Notes On Organic Compounds: Nomenclature-Substituted Benzene Compounds - CBSE Class 11 Chemistry
Mono substituted benzene has only one substituent attached to the benzene ring. While writing the IUPAC name of the mono substituted benzene, the substituent name is placed as a prefix to the word 'Benzene'. Ex: If Nitro group (-NO2) present on Benzene ring, then its name will be Nitro benzene. And if methyl group present on benzene ring, called as methyl benzene, commonly called as Toluene. Following table giving some of the mono-substituted benzene compounds along with common names. Disubstituted benzene has two substituents attached to the benzene ring. The three isomers of a disubstituted benzene are differentiated in the trivial system by using the names 'ortho', 'para' and 'meta', which are abbreviated as o, p, m respectively. Trisubstituted benzene has three substituents attached to the benzene ring. If more than two substituents are present, then the positions of the groups are indicated by numbering the carbon atoms according to the lowest locant rule. According to this rule, the sequence in which the numbering is done should have the lowest combination of numbers. Ex: Case I is preferred among the following. Case I is preferred among the following.

#### Summary

Mono substituted benzene has only one substituent attached to the benzene ring. While writing the IUPAC name of the mono substituted benzene, the substituent name is placed as a prefix to the word 'Benzene'. Ex: If Nitro group (-NO2) present on Benzene ring, then its name will be Nitro benzene. And if methyl group present on benzene ring, called as methyl benzene, commonly called as Toluene. Following table giving some of the mono-substituted benzene compounds along with common names. Disubstituted benzene has two substituents attached to the benzene ring. The three isomers of a disubstituted benzene are differentiated in the trivial system by using the names 'ortho', 'para' and 'meta', which are abbreviated as o, p, m respectively. Trisubstituted benzene has three substituents attached to the benzene ring. If more than two substituents are present, then the positions of the groups are indicated by numbering the carbon atoms according to the lowest locant rule. According to this rule, the sequence in which the numbering is done should have the lowest combination of numbers. Ex: Case I is preferred among the following. Case I is preferred among the following.

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