| abstract |
Bis(aminoalkyl)piperazine derivatives of the formula:n wherein n is 2 or 3 and wherein substituents A, B, X and Y each are independently selected from hydrogen, hydroxyalkyl (wherein the alkyl group contains 2-6 carbon atoms), methylenephosphonic, methylene-, ethylene- and propylene-sulfonic, hydroxymethyl, hydroxyethyl- and hydroxypropyl-sulfonic acid radicals, carboxylic acid radicals (having 2-4 carbon atoms) and the alkali or alkaline earth metal, ammonium and amine salts of any of the phosphonic, sulfonic or carboxylic acid derivatives, and wherein at least one of A, B, X and Y is other than a hydrogen, are sequestering and/or chelating agents. Those derivatives containing at least one methylenephosphonic acid radical or a salt thereof are threshold agents to prevent metal ion precipitation in aqueous solutions and also are cement set retarding additives. |