Rhodium‐catalyzed emulsion polymerization of butadiene

Abstract

AbstractRecent work has shown that rhodium salts in aqueous solution are capable of polymerizing butadiene to a high trans‐1,4 polymer, especially in the presence of certain surfactants of the sulfate or sulfonate types, which act as ligands for the rhodium. It has now been confirmed that the effective surfactants are of two types: sodium lauryl sulfate and the sodium alkyl benzene sulfonates having alkyl chains greater than C5. Studies of these systems have also been conducted in homogeneous solution, in an attempt to elucidate the mechanism. For this purpose, solvents such as tetrahydrofuran, dimethoxyethane, and the dimethyl ester of ethylene glycol were found to be effective. However, the polymerization rate was much slower than in the heterogeneous aqueous systems and also appeared to be independent of the presence of the surfactant. This phenomenon was apparently due to the fact that these solvents also act as ligands for the rhodium, thus giving rise to catalyst complexes which are less effective in polymerization.