A Publication of Reliable Methods for the Preparation of Organic
Compounds Annual Volume Org. Synth. 1942, 22, 59 DOI:
10.15227/orgsyn.022.0059 Submitted by E. Brand and F. C. Brand.
Checked by C. F. H. Allen and John W. Gates, Jr.. 1. Procedure
A. S-Ethylthiourea hydrobromide. A mixture of 150 g. of powdered
thiourea (1.97 moles) (Note 1), 250 g. of ethyl bromide (2.29
moles), and 200 ml. of absolute ethanol is placed in a 1-l.
round-bottomed flask equipped with an efficient condenser. The
mixture is warmed on a water bath (bath temperature 55–65°) for
3 hours, with occasional shaking. During this time all the
thiourea dissolves. The reflux condenser is replaced by one set
for downward distillation, and the ethanol and excess ethyl
bromide are removed under the vacuum of a water pump. During the
distillation, the temperature of the bath is slowly raised to
the boiling point (Note 2). The residual oil is poured into a
500-ml. beaker and allowed to crystallize (Note 3). The solid is
pulverized and dried in a d