Organotin mercapto dicarboxylic acid esters and compositions

A mixture of organotin mercapto dicarboxylic acid esters useful as a stabilizer for improving the resistance to deterioration of polyvinyl chloride resins when heated at 350.degree. F, and having at least one tin atom to which organic groups are linked only through carbon and sulfur, having linked to tin through sulfur at least one mercapto dicarboxylic acid ester group, each of the organotin mercapto dicarboxylic acid esters having per tin atom one or two alkyl, cycloalkyl or alkylcycloalkyl groups attached to tin through carbon;

• the alkyl having from 1 to about 12 carbon atoms, the cycloalkyl having from 3 to about 12 carbon atoms, and the alkyl cycloalkyl having from 4 to about 12 carbon atoms;
• and two or three mercapto dicarboxylic acid ester groups attached to tin through sulfur, the mercapto dicarboxylic acid having from about 4 to about 24 carbon atoms, and having at least one esterifying group selected from the group consisting of alkyl, cycloalkyl, and alkylcycloalkyl, the alkyl having from 1 to about 12 carbon atoms, the cycloalkyl having from 3 to about 12 carbon atoms, and the alkyl cycloalkyl having from 4 to about 12 carbon atoms, and at least one esterifying group selected from the group consisting of bivalent alkylene, cycloalkylene and alkylenecycloalkylene, the alkylene having from about 2 to about 12 carbon atoms, the cycloalkylene having from 3 to about 12 carbon atoms, and the alkylenecycloalkylene having from 4 to about 12 carbon atoms, each of the two valences of the bivalent alkylene, cycloalkylene and alkylcycloalkylene being linked to groups selected from the group consisting of one hydroxyl and one carboxylic group of mercapto dicarboxylic acid;
• and two carboxylic acid groups of mercapto dicarboxylic acid, one of said organotin mercapto dicarboxylic acid esters having per tin atom one alkyl group linked to tin and three mercapto dicarboxylic acid ester groups esterified with alkyl and alkylene groups;
• and one of said organotin mercapto dicarboxylic acid esters having per tin atom two alkyl groups linked to tin, and two mercapto dicarboxylic acid ester groups esterified with alkyl and alkylene groups.

An organotin mercapto dicarboxylic acid mixed monohydric and polyhydric alcohol ester having per tin atom one or two alkyl, cycloalkyl, or alkylcycloalkyl groups attached to tin through carbon, and two or three thiodicarboxylic acid ester groups attached to tin through sulfur, and having the formula:

• ##STR26## wherein m.sub.1 and m.sub.3 are numbers within the range from 0 to about 7;
• m.sub.2 is a number within the range from 1 to about 7;
• n is 1 or 2;
• R is selected from the group consisting of alkyl, cycloalkyl, and alkycycloalkyl, the alkyl having from one to about twelve carbon atoms, the cycloalkyl having from 3 to about 12 carbon atoms, and the alkylcycloalkyl having from 4 to about 12 carbon atoms linked to tin through carbon;
• and
• at least one of Z.sub.1 and Z.sub.2 is selected from the group consisting of alkyl, cycloalkyl, and alkylcycloalkyl, the alkyl having from 1 to about 12 carbon atoms, the cycloalkyl having from 3 to about 12 carbon atoms, and the alkylcycloalkyl having from 4 to about 12 carbon atoms;
• and at least one of Z.sub.1 and Z.sub.2 is selected from the group consisting of
• i. bivalent alkylene, cycloalkylene and alkylenecycloalkylene taken together with the other of Z.sub.1 and Z.sub.2 of the organotin mercapto dicarboxylic acid ester;
• the alkylene having from about 2 to about 12 carbon atoms, the cycloalkylene having from 3 to about 12 carbon atoms, and the alkylenecycloalkylene having from 4 to about 12 carbon atoms;
• ii. hydroxyalkyl, hydroxycycloalkyl and hydroxyalkylcycloalkyl having from 2 to about 12 carbon atoms;
• the alkyl having from 1 to about 12 carbon atoms, the cycloalkyl having from 3 to about 12 carbon atoms, and the alkylcycloalkyl having from 4 to about 12 carbon atoms linked to tin through carbon;
• and
• iii. bivalent alkylene, cycloalkylene and alkylenecycloalkylene having from about 2 to about 12 carbon atoms and linked to a carboxylic acid ester group of a second organotin mercapto dicarboxylic acid ester;
• the alkylene having from about 2 to about 12 carbon atoms, the cycloalkylene having from 3 to about 12 carbon atoms, and the alkylenecycloalkylene having from 4 to about 12 carbon atoms.