Re: new entries

Yevdokimov Artiom (
Tue, 14 Feb 95 14:51:16 +0200

Donovan C. Haines wrote : "... I consider stereoisomers to be two
conformations of one molecule that are interconvertible but generally have
very high barriers to this inversion reaction ..."

I cannot agree with this. It is more or less true for chiral N compounds,
and , BTW, not for all of 'em but it is wrong for e.g. C - centered chirality.
One cannot transform C-chiral molecule into its stereoisomer without
braking bonds - and braking bonds is not allowed in the understanding
of the term "conformation". Chirality in general has to do with
configuration - absolute or sometimes relative, not conformation.

In general, I feel sorry for starting the discussion on such a painful
theme by making a mistake in the glossary entry.
Maybe it would be a nice idea to introduce a URL on this subject, if none
exist - I may try to make one. The understanding of chirality is just
a subtask in the group theory, one may consider, that we need terms
"isomorphicity", "anisomorphisity", "symmetry", "topochirality", "topicity"
and many-many others. I'm not sure that biologists need all this - but
str. biologists and XRAY - ist's certainly do need.
Concerning the the notes , that E,Z - isomers have nothing to do with chirality
- I want to say, that I've included them for the sake of completeness. BTW it
seems to me, that to say, that E,Z isomerism does not alter the optical\
properties of the substances is a slight exaggeration. It does. Not exactly
it a way, like polyhedral isomerism does - but it does.

Oh, I'm sorry for the word "brake" it has to be "break", I know, but sometimes
I make silly mistakes in English. :) (some other words too) :(