chirality (chemistry)

 

  • [22] • A chiral substance is enantiopure when only one of two possible enantiomers is present so that all molecules within a sample have the same chirality sense.

  • A chiral molecule or ion exists in two stereoisomers that are mirror images of each other, called enantiomers; they are often distinguished as either “right-handed” or “left-handed”
    by their absolute configuration or some other criterion.

  • In the case of organic compounds, stereocenters most frequently take the form of a carbon atom with four distinct (different) groups attached to it in a tetrahedral geometry.

  • This stereogenic center usually has four or more bonds to different groups, and may be carbon (as in many biological molecules), phosphorus (as in many organophosphates),
    silicon, or a metal (as in many chiral coordination compounds).

  • However, whether the molecule itself is considered to be chiral depends on whether its chiral conformations are persistent isomers that could be isolated as separated enantiomers,
    at least in principle, or the enantiomeric conformers rapidly interconvert at a given temperature and timescale through low-energy conformational changes (rendering the molecule achiral).

  • Liquid chromatography (HPLC and TLC) may also be used as an analytical method for the direct separation of enantiomers and the control of enantiomeric purity, e.g.

  • An achiral molecule having chiral conformations could theoretically form a mixture of right-handed and left-handed crystals, as often happens with racemic mixtures of chiral
    molecules (see Chiral resolution Spontaneous resolution and related specialized techniques), or as when achiral liquid silicon dioxide is cooled to the point of becoming chiral quartz.

  • A given stereocenter has two possible configurations (R and S), which give rise to stereoisomers (diastereomers and enantiomers) in molecules with one or more stereocenter.

  • Many chiral molecules have point chirality, namely a single chiral stereogenic center that coincides with an atom.

  • [29] Different enantiomers or diastereomers of a compound were formerly called optical isomers due to their different optical properties.

  • The molecule would then be considered to be chiral at that temperature.

  • A homogeneous mixture of the two enantiomers in equal parts is said to be racemic, and it usually differs chemically and physically from the pure enantiomers.

  • Chirality is important in context of ordered phases as well, for example the addition of a small amount of an optically active molecule to a nematic phase (a phase that has
    long range orientational order of molecules) transforms that phase to a chiral nematic phase (or cholesteric phase).

  • An example of a molecule that does not have a mirror plane or an inversion and yet would be considered achiral is 1,1-difluoro-2,2-dichlorocyclohexane (or 1,1-difluoro-3,3-dichlorocyclohexane).

  • In living organisms, one typically finds only one of the two enantiomers of a chiral compound.

  • Chirality can also arise from isotopic differences between atoms, such as in the deuterated benzyl alcohol PhCHDOH; which is chiral and optically active, even though the non-deuterated
    compound PhCH2OH is not.

  • In this case, circularly polarised radiation (which makes up 17% of stellar radiation) could have caused the selective destruction of one chirality of amino acids, leading
    to a selection bias which ultimately resulted in all life on Earth being homochiral.

  • Such a molecule may be chiral without having any stereogenic centers.

  • Finally, the inherent curvature of a molecule can also give rise to chirality (inherent chirality).

  • BINOL is a typical example of an axially chiral molecule, while trans-cyclooctene is a commonly cited example of a planar chiral molecule.

  • Chiral molecules are always dissymmetric (lacking Sn) but not always asymmetric (lacking all symmetry elements except the trivial identity).

  • This often involves forming crystals of a salt composed of one of the enantiomers and an acid or base from the so-called chiral pool of naturally occurring chiral compounds,
    such as malic acid or the amine brucine.

  • For example, despite having chiral gauche conformers that belong to the C2 point group, butane is considered achiral at room temperature because rotation about the central
    C–C bond rapidly interconverts the enantiomers (3.4 kcal/mol barrier).

  • of R contains 70% R and 30% S.[25] History The rotation of plane polarized light by chiral substances was first observed by Jean-Baptiste Biot in 1812,[26] and gained considerable
    importance in the sugar industry, analytical chemistry, and pharmaceuticals.

  • However, if the temperature in question is low enough, the process that interconverts the enantiomeric chiral conformations becomes slow compared to a given timescale.

  • These types of chirality are far less common than central chirality.

