Penicillamine hydrochloride → Penicillamine

2.50 g (0.02 mole) of o-amino-thiophenol and 8.84 g (0.02 mole) of benzylpenicilloic acid α-benzylamide were added to a solution of 0.73 g (0.02 mole) of concentrated hydrochloric acid in 50 ml of water. The mixture was heated under reflux, with stirring, for 2 hours in a nitrogen atmosphere. After the completion of the reaction, the resulting mixture was allowed to stand at room temperature for an hour. The crystals which formed were separated by filtration, washed with a small amount of water and discarded. The filtrate and washings were combined and concentrated in vacuo to give D-penicillamine hydrochloride. The hydrochloride was dissolved in ethanol, and the solution was filtered, adjusted to a pH of 5-6 with triethylamine with stirring and cooling, and allowed to stand. The crystals which formed were separated by filtration, washed with cold methanol, and dried in vacuo to give D-penicillamine as colorless crystals: yield 1.77 g (59.4%), m.p. 200°-202° C.