Verfahren zur Herstellung von Alkalisalzen der Nitrilotriessigsäure

1,268,655. Alkali metal salts of nitrilotriacetic acid. BADISCHE ANILIN- & SODA-FABRIK A.G. 15 Aug., 1969 [17 Aug., 1968], No. 40917/69. Addition to 1,224,043. Heading C2C. Alkali metal salts of nitrilotriacetic acid are prepared by a two stage process, without continuous flow of reaction mixture through the process, in the first stage of which an alkali metal cyanide is reacted with formaldehyde in a stoichiometric ratio at a temperature of from 50 to 200‹ C. and a pressure of from 2 to 50 atmospheres gauge in the presence of excess ammonia to give a solution containing aminoacetate as the principal organic acid anion, decompressing the resultant solution to atmospheric pressure and treating it in one or more further stages with further alkali metal cyanide and formaldehyde at a temperature of from 60‹ to 110‹ C. whilst simultaneously removing ammonia to convert the aminoacetic acid into nitrilotriacetic acid. The different stages are preferably effected in separate vessels and the final product may be recovered from the aqueous solution by evaporation or spray drying.