ohalotoluene

O-halotoluene refers to a family of aromatic compounds in which a halogen atom (fluorine, chlorine, bromine, or iodine) is substituted at the ortho position relative to the methyl group on the benzene ring. The general formula is C7H7X, where X is F, Cl, Br, or I. Specific members include 2-fluorotoluene, 2-chlorotoluene, 2-bromotoluene, and 2-iodotoluene.

These compounds are part of the larger set of halotoluenes, with the ortho isomer distinguished from the meta and para isomers by the placement of the halogen adjacent to the methyl group. They are typically colorless liquids or solids, and their physical properties—such as boiling and melting points—vary with the halogen atom, generally increasing with heavier halogens.

Preparation usually involves electrophilic halogenation of toluene, often under radical or catalytic conditions. The methyl group directs substitution to the ortho and para positions, so mixtures of 2- and 4-halotoluenes are common and require separation. These aryl halides are versatile intermediates in organic synthesis, serving as substrates for cross-coupling reactions (for example Suzuki, Kumada, or Sonogashira couplings) and for further functionalization leading to dyes, pharmaceuticals, agrochemicals, and other fine chemicals.

Safety and environmental considerations apply to halogenated aromatics in general: they can be irritants and, depending on the halogen, may pose toxicity or persistence concerns. Proper handling, containment, and disposal are important in laboratory and industrial settings. The term ohalotoluene also functions as a class name; specific work usually specifies the halogen and exact isomer, e.g., 2-chlorotoluene.