stereochemistry - uniurb.it · nc cn enantiomers and chirality oh ho cn the enantiomers a and b are...
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StereochemistrySome compounds can exist as a pair of mirror-‐image forms
Some compounds can exist as a pair of mirror-‐image forms
Some compounds can exist as a pair of mirror-‐image forms
Chiral molecules have no plane of symmetry
Stereogenic centres
Stereogenic centres
Many chiral molecules are present in nature as single enan:omers
R and S can be used to describe the confi gura:on of a chiral centre
Is there a chemical difference between two enan:omers?
The rota:on of plane-‐polarized light is known as op:cal ac:vity
Enan:omers can be described as (+) or (–)
Enan:omers can be described as D or L
Diastereoisomers are stereoisomers that are not enan:omers
Diastereoisomers can be chiral or achiral
Absolute and rela:ve stereochemistry
Diastereoisomers can arise when structures have more than one stereogeniccentre
Diastereoisomers can arise when structures have more than one stereogenic centre
Why only usually?—achiral compounds with more than one stereogenic centre
Inves:ga:ng the stereochemistry of a compound
Chiral compounds with no stereogenic centres
Axes and centres of symmetry
Axes and centres of symmetry
Separa:ng enan:omers is called resolu:on
Separa:ng enan:omers is called resolu:on
Resolu:ons using diastereoisomeric salts
Resolu:ons can be carried out by chromatography on chiral materials