Organic Syntheses, CV 2, 87
Submitted by F. A. Long and J. W. Howard.
Checked by W. W. Hartman and G. L. Boomer.
1. Procedure
In a
2-l. three-necked, round-bottomed flask, fitted with a
liquid-sealed mechanical stirrer, a
dropping funnel, and an
efficient reflux condenser, are placed
720 g. (230 cc., 4.5 moles) of bromine (Note
1) and
1.5 g. of sulfur (Note
2). A
glass tube is connected to the top of the condenser to carry the evolved
hydrogen bromide to a
gas trap.
Sixty-nine grams (69 cc., 0.52 mole) of dry paraldehyde (Note
1) is added slowly, with stirring, over a period of about four hours. The reaction proceeds under its own heat during the addition of the
paraldehyde; subsequently the mixture is heated externally for two hours at 60–80°. The solution is distilled and a fraction collected over the range 155–175° (Note
3).
On redistillation under reduced pressure there is obtained
220–240 g. (
52–57 per cent of the theoretical amount) of reddish yellow
bromal, boiling at
59–62°/9 mm., or
71–74°/18 mm.
2. Notes
2. The use of
sulfur as a catalyst increases the yield
5–10 per cent and causes no trouble in the purification.
3. Discussion
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