  • [13] In biochemistry Many biologically active molecules are chiral, including the naturally occurring amino acids (the building blocks of proteins) and sugars.

  • Less commonly, other atoms like N, P, S, and Si can also serve as stereocenters, provided they have four distinct substituents (including lone pair electrons) attached to
    them.

  • In chemistry, a molecule or ion is called chiral (/ˈkaɪrəl/) if it cannot be superposed on its mirror image by any combination of rotations, translations, and some conformational
    changes.

  • This is the case, for example, of most amines with three different substituents (NRR′R″), because of the low energy barrier for nitrogen inversion.

  • [19] Methods and practices The term optical activity is derived from the interaction of chiral materials with polarized light.

  • Molecules that are chiral at room temperature due to restricted rotation about a single bond (barrier to rotation ≥ ca.

  • As another example, amines with three distinct substituents (R1R2R3N:) are also regarded as achiral molecules because their enantiomeric pyramidal conformers rapidly undergo
    pyramidal inversion.

  • For example, a common case is a tetrahedral carbon bonded to four distinct groups a, b, c, and d (Cabcd), where swapping any two groups (e.g., Cbacd) leads to a stereoisomer
    of the original, so the central C is a stereocenter.

 

Works Cited

[‘1. Organic Chemistry (4th Edition) Paula Y. Bruice. Pearson Educational Books. ISBN 9780131407480
2. ^ Organic Chemistry (3rd Edition) Marye Anne Fox, James K. Whitesell Jones & Bartlett Publishers (2004) ISBN 0763721972
3. ^ IUPAC, Compendium
of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “Chirality”. doi:10.1351/goldbook.C01058
4. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–)
“Superposability”. doi:10.1351/goldbook.S06144
5. ^ Cotton, F. A., “Chemical Applications of Group Theory,” John Wiley & Sons: New York, 1990.
6. ^ ^ Streitwieser, A. Jr.; Wolfe, J. R. Jr.; Schaeffer, W. D. (1959). “Stereochemistry of the Primary
Carbon. X. Stereochemical Configurations of Some Optically Active Deuterium Compounds”. Tetrahedron. 6 (4): 338–344. doi:10.1016/0040-4020(59)80014-4.
7. ^ Jump up to:a b Pashenko, Alexander E.; Gaidai, Alexandr; Hryhoriev, Nazar; et al. (2023).
“Scale-Up Synthesis of 1-Methyladamantane and Its Functionalization as a Key Point for Promising Antiviral Agents”. Organic Process Research & Development. 27 (3): 477–487. doi:10.1021/acs.oprd.2c00305. ISSN 1083-6160.
8. ^ Mislow, Kurt; Siegel,
Jay (May 1984). “Stereoisomerism and local chirality”. Journal of the American Chemical Society. 106 (11): 3319–3328. doi:10.1021/ja00323a043. ISSN 0002-7863.
9. ^ Gal, Joseph (2012). “The Discovery of Stereoselectivity at Biological Receptors:
Arnaldo Piutti and the Taste of the Asparagine Enantiomers-History and Analysis on the 125th Anniversary”. Chirality. 24 (12): 959–976. doi:10.1002/chir.22071. PMID 23034823.
10. ^ Jump up to:a b c Theodore J. Leitereg; Dante G. Guadagni; Jean Harris;
Thomas R. Mon; Roy Teranishi (1971). “Chemical and sensory data supporting the difference between the odors of the enantiomeric carvones”. J. Agric. Food Chem. 19 (4): 785–787. doi:10.1021/jf60176a035.
11. ^ Lepola U, Wade A, Andersen HF (May 2004).
“Do equivalent doses of escitalopram and citalopram have similar efficacy? A pooled analysis of two positive placebo-controlled studies in major depressive disorder”. Int Clin Psychopharmacol. 19 (3): 149–55. doi:10.1097/00004850-200405000-00005.
PMID 15107657. S2CID 36768144.
12. ^ Hyttel, J.; Bøgesø, K. P.; Perregaard, J.; Sánchez, C. (1992). “The pharmacological effect of citalopram resides in the (S)-(+)-enantiomer”. Journal of Neural Transmission. 88 (2): 157–160. doi:10.1007/BF01244820.
PMID 1632943. S2CID 20110906.
