How do you identify and name alcohols?

Alcohols are identified by the presence of a hydroxyl (-OH) group and named based on their carbon chain length and position of the -OH group.

Alcohols are a class of organic compounds that contain one or more hydroxyl (-OH) functional groups attached to a carbon atom. The general formula for alcohols is CnH2n+1OH. The presence of the hydroxyl group is what characterises an alcohol and differentiates it from other organic compounds.

To name alcohols, you first identify the longest continuous carbon chain in the molecule. This chain gives the base name of the alcohol, based on the number of carbons it contains. For example, a chain of one carbon is named 'meth-', two carbons 'eth-', three 'prop-', and so on.

The next step is to identify the position of the hydroxyl group on the carbon chain. The carbon atoms in the chain are numbered starting from the end closest to the hydroxyl group. The position of the hydroxyl group is indicated by this number. For example, if the hydroxyl group is on the second carbon atom in a three-carbon chain, the alcohol is named 'propan-2-ol'.

If there are multiple hydroxyl groups, the name reflects this with a prefix (di-, tri-, etc.) and multiple numbers are used to indicate their positions. For example, an alcohol with two hydroxyl groups on a three-carbon chain would be named 'propane-1,2-diol'.

Lastly, if the alcohol is a secondary or tertiary alcohol (meaning the carbon atom attached to the hydroxyl group is also attached to two or three other carbon atoms, respectively), this is indicated in the name. For example, 'secondary butan-2-ol' or 'tertiary pentan-3-ol'.

Remember, the key to naming alcohols is identifying the longest carbon chain, the position of the hydroxyl group(s), and the type of alcohol (primary, secondary, tertiary).