Thio(cyclo)alkanepolycarboxylic acids containing heterocyclic substituents

Claim 1

A process for inhibiting corrosion in an aqueous system in contact with a metal which formula I adding to said aqueous system an effective inhibiting amount of at least one compound of comprises ##STR21## in which each R independently of the others is H, C 1 -C 12 -alkyl, C 1 -C 12 -alkoxy, C 1 -C 4 -halogenoalkyl, C 1 -C 12 -alkylthio, C 1 -C 12 -alkylsulfonyl, phenyl, C 1 -C 16 -alkylphenyl, C 7 -C 16 -phenylalkyl, C 5 -C 8 -cycloalkyl, halogen, --NO 2 , --CN, --COOH, --COO(C 1 -C 4 -alkyl), --OH or a primary, secondary or tertiary amino or carbamoyl group having up to 20 C atoms, X is --O--, --S-- or --NH--, n is zero or 1, and, if n is 1, R 1 , R 2 , R 3 and R 4 independently of one another are H, C 1 -C 18 -alkyl, C 1 -C 4 -hydroxyalkyl, C 2 -C 12 -carboxyalkyl, C 1 -C 4 -halogenoalkyl, C 2 -C 10 -alkoxyalkyl, --COOH or aryl or aralkyl having 6-10 C atoms which is unsubstituted or substituted by C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, --NO 2 , --COOH, --OH or halogen, or R 1 and R 2 or R 1 and R 3 together are linear or branched C 3 -C 8 -alkylene which can be substituted by 1 or 2 carboxyl groups, or R 1 and R 2 together are a direct bond, and, if n is 0, R 2 and R 4 are carboxyl, subject to the proviso that the group ##STR22## contains at least two and not more than four carboxyl groups and that, in the event that X is NH and three of the radicals R are hydrogen, the group --C(R 1 )(R 3 )--CH(R 2 )(R 4 ) is not a 1,2 dicarboxyethyl group, and a base addition salt of this compound.