13. ^ JAFFE, IA; ALTMAN, K; MERRYMAN, P (Oct 1964). “The Antipyridoxine Effect of Penicillamine in Man”. The Journal of Clinical Investigation. 43 (10): 1869–73. doi:10.1172/JCI105060. PMC 289631. PMID 14236210.
14. ^
Jump up to:a b Meierhenrich, Uwe J. (2008). Amino acids and the Asymmetry of Life. Berlin, GER: Springer. ISBN 978-3540768852.
15. ^ McKee, Maggie (2005-08-24). “Space radiation may select amino acids for life”. New Scientist. Retrieved 2016-02-05.
16. ^
Meierhenrich Uwe J., Nahon Laurent, Alcaraz Christian, Hendrik Bredehöft Jan, Hoffmann Søren V., Barbier Bernard, Brack André (2005). “Asymmetric Vacuum UV photolysis of the Amino Acid Leucine in the Solid State”. Angew. Chem. Int. Ed. 44 (35): 5630–5634.
doi:10.1002/anie.200501311. PMID 16035020.
17. ^ Srinivasarao, M. (1999). “Chirality and Polymers”. Current Opinion in Colloid & Interface Science. 4 (5): 369–376. doi:10.1016/S1359-0294(99)00024-2.
18. ^ von Zelewsky, A. (1995). Stereochemistry
of Coordination Compounds. Chichester: John Wiley.. ISBN 047195599X.
19. ^ Hartwig, J. F. Organotransition Metal Chemistry, from Bonding to Catalysis; University Science Books: New York, 2010. ISBN 189138953X
20. ^ Bhushan, R.; Tanwar, S. J. Chromatogr.
A 2010, 1395–1398. (doi:10.1016/j.chroma.2009.12.071)
21. ^ Ravi Bhushan Chem. Rec. 2022, e102100295. (doi:10.1002/tcr.202100295)
22. ^ Eliel, E.L. (1997). “Infelicitous Stereochemical Nomenclatures”. Chirality. 9 (56): 428–430. doi:10.1002/(sici)1520-636x(1997)9:5/6
<428::aid-chir5>3.3.co;2-e. Archived from the original on 3 March 2016. Retrieved 5 February 2016.
23. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “asymmetric synthesis”. doi:10.1351/goldbook.E02072
24. ^
IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “enantiomerically enriched (enantioenriched)”. doi:10.1351/goldbook.E02071
25. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed.
(the “Gold Book”) (1997). Online corrected version: (2006–) “enantiomer excess (enantiomeric excess)”. doi:10.1351/goldbook.E02070
26. ^ Frankel, Eugene (1976). “Corpuscular Optics and the Wave Theory of Light: The Science and Politics of a
Revolution in Physics”. Social Studies of Science. 6 (2). Sage Publications Inc.: 147–154. doi:10.1177/030631277600600201. JSTOR 284930. S2CID 122887123.
27. ^ Pasteur, L. (1848). Researches on the molecular asymmetry of natural organic products,
English translation of French original, published by Alembic Club Reprints (Vol. 14, pp. 1–46) in 1905, facsimile reproduction by SPIE in a 1990 book.
28. ^ Eliel, Ernest Ludwig; Wilen, Samuel H.; Mander, Lewis N. (1994). “Chirality in Molecules
Devoid of Chiral Centers (Chapter 14)”. Stereochemistry of Organic Compounds (1st ed.). New York, NY, USA: Wiley & Sons. ISBN 978-0471016700. Retrieved 2 February 2016.
29. ^ Bentley, Ronald (1995). “From Optical Activity in Quartz to Chiral
Drugs: Molecular Handedness in Biology and Medicine”. Perspect. Biol. Med. 38 (2): 188–229. doi:10.1353/pbm.1995.0069. PMID 7899056. S2CID 46514372.
30. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected
version: (2006–) “Optical isomers”. doi:10.1351/goldbook.O04308
31. ^ Werner, A. (May 1911). “Zur Kenntnis des asymmetrischen Kobaltatoms. I”. Berichte der Deutschen Chemischen Gesellschaft (in German). 44 (2): 1887–1898. doi:10.1002/cber.19110440297.
32. ^
Friedman, L.; Miller, J. G. (1971). “Odor Incongruity and Chirality”. Science. 172 (3987): 1044–1046. Bibcode:1971Sci…172.1044F. doi:10.1126/science.172.3987.1044. PMID 5573954. S2CID 25725148.
33. ^ Ohloff, Günther; Vial, Christian; Wolf,
Hans Richard; Job, Kurt; Jégou, Elise; Polonsky, Judith; Lederer, Edgar (1980). “Stereochemistry-Odor Relationships in Enantiomeric Ambergris Fragrances”. Helvetica Chimica Acta. 63 (7): 1932–1946. doi:10.1002/hlca.19800630721.

