In organic chemistry, a thiol is a compound that contains the -SH functional group, which is the sulfur analogue of a hydroxyl or alcohol group. The functional group is referred to as either a thiol group or a sulfhydryl group. Thiols are more traditionally referred to as mercaptans. Thiols and alcohols have similar molecular structure, although the C-S-H bond angle is closer to 90° than the C-O-H bond angle of an alcohol. In the solid or liquid state, the hydrogen bonding between individual thiol groups is weak, the main cohesive force being van der Waals interactions between the polar sulfur centers.
Due to the similar electronegativities of sulfur and hydrogen, thiols are less polar and have a lower dipole moment than the corresponding alcohols. Thiols only weakly hydrogen bond with both water and other thiols. Hence, they have lower boiling points and are less soluble in water and other polar solvents than the corresponding alcohols. Akin to the chemistry of...