Org. Synth. 1938, 18, 1
DOI: 10.15227/orgsyn.018.0001
2-ACETOTHIENONE
[Ketone, methyl 2-thienyl]
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
1.
By shaking the recovered
benzene-thiophene mixture with a solution of
5.5 g. of mercuric chloride,
10 g. of sodium acetate, and
10 cc. of alcohol in 80 cc. of water, the unchanged
thiophene is converted to the
2-chloromercurithiophene (containing a small amount of the dimercurichloride); from this the free
thiophene can be obtained by treatment with
hydrochloric acid. The recovered
thiophene amounts to 2–2.5 g.2.
2-Acetothienone has the following physical constants:
d204 1.168,
n20D 1.566. Its semicarbazone melts at 186–187° (corr.).
3. Discussion
2-Acetothienone has been prepared by treating
thiophene with
acetyl chloride in the presence of
aluminum chloride1 or
stannic chloride,
2 and by treating
2-chloromercurithiophene with
acetyl chloride.
3 The present method is essentially that of Stadnikoff and Goldfarb.
2 Stannic chloride is superior to
aluminum chloride as a catalyst for this reaction as
aluminum chloride induces polymerization of the
thiophene.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
benzene-thiophene
dimercurichloride
alcohol (64-17-5)
calcium chloride (10043-52-4)
hydrochloric acid (7647-01-0)
Benzene (71-43-2)
sodium acetate (127-09-3)
acetyl chloride (75-36-5)
aluminum chloride (3495-54-3)
mercuric chloride (7487-94-7)
Ketone, methyl 2-thienyl (88-15-3)
Thiophene (110-02-1)
stannic chloride (7646-78-8)
2-chloromercurithiophene
2-Acetothienone (88-15-3)
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