In a
5-l. round-bottomed flask, fitted with a
reflux condenser, a
mechanical stirrer, and a
separatory funnel, are placed
615 g. (3.3 moles) of ethylene dibromide (Note
1),
1250 cc. of 95 per cent alcohol, and 450 cc. of water (Note
2). The stirrer is started and the mixture heated to boiling. To the well-stirred boiling mixture a solution of
125 g. (1 mole) of anhydrous sodium sulfite in 450 cc. of water is added through the separatory funnel over a period of about two hours. The solution is boiled under a reflux condenser for two hours after all the sulfite solution has been added. The condenser is then set for distillation, and the alcohol and the
ethylene bromide are distilled (Note
3). The remaining water solution is poured into a
large evaporating dish and evaporated to dryness on the
water bath. The
sodium 2-bromoethanesulfonate is extracted from the
sodium bromide and unchanged
sodium sulfite with
2 l. of boiling 95 per cent alcohol. On cooling the solution, most of the salt crystallizes; the mother liquor is used for a second extraction of the residue. The yield is
165–190 g. (
78–90 per cent of the theoretical amount). The product (Note
4) may be further purified by recrystallizing from alcohol and drying in an
oven at 110° (Note
5). The recovery on recrystallization is
75–80 per cent.