Axial chirality

Axial chirality

Axial chirality is a special case of chirality in which a molecule does not possess a stereogenic center (the most common form of chirality in organic compounds) but an axis of chirality - an axis is about which a set of substituents is held in a spatial arrangement that is not superposable on its mirror image. Axial chirality is most commonly observed in atropisomeric biaryl compounds wherein the rotation about the aryl-aryl bond is restricted, for example, biphenyl, binaphthyls, e.g., 1,1'-bi-2-naphthol, and certain dihydroanthracenone compounds [ "Absolute stereochemistry of fungal metabolites: Icterinoidins A1 and B1, and atrovirins B1 and B2" Melvyn Gill and Peter M. Morgan Arkivoc (RI-1154C)2004 [http://www.arkat-usa.org/ark/journal/2004/I10_Rickards/RI-1154C/RI-1154C.asp Online article] ] . Certain allene compounds also display axial chirality. The enantiomers of axially chiral compounds are usually given the stereochemical labels Ra and Sa, although the plus (P) or minus (M) notation is occasionally employed. [Compendium of Chemical Terminology, [http://goldbook.iupac.org/A00547.html axial chirality] ] P/M is used particularly for molecules that resemble a helix, such as hexahelicene, in which case a right-handed helix is denoted P and a left-handed helix is denoted M. [VLU: Additional Chirality Elements - Chemgapedia [http://www.chemgapedia.de/vsengine/vlu/vsc/en/ch/12/oc/vlu_organik/stereochemie/weitere_chiralitaetselem.vlu/Page/vsc/en/ch/12/oc/stereochemie/helicale_chiralitaet/helicale_chiralitaet.vscml.html] ]

This can also be called helicity, which is the chirality of a helical, propeller or screw-shape molecular entity. "P" (plus) is a right-handed helix, where "M" (minus) is a left-handed helix. [Compendium of Chemical Terminology, helicity, [http://old.iupac.org/goldbook/H02763.pdf] ]

External links

* Axial Chirality in 6,6'-Dinitrobiphenyl-2,2'-dicarboxylic acid 3D representation [http://siggy.chem.ucla.edu/VOH/30A/Dinitrobiphenyl_(COOH)2.pdf#search='axial%20chirality' Link]

References


Wikimedia Foundation. 2010.

Поможем решить контрольную работу

Look at other dictionaries:

  • Chirality (chemistry) — L form redirects here. For the bacterial strains, see L form bacteria. Two enantiomers of a generic amino acid …   Wikipedia

  • Crystallization — Crystallizing and Crystallized redirect here. For the action adventure video game, see Crystalis. For the 2009 song by The xx, see Crystalised. For other uses, see Crystallization (disambiguation). Crystallization …   Wikipedia

  • Atropisomer — s.cite journal author=Bringmann G, Mortimer AJP, Keller PA, Gresser MJ, Garner J, Breuning M title=Atroposelective Synthesis of Axially Chiral Biaryl Compounds journal=Angewandte Chemie International Edition volume=44 issue=34 pages=5384 5427… …   Wikipedia

  • Stereocenter — A stereocenter or stereogenic center is an atom, bearing groups such that an interchanging of any two groups leads to a stereoisomer.[1] A chirality center is a stereocenter consisting of an atom holding a set of ligands (atoms or groups of… …   Wikipedia

  • Enantioselective synthesis — Enantioselective synthesis: Sharpless epoxidation Enantioselective synthesis, also called chiral synthesis, asymmetric synthesis or stereoselective synthesis, is organic synthesis that introduces one or more new and desired elements of… …   Wikipedia

  • Enantiomer — This article is about the concept in chemistry. For a discussion of enantiomers in mathematics, see Chirality (mathematics). (S) (+) lactic acid (left) and (R) (–) lactic acid (right) are nonsuperposable mirror images of each other In chemistry,… …   Wikipedia

  • Stereoisomerism — The different types of isomers. Stereochemistry focuses on stereoisomers Stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms (constitution), but that differ only in the three dimensional… …   Wikipedia

  • Chiral auxiliary — A chiral auxiliary is a chemical compound or unit that is temporarily incorporated into an organic synthesis so that it can be carried out asymmetrically with the selective formation of one of two enantiomers[1][2] . Chiral auxiliaries are… …   Wikipedia

  • Optical rotation — (optical activity) is the turning of the plane of linearly polarized light about the direction of motion as the light travels through certain materials. It occurs in solutions of chiral molecules such as sucrose (sugar), solids with rotated… …   Wikipedia

  • Chiral pool synthesis — is a strategy that aims to improve the efficiency of chiral synthesis. It starts the organic synthesis of a complex enantiopure chemical compound from a stock of readily available enantiopure substances. Common chiral starting materials include… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”