Kinetics and mechanism of triphenylstibonium-ylide-initiated terpolymerization of styrene, methyl acrylate and acrylonitrile

Abstract

Terpolymerization of styrene, methyl acrylate and acrylonitrile in 1,4-dioxane flushed with nitrogen, initiated by the ylide 1,2,3,4-tetraphenylcyclopentadiene-triphenylstibonium, was carried out for 1 h at 60 ± 0.2°C. The kinetic expression is R p α [I]0.27 [Sty]0.86 [MA]0.91 [AN]0.88. It indicates non-ideal radical kinetics due to primary radical termination, as well as degradative chain-transfer reactions. The overall activation energy, calculated from the slope of the Arrhenius plot, is 47 kJ/mol. The values of reactivity ratios, calculated using the Kelen–Tüdos method, are 0.25 ± 0.05 and 0.22 ± 0.05 for r 1 (Sty) and r 2 (MA + AN) respectively. The NMR spectrum shows a singlet at 7.1δ for the phenyl group in styrene and three distinct peaks at 2.1δ, 2.5δ and (3.4–3.8)δ for the methoxy group in methyl acrylate. The reaction was retarded by hydroquinone, which confirms the radical mode of terpolymerization. The possible mechanism for the synthesis of terpolymer has been elucidated.