2OH

2OH is a shorthand notation encountered in chemical literature to indicate the presence of two hydroxyl (OH) groups within a molecule. It is not a formal IUPAC term, but a contextual label used in reaction schemes, data tables, or discussions of functionality. The exact meaning of 2OH can vary with context: it may refer to a difunctional diol unit (a molecule containing two hydroxyl groups), or to a functional group count when describing a compound’s reactivity or classification.

In practice, 2OH is commonly used to signal that a molecule has two hydroxyl groups, which can influence properties such as hydrogen bonding, solubility, and reactivity in condensation or esterification reactions. For example, a diol like ethylene glycol is an archetypal substance described as having two OH groups. In carbohydrate chemistry, the notation 2-OH may denote a hydroxyl substituent at the second carbon in a sugar or in a ring form. In polymer chemistry, a monomer or chain segment labeled with 2OH indicates difunctionality that can participate in multiple bonding events during polymerization.

Caution is warranted because 2OH can be misinterpreted as the hydroxide anion (OH−) in some contexts. When encountered, the surrounding text should be consulted to determine whether 2OH refers to two hydroxyl groups within a molecule, a specific position of a hydroxy substituent, or a broader functional descriptor.

See also: diol, polyol, hydroxyl group, difunctional compound.