractionating column (Note 5)
until all the alcohol is removed (Note 6)
, separating the water, and distilling, there is obtained an additional 55–65 g.
of product boiling at 146–151°
. The total yield is 385–400 g.
per cent of the theoretical amount). On redistillation of the combined fractions boiling at 146–151°, practically the entire amount distils at 149–151°
A vigorous mechanical stirrer
must be used to prevent the precipitated sodium bromide
from settling to the bottom and causing bumping.
A technical grade of sodium thiocyanate
was used. Potassium thiocyanate
does not possess any advantages over the sodium salt.
is used to extract the aqueous layer, three fractionations are necessary to obtain the same yields.
The sodium sulfate
does not remove the water entirely, and in the subsequent fractionation the water layer should be removed by means of a separatory funnel wherever it appears.
An eight-bubbler fractionating column
of the type described by Clarke and Rahrs1
Distillation was continued until water began to appear in the lowest bubbler.
has been prepared by the action of isopropyl iodide
on potassium thiocyanate
Chemical Abstracts Nomenclature (Collective Index Number);
sodium bromide (7647-15-6)
Isopropyl bromide (75-26-3)
sodium sulfate (7757-82-6)
potassium thiocyanate (333-20-0)
isopropyl iodide (75-30-9)
Thiocyanic acid, isopropyl ester (625-59-2)
sodium thiocyanate (540-72-7)
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved