A
300-ml., one-necked flask equipped with a
reflux condenser, the top of which is attached to a
nitrogen inlet tube, is charged with
3.85 g. (0.0338 mole) of 2-hydroxymethylenecyclohexanone (Note
1),
10 g. (0.025 mole) of ethylene dithiotosylate (Note
2), and
10 g. of potassium acetate in
150 ml. of methanol. The mixture is refluxed under
nitrogen for 3 hours with stirring, the solvent is removed from the reaction mixture on a
rotary evaporator, and the residue is extracted with three
50-ml. portions of diethyl ether. The combined ethereal extracts are washed with cold, aqueous
2 N sodium hydroxide (Note
3) until the aqueous layer is basic to litmus, then with
50 ml. of saturated aqueous sodium chloride. The ethereal layer is dried over anhydrous
magnesium sulfate, filtered, and concentrated on a rotary evaporator. The oily residue is diluted with
1 ml. of benzene and
3 ml. of cyclohexane and transferred to a chromatographic
column (14 × 2 cm.) prepared with
50 g. of alumina (Note
4) and a 3:1 mixture of
cyclohexane and
benzene. With this solvent system the desired product moves with the solvent front, and the first 100 ml. of eluent contains 85% of the total product. Further elution with approximately 100 ml. of the same solvent mixture removes the rest of the material before a second component begins to come off. Evaporation of the solvent from the combined 200 ml. of eluent leaves an oily residue which crystallizes on standing, yielding
2.76–3.04 g. (
57–64%) of crude
2,2-(ethylenedithio)cyclohexanone. Recrystallization from approximately
50 ml. of pentane affords
2.1–2.6 g. (
45–55%) of needles, m.p.
56–57° (Note
5).