The reaction of group V metal alkoxides with sulfur dioxide and selenium dioxide.

Trialkoxyarsines (I) and -stibines (II) react with sulfur dioxide to give the corresponding dialkyl sulfites and arsenic trioxide or polymeric residues containing antimony. The reactivity of the compounds (I) is very low, and the yield is poor. Reactions of I and II with selenium dioxide afford dialkyl selenites together with arsenic trioxide or the same polymeric residues containing antimony as in the case of the reaction with sulfur dioxide. The reaction followed a stoichiometry of three moles of trialkyl phosphites (III) and one mole of selenium dioxide yields a 2 : 1 molar ratio of the phosphates : the phosphoroselenoates. A similar reaction of the phosphites with selenium dioxide in a 2 : 1 stoichiometry gives the phosphates and red selenium quantitatively. The rate of oxidation of the phosphorus compounds by selenium dioxide decreases in the order Bu3P>BuP(OEt)2>P(OEt)3. Based on these results, the possible mechanisms have been discussed.