quaternary carbon
{{Short description|A carbon atom bound to four other carbon atoms}}
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! quaternary carbon |
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| Structural formula of neopentane (quaternary carbon is highlighted red) |
A quaternary carbon is a carbon atom bound to four other carbon atoms.{{cite book |last1=Smith |first1=Janice Gorzynski |title=Organic chemistry |date=2011 |publisher=McGraw-Hill |location=New York, NY |isbn=978-0-07-337562-5 |page=116 |edition=3rd |url=http://highered.mheducation.com/sites/007340277x/student_view0/index.html |language=en |format=Book |chapter=Chapter 4 Alkanes |access-date=2018-06-26 |archive-url=https://web.archive.org/web/20180628152511/http://highered.mheducation.com/sites/007340277x/student_view0/index.html |archive-date=2018-06-28 |url-status=dead }} For this reason, quaternary carbon atoms are found only in hydrocarbons having at least five carbon atoms. Quaternary carbon atoms can occur in branched alkanes, but not in linear alkanes.{{citation|surname1=Hans Peter Latscha, Uli Kazmaier, Helmut Alfons Klein|title=Organische Chemie: Chemie-Basiswissen II|edition=7. Auflage|publisher=Springer Spektrum|publication-place=Berlin|page=40|isbn=978-3-662-46180-8|date=2016|language=German
}}
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| | style="background-color:#7A91FF" | primary carbon
| style="background-color:#7A91FF" | secondary carbon | style="background-color:#7A91FF" | tertiary carbon | style="background-color:#AAC1FF" | quaternary carbon |
| align="center" style="background-color:#CAE1FF; height:80px; width:20%" | General structure (R = Organyl group) | style="background-color:#BFBFBF" | File:Primäres_Kohlenstoffatom_V1.svg | style="background-color:#BFBFBF" | File:Sekundäres_Kohlenstoffatom_V1.svg | style="background-color:#BFBFBF" | File:Tertiäres_Kohlenstoffatom_V1.svg | style="background-color:#FFFFFF" | File:Quartäres_Kohlenstoffatom_V1.svg |
| align="center" style="background-color:#CAE1FF; height:80px; width:20%" | Partial Structural formula | style="background-color:#BFBFBF" | File:Primäres_Kohlenstoffatom_V2.svg | style="background-color:#BFBFBF" | File:Sekundäres_Kohlenstoffatom_V2.svg | style="background-color:#BFBFBF" | File:Tertiäres_Kohlenstoffatom_V2.svg | style="background-color:#FFFFFF" | File:Quartäres_Kohlenstoffatom_V2.svg |
Synthesis
File:Synthesis Bisphenol A.svg
The formation of chiral quaternary carbon centers has been a synthetic challenge. Chemists have developed asymmetric Diels–Alder reactions,Nicolaou, K. C.; Vassilikogiannakis, G.; Mägerlein, W.; Kranich, R Angew. Chem. Int. Ed. Volume 2001, Issue 40, Pages 2482–2486 {{DOI: 10.1002/1521-3773(20010702)40:13<2482::AID-ANIE2482>3.0.CO;2-A}} Heck reaction, Enyne cyclization, cycloaddition reactions,Quasdorf, K.W.; Overman, L. E. Nature Volume 2014, Volume 516, Pages 181 {{doi:10.1038/nature14007}} C–H activation, Allylic substitution,{{cite journal|vauthors=Feng C, Kobayashi Y |title= Allylic Substitution for Construction of a Chiral Quaternary Carbon Possessing an Aryl Group|journal= J. Org. Chem.|year= 2013|volume= 78|issue= 8|pages= 3755–3766|doi=10.1021/jo400248y|pmid= 23496084}} Pauson–Khand reaction,Ishizaki, M.; Niimi, Y.; Hoshino, O.; Hara, H.; Takahashi, T. Tetrahedron Volume 2001, Issue 61, Pages 4053–4065 etc. to construct asymmetric quaternary carbon atoms.
One of the most industrially important compounds containing a quaternary carbon is bis-phenol A (BPA). The central atom is a quaternary carbon. Retrosynthetically, that carbon is the central atom of an acetone molecule before condensation with two equivalents of phenol - BPA Production Process