Methanol → Methyl DL-prolinate hydrochloride

Participants

Reaction Conditions

Reaction Steps

600 ml of technical-grade methanol are introduced into a multinecked flask equipped with dropping funnel and internal thermometer, with ice/sodium chloride cooling. 2.4 mol of thionyl chloride are added dropwise in such a way that the temperature of the reaction solution does not exceed -5° C. Then, 2.18 mol of proline are added in portions in the course of approximately 10 minutes. The mixture is stirred for approximately 4 hours at 40° C. and subsequently for three days at room temperature, and the solution is greatly concentrated, the residue is taken up several times in methanol to remove excess thionyl chloride, and the mixture is reconcentrated. After drying the product for several hours in a lukewarm water bath in an evacuated flask, the target compound is obtained in quantitative yield. Some of the oily crude product crystallises after being left to stand over several days.

Provenance & Evidence