A kinetic and mechanistic study of the formation of a diaryl ditelluride in solution by the sulphite reduction of the aryltellurium trichloride
Abstract
When an aqueous dioxane solution of Na2SO3 or of Na2S2O5 is added to a solution of p-ethoxyphenyltellurium trichloride (RTeCl3) in dioxane the reaction mixture remains homogeneous and the related ditelluride R2Te2 is formed quantitatively. This reaction has been investigated kinetically. The first step in the process is the hydrolysis of the trichloride to give the aryltellurate, RTeO2–. When the water content of the solvent is low this acid-catalysed step becomes rate determining. More usually that step is rapid and the slow step is the reduction of the RTeO2– by HSO3– to give RTeO–. This tellurium(II) intermediate is believed to dimerize to R(HO)TeTe(OH)R before being reduced by another mole of bisulphite to the ditelluride.
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