A
600-ml. steel reaction vessel (Note
1) is precooled before loading by filling it between one-fourth and one-half full of
methanol and Dry Ice. After removal of the
methanol and Dry Ice, the
autoclave is charged with
120 g. (176 ml., 1.76 moles) of isoprene (Note
2),
113 g. (80 ml., 1.76 moles) of liquid sulfur dioxide,
88 ml. of methanol, and
4 g. of hydroquinone. The vessel is sealed, heated slowly to 85°, and maintained at that temperature for 4 hours. It is then cooled, the sulfone removed, the bomb rinsed with
methanol, and the combined product and washings are treated hot with
5 g. of Norite. The filtered solution is concentrated to a volume of 250–300 ml., and the sulfone is allowed to crystallize. The material is filtered and washed with
50 ml. of cold methanol. Recrystallization from
methanol (20 ml. per 25 g. of sulfone) yields
140–150 g. of thick, colorless plates. Concentration of the mother liquors raises the total yield to
182–191 g. (
78–82%) (Note
3), melting at
63.5–64° (Note
4).