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Chapter 7 : Stereochemistry |
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Enantiomers
Molecules that are non-superimposable mirror images are enantiomers,
look at the two CHIME images of molecules shown below and make sure you
can see this. Note that your left and right hands are a pair of enantiomers.
Can you think of any other body parts that exist as enantiomers ? 
You should be able to draw molecules, such
as those given below the CHIME images, to show that they are mirror images!
A molecule that can exist as a pair of enantiomers has the property
of chirality (derived from the Greek meaning handedness),
or is described as chiral. A molecule that lacks this property
is achiral.
You should be able to draw the two mirror
images of an achiral molecule and then see how if you rotate one of the
images the two molecules are actually the same (i.e. that they are superimposable)
Important properties of enantiomers that you should
know:
-
Same physical properties except that they rotate plane polarised
light in opposite directions (see later).
-
Same chemical properties except when another chiral molecule is
involved.
Other things to know:
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A mixture that contains equal quantities of enantiomers is
called a racemate or a racemic mixture.
