8-9th enantiomers - CM1012 Engineer Chemistry Chapter 9 in...

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1 CM1012 – Engineer Chemistry Chapter 9 in Burrow, Halman, Parsons, Pilling, Price ‘Carbon with chiral centre’ Dr Hai Deng Room 034 Meston Building Email: h.deng@abdn.ac.uk
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Configurational isomers: isomers with chiral centres h any structure that has no plane of symmetry can exist as two mirror-image forms (enantiomers) h any structure with a plane of symmetry cannot exist as two enantiomers
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Chirality and achirality in daily life hands are chiral (Greek: cheir ) feet are chiral (shoes too) gloves are chiral (apart from most lab gloves!) socks are not chiral (usually!)
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Configurational isomers: isomers with chiral centres h if a molecule contains one carbon atom carrying four different groups it will not have a plane of symmetry and must therefore be chiral h a carbon atom carrying four different groups is a stereogenic or chiral centre h A chiral molecule and its non-superimposable mirror image are special types of configurational isomers called enantiomers
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Optical activity: rotation of plane-polarized light polarimetry : observation of the rotation of plane-polarized light • rotation in a clockwise direction is given a positive value, rotation in an anticlockwise is a negative one c enantiomers have different interactions with plane-polarized light;
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Properties of enantiomers h enantiomers have identical physical properties (e. g. melting points) h enantiomers have identical spectroscopical properties (e. g. UV, IR, NMR spectra, MS) h enantiomers cannot be separated by conventional chromatographic techniques (e. g. TLC, GC, HPLC) h single important exception: enantiomers rotate plane-polarized light in opposite directions
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Properties of enantiomers h enantiomers have identical physical properties (e. g. melting points) h enantiomers have identical spectroscopical properties (e. g. UV, IR, NMR spectra, MS) h enantiomers cannot be separated by conventional chromatographic techniques (e. g. TLC, GC, HPLC) h single important exception: enantiomers rotate plane-polarized light in opposite directions
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Properties of enantiomers h If only one enaniomer is present, a sample is considered to be opitcally pure . h Racemate (Racemic mixture): an equal mixture of two enantiomers and can be designated as (±). h Racemization : a process that a pure enantiomer can be transformed into a racemate h Resolution : a process that a racemate can be separated into its component enantiomers. h
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8-9th enantiomers - CM1012 Engineer Chemistry Chapter 9 in...

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