1. Organic
Chemistry (4th Edition) Paula Y. Bruice. Pearson Educational Books. ISBN 9780131407480
2. ^ Organic Chemistry (3rd Edition) Marye Anne Fox, James K. Whitesell Jones & Bartlett Publishers (2004) ISBN 0763721972
3. ^ IUPAC, Compendium of Chemical
Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “Chirality”. doi:10.1351/goldbook.C01058
4. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “Superposability”.
doi:10.1351/goldbook.S06144
5. ^ Cotton, F. A., “Chemical Applications of Group Theory,” John Wiley & Sons: New York, 1990.
6. ^ ^ Streitwieser, A. Jr.; Wolfe, J. R. Jr.; Schaeffer, W. D. (1959). “Stereochemistry of the Primary Carbon. X.
Stereochemical Configurations of Some Optically Active Deuterium Compounds”. Tetrahedron. 6 (4): 338–344. doi:10.1016/0040-4020(59)80014-4.
7. ^ Jump up to:a b Pashenko, Alexander E.; Gaidai, Alexandr; Hryhoriev, Nazar; et al. (2023). “Scale-Up
Synthesis of 1-Methyladamantane and Its Functionalization as a Key Point for Promising Antiviral Agents”. Organic Process Research & Development. 27 (3): 477–487. doi:10.1021/acs.oprd.2c00305. ISSN 1083-6160.
8. ^ Mislow, Kurt; Siegel, Jay (May
1984). “Stereoisomerism and local chirality”. Journal of the American Chemical Society. 106 (11): 3319–3328. doi:10.1021/ja00323a043. ISSN 0002-7863.
9. ^ Gal, Joseph (2012). “The Discovery of Stereoselectivity at Biological Receptors: Arnaldo
Piutti and the Taste of the Asparagine Enantiomers-History and Analysis on the 125th Anniversary”. Chirality. 24 (12): 959–976. doi:10.1002/chir.22071. PMID 23034823.
10. ^ Jump up to:a b c Theodore J. Leitereg; Dante G. Guadagni; Jean Harris;
Thomas R. Mon; Roy Teranishi (1971). “Chemical and sensory data supporting the difference between the odors of the enantiomeric carvones”. J. Agric. Food Chem. 19 (4): 785–787. doi:10.1021/jf60176a035.
11. ^ Lepola U, Wade A, Andersen HF (May
2004). “Do equivalent doses of escitalopram and citalopram have similar efficacy? A pooled analysis of two positive placebo-controlled studies in major depressive disorder”. Int Clin Psychopharmacol. 19 (3): 149–55. doi:10.1097/00004850-200405000-00005.
PMID 15107657. S2CID 36768144.
12. ^ Hyttel, J.; Bøgesø, K. P.; Perregaard, J.; Sánchez, C. (1992). “The pharmacological effect of citalopram resides in the (S)-(+)-enantiomer”. Journal of Neural Transmission. 88 (2): 157–160. doi:10.1007/BF01244820.
PMID 1632943. S2CID 20110906.
13. ^ JAFFE, IA; ALTMAN, K; MERRYMAN, P (Oct 1964). “The Antipyridoxine Effect of Penicillamine in Man”. The Journal of Clinical Investigation. 43 (10): 1869–73. doi:10.1172/JCI105060. PMC 289631. PMID 14236210.
14. ^
Jump up to:a b Meierhenrich, Uwe J. (2008). Amino acids and the Asymmetry of Life. Berlin, GER: Springer. ISBN 978-3540768852.
15. ^ McKee, Maggie (2005-08-24). “Space radiation may select amino acids for life”. New Scientist. Retrieved 2016-02-05.
16. ^
Meierhenrich Uwe J., Nahon Laurent, Alcaraz Christian, Hendrik Bredehöft Jan, Hoffmann Søren V., Barbier Bernard, Brack André (2005). “Asymmetric Vacuum UV photolysis of the Amino Acid Leucine in the Solid State”. Angew. Chem. Int. Ed. 44 (35):
