Patent ID: 6083403
Filing Date: 2000-07-04
Classification: C02F

Abstract:
A method for preventing scale formation on metal surfaces in contact with scale-forming industrial water within an industrial system which comprises the step of treating said water with an effective scale-inhibiting amount of a water-soluble calcium tolerated and biocide stable 1,1-diphosphonic acid N-oxide selected from the group consisting of:compounds of formula (I) ##STR11## wherein R.sup.1 and R.sup.2 are selected from the group consisting of: straight chained alkyl groups, branched alkyl groups, alcohols, ethers, thioethers, amines, esters, amides and carboxylic acids, R.sup.3 is selected from the group consisting of hydrogen and C.sub.1 -C.sub.6 alkyl groups, and M is selected from the group consisting of hydrogen, alkaline metal ions, alkaline earth metal ions, ammonium salts, zinc salts and aluminum salts,compounds of formula (II): ##STR12## wherein circle A represents a nitrogen-containing heterocycle, R.sub.3 is selected from the group consisting of: hydrogen and C.sub.1 -C.sub.6 alkyl groups, and M is selected from the group consisting of hydrogen, alkaline metal ions, alkaline earth metal ions, ammonium salts, zinc salts and aluminum salts,compounds of formula (III): ##STR13## wherein n is an integer of from 1 to about 8, R.sup.4 and R.sup.5 are C.sub.1 -C.sub.6 alkyl groups, and M is selected from the group consisting of hydrogen, alkaline metal ions, alkaline earth metal ions, ammonium salts, zinc salts and aluminum salts,and compounds of formula (IV): ##STR14## wherein n is an integer of from about 1 to about 8, R.sup.3 is selected from the group consisting of: hydrogen and C.sub.1 -C.sub.6 alkyl groups, R.sup.4 is a C.sub.1 -C.sub.6 alkyl group and M is selected from the group consisting of hydrogen, alkaline metal ions, alkaline earth metal ions, ammonium salts, zinc salts and aluminum salts.