Dimethyl polysulfides have been reported in the supercritical
methanol extracts of coal and in
the pyrolysis products of a high-sulfur Spanish coal that was first
extracted with a mixture of
dichloromethane and methanol. Dimethyl polysulfides and other
products are shown to be formed
by the reaction of methanol with elemental sulfur at elevated
temperature and pressure. This
reaction is a possible source of some of the dimethyl polysulfides
observed by others in high-temperature methanol extracts.