Organic Syntheses, CV 2, 140
Submitted by R. L. Shriner, S. G. Ford, and L. J. Roll.
Checked by C. R. Noller
1. Procedure
(
A)
Citraconic Anhydride.—
Two hundred and fifty grams of itaconic anhydride (Note
1) is distilled rapidly at atmospheric pressure in a
500-cc. modified Claisen flask with a 15-cm. (6-in.) fractionating column (Note
2). The
receivers for the distillate must be changed without interrupting the distillation. The distillate passing over below 200° consists of water and other decomposition products. The fraction which distils at 200–215° consists of
citraconic anhydride and is collected separately. The yield is
170–180 g. (
68–72 per cent of the theoretical amount) of a product melting at
5.5–6°. On redistillation under reduced pressure there is obtained
155–165 g. (
62–66 per cent of the theoretical amount) of a product which boils at
105–110°/22 mm. and melts at
7–8° (Note
3).
(
B)
Citraconic Acid.—To
22.4 g. (0.2 mole) of pure citraconic anhydride in a
100-cc. beaker is added from a pipet exactly 4 cc. (0.22 mole) of distilled water. The mixture is stirred on a hot plate until a homogeneous solution is formed, then covered with a
watch glass and allowed to stand for forty-eight hours. At the end of this time the mixture has solidified completely. The yield is
26 g. of a product melting at
87–89°. For further purification it is finely ground in a
mortar, washed with
50 cc. of cold benzene, dried in the air, and then dried for twenty-four hours in a
vacuum desiccator over
phosphorus pentoxide. This furnishes
24.4 g. (
94 per cent of the theoretical amount) of
citraconic acid which melts at 92–93°.
2. Notes
2. The success of the preparation depends upon a rapid distillation and changing the receivers without interrupting the distillation. The best yields are obtained when the heating period is of short duration.
3. Discussion
This preparation is referenced from:
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