L-Phenylalanine, methyl ester → L-Phenylalanine, L-alpha-aspartyl-, 2-methyl ester, hydrochloride (1:1)

Participants

Reaction Conditions

Reaction Steps

150 Grams of N-chloroacetyl-L-aspartic acid anhydride are quickly added, at -5° C., to the solution of 140 grams of methyl L-phenylalaninate in 400 ml of dichloroethane plus 200 ml of acetic acid. The mixture is stirred for 1 hour at -5° C.; the temperature is then raised, in 2 hours, to 15° C., then, in 30 minutes, to 40° C. The dichloroethane is evaporated under vacuum; 500 ml of methanol and 60 grams of thiourea are added and the mixture is refluxed for 3 hours. After cooling to 20° C., 200 ml of methanol, containing 11% (by weight) of HCl, are added, the solution is cooled to 0° C. for 1 hour, filtered and evaporated to dryness in vacuo. The residue is crystallized from 600 ml of water containing 70 g of NaCl: a very pure aspartame hydrochloride is obtained, in a 48% yield.

Provenance & Evidence