Preparation and polymerization of dimethylamino(methyl)styrenes

Abstract

AbstractThree isomers of methylstyrene derivatives with a dimethylamino group in ortho position to the methyl group were prepared through the coupling reaction of the corresponding Grignard reagent and vinyl bromide using a Pd(0) catalyst, and their radical and anionic polymerization was examined. Monomer reactivity ratios in the radical copolymerization with styrene indicate that 3‐dimethylamino‐4‐methylstyrene (3‐DMA‐4‐MS) and 4‐dimethylamino‐3‐methylstyrene (4‐DMA‐3‐MS) have a higher reactivity than styrene, while the reactivity of 3‐dimethyl‐amino‐2‐methylstyrene (3‐DMA‐2‐MS) is lower than that of styrene. The 13C NMR chemical shift of vinyl carbons as well as the e‐values indicate that the electron density at the vinyl carbons of 3‐DMA‐4‐MS and 4‐DMA‐3‐MS is increased by the electron donating effect of the dimethylamino group, which results in lower reactivity of the monomers in anionic polymerization. The anionic copolymerization with 1,1‐diphenylethylene gave an alternating copolymer. In the anionic polymerization of 3‐DMA‐2‐MS, proton transfer reaction from the methyl group to the propagating chain end occurred to some extent to incorporate o‐phenylene units in the chain.