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.