Editing Elimination reaction (section)

== Elimination reactions other than β-elimination ==
β-Elimination, with loss of electrofuge and nucleofuge on vicinal carbon atoms, is by far the most common type of elimination.  The ability to form a stable product containing a C=C or C=X bond, as well as orbital alignment considerations, strongly favors β-elimination over other elimination processes.<ref>{{Cite book|title=Modern physical organic chemistry|author=Anslyn, Eric V.|date=2006|publisher=University Science|others=Dougherty, Dennis A., 1952-|isbn=1891389319|location=Sausalito, CA|oclc=55600610}}</ref> However, other types are known, generally for systems where β-elimination cannot occur.
[[File:Eliminationrxns.png|center|frameless|400x400px]]

The next most common type of elimination reaction is α-elimination.  For a carbon center, the result of α-elimination is the formation of a carbene, which includes "stable carbenes" such as [[carbon monoxide]] or [[isocyanide]]s.  For instance, α-elimination the elements of HCl from chloroform (CHCl<sub>3</sub>) in the presence of strong base is a classic approach for the generation of [[dichlorocarbene]], :CCl<sub>2</sub>, as a reactive intermediate.  On the other hand, formic acid undergoes α-elimination to afford the stable products water and carbon monoxide under acidic conditions.  α-Elimination may also occur on a metal center, one particularly common result of which is lowering of both the metal oxidation state and coordination number by 2 units in a process known as [[reductive elimination]].  (Confusingly, in organometallic terminology, the terms ''α-elimination'' and ''α-abstraction'' refer to processes that result in formation of a metal-carbene complex.<ref>{{Cite book|title=The organometallic chemistry of the transition metals|author=Crabtree, Robert H.|date=2009|publisher=Wiley|isbn=9780470257623|edition=5th |location=Hoboken, N.J.|oclc=268790870}}</ref>  In these reactions, it is the carbon adjacent to the metal that undergoes α-elimination.)

In certain special cases, γ- and higher eliminations to form three-membered or larger rings is also possible in both organic and organometallic processes. For instance, certain Pt(II) complexes undergo γ- and δ-elimination to give metallocycles.<ref>{{Cite journal|last=Moore|first=Stephen S.|last2=DiCosimo|first2=Robert|last3=Sowinski|first3=Allan F.|last4=Whitesides|first4=George M.|date=1981-02-01|title=Ring strain in bis(triethylphosphine)-3,3-dimethylplatinacyclobutane is small|journal=Journal of the American Chemical Society|volume=103|issue=4|pages=948–949|doi=10.1021/ja00394a043|issn=0002-7863}}</ref> More recently, γ-silyl elimination of a silylcyclobutyl tosylate has been used to prepare strained bicyclic systems.<ref>{{Cite journal|last=Kelly|first=Christopher B.|last2=Colthart|first2=Allison M.|last3=Constant|first3=Brad D.|last4=Corning|first4=Sean R.|last5=Dubois|first5=Lily N. E.|last6=Genovese|first6=Jacqueline T.|last7=Radziewicz|first7=Julie L.|last8=Sletten|first8=Ellen M.|last9=Whitaker|first9=Katherine R.|date=2011-04-01|title=Enabling the Synthesis of Perfluoroalkyl Bicyclobutanes via 1,3 γ-Silyl Elimination|journal=Organic Letters|volume=13|issue=7|pages=1646–1649|doi=10.1021/ol200121f|pmid=21366262|issn=1523-7060}}</ref>