ETHYLATION OF METHYLARSENIC(III) COMPOUNDS BY SODIUM TETRAETHYLBORATE

The compounds MeAsBr2 and Me2AsBr at concentrations of (1-5) X 10(-3) M in acetone solution are ethylated in high yield by NaBEt4 to MeEt2As and Me2EtAs, as shown by H-1 NMR spectroscopy. The extents of ethylation of MeAs2+ and Me2As+ (expressed as ions, by convention) in aqueous acid solutions [at concentrations of (5-20) x 10(-6) ml were investigated using cold trap/AA and GC AA procedures. The species Me2As+ was ethylated (to give Me2EtAs) in good yield (88%); in contrast, MeAS2+ produced the volatile trialkylarsine, MeEt2As, in poor yield (30%). No volatile trialkylarsine could be obtained on treating inorganic arsenic(III) (As3+) solutions with NaBEt4.