Silicotungstic, phosphorotungstic, and phosphoromolybdic heteropolyaci
ds (in the bulk or supported on SiO2 or Al2O3) accelerate disproportio
nation reactions in the system methyl mercaptan/dimethyl sulfide, reac
tions of methanol with H2S and methyl mercaptan, and reactions of H2S
with tetrahydrofuran. The reactions proceeds through a protolytic mech
anism.