orthoisomer

Ortho isomer refers to a specific arrangement of substituents on an aromatic ring. In a disubstituted benzene ring, the ortho position is one of two adjacent carbon atoms relative to a reference substituent. This means the two substituents are located on carbons that share a common bond. For example, in ortho-xylene, the two methyl groups are attached to adjacent carbon atoms of the benzene ring.

The term "ortho" is derived from the Greek word "orthos," meaning "straight" or "correct." This nomenclature is part of a system used to describe the relative positions of two substituents on a benzene ring, along with meta and para. Meta isomers have substituents on carbons separated by one other carbon atom, and para isomers have substituents on opposite sides of the ring.

The physical and chemical properties of ortho isomers often differ significantly from their meta and para counterparts. These differences arise due to variations in steric hindrance and electronic effects caused by the substituent positions. For instance, the proximity of substituents in ortho isomers can lead to increased reactivity in certain reactions or influence the molecule's boiling point and solubility. The study of these positional isomers is fundamental in organic chemistry, impacting synthesis, reaction mechanisms, and the understanding of molecular behavior.