cyclohexyl

Cyclohexyl is a saturated hydrocarbon substituent derived from cyclohexane by removal of one hydrogen atom, giving the formula C₆H₁₁–. In IUPAC nomenclature it is designated as cyclohexyl and is considered an alkyl group; its systematic name is cyclohexyl. The substituent can be attached to a wide variety of functional groups, forming compounds such as cyclohexylamine, cyclohexylbenzene, and cyclohexyl chloride. The cyclohexyl ring adopts a chair conformation in most cases, which minimizes steric strain and confers relative stability to the attached derivatives.

Cyclohexyl radicals are generated in laboratory settings by homolytic cleavage of a cyclohexyl‑containing bond, often using heat, UV light, or radical initiators. These radicals readily add to unsaturated systems, enabling the synthesis of a range of cyclohexyl‑substituted products. Electrophilic substitution on aromatic rings bearing a cyclohexyl group typically occurs at the para position relative to directing groups, while nucleophilic reactions may involve substitution of a cyclohexyl halide via SN2 pathways, though steric bulk can slow such processes.

Industrial applications of cyclohexyl derivatives include their use as intermediates in the manufacture of nylon precursors, rubber accelerators, and plasticizers. Cyclohexylamine, for example, serves as a building block for pharmaceuticals and surfactants. Physical properties of the cyclohexyl group reflect those of cyclohexane: the parent hydrocarbon is a color‑less liquid with a boiling point of 80 °C and a density of 0.778 g cm⁻³ at 20 °C. The group is generally non‑reactive toward mild oxidants but can be oxidized to cyclohexanone or cyclohexanol under stronger conditions.

Safety considerations for cyclohexyl‑containing chemicals follow standard organic‑chemical guidelines; many are flammable liquids or vapors, and appropriate handling, ventilation, and protective equipment are required.