6-Methylbenzothiopyran-4(4H)-one

13739-35-0

6948-34-1

General procedure for the synthesis of 6-methylthiobenzodihydropyran-4-one from 3-[(4-methylphenyl)thio]propionic acid: 20 g (0.1 mol) of 3-[(4-methylphenyl)thio]propionic acid was dissolved in a 1000 ml beaker containing 70 ml of concentrated sulphuric acid, and the reaction was carried out for 12 h at room temperature. Upon completion of the reaction, the reaction mixture was cooled in an ice-water bath to precipitate a large amount of yellow solid precipitate, which was subsequently filtered. The filter cake was washed sequentially with 5% sodium bicarbonate solution and distilled water until neutral. The crude product was purified by recrystallization from 50% ethanol solution to give 16.88 g of light yellow solid 6-methylthiobenzodihydropyran-4-one in 93% yield.