Formation of dimeric 1-alkoxy-3-acyloxytetrabutyldistannoxanes by reaction of dibutyltin oxide with esters: I. Characterization in solution by multinuclear NMR spectroscopy and application to polymer crosslinking

Abstract

The product of the reaction of both ethylene-vinyl acetate copolymers (EVA) and ethylene-methyl acrylate copolymers (EMA) with dibutyltin oxide at 200°C, which leads to the crosslinking of the polymer matrix, is shown to be a dimeric 1-alkoxy-3-acyloxy-distannoxane. The reaction mechanism was studied with model esters (n-octyl acetate, n-octadecyi acetate and methyl nonanoate) in absence of solvent at 200°C. The formation of the main reaction product, (R-CO-O-(C 4H 9) 2Sn-O-(C 4H 9) 2Sn-OR') 2, is complete after heating for 25 min. This non-crystalline compound with an inorganic skeleton and an organic exterior was characterized in solution by 1H, 13C and 119Sn NMR spectroscopy.