Organic Syntheses, CV 2, 8
Submitted by John R. Johnson and G. E. May.
Checked by Reynold C. Fuson and E. A. Cleveland.
1. Procedure
In a
500-cc. round-bottomed, three-necked flask provided with a
thermometer,
dropping funnel, a
liquid-sealed stirrer, and
calcium chloride tube are placed
16.8 g. (0.2 mole) of thiophene (p. 578),
15.6 g. (14 cc., 0.2 mole) of acetyl chloride, and
200 cc. of dry benzene. The solution is cooled to 0°, and
52 g. (23 cc., 0.2 mole) of freshly distilled stannic chloride is added dropwise, with efficient stirring, during the course of about forty minutes. The reaction mixture assumes a purple color when the first drops of
stannic chloride are added, and soon a purple solid precipitates.
After all the
stannic chloride has been added, the
cooling bath is removed and the mixture stirred for one hour longer. The addition product is hydrolyzed by the slow addition of a mixture of 90 cc. of water and
10 cc. of concentrated hydrochloric acid. The yellow
benzene layer is separated, washed with 25 cc. of water, and dried over
5–10 g. of anhydrous calcium chloride.
Benzene and unchanged
thiophene (Note
1) are distilled through a
short fractionating column (using an
oil bath), and the residual liquid is distilled under reduced pressure. The yield of
2-acetothienone, b.p.
89–91°/9 mm., is
20–21 g. (
79–83 per cent of the theoretical amount) (Note
2).
2. Notes
2.
2-Acetothienone has the following physical constants:
d204 1.168,
n20D 1.566. Its semicarbazone melts at 186–187° (corr.).
3. Discussion
This preparation is referenced from:
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