Hydrogen Sulfide → 2,6-Dimethyl-5,6-dihydro-2H-thiopyran-3-carbaldehyde

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Reaction Steps

17 g of hydrogen sulfide were passed into a mixture of 500 ml of toluene, 70 g of crotonaldehyde and 10 ml of triethylamine at 30° C. and the mixture was then stirred for 12 hours at room temperature, after which 300 ml of 37% strength by weight phosphoric acid were added. Stirring was continued for 8 hours at 90° C., after which the mixture was cooled to room temperature and the organic phase was separated off. The aqueous phase was extracted once with toluene, the combined organic phases were washed once with water and dried over sodium sulfate, the solvent was removed under reduced pressure and the residue was distilled under 0.6 mbar to give 64 g (82% of theory) of 3-formyl-5,6-dihydro-2,6-dimethyl-2H-thiopyran of boiling point 73°-76° C.

Provenance & Evidence