Ethoxide ions, decomposition

Hexabutyldistannane, which is an important reagent in many organic syntheses, can be prepared very conveniently by reducing bis(tributyltin) oxide with sodium borohydride in ethanol at room temperature. After 5 min, the only tin species present is tributyltin hydride, but in 2 h, its decomposition is catalyzed by the ethoxide ion that is formed to give the distannane in 83% yield.444 Hexaalkyldistannanes, R3SnSnR3 (R = Et, Pr, or Bu), are obtained in ca. 50% yield when the corresponding trialkyltin halides are treated with zinc powder in THF.445... 

Similar findings were obtained for the alkaline decomposition of triarylsulfonium halides with ethoxide ion in aqueous ethanol at 120 °C [71], The results indicate that the decomposition rate is decreased about 10 -fold by increasing the water content from 2.3 to 98.2 cmol/mol [71]. 

The reduction of bis(tributyltin) oxide with sodium borohydride in ethanol apparently falls into this group of reactions. After 5 min, the only tin compound present is tribu-tyltin hydride, but, during 2 h, this is converted into hexabutylditin in good yield. The catalyst for the decomposition of the hydride appears to be the ethoxide ion which is generated from the NaBH4 and ethanol.22... 

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