5630–5634. doi:10.1002/anie.200501311. PMID 16035020.
17. ^ Srinivasarao, M. (1999). “Chirality and Polymers”. Current Opinion in Colloid & Interface Science. 4 (5): 369–376. doi:10.1016/S1359-0294(99)00024-2.
18. ^ von Zelewsky, A. (1995).
Stereochemistry of Coordination Compounds. Chichester: John Wiley.. ISBN 047195599X.
19. ^ Hartwig, J. F. Organotransition Metal Chemistry, from Bonding to Catalysis; University Science Books: New York, 2010. ISBN 189138953X
20. ^ Bhushan,
R.; Tanwar, S. J. Chromatogr. A 2010, 1395–1398. (doi:10.1016/j.chroma.2009.12.071)
21. ^ Ravi Bhushan Chem. Rec. 2022, e102100295. (doi:10.1002/tcr.202100295)
22. ^ Eliel, E.L. (1997). “Infelicitous Stereochemical Nomenclatures”. Chirality.
9 (56): 428–430. doi:10.1002/(sici)1520-636x(1997)9:5/6
<428::aid-chir5>3.3.co;2-e. Archived from the original on 3 March 2016. Retrieved 5 February 2016.
23. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “asymmetric synthesis”. doi:10.1351/goldbook.E02072
24. ^
IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “enantiomerically enriched (enantioenriched)”. doi:10.1351/goldbook.E02071
25. ^ IUPAC, Compendium of Chemical Terminology, 2nd
ed. (the “Gold Book”) (1997). Online corrected version: (2006–) “enantiomer excess (enantiomeric excess)”. doi:10.1351/goldbook.E02070
26. ^ Frankel, Eugene (1976). “Corpuscular Optics and the Wave Theory of Light: The Science and Politics
of a Revolution in Physics”. Social Studies of Science. 6 (2). Sage Publications Inc.: 147–154. doi:10.1177/030631277600600201. JSTOR 284930. S2CID 122887123.
27. ^ Pasteur, L. (1848). Researches on the molecular asymmetry of natural organic
products, English translation of French original, published by Alembic Club Reprints (Vol. 14, pp. 1–46) in 1905, facsimile reproduction by SPIE in a 1990 book.
28. ^ Eliel, Ernest Ludwig; Wilen, Samuel H.; Mander, Lewis N. (1994). “Chirality
in Molecules Devoid of Chiral Centers (Chapter 14)”. Stereochemistry of Organic Compounds (1st ed.). New York, NY, USA: Wiley & Sons. ISBN 978-0471016700. Retrieved 2 February 2016.
29. ^ Bentley, Ronald (1995). “From Optical Activity in
Quartz to Chiral Drugs: Molecular Handedness in Biology and Medicine”. Perspect. Biol. Med. 38 (2): 188–229. doi:10.1353/pbm.1995.0069. PMID 7899056. S2CID 46514372.
30. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”)
(1997). Online corrected version: (2006–) “Optical isomers”. doi:10.1351/goldbook.O04308
31. ^ Werner, A. (May 1911). “Zur Kenntnis des asymmetrischen Kobaltatoms. I”. Berichte der Deutschen Chemischen Gesellschaft (in German). 44 (2): 1887–1898.
doi:10.1002/cber.19110440297.
32. ^ Friedman, L.; Miller, J. G. (1971). “Odor Incongruity and Chirality”. Science. 172 (3987): 1044–1046. Bibcode:1971Sci…172.1044F. doi:10.1126/science.172.3987.1044. PMID 5573954. S2CID 25725148.
33. ^
Ohloff, Günther; Vial, Christian; Wolf, Hans Richard; Job, Kurt; Jégou, Elise; Polonsky, Judith; Lederer, Edgar (1980). “Stereochemistry-Odor Relationships in Enantiomeric Ambergris Fragrances”. Helvetica Chimica Acta. 63 (7): 1932–1946. doi:10.1002/hlca.19800630721.

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