One kilogram (805 cc., 9.8 moles) of 90 per cent glycerol (sp. gr., 1.243) and
20 g. of acetic acid are placed in a weighed
2-l. flask which is immersed in an
oil bath heated to 100–110° (Note
1). The flask is fitted with a
two-holed stopper, which carries a long tube reaching to the bottom of the flask and a short exit tube. The long tube is connected to a
hydrogen chloride generator (Note
2); the short one, to a
catch-bottle and some system for absorbing any excess of
hydrogen chloride (see
Fig. 7 on p. 97). A stream of dry
hydrogen chloride is passed into the mixture. The absorption of gas is very rapid at the start but gradually falls off towards the end of the reaction; the stream of
hydrogen chloride should be regulated accordingly. The flask is removed from time to time and weighed; when the absorption of gas practically ceases, the increase in weight will be about
875 g. (
25 per cent more than the theoretical amount).
The product is now cooled, placed in a
4-l. beaker, and treated with solid
sodium carbonate until just alkaline to litmus. water is added from time to time, to facilitate the reaction with the
sodium carbonate and to prevent the separation of salt; about 500 cc. is required. The mixture is transferred to a
separatory funnel and the aqueous layer separated. The crude dichlorohydrin, which weighs
1250 g., is distilled under reduced pressure. The first fraction boiling below
68°/14 mm. weighs
225 g., and consists of water and some dichlorohydrin; the dichlorohydrin is collected between
68° and
75°/14 mm., and weighs about
775 g. The water is separated from the first fraction, which is then redistilled and yields
100 g. of dichlorohydrin. A further amount of material (
40–45 g.) may be obtained by extracting the aqueous layer obtained in the neutralization process with
benzene. This is, however, hardly profitable. The neutralization and distillation will require about four hours.
The
875 g. of dichlorohydrin thus obtained boils over a
7° range; this is
70 per cent of the theoretical amount (Note
3). Redistillation yields
700–720 g. boiling at
70–73°/14 mm. (
55–57 per cent of the theoretical amount).