A method of treating an aqueous system to inhibit the corrosion of metals in contact therewith and/or inhibit the deposition of scale therefrom comprising adding to the aqueous system a minor proportion of a compound of the formula: ##STR1## wherein n is 0 or 1 and when n is O, R.sub.3 and R.sub.4 are the same or different and each is hydrogen, an alkyl group having from 1 to 4 carbon atoms, a benzyl, allyl, --CH.sub.2 PO.sub.3 H.sub.2 -- or --CHCOOH.CH.sub.2 COOH group or a group of formula ##STR2## wherein R.sub.5 is hydrogen, a methyl, --CH.sub.2 COOH or --CH.sub.2 CH.sub.2 COOH group and Z is a group --COOH or --PO.sub.3 H.sub.2, with the proviso that when Z is a PO.sub.3 H.sub.2 group then R.sub.5 is hydrogen or methyl, and when n is 1, R.sub.1 and R.sub.2 are the same or different and each is hydrogen, or a methyl or phenyl residue and R.sub.3 is hydrogen and R.sub.4 is hydrogen, an alkyl group having from 1 to 4 carbon atoms or a --CH.sub.2 CH.sub.2 COOH group, or R.sub.3 and R.sub.4 together may form a methylene group .dbd.CH.sub.2.
A compound or mixture of compounds of the general formula: ##STR1## in which m and n may be 0 or 1 but both cannot be 1, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently H or CH.sub.3, X.sup.1, X.sup.2, Z.sup.1 and Z.sup.2 are independently hydrogen or straight or branched chain C.sub.1 -C.sub.4 alkyl; and the water-soluble inorganic or organic salts thereof, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 must be CH.sub.3, and when m and n are both 0, R.sup.2 and R.sup.3 are each methyl and R.sup.4 and R.sup.5 have their previous significance, when added to an aqueous system imparts one or more of the following beneficial effects to be treated system: (a) the corrosion of ferrous metals in contact with the system is inhibited; (b) the precipitation of scale-forming salts of calcium, magnesium, barium and strontium from the treated aqueous system is inhibited; and (c) inorganic materials present in the treated aqueous system are dispersed.
A cavitation-inhibiting, nonfreezing, cooling and/or heat-transfer liquid comprises a glycol and a cavitation-inhibiting effective amount of at least one phosphonocarboxylic acid of the formula ##STR1## wherein R is H or C.sub.1-6 alkyl, the latter optionally substituted by carboxy, R.sub.1 is H or C.sub.1-3 alkyl, the latter optionally substituted by carboxy, X is C.sub.1-3 alkylene optionally substituted by COOH or PO.sub.3 H.sub.2 groups, and n is 0 or 1.
A compound or mixture of compounds of the general formula: ##STR1## in which m and n may be 0 or 1 but both cannot be 1, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently H or CH.sub.3, X.sup.1, X.sup.2, Z.sup.1 and Z.sup.2 are independently hydrogen or straight or branched chain C.sub.1 -C.sub.4 alkyl; and the water-soluble inorganic or organic salts thereof, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 must be CH.sub.3, and when m and n are both 0, R.sup.2 and R.sup.3 are each methyl and R.sup.4 and R.sup.5 have their previous significance, when added to an aqueous system imparts one or more of the following beneficial effects to be treated system: (a) the corrosion of ferrous metals in contact with the system is inhibited; (b) the precipitation of scale-forming salts of calcium, magnesium, barium and strontium from the treated aqueous system is inhibited; and, (c) inorganic materials present in the treated aqueous system are dispersed.
Process for conditioning metal surfaces to inhibit their corrosion and/or to inhibit scale deposition thereon by treating said surfaces: (A) prior to contact with a corrosive or scaling environment, with 2-hydroxy-phosphonoacetic acid or a metal salt thereof and optionally with a metal ion component (b) as hereinafter defined (B) during contact with an aqueous system capable of corroding said metal surfaces or depositing scale thereon, with a combination of: (a) 2-hydroxy-phosphonacetic acid or a water-soluble salt thereof; and (b) a metal ion which enhances, synergistically, the metal conditioning effected, individually, by 2-hydroxy-phosphonoacetic acid and the metal ion.
A method of inhibiting the corrosion of aluminum in contact with an alkaline solution comprising adding 2-phosphono-butane-1,2,4-tricarboxylic acid or a water-soluble salt thereof as inhibitor to the alkaline solution.
