Nomenclature Of Phenols, Isomerism, Important Topics For JEE Main Chemistry 2024

Nomenclature Of Phenols : The organic compounds known as phenols are made up of a hydroxyl group and a benzene ring. Another name for them is carbolic acids. Therefore, an aryl group and a hydroxyl group make up the two parts of a phenol molecule. One can categorize aryl groups into mono-, di-, tri-, or polyhydric phenols based on how many hydroxyl groups are linked to them.

Rules for Nomenclature Of Phenols

Rules for Nomenclature Of Phenols : The IUPAC states that it is imperative to adhere to the following guidelines when using nomenclature. The longest chain rule states that parent hydrocarbons should be recognized and categorized as a result. The lowest set of locants: According to this rule, the carbon atoms that make up the hydrocarbons are numbered.

Multiple occurrences of the identical substitute: The usage of prefixes like di-, tri-, mono-, or poly- is governed by this rule. The naming of various substituents: When naming unique substituents within a single compound, alphabetical order must be followed.

Nomenclature of Phenols : Previously, the majority of compounds sharing the same structural formula were referred to by distinct names based on the regions in which they were produced. This naming system caused a great deal of confusion, which made it extremely trivial. Ultimately, IUPAC established a standard naming system with a list of rules for naming compounds. For compounds having a benzene ring joined to a hydroxyl group, it serves as both a common name and an IUPAC name. The most basic hydroxy derivative of the benzene ring structurally is phenol. There are guidelines that the IUPAC uses when naming phenols.

Rules for the Nomenclature of Phenols

1. Find the location where the hydroxyl group is connected to the benzene ring.

2. In order to indicate the number of similar hydroxyl groups attached to a benzene ring, benzene rings that are attached to multiple hydroxyl groups are labeled with Greek numerical prefixes like di, tri, and tetra. If the benzene ring's neighboring carbon atoms have two hydroxyl groups attached to them, the compound is known as benzene 1,2-diol.

3. For substituted phenols, we begin by determining the other functional groups' locations in relation to the hydroxyl group's attachment point.

4. Phenol nomenclature also uses terms such as ortho (when the functional group is attached to the adjacent carbon atom), para (when the functional group is attached to the third carbon atom from the hydroxyl group), and meta (when the functional group is attached to the second carbon atom from the hydroxyl group) depending on the position of the substituted functional group with respect to the hydroxyl group.

Isomerism

Isomerism: Isomers are molecules or polyatomic ions that have different spatial arrangements of atoms but the same molecular formula, or the same number of atoms in each element. Isomerism is the study of isomers and their potential. Isomers do not always have the same physical or chemical characteristics.

Isomerism in Phenol

Isomerism in Phenol: Cresols are the names given to the three isomeric hydroxyl toluenes. Dihydric phenols: Known more commonly by their common names, catechol, resorcinol, and quinol are the three isomeric dihydroxy benzenes.

Examples of isomerism in phenol

• Alcohol, Phenol and ethers