Carbon Disulfide → Acetic acid, 2-isothiocyanato-, ethyl ester

Participants

Reaction Conditions

Reaction Steps

Carbon disulfide (22.8 g., 0.3 mol.) in chloroform (40 ml.) was added over a period of one hour to a stirred suspension of glycine ethyl ester hydrochloride (41.7 g. 0.3 mol.) and triethylamine (60.7 g., 0.6 mol.) in methylene chloride (300 ml.) at -10° C. The reaction mixture was allowed to warm up to 10° C. and was stirred for 10 minutes at this temperature. The mixture was treated dropwise with ethyl chloroformate (32.6 g., 0.3 mol.) in chloroform (50 ml.) at 0°-5° C. over a period of 0.5 hour. The mixture was stirred for another 40 minutes at room temperature and triethylamine (30.4 g., 0.3 mol.) was added dropwise over a period of 15 minutes. The mixture was stirred for 1/4 hour at 0° C. and an additional 1/2 hour at room temperature and finally stored over night at 25° C. The mixture was washed with water (250 ml.), 2N hydrochloric acid (2 × 300 ml.), 5% sodium bicarbonate solution (4 × 300 ml.) and dried over anhydrous sodium sulfate. The solvent was evaporated at 40° C. (15 mm.) to yield 38.1 g. of crude isothiocyanate. Upon storage overnight, a red dye was produced. This may be eliminated by distillation of the isothiocyanate.*

Provenance & Evidence