Hydrochloric Acid → N-Acetyl-L-phenylalanine

Participants

Reaction Steps

In 100-ml tightly-sealed glass vessel were charged 9.36 g of 2-methyl-4-benzylidene-5-oxazolone and 40 ml of water. 4.15 g of potasium carbonate was then added thereto and the resulting mixture was stirred at 40°-45° C. for two hours. Concentrated hydrochloric acid was added to the resulting solution to adjust its pH at 6.8 and 0.2 g of 5%-palladium-carbon was added thereto. The gas phase in the vessel was purged with nitrogen and then with hydrogen, and thereafter the reaction mixture in the vessel was subjected to catalytic reduction at 40°-45° C. under atmospheric pressure. The reaction time during which hydrogen absorption was completed was 100 minutes. It was observed that one mole of hydrogen was absorbed to one mole of 2-methyl-4-benzylidene-5-oxazolone during this period. After the gas phase in the vessel was purged with nitrogen upon completion of the reaction, the catalyst was filtered and washed with a small amount of water. The filtrate and the washings were combined, to which concentrated hydrochloric acid was added at a temperature lower than 30° C. to adjust pH of the resulting mixture at 1. The mixture was cooled to 0°-5° C. The crystal was filtered, washed with a cold water and dried to obtain 9.81 g of N-acetylphenylalanine having a melting point 150°-151° C. as a white crystal. Its yield was 94.7%.

Provenance & Evidence