Direct production of butyltin chlorides from a paired electro-organic synthesis

Abstract

Butyltin chlorides were produced directly from butyl chloride and a tin cathode in several undivided cell reactors with tetraethylammonium chloride and acetonitrile solvent. The complex reaction chemistry was investigated primarily in a small batch cell with a 1 cm2 planar cathode. Current densities from cathodic linear potential sweeps at 1 mV s−1 were correlated successfully with current densities and butyltin products from potentiostatic experiments. Potential windows on product formation and other major limiting reactions were thereby identified. Product yield was shown to be strongly dependent on electrolyte gas conditions, with yield decreasing as the reactor is increasingly deaerated. Use of the initial open circuit potential (i.o.c.p.) as an indicator of reaction gas conditions proved to be a convenient and reproducible technique. Under favourably oxidized conditions, current densities in the product formation potential region ranged from 66 mA cm−2 at −2.74V vs SCE to 250 mA cm−2 at −2.98 Vvs SCE which are considerably higher than previously reported current densities for this synthesis. Surprisingly, the aeration history of butyl chloride prior to synthesis may be an important factor in subsequent product yield.