Mercaptans

Mercaptans are organic compounds in which an -SH functional group is bonded to a carbon atom in the molecule. In this case, S stands for a sulfur atom and H stands for a hydrogen atom bonded to the sulfur. Mercaptans are often called thiols, meaning they have chemical structures like alcohols except that sulfur is substituted for the oxygen in the hydroxyl group. The prefix thio often implies that sulfur is substituted for oxygen in a molecule's functional group. The -SH group can also be called a hydrogen sulfide or hydrosulfide group.

Mercaptans are colorless liquids having an odor resembling that of garlic; strong and repulsive. Looking at its binding states for metals, particularly mercury, one can see the reason for its name, from the Latin mercurius captans, laying hold of mercury.

Examples:

Methyl mercaptan - CH₃SH

Ethyl mercaptan - C₂H₅SH