From: Jonathan Brecher (jsb$##$cambridgesoft.com)
Date: Thu Dec 04 2003 - 12:00:07 EST
At 8:41 PM -0500 12/3/03, Jacob Zabicky wrote:
>What is the correct nomenclature for the relative configuration of two
>groups sticking out on the same side or opposite sides of the "plane"
>defined by a ring? For example, in 1,2-dimethylcyclohexane.
>
>a. The cis-trans nomenclature is unfit because I use it for double
>bonds in the same paragraph.
You don't have to like it, but that is the correct notation. See
http://www.chem.qmul.ac.uk/iupac/stereo/BC.html#26
>b. The alpha-beta convention of saccharides or steroids is unfit
>because I have no convened representation for the ring system as
>reference.
Correct. alpha/beta should not be used without a reference.
>c. Perhaps syn-anti?
No, refers to configuration in bicyclic systems. See
http://www.chem.qmul.ac.uk/iupac/stereo/DE.html#36
>d. Perhaps E-Z?
No, *only* refers to double bonds. See
http://www.chem.qmul.ac.uk/iupac/stereo/DE.html#17
>e. Perhaps erythro-threo?
No, is primarily used for acyclic structures
http://www.chem.qmul.ac.uk/iupac/stereo/DE.html#42
>f. Perhaps something else?
The only nomenclature that is both (a) right and (b) likely to be
understood is cis-trans. You could try some thing like "cis relative to
the ring" if you need to distinguish it from the double bond...
Jonathan Brecher
CambridgeSoft Corporation
jsb$##$cambridgesoft.com
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