Synthesis of Poly(keto sulfoxide) by the Reaction of Poly(methyl methacrylate) with Sodium Methylsulfinylmethanide

Abstract

The synthesis of poly(keto sulfoxide)s by the reaction of polymers containing ester groups, poly(methyl methacrylate) (PMMA) and MMA-styrene copolymer (MSC), with sodium methylsulfinylmethanide (CH₃SOCH₂Na) in dimethyl sulfoxide and the subsequent acidification was investigated. The structure of the resulting poly(keto sulfoxide)s was determined by infrared and 'H-nuclear magnetic resonance spectroscopies and elemental analyses.
The reaction with PMMA was carried out at a molar ratio of CH, SOCH, Na/COOCH3 group =2.3 and 4.1 at 25 and 40°C. The resulting poly(keto sulfoxide)s contained β-keto sulfoxide sidceh a(-CO-CO-CHSOCH₃) [3] as well as β, β'-diketo sulfoxide side chains(-CO-CO-CHSOCH₃) [4]. The latter groups resulted from an attack of the a-keto-a-sulfinylmethanide anion to neighboring ester groups. Poly (keto sulfoxide) with a composition of [3]/[4] =2.0, containing no ester groups, was obtained by the reaction at 40°C for 18 h at a molar ratio of CH₃SOCH₂Na/COOCH₃ group =4.1. The results obtained in the present study showed that the ratio of [4]/[3] was increased to a greater extent by a rise in the reaction temperature rather than an increase in molar ratio of CH₃SOCH₂Na/COOCH₃ group.
The reaction with MSC having no sequential MMA units (MMA content, 28.4 mol%) gave a product which ester groups of the copolymer were completely converted to only 8-keto sulfoxide side chains [3].