TDM

In the process of manufacturing latex such as styrene-butadiene, a chain transfer agent is required. The chain transfer agent assists in the polymerization to make products of the desired molecular distribution. Previously, chlorinated compounds such as carbon tetrachloride and chloroform have been used for this application, but because of their toxicity and negative environmental effects, it is no longer a practice to employ said compounds for the manufacturing of latex used for the carpet and paper industries. Instead, use of tertiary dodecyl mercaptan (TDM) is preferred for the applications described. As a result of the world demand for latex and the magnitude of the associated industries, TDM has become a chemical of industrial significance. From a manufacturing standpoint, TDM is a mixture of isomeric thiols produced from oligomers of propylene tetramer or sometimes, isobutylene trimer. Propylene tetramer is produced by oligomerization of propylene in the presence of a Friedel Crafts type catalyst such as sulfuric acid. TDM is produced by passing hydrogen sulfide and either propylene tetramer or isobutylene trimer over a catalyst such as boron trifluoride (1, 2). Because of the fact that there are many permutations of the tetramer structure, and hence the location of the –C=C– bond, the thiol group can be located in many different positions, resulting in a product mixture of isomers with an average boiling point range around 230°C.