GB806146A - Improvements in or relating to l-glutamine synthesis - Google Patents

Abstract

L-glutamine is produced by preparing a solution of the gamma-amide of an N-carboallyloxy-L-glutamic acid (the term "allyloxy" denoting the unsubstituted or 2-alkyl or 2-phenyl-substituted allyloxy group), in a solvent mixture in which the L-glutamine is insoluble and in which hydrogen halide behaves as a weak electrolyte, the mixture comprising an aliphatic carboxylic acid having less than 8 carbon atoms in the molecule and a non-acidic organic solvent which is inert with respect to hydrogen halide and preferably to ammonia, reacting the solution under anhydrous conditions with hydrogen chloride or bromide, adding an alcohol to the reaction mixture in an amount sufficient to dissolve precipitated solids, neutralizing the reaction mixture and crystallizing L-glutamine therefrom. The carboxylic acid may be formic, acetic, propionic or n- or isobutyric acid and the second solvent may be, for example, methyl, ethyl, propyl or n- or iso-butyl acetate, methyl or ethyl propionate, chloroform or dioxane. The starting material, which may be used in the form of its ammonium salt, may be prepared from L-glutamic acid by the method given in Specification 789,328. In a typical example, the gamma amide of N-carboallyloxy-L-glutamic acid and its NH4 salt, obtained as indicated above, is dissolved in a mixture of acetic acid and ethyl acetate; HBr gas is passed into the solution with cooling to 30 DEG C.; methanol is added to dissolve precipitated solids, the pH of the solution is adjusted to about 7.5 with diethylamine or ammonia and the solution is then cooled to crystallize out the resulting L-glutamine. Specification 752,889 also is referred to.