Anionic Oligomerization of Methyl Methacrylate by Alkali Metal Alkoxides

Abstract

The kinetics of the oligomerization of methyl methacrylate (MMA) by methoxide/methanol solutions was studied using gas chromatography techniques. The effects of the type of the alkali metal, [CH OH]/[monomer] ratio, solvent, and initiator concentration were investigated. The rate of conversion using different alkali metal alkoxides was in the order CH₃OLi < CH₃ONa < CH₃OK, but no oligomers higher than the addition product, RO—MMA (n=1), could be obtained by CH₃OLL DP_n decreased with increasing the [CH₃OH]/[monomer] ratio and with lowering of the initiator concentration. Using DMSO as solvent increased the yields of the higher oligomers. The formation of n=1 was reversible, contrary to the formation of the higher oligomers. Some of the rate constants of the various steps of the oligomerization were estimated by taking into account the reversibility of the initiation reaction and assuming steady-state conditions in the concentration of the various anions present in the system.