L:glutamic acid gamma ethyl ester prepn. - from L:glutamic acid by mono:sodium salt formation and ethyl iodide treatment

摘要

The gamma ethyl ester of L-glutamic acid (I) suitable for pharmaceutical use, is prepared by dissolution of L-glutamic acid (II) in ethanol, treatment with sodium methylate to form the monosodium salt with the gamma carboxylic group, treatment with ethyl iodide, and purification by suspension in aqueous ethanol. The above process gives a product suitable for oral administration. For intravenous administration the product is recrystallised from aqueous ethanol under sterile conditions. The solution is kept at 20-50 deg.C, pref. 35-40 deg. C, prior to addition of ethyl iodide. When recrystallisation of the produce is carried out, the aqueous ethanol solvent is pref. 40-80% ethanol, esp. 65% ethanol. This process gives a product that is free from the diethyl ester and the free acid (I).