Ciba-Geigy Corporation

Michael P Savage

Robert L Bentley

Kenneth W Shelton

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.

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Heald Green, United Kingdom

Michael P Savage