The mixture is now boiled in a
3-l. flask, the vapors being passed through an
efficient condenser and the condensed liquid run into an
automatic separator (p. 422) so arranged that the heavy liquid is returned to the flask and the lighter aqueous liquid discarded. If the boiling is sufficiently vigorous no more water will separate after two to two and one-half hours' boiling (Note
3). The reaction mixture is now cooled, washed with dilute
sodium carbonate solution, and distilled with the use of a
column until the temperature of the vapor reaches 85° and that of the liquid in the flask about 115°. The residue is then transferred to a flask provided with a column for distillation under reduced pressure
(Fig. 9, p. 130) and distilled. The fraction boiling at
60–65°/15 mm. is collected,
690–700 g. of pure
ethyl β-bromopropionate being obtained (
85–87 per cent of the theoretical amount). A high-boiling residue, probably consisting of
ethyl hydracrylate, remains in the flask, but the amount is practically negligible.