Utente:Grasso Luigi/sanbox1/Anione nitrile: differenze tra le versioni
Contenuto cancellato Contenuto aggiunto
Riga 19:
===Reazioni===
The mechanisms of reactions involving nitrile anions depend primarily on the nature of the [[electrophile]] involved. Simple alkylations take place by [[bimolecular nucleophilic substitution|S<sub>N</sub>2]] displacement<ref>{{cite journal|title=The Alkylation of Esters and Nitriles|first1=A. C.|last1=Cope |first2=H. L. |last2=Holmes |first3=H. O. |last3=House |journal=Org. React. |volume=9 |page=107 |date=1957|doi= 10.1002/0471264180.or009.04|isbn=0471264180}}</ref> and are subject to the usual stereoelectronic requirements of the process. [[Phase-transfer catalysis]] has been employed in alkylations of arylacetonitriles.<ref>{{cite journal|title=Heterogeneous ethylation of phenylacetonitrile|first1=R. |last1=Solaro |first2=S. |last2=D'Antone |first3=E. |last3=Chiellini |journal=J. Org. Chem. |volume=45 |issue=21 |page=4179 |date=1980|doi=10.1021/jo01309a023}}</ref><ref>{{cite journal|last1=Makosza|first1=M.|last2=Jonczyk|first2=A.|title=Phase-Transfer Alkylation of Nitriles: 2-Phenylbutyronitrile|journal=Organic Syntheses|date=1976|volume=55|page=91|doi=10.15227/orgsyn.055.0091}}</ref> Nitrile anions can also be involved in [[Michael reaction|Michael]]-type additions to activated double bonds and vinylation reactions with a limited number of polarized, unhindered acetylene derivatives.<ref>{{cite journal|title=Reactions of organic anions. XII. Vinylation of phenylacetonitrile derivatives|first=M. |last=Makosza |journal=Tetrahedron Lett. |date=1966|volume=1966|issue=45 |page=5489|doi=10.1016/S0040-4039(00)70128-6}}</ref>
[[File:NitrilePTC.png|200px]]
Arylation of nitrile anions is also possible, and can take place through different mechanisms depending on the substrates and reaction conditions. Aryl halides lacking electron-withdrawing groups react through an addition-elimination mechanism involving [[benzyne]] intermediates. Aryl phosphates and ammoniums react through the [[Radical-nucleophilic aromatic substitution|S<sub>RN</sub>1]] pathway, which involves the generation of an aryl radical anion, fragmentation, and bond formation with a nucleophile. Electron transfer to a second molecule of arene carries on the radical chain.
[[File:NitrileSRN1.png|center]]
| |||