Mercaptans (also known as alkane thiols) are the sulfur analogs of alcohols. Sulfur is in the same group as oxygen in the Periodic table and forms similar compounds, among which mercaptans RSH. The —SH group is called the mercapto-, thiol-, or sulfhydryl group. The boiling points are much lower than those of the corresponding alcohols, for example: CH3SH 6 0C. A distinguishing feature of volatile mercaptans is their disagreeable odor.