Editing Enamine (section)

==Formation==
:[[File:Enamine.png|thumb|center|320px|Condensation to give an enamine.<ref>{{OrgSynth|author=R. D. Burpitt and J. G. Thweatt |year=1968|title=Cyclodecanone|volume=48|pages=56|collvol=5|collvolpages=277|prep=CV5P0277}}</ref>]]
Enamines can be easily produced from commercially available starting reagents. Commonly enamines are produced by an acid-catalyzed nucleophilic reaction of ketone<ref>{{Cite journal |last1=Stork |first1=Gilbert. |last2=Brizzolara |first2=A. |last3=Landesman |first3=H. |last4=Szmuszkovicz |first4=J. |last5=Terrell |first5=R. |date=1963 |title=The Enamine Alkylation and Acylation of Carbonyl Compounds |url=https://pubs.acs.org/doi/abs/10.1021/ja00885a021 |journal=Journal of the American Chemical Society |language=en |volume=85 |issue=2 |pages=207–222 |doi=10.1021/ja00885a021 |bibcode=1963JAChS..85..207S |issn=0002-7863}}</ref> or aldehyde<ref>{{Cite journal |last1=Mannich |first1=C. |last2=Davidsen |first2=H. |date=1936 |title=Über einfache Enamine mit tertiär gebundenem Stickstoff |trans-title=On simple enamines with triple-bonded nitrogen |url=https://onlinelibrary.wiley.com/doi/10.1002/cber.19360690921 |journal=Berichte der Deutschen Chemischen Gesellschaft (A and B Series) |language=de |volume=69 |issue=9 |pages=2106–2112 |doi=10.1002/cber.19360690921 |issn=0365-9488|url-access=subscription }}</ref> species containing an [[α-hydrogen]] with secondary amines.  Acid catalysis is not always required, if the pK<sub>aH</sub> of the reacting amine is sufficiently high (for example, [[pyrrolidine]], which has a pK<sub>aH</sub> of 11.26). If the pK<sub>aH</sub> of the reacting [[amine]] is low, however, then acid catalysis is required through both the addition and the dehydration steps<ref>{{cite journal|last1=Capon|first1=Brian|last2=Wu|first2=Zhen Ping|title=Comparison of the tautomerization and hydrolysis of some secondary and tertiary enamines|journal=The Journal of Organic Chemistry|date=April 1990|volume=55|issue=8|pages=2317–2324|doi=10.1021/jo00295a017}}</ref> (common [[Desiccant|dehydrating agents]] include [[MgSO4|MgSO<sub>4</sub>]] and [[Na2SO4|Na<sub>2</sub>SO<sub>4</sub>]]).<ref name="scripps_Lockner_Nov_07">{{cite web|last1=Lockner|first1=James|title=Stoichiometric Enamine Chemistry|url=http://www.scripps.edu/baran/images/grpmtgpdf/Lockner_Nov_07.pdf|publisher=Baran Group, The Scripps Research Institute|access-date=26 November 2014}}</ref> Primary amines are usually not used for enamine synthesis due to the preferential formation of the more thermodynamically stable imine species.<ref name="chemwiki_Enamine_Reactions">{{cite web|last1=Farmer|first1=Steven|title=Enamine Reactions|publisher=UC Davis Chem Wiki|url=http://chemwiki.ucdavis.edu/Organic_Chemistry/Reactivity_of_Alpha_Hydrogens/Enamine_Reactions|date=2013-10-16}}</ref> Methyl ketone self-condensation is a side-reaction which can be avoided through the addition of [[Titanium tetrachloride|TiCl<sub>4</sub>]]<ref>{{cite journal|last1=Carlson|first1=R|last2=Nilsson|first2=A|title=Improved Titanium Tetrachloride Procedure for Enamine Synthesis|journal=Acta Chemica Scandinavica|date=1984|volume=38B|pages=49–53|doi=10.3891/acta.chem.scand.38b-0049 |doi-access=free}}</ref> into the reaction mixture (to act as a water [[Scavenger (chemistry)|scavenger]]).<ref name="scripps_Lockner_Nov_07"/><ref>{{cite journal|last1=White|first1=William Andrew|last2=Weingarten|first2=Harold|title=A versatile new enamine synthesis|journal=The Journal of Organic Chemistry|date=January 1967|volume=32|issue=1|pages=213–214|doi=10.1021/jo01277a052}}</ref> An example of an aldehyde reacting with a secondary amine to form an enamine via a [[carbinolamine]] intermediate is shown below:
:{{chem2|R2NH  +  R'CH2CHO  <->  R2NC(OH)(H)CH2R'}} (carbonolamine formation)
:{{chem2|R2NC(OH)(H)CH2R' <->  R2NCH\dCHR' + H2O}} (enamine formation)