In a
4-l. beaker (Note
1) provided with a
mechanical stirrer and
thermometer are placed
600 g. (4.76 moles) of anhydrous sodium sulfite,
420 g. (5.0 moles) of sodium bicarbonate, and 2.4 l. of water. The mixture is heated on a hot plate at 70–80° and is maintained at this temperature by switching the hot plate off occasionally, while
484 g. (2.54 moles) of p-toluenesulfonyl chloride (Note
2) is added in portions of 5–10 g., with stirring, during 3 hours. When addition is complete, the mixture is heated and stirred at 70–80° for 1 hour (Note
3). The mixture is then removed from the hot plate and allowed to stand for 4 to (preferably) 10 hours.
The solid
sodium p-toluenesulfinate which separates is collected by filtration and mixed with
400 g. (4.76 moles) of sodium bicarbonate and
490 g. (370 ml., 3.88 moles) of dimethyl sulfate (Note
4) in a
3-l. three-necked round-bottomed flask equipped with a mechanical stirrer, a reflux condenser, and a 1-l. separatory funnel containing 925 ml. of water. Water (75–100 ml.) is added from the separatory funnel to make the mixture fluid enough for stirring. The remainder of the water is then added dropwise, with stirring, during 3 hours. The mixture is then heated under reflux for 20 hours.
After the mixture is cooled to 75°,
200 ml. of benzene is added (Note
5). The mixture is stirred briefly, and the liquid is decanted from the solid into a
5-l. separatory funnel. The aqueous layer is separated and extracted again with
200 ml. of benzene. The aqueous layer is then returned to the separatory funnel, and the solid in the reaction flask is washed in with it by means of 2 l. of water. The mixture is shaken with
200-ml. portions of benzene until all solid has dissolved (usually three portions of
benzene suffice). All the
benzene extracts are combined and dried with
20 g. of anhydrous calcium chloride. The drying agent is removed by filtration and washed with two
20-ml. portions of benzene.
Benzene is removed from the filtrate by distillation under reduced pressure (Note
6), and the solid which separates is dried further at about 10 mm. and room temperature to constant weight. The yield (Note
2) of
methyl p-tolyl sulfone is
298–317 g. (
69–73%), m.p.
83–87.5°. Further purification is generally unnecessary, but, if desired, the product may be recrystallized from
carbon tetrachloride or ethanol-water (1:1). The submitters state that the method may be extended to the preparation of
methyl phenyl sulfone and, presumably, of methyl aryl sulfones generally (Note
7).