Ethanol → Ethyl 5-oxo-L-prolinate

Participants

Reaction Conditions

Reaction Steps

Thionyl chloride (217 ml) is slowly added to a stirred suspension of L-glutamic acid (417 g) in dry ethanol (1 L), and the mixture is refluxed for 5 hours. Ethanol is removed under vaccum to give a residue, which is dissolved in water (500 ml). The water solution is made alkaline with saturated sodium carbonate solution and extracted with chloroform (4×200 ml). The chloroform extract is dried (Na2SO4) and evaporated to give crude product (178 g). This material is heated (160° C.) under vaccum (10 mm Hg) for 3 hours. Subsequent distillation gives pure ethyl L-pyroglutamate (126.6 g; b.p. 126° C./0.07 mm Hg; [α]D =-2.15°±0.01 (H2O, c=17.8).

Provenance & Evidence