Chirality

Cornelius Krasel (krasel@alf.biochem.mpg.de)
Fri, 20 Jan 1995 21:07:30 +0100 (GMT)

Hi together,

to fill this list with a bit more of life ...

> BTW, look at "chirality" - have the pictures came through ?

I had a look at the "chiral" definition and it's excellent! However, I would
like to ask two questions since the given definition of chirality seems to be
different from what I have learned when I wasn't a PhD student yet:

1) Chirality as defined in the glossary applies to about any stereoisomer.
I believe that I have learned (a long time ago) that the definition
of chirality comprises only isomers which are mirror images of
each other -- that is, it includes what is called Point chirality,
Dot chirality and Planar chirality, but not Axial chirality. Am
I completely wrong here?

2) I would like to point out that many but not all substances with
an asymmetric carbon atom are chiral (in my definition). E.g.

OH
!
H-C-CH3
!
H-C-CH3
!
OH

definitely contains two assymmetric C atoms but does not form
stereoisomers, since a symmetry axis can be put through the
C-C-bond between C2 and C3.

3) The three guys who invented the R,S nomenclature were
Cahn, Ingold and Prelog (so much for the typo side :-).

4) Some bonds in the GIFs are missing on my viewer (NCSA Mosaic 200A17
PPC). In detail:

In R-1-bromo,1-deutero ethane the C-Me and the C-Br bond
In S-1-bromo,1-deutero ethane the C-Me bond
In E-1-chloro,2-methyl ethylene the C-Me bond
In Z-1-chloro,2-methyl ethylene the C-Me bond
In the dot chirality example all bonds from the rings to the
substituents (sorry, I'm to lazy to figure out the systematic
name :-)
In the planar chirality example the bond between the benzene ring
and the Br.

I will have a look at those pictures tomorrow with Xmosaic, maybe
it's a fault of the viewer (I am under the impression that this
Mac version of Mosaic has sometimes troubles with Inline-Gifs).

See you during the course,

--Cornelius.

-- 
/* Cornelius Krasel, Abt. Lohse, Genzentrum, D-82152 Martinsried, Germany  */
/* email: krasel@alf.biochem.mpg.de                 fax: +49 89 8578 3795  */
/* "Science is the game you play with God to find out what His rules are." */