2hydroxyl

2hydroxyl refers to a hydroxyl group (–OH) that is attached to the second carbon of a carbon chain or ring. It is a functional-group descriptor used in organic chemistry to indicate the position of the hydroxyl group within a molecule. The same concept appears in systematic IUPAC naming, where a substituent prefix such as 2-hydroxy- or a parent name with a locant 2 denotes a hydroxyl on carbon 2.

In naming, a single hydroxyl group is typically indicated by the suffix -ol and the locant is chosen to give the lowest possible number for the hydroxy group. When the molecule has several hydroxyls or a symmetric skeleton, 2-hydroxy- can describe a hydroxyl at carbon 2. Common examples include 2-propanol (isopropanol) and 2-butanol (butan-2-ol), where the OH group is on the second carbon. A molecule with two hydroxyls on adjacent carbons, such as ethane-1,2-diol, is known as ethylene glycol. The term 2-hydroxyl is often used more as a descriptor for a hydroxyl location rather than a standalone chemical entity.

In carbohydrates and related biochemicals, the position of the 2-hydroxyl is important for stereochemistry and identity of epimers. For example, the configuration of the C2 hydroxyl in hexoses helps distinguish glucose from galactose and mannose, influencing properties such as reactivity and solubility.

Overall, 2hydroxyl is a positional descriptor that helps specify where a hydroxyl group resides in a molecule, with broad relevance across organic chemistry and biochemistry.