phenylpropene

Phenylpropene is a term used to describe a class of organic compounds that consist of a phenyl group (a benzene ring) attached to a three-carbon side chain containing a carbon–carbon double bond. It does not designate a single compound but rather two common constitutional isomers in which the double bond is located at different positions along the side chain.

The two principal isomers are 1-phenylpropene (phenylprop-1-ene), with a structure of Ph–CH=CH–CH3, and allylbenzene (phenylprop-2-en-1-yl), with a structure of Ph–CH2–CH=CH2. 1-Phenylpropene features conjugation between the aromatic ring and the adjacent double bond, while allylbenzene contains a benzylic CH2 group followed by a terminal double bond. In some texts these compounds may be referred to by alternative names such as α- or β-phenylpropene, reflecting the position of the double bond.

Occurrence and applications of phenylpropene derivatives are mainly in chemical synthesis and flavor/fragrance contexts. Allylbenzene occurs in trace amounts in certain essential oils and is used as a synthetic intermediate and fragrance component. 1-Phenylpropene and related derivatives are typically produced for use as intermediates in organic synthesis rather than as common natural products.

Synthesis and reactivity are characteristic of unsaturated benzenyl compounds. They can be prepared by methods such as Friedel–Crafts-type alkylation or allylation of benzene with appropriate propene-derived reagents, and by subsequent functional-group manipulations. The carbon–carbon double bonds impart typical alkene reactivity, including addition and polymerization under suitable conditions. Safety considerations include flammability and potential irritation; standard precautions for handling unsaturated hydrocarbons apply.