Cyclohexylidene

Cyclohexylidene is a term used in organic chemistry to denote the cyclohexylidene substituent, a hydrocarbon group derived from cyclohexane through the formation of a carbon–carbon double bond to the rest of the molecule. The group is characteristic as an exocyclic alkene substituent: one of the double-bonded carbons is part of the cyclohexane ring, and the other carbon is connected to the remainder of the molecule. In chemical names the cyclohexylidene moiety is often written as cyclohexylidene- and indicates that the ring is joined to the rest of the molecule by a C=C linkage rather than by a single bond.

The cyclohexylidene unit is discussed in the context of exocyclic alkenes and alkylidene chemistry. It can appear in a variety of compounds where the cyclohexane ring is linked to other functional groups or unsaturated systems through the exocyclic double bond. The exact arrangement, including potential E/Z stereochemistry, depends on the substituents attached to the double-bonded carbon atoms.

In practical terms, the cyclohexylidene group is encountered in synthetic and mechanistic discussions as a reactive alkene fragment that can participate in typical alkene transformations, such as additions or condensations, and as a structural motif in certain cyclohexane-containing frameworks. Its usage is primarily of interest in naming conventions and in describing the connectivity of exocyclic double-bond systems involving cyclohexane.

See also: benzylidene, arylidene, alkylidene, exocyclic double bond.