Benzothiazole,2,4-dimethyl-(6CI,7CI,8CI,9CI)

White solid

[step 2] To a mixture of potassium hexacyanoferrate (III) (22.1 g) To a mixture of 2-acetotoluidine (5.00 g) and tetrahydrofuran (75 ml) was added a Lawesson reagent (9.48 g) and the mixture was stirred with heating under reflux for about 5 hr. The reaction mass was cooled to room temperature, water (100 ml) was added, and the mixture was extracted twice with ethyl acetate (100 ml) . The combined organic layer was washed with saturated brine (100 ml) , dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to give N-(2-methylphenyl ) ethanethioamide (6.60 g) . To a mixture of potassium hexacyanoferrate (III) (22.1 g) and water (35 ml) was added a mixture of N-(2-methylphenyl ) ethanethioamide (6.60 g) obtained in step 1, sodium hydroxide (3.69 g) and water (50 ml), and the mixture was stirred at 40°C for about 2 hr. The reaction mass was cooled to room temperature, and the mixture was extracted twice with ethyl acetate (50 ml). The combined organic, layer was washed with saturated brine (50 ml), dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to give 2, 4-dimethyl-1, 3-benzothiazole (hereinafter to be indicated as the present compound 13) (2.82 g) .