Photochemical Conversion of Triethyl-tin to Diethyl-tin

Abstract

DURING the development of a method for the determination of organo-tin compounds¹ it was found that exposure to light of the yellow triethyl-tin–dithizone complex in chloroform produced a rapid change to orange. Examination of the absorption spectra of these solutions has shown that the absorption maxima change from 440 mµ (triethyl-tin–dithizone complex) to 485 mµ (diethyl-tin–dithizone complex) if the complexes are formed in the presence of borate–versene buffer pH 8.75. Both the diethyl-tin–dithizone and the irradiated triethyl-tin–dithizone complex change to one with an absorption maximum at 510 mµ upon the addition of one drop 10 per cent alcoholic trichloroacetic acid. Also, triethyl-tin–dithizone, diethyl-tin–dithizone and the irradiated triethyl-tin–dithizone complexes all dissociate upon the addition of one drop of glacial acetic acid to give the spectrum of dithizone. It seems certain that the triethyl-tin–dithizone complex is converted by light to the diethyl-tin–dithizone complex. There is a slow formation of diethyl-tin upon storage on the laboratory bench of a triethyl-tin solution in chloroform, though under these conditions it would take months to effect the conversion obtained in 1 min. in sunlight in the presence of dithizone.