Names and Molecular and Structural Formulae for Alcohols

General Information About Alcohols

An alcohol is an organic compound in which one or more hydrogen atoms in an alkane have been replaced with an -OH (hydroxyl) group.
Alcohols are a homologous series with the general molecular formula CnH2n+1OH where ‘n’ ranges from 1 upwards.
Alcohols have similar properties because they all contain the same functional group, the hydroxyl group (-OH).

Naming Alcohols

The naming of alcohols follows the rule that the longest carbon chain attached to the hydroxyl group provides the stem of the name.
The parent alkane name is then modified by replacing the ‘e’ ending with ‘ol’. If necessary, the position of the hydroxyl group is indicated with a number placed before the ‘ol’.
For instance, if the longest chain contains one carbon atom, it is methane, and the corresponding alcohol is methanol (CH3OH).
For a two-carbon chain, the alcohol is ethanol (C2H5OH). For a three-carbon chain, it’s propanol, and so forth.

Structural Formulae For Alcohols

The structural formula of an alcohol represents its structure and shows how atoms are bonded to each other.
For example, in methanol, the structural formula is CH3OH.
In ethanol, it’s C2H5OH or more explicitly, CH3CH2OH.
In larger alcohols, like 1-propanol and 2-propanol, the structural formulae differ due to the different positions of the hydroxyl group, CH3CH2CH2OH and CH3CH(OH)CH3 respectively.

Remember, understanding the naming conventions and being able to write the structural formulae for alcohols is essential in examinations. An ability to identify and name the functional group will also be beneficial.