Process of producing alkali metal salts of lower alkylene- and hydroxalkylene-diamino or polyamino polyacetic acids

摘要

Alkali metal salts of alkylene- or hydroxyalkylene-diamino or polyamino polyacetic acids, in which the alkylene group contains up to 6 carbon atoms, are prepared by forming an aqueous solution containing from 50% to 80% by weight of water, and a C1-6 alkylene- or hydroxyalkylene polyamine and an alkali metal hydroxide in the mol. ratio of 1,0:4,1 to 5,1, adding thereto a selected amount of HCN and a lesser amount of formaldehyde, said amounts being in the mol. ratios to said polyamine of 1:4,05 to 5,05 and 1:4,0 to 5,0, respectively, the HCN being present in excess over the formaldehyde by at least 0,05 mol. per mol. of said polyamines, at least 30% of said HCN being initially added, then simultaneously adding formaldehyde and additional HCN at such rates that an excess of cyanide over formaldehyde is maintained, then adding the remaining formaldehyde, supplying to the reacting mixture throughout the operation sufficient heat to obtain active evolution of water vapour, continuing to supply heat for sufficient time to allow the reaction to be substantially completed and to produce a terminal total solids content of from 35 to 60%, and collecting and cooling the resultant solution. Specified amine starting materials are ethylene and propylene diamine, diethylenetriamine and N-aminoethylethanolamine.