FORMATION OF DIMERIC 1-ALKOXY-3-ACYLOXYTETRABUTYLDISTANNOXANES BY REACTION OF DIBUTYLTIN OXIDE WITH ESTERS .1. CHARACTERIZATION IN SOLUTION BY MULTINUCLEAR NMR-SPECTROSCOPY AND APPLICATION TO POLYMER CROSS-LINKING

The product of the reaction of both ethylene-vinyl acetate copolymers (EVA) and ethylene-methyl acrylate copolymers (EMA) with dibutyltin oxide at 200 degrees 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-octadecyl acetate and methyl nonanoate) in absence of solvent at 200 degrees C. The formation of the main reaction product, (R-CO-O-(C4H9)(2)Sn-O-(C4H9)(2)Sn-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 H-1,C-13 and Sn-119 NMR spectroscopy.