Organic Syntheses, CV 4, 571
Submitted by Peter J. Hearst and C. R. Noller
1.
Checked by R. S. Schreiber, B. D. Aspergren, and R. V. Heinzelmann.
1. Procedure
In a
1-l. three-necked flask fitted with a mechanical stirrer, a reflux condenser, a thermometer, and a separatory funnel (Note
1), and set up in a
hood, is placed
152 g. (105 ml., 1.5 moles) of methanesulfonic acid (Note
2). The acid is heated to 95° on a
steam bath, and
238 g. (146 ml., 2.0 moles) of thionyl chloride (Note
3) is added over a period of 4 hours. The temperature is kept at 95° throughout the addition and for 3.5 hours after it is completed.
The product is transferred to a
modified Claisen flask (Note
4) and distilled under reduced pressure, heat being supplied by an
oil bath (Note
5). Most of the
thionyl chloride distils at room temperature. The yield of almost colorless product distilling at
64–66°/20 mm. (Note
6) is
122–143 g. (
71–83%);
nD23 1.451.
2. Notes
1. The checkers recommend the use of silicone grease on all glass joints.
2. The
methanesulfonic acid is a commercial product supplied by the Standard Oil Company of Indiana and reported to be 95% pure and to contain 2% water.
3.
Eastman Kodak Company thionyl chloride (b.p.
75–76°) was used without further purification.
4. The checkers used a Claisen head with an attached
10-cm. Vigreux column.
5. A free flame should be avoided, because local superheating causes charring and decomposition. The fumes from the decomposition cause the product (which normally is colorless) to darken. The bath temperature should not exceed 115° at the end of the distillation.
6. The checkers observed a boiling point of
61–62°/18 mm.
3. Discussion
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