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pseudo-asymmetric carbon atom

The traditional name for a tetrahedrally coordinated carbon atom bonded to four different entities, two and only two of which have the same constitution but opposite chirality sense. The r/s descriptors of pseudo-asymmetric carbon atoms are invariant on reflection in a mirror (i.e. r remains r, and s remains s), but are reversed by the exchange of any two entities (i.e. r becomes s, and s becomes r). An example is C-3 of ribaric (C-3 is r) or xylaric acid (C-3 is s) or hyoscyamine (C-3 is r). The hyphen in pseudo-asymmetric may be omitted.
P04921
Source:
PAC, 1996, 68, 2193 (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2214
InChI=1/C5H8O7/c6-1(2(7)4(9)10)3(8)5(11)12/h1-3,6-8H,(H,9,10)(H,11,12)/f/h9,11H
NPTTZSYLTYJCPR-FLKJISBTCY
InChI=1/C5H8O7/c6-1(2(7)4(9)10)3(8)5(11)12/h1-3,6-8H,(H,9,10)(H,11,12)/f/h9,11H
NPTTZSYLTYJCPR-FLKJISBTCY
InChI=1/C17H21NO4/c1-18-12-7-8-13(18)10-14(9-12)22-17(21)15(16(19)20)11-5-3-2-4-6-11/h2-6,12-15H,7-10H2,1H3,(H,19,20)/t12?,13?,14?,15-/m1/s1/f/h19H
QDTDAWBMOSCLIB-YXIHWNHFDT
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Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: doi:10.1351/goldbook.P04921.
Original PDF version: http://www.iupac.org/goldbook/P04921.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
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