Patent AT-E40129-T1: [Translated] PROCESS FOR THE PREPARATION OF 5,6-DIHYDRO-2HTHIOPYRAN-3-CARBOXALDEHYDE.

5,6-Dihydro-2H-thiopyran-3-carboxaldehydes of the formula <IMAGE> where R denotes hydrogen or methyl, are prepared by a method in which acrolein or crotonaldehyde is reacted with hydrogen sulfide in a mineral oil whose boiling point is higher than those of the starting materials and of the end product, and the 5,6-dihydro-2H-thiopyran-3-carboxaldehyde is obtained by distillation. These aldehydes are important intermediates for the preparation of some crop protection agents.