and applications This heightened reactivity of allylic groups has many practical consequences. The sulfur vulcanization or various rubbers exploits the conversion of allylic groups into crosslinks. Similarly drying oils such as linseed oil crosslink via oxygenation of allylic (or doubly allylic) sites. This crosslinking underpins the properties of paints and the spoilage of foods by rancidification. The industrial production of acrylonitrile by ammoxidation of propene exploits the easy oxidation of the allylic C−H centers: 2CH3-CH=CH2 + 2 NH3 + 3 O2 -> 2CH2=CH-C#N + 6 H2O An estimated 800,000 tonnes (1997) of allyl chloride is produced by the chlorination of propylene: CH3CH=CH2 + Cl2 -> ClCH2CH=CH2 + HCl It is the precursor to allyl alcohol and epichlorohydrin. Allylation Allylation is the attachment of an allyl group to a substrate, usually another organic compound. Classically, allylation involves the reaction of a carbanion with allyl chloride. Another well-developed process involves addition of allyltrimethylsilane to carbonyls, i.e. carbonyl allylation. Allylation can be effected also by conjugate addition: the addition of an allyl group to the beta-position of an enone. The Hosomi-Sakurai reaction is a common method for conjugate allylation. Allyl compounds Many substituents can be attached to the allyl group to give stable compounds. Commercially important allyl compounds include: Crotyl alcohol (CH3CH=CH−CH2OH) Dimethylallyl pyrophosphate, central in the biosynthesis of terpenes, a precursor to many natural products, including natural rubber. Transition-metal allyl complexes, such as allylpalladium chloride dimer See also Allylic strain Carroll rearrangement Allylic palladium complex Tsuji–Trost reaction Propargylic/Homopropargylic Benzylic Vinylic Acetylenic Naloxone Allylic rearrangement References Alkenyl groups Allyl compounds