Hydrochloric Acid → N-Acetyl-S-methyl-L-cysteine

Participants

Reaction Steps

S-Methyl-L-cysteine (119.6 g, 0.89 mole) was dissolved in 1.87 l (1.87 mole) of 1 N sodium hydroxide solution and then ice-cooled. Thereafter, 92.6 ml (0.98 mole) of acetic anhydride was added dropwise and the mixture was stirred for 2.0 hours at room temperature. The reaction mixture was acidified to pH 1.0 with 6 N hydrochloric acid and extracted with 1 liter of ethyl acetate five times. The extracts were dried over anhydrous magnesium sulfate and concentrated in vacuo to give 126.4 g of S-methyl-N-acetyl-L-cysteine as an oil (80.6% yield). A second crop of 5.17 g (3.3%) was recovered by reextraction of the aqueous layer.

Provenance & Evidence