Ciba-geigy Corporation

Kenneth W Shelton

Robert L Bentley

Michael P Savage

Michael A Finan

Colin D Campbell

Compounds of the formula ##STR1## in which X is --S--, --O-- or --NH--, R is H or a monovalent substituent, n is 0 or 1 and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are H, alkyl, alkyl which is substituted by OH, halogen, COOH or alkoxy, unsubstituted or substituted aryl or aralkyl, or carboxyl, or R.sup.1 and R.sup.2 or R.sup.1 and R.sup.3 together are alkylene or R.sup.1 and R.sup.2 are a direct bond, at least two of the groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4 being carboxyl or carboxyalkyl groups, and base addition salts thereof are effective corrosion inhibitors. The preparation of these novel polycarboxylic acids can be effected by various processes.

Thio(cyclo) alkanepolycarboxylic acids containing heterocyclic

Compounds of the formula I ##STR1## in which X is --S--, --O-- or --NH--, R is H or a monovalent substituent, n is 0 or 1 and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are H, alkyl, alkyl which is substituted by OH, halogen, COOH or alkoxy, unsubstituted or substituted aryl or aralkyl, or carboxyl, or R.sup.1 and R.sup.2 or R.sup.1 and R.sup.3 together are alkylene or R.sup.1 and R.sup.2 are a direct bond, at least two of the groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4 being carboxyl or carboxyalkyl groups, and base addition salts thereof are effective corrosion inhibitors. The preparation of these novel polycarboxylic acids can be effected by various processes.

Thio(cyclo)alkanepolycarboxylic acids containing heterocyclic

Oxo-polycarboxylic acids act as set control agents, preferably as set retarders for plasters. Examples of usable acids are 2,2,6,6-tetra(.beta.-carboxyethyl)cyclohexanone, 2,2-di(.beta.-carboxyethyl)-3,5,5-trimethylcyclohexanone or 3-acetyl-3(.beta.-carboxyethyl)-pimelic acid. Also the salts of these acids are usable. The set control agents are added to the plaster in amounts of 5 to 5000 ppm.

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Kenneth W Shelton