Nomenclature Of Alcohol, Important Topics For JEE Chemistry 2024

Nomenclature of Alcohol : Alcohol, like all other organic molecules, have both formal and common names. In 1919, chemists from industry and academia formed the International Union of Pure and Applied Chemistry (IUPAC). These chemists recognized the need for international standardization of chemistry weights, measures, names, and symbols.

The name of alcohol includes the parent alkane's name, a number designating the location of the hydroxyl group, and the -ol suffix, as per the IUPAC system. Names for organic compounds can take various forms.

1. Common name system: - In this system, alcohol is added as a separate word after the alkyl group that is attached to the -OH group. Alcohols with one to four carbon atoms are frequently called by common names, in which the name of the alkyl group is followed by the word alcohol.

2. Carbinol system: In this system, the simplest alcohol, СН ₃ ОН, is called carbinol. More complex alcohols are named as alkyl substituted carbinols. The names are written as one word.

2. IUPAC system: In 1919, chemists from industry and academia formed the International Union of Pure and Applied Chemistry (IUPAC). These chemists recognized the need for international standardization of chemistry weights, measures, names, and symbols. An alcohol gets its name from the hydrocarbon from which it was derived. The final -e in the hydrocarbon's name is replaced by -ol, and the carbon atom to which the hydroxyl group (OH group) is bonded is indicated by a number preceding the name.

Rules for naming the alcohols :

1. Identify the longest chain that has an OH (hydroxyl) group. The term "subsitutent" refers to a chain that has more carbons than the one that contains the OH group.

2. Put the OH on the chain's lowest possible number. Alphabetic or hydroxy groups are given priority when it comes to naming, apart from carbonyl groups like ketones and aldehydes.

3. When naming a cyclic structure, the -OH is assumed to be on the first carbon unless the carbonyl group is present, in which case the later will get priority at the first carbon.

4. When multiple -OH groups are on the cyclic structure, number the carbons on which the -OH groups reside.

5. Add -ol and remove the last e from the parent alkane chain. Use di, tri, etc. before the ol, after the parent name, when there are several alcohols present. for instance, 2,3-hexanediol. Should there be a carbonyl group, the -OH group is given the prefix "hydroxy," and the carbonyl group is appended to the parent chain name so that it concludes in -al or -one.

Rules For Naming The Alcohols Examples

8-chlorooctan-3-ol

Nomenclature of Alcohol