Abstract: 3-R.sup.1 -3-oxoprop-1-ene-1,1-diphosphonic acids corresponding to the following general formula ##STR1## in which R.sup.1 is a tertiary substituted alkyl group, an optionally substituted cycloalkyl group, or an optionally substituted aryl or heteroaryl group, andM is hydrogen or the cation of a base;to a process for their production in which 3-R.sup.1 -3-oxo-1-aminopropane-1,1-diphosphonic acids corresponding to the following general formula ##STR2## in which R.sup.1 is as defined above, are reacted with an aqueous or alcoholic alkali metal hydroxide solution; then water followed by an alcohol infinitely miscible with water is added to the reaction mixture, and the pure olefinic diphosphonic acids are obtained by addition of an acid; to the use of the above compounds of formula III as complexing agents and as thresholders; and to compositions containing one or more compounds of formula (III).

Abstract: Hydroxyacetonitrile diphosphonic acid corresponding to the following general formula ##STR1## in which M represents H or a cation of a base, and salts thereof; to a process for their preparation comprising reacting 3-R.sup.1 -3-oxo-1-aminopropane-1,1-diphosphonic acids corresponding to the following general formula ##STR2## in which R.sup.1 is a tertiary substituted alkyl group, an optionally substituted cycloalkyl group or an optionally substituted aryl or heteroaryl radical, with nitrous acid, the secondary product R.sup.1 -COOH and unreacted starting material are separated off from the reaction mixture and the hydroxyacetonitrile diphosphonic acid is obtained in the form of a salt by addition of a base; and to the use of the above compounds as complexing agents and as thresholders.

Abstract: Oxa-alkane polyphosphonic acids corresponding to general formula (I) ##STR1## in which R.sup.1 is a C.sub.1 -C.sub.10 alkyl group, an optionally substituted C.sub.6 -C.sub.10 aryl group, a phenyl- or naphthylalkyl group, a group having the general formula ##STR2## or a group having the general formula ##STR3## R.sup.2 represents H or methyl, A represents the structural unit ##STR4## where n is an integer of from 1 to 20 and M represents H or the cation of a base, to the use of the above compounds as complexing agents and as thresholders, and to compositions containing one or more compounds of general formula (I).

Abstract: 3-R.sup.1 -3-oxoprop-1-ene-1,1-diphosphonic acids corresponding to the following general formula ##STR1## in which R.sup.1 is a tertiary substituted alkyl group, an optionally substituted cycloalkyl group, or an optionally substituted aryl or heteroaryl group, andM is hydrogen or the cation of a base;to a process for their production in which 3-R.sup.1 -3-oxo-1-aminopropane-1,1-diphosphonic acids corresponding to the following general formula ##STR2## in which R.sup.1 is as defined above, are reacted with an aqueous or alcoholic alkali metal hydroxide solution; then water followed by an alcohol infinitely miscible with water is added to the reaction mixture, and the pure olefinic diphosphonic acids are obtained by addition of an acid; to the use of the above compounds of formula III as complexing agents and as thresholders; and to compositions containing one or more compounds of formula (III).

Abstract: A reaction medium of ethanol condensed with 1-20, most preferably 4-6 moles, of ethylene or propylene oxide per mole of ethanol greatly improves the practicality of the preparation of azacycloalkane-2,2-diphosphonic acids of the general formula I: ##STR1## where R means a hydrogen or a lower alkyl radical with from 1 to 3 carbon atoms, and n means an integer between 3 and 11, by phosphonylating the corresponding lactams with phosphonic acid and phosphorous trihalides in the presence of water.

Abstract: 3-Alkyl-3-oxo-1-aminopropane-1,1-diphosphonic acids and water-soluble salts thereof corresponding to the formula ##STR1## in which R.sup.1 represents an unbranched or branched C.sub.1 -C.sub.8 alkyl group, R.sup.2 and R.sup.3 independently of one another represent methyl or ethyl, and each M represents H or a cation of a water-soluble base, to a process for producing these compounds wherein oxonitriles corresponding to the formula: ##STR2## in which R.sup.1, R.sup.2 and R.sup.3 are as defined above, are reacted with mixtures of a phosphorus trihalide PX.sub.3, where X represents fluorine, chlorine or bromine, with phosphorous acid, the reaction mixture is hydrolyzed, and the reaction products are optionally converted into water-soluble salts; and to the use of the resulting compounds corresponding to general formula (III).

Abstract: 4-Dimethylamino-1-hydroxybutane-1,1-diphosphonic acid and water-soluble salts thereof, methods for their preparation, and uses thereof as complexing agents.