Silyl enol ethers as monomer. I. Radical copolymerizability of α‐trimethylsilyloxystyrene

Abstract

Abstractα‐Trimethylsilyloxystyrene (TMSST), the silyl enol ether of acetophenone, was not homopolymerized either by a radical or a cationic initiator. Radical copolymerization of TMSST with styrene (ST) and acrylonitrile (AN) in bulk and the terpolymerization of TMSST, ST, and maleic anhydride (MA) in dioxane were studied at 60°C and the polymerization parameters of TMSST were estimated. The rate of copolymerization decreased with increased amounts of TMSST for both systems. Monomer reactivity ratios were found as follows: r1 = 1.48 and r2 = 0 for the ST (M1)–TMSST (M2) system and r1 = 0.050 and r2 = 0 for the AN (M1)–TMSST (M2) system. The terpolymerization of ST (M1), TMSST (M2), and MA (M3) gave a terpolymer containing ca. 50 mol % of MA units with a varying ratio of TMSST to ST units and the ratio of rate constants of propagation, k32/k31, was found to be 0.39. Q and e values of TMSST were determined using the values shown above to be 0.88 and −1.13, respectively. Attempted desilylation by an acid catalyst for the copolymer of TMSST with ST afforded polystyrene partially substituted with hydroxyl groups at the α‐position.