GB601816A - Process for making an alkali metal salt of an amino carboxylic acid - Google Patents

Abstract

Amino carboxylic acid salts are prepared by heating a primary, secondary or tertiary amino alcohol containing one or more primary alcohol groups with an aqueous solution of an alkali metal hydroxide completely miscible therewith, at an elevated temperature at which hydrogen is liberated from the reaction mixture, but below that at which substantial decomposition of the product takes place, the alkali metal hydroxide solution having a weight concentration of not less than about 85 per cent metal hydroxide in the case of primary and secondary amino alcohols and not less than about 35 per cent in the case of tertiary amino alcohols. The reaction temperature is normally not exceeding 285 DEG C. and reaction may be effected under pressure. The compounds treated include mono- and poly-amino mono- and polyhydric alcohols which may contain alkyl, aryl or aralkyl groups. In examples: (1) monoethanolamine is heated with excess 85 per cent caustic potash yielding a mixture of potassium glycine and potassium oxalate; (2) tetraethanol ethylene diamine is heated with excess of 85 per cent caustic potash or 95 per cent or 35 per cent caustic soda to yield the corresponding salt of tetracarboxy-methyl ethylene diamine; (3) triethanolamine and about 85 per cent caustic potash are heated yielding tripotassium carboxy-methylamine. The free acids are obtained by acidifying the salts. Other compounds which may be prepared similarly are tetracarboxymethyl propylene diamine from tetraethanol propylene diamine, pentacarboxymethyl diethylene triamine from pentaethanol diethylene triamine, hexacarboxymethyl triethylene tetramine from hexaethanol triethylene tetramine, dicarboxymethylamine from diethanolamine and isopropyl- and butyl-dicarboxymethylamines from the corresponding isopropyl- and butyl-diethanolamines. Specification 601,817 is referred to.