Alcohols, phenols, and Thiols:
Alcohols
In chemistry, an alcohol is an organic compound where the hydroxyl functional group (-OH) is bound to a carbon atom. Particularly, this carbon center should be saturated, comprising single bonds to three other atoms.
A significant class of alcohols is the simple acyclic alcohols, the general formula for which is CnH2n+1OH. Of those, ethanol (C2H5OH) is the kind of alcohol found in alcoholic beverages, and in general speech the word alcohol refers particularly to ethanol.
Phenols
In organic chemistry, phenols, occasionally called phenolics, are a class of chemical compounds containing a hydroxyl group (-OH) bonded directly to an aromatic hydrocarbon group. The simplest of the class is phenol as well known as carbolic acid C6H5OH.
Thiols
In organic chemistry, a thiol is an organosulfur compound that consists of a carbon-bonded sulfhydryl (-C-SH or R-SH) group (in which R represents an alkane, alkene, or another carbon-containing group of atoms). Thiols are sulfur analogue of alcohols (i.e., sulfur takes the place of oxygen in the hydroxyl group of an alcohol). The -SH functional group itself is considered to as either a thiol group or sulfhydryl group.