Patent ID: 6278020
Filing Date: 2001-08-21
Classification: C07C

Abstract:
A process for the preparation of amino acid derivatives in free acid or salt form, in which the nitrogen atoms of two or more amino acid molecules are linked by a hydrocarbyl or substituted hydrocarbyl group, which process includes a reaction step comprising reacting, in an aqueous medium at a pH in the range 7-14, a compound of the formula X--A--Y where X and Y are halo atoms which may be the same or different and A is a hydrocarbyl or substituted hydrocarbyl group, in which X and Y are attached to aliphatic or cycloaliphatic carbon atoms, with an amino acid (or salt thereof); wherein the process includes the step of recovering unreacted amino acid by acidification of the reaction mixture so that the desired product crystallises out, separating the crystallised product from the mother liquor with alkali, passing it through a nanofiltration membrane and acidifying the retentate and recycling the unreacted amino acid to the reaction step.