Editing Allyl group (section)

==Reactions and applications==
{{See also|Allylic substitution}}
This heightened reactivity of allylic groups has many practical consequences. The [[sulfur vulcanization]] or various rubbers exploits the conversion of allylic {{chem2|CH2}} groups into {{chem2|CH\sS_{x}\sCH}} crosslinks.  Similarly [[drying oil]]s 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:
:<chem>2CH3-CH=CH2 + 2 NH3 + 3 O2 -> 2CH2=CH-C#N + 6 H2O</chem>

An estimated 800,000 tonnes (1997) of [[allyl chloride]] is produced by the [[Halogenation|chlorination]] of [[propylene]]:
:<chem>CH3CH=CH2 + Cl2  -> ClCH2CH=CH2 + HCl</chem>
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.  Alternatives include [[carbonyl allylation]] with allylmetallic reagents, such as [[allyltrimethylsilane]],<ref>{{cite journal |doi=10.1021/cr400008h|title=Diastereoselective Allylation of Carbonyl Compounds and Imines: Application to the Synthesis of Natural Products |year=2013 |last1=Yus |first1=Miguel |last2=González-Gómez |first2=José C. |last3=Foubelo |first3=Francisco |journal=Chemical Reviews |volume=113 |issue=7 |pages=5595–5698 |pmid=23540914 |hdl=10045/38276 |hdl-access=free }}</ref><ref>{{cite journal |doi=10.1021/cr1002744|title=Transition Metal-Catalyzed Decarboxylative Allylation and Benzylation Reactions |year=2011 |last1=Weaver |first1=Jimmie D. |last2=Recio |first2=Antonio |last3=Grenning |first3=Alexander J. |last4=Tunge |first4=Jon A. |journal=Chemical Reviews |volume=111 |issue=3 |pages=1846–1913 |pmid=21235271 |pmc=3116714 }}</ref><ref>{{cite journal |doi=10.1021/cr1004474|title=Catalytic Enantioselective Allylation of Carbonyl Compounds and Imines |year=2011 |last1=Yus |first1=Miguel |last2=González-Gómez |first2=José C. |last3=Foubelo |first3=Francisco |journal=Chemical Reviews |volume=111 |issue=12 |pages=7774–7854 |pmid=21923136 }}</ref> or the iridium-catalyzed [[Krische allylation]].

Allylation can be effected also by [[conjugate addition]]: the addition of an allyl group to the beta-position of an [[Alpha-beta Unsaturated carbonyl compounds|enone]]. The [[Sakurai reaction|Hosomi-Sakurai reaction]] is a common method for conjugate allylation.<ref>{{cite journal |doi=10.15227/orgsyn.062.0086|title=Conjugate Allylation of α,β-Unsaturated Ketones with Allylsilanes: 4-Phenyl-6-Hepten-2-one |journal=Organic Syntheses |year=1984 |volume=62 |page=86|author1=Sakurai Hideki|author2=Hosomi Akira|author3=Hayashi Josabro}}</ref>
[[File:Carbonyl Allylation Scheme 4.png|center|frameless|349x349px|insert a caption here]]

===Oxidation===
Allylic C-H bonds are susceptible to oxidation.<ref>{{cite journal |doi=10.1055/s-0033-1338491 |title=Allylic Oxidations of Olefins to Enones |date=2013 |last1=Maison |first1=Wolfgang |last2=Weidmann |first2=Verena |journal=Synthesis |volume=45 |issue=16 |pages=2201–2221 |s2cid=196767407 }}</ref>  One commercial application of '''allylic oxidation''' is the synthesis of [[nootkatone]], the fragrance of [[grapefruit]], from [[valencene]], a more abundantly available [[sesquiterpenoid]]:<ref>{{cite journal |doi=10.1038/nature17431 |title=Scalable and sustainable electrochemical allylic C–H oxidation |date=2016 |last1=Horn |first1=Evan J. |last2=Rosen |first2=Brandon R. |last3=Chen |first3=Yong |last4=Tang |first4=Jiaze |last5=Chen |first5=Ke |last6=Eastgate |first6=Martin D. |last7=Baran |first7=Phil S. |journal=Nature |volume=533 |issue=7601 |pages=77–81 |pmid=27096371 |pmc=4860034 |bibcode=2016Natur.533...77H }}</ref>  
[[File:ValenceneToNootkatone.svg|thumb|center|322px|The conversion of valencene to nootkatone is an example of allylic oxidation.]]

In the synthesis of some fine chemicals, [[selenium dioxide]] is used to convert alkenes to allylic alcohols:<ref>{{cite book |doi=10.1002/047084289X.rs008.pub3 |chapter=Selenium(IV) Oxide |title=Encyclopedia of Reagents for Organic Synthesis |date=2017 |last1=Hoekstra |first1=William J. |last2=Fairlamb |first2=Ian J. S. |last3=Giroux |first3=Simon |last4=Chen |first4=Yuzhong |pages=1–12 |isbn=978-0-470-84289-8 }}</ref>
:R<sub>2</sub>C=CR'-CHR"<sub>2</sub>  +  [O] →  R<sub>2</sub>C=CR'-C(OH)R"<sub>2</sub>
where R, R', R" may be [[alkyl]] or [[aryl]] substituents.

From the industrial perspective, oxidation of benzylic C-H bonds are conducted on a particularly large scale, e.g. production of [[terephthalic acid]], [[benzoic acid]], and [[cumene hydroperoxide]].<ref>{{cite journal |doi=10.1021/cr040170k |title=Free Radical Functionalization of Organic Compounds Catalyzed by ''N-'' Hydroxyphthalimide |date=2007 |last1=Recupero |first1=Francesco |last2=Punta |first2=Carlo |journal=Chemical Reviews |volume=107 |issue=9 |pages=3800–3842 |pmid=17848093 }}</ref>