Stereochemistry Chemistry^3 Mindmap
- Created by: Strelly22
- Created on: 15-12-22 17:52
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- Stereochemistry
- Isomerism
- structural isomers = atoms are joined together in a different order
- chain, position or functional group
- stereoisomers = joined together in the same order but different positions
- eg. e/z or with chiral centre
- structural isomers = atoms are joined together in a different order
- Conformational Isomers
- conformer = different spatial arrangements of the same compound that are readily interconverted by rotation
- ethane
- staggered
- H atoms on adjacent carbons are as far apart as possible
- eclipsed
- H atoms on adjacent carbons are as close as possible
- torsional strain = energy difference between eclipsed and staggered
- staggered
- butane
- eclipsed = syn-periplanar and anticlinal
- staggered = anti-periplanar and synclinal
- 1. syn-periplanar [severe steric and torsional strain]
- 2. synclinal [60 degree ch3 rotation from 1 carbon]
- 3. anticlinal [120 degree ch3 rotation]
- 4. anti-periplanar [180 degree ch3 rotation, as far apart as possible]
- 3. anticlinal [120 degree ch3 rotation]
- 2. synclinal [60 degree ch3 rotation from 1 carbon]
- cycloalkanes
- cyclopropane - high torsional and angle strain
- overlap between 2sp3 orbitals is less than normal C-C ? weaker ? more reactive
- cyclobutane - planar is highly strained ? butterfly conformation ? reduce torsional strain [does ? angle strain but worth it]
- cyclopentane - high torsional strain, low angle strain ? envelope conformation [? angle strain but worth it]
- cyclohexane - angle and torsional strain ? chair conformation
- axial = up and down, equatorial = parallel in the ring
- interconnecting conformations = ring flip / inversion
- cycloalkane increases, angle strain reduces
- cyclopropane - high torsional and angle strain
- Configurational isomers
- E and Z isomers
- E = opposite sides
- Z = same side
- trans = E, cis = Z
- Isomers with chiral centres
- enantiomer = non-identical molecules that are mirror images [identical physical and chemical properties]
- - enantiomer ? anticlockwise, laevorotary
- + enantiomer ? clockwise, dextrorotary
- optical rotation = observed rotation x 100 / path length x concentration
- 1 enantiomer = optically pure
- racemate / racemic mixture = equal mixture of 2 enantiomers, optically inactive
- enantiomeric excess = % major enantiomer - % minor enantiomer = observed optical rotation x 100 / optical rotation of pure enantiomer
- R = clockwise S = anticlockwise
- diastereoisomers = stereoisomers with more than 1 chiral centre that aren't mirror images
- have different physical and chemical properties
- meso compounds = more than 1 chiral centre but is achiral because of an internal plane of symmetry
- enantiomer = non-identical molecules that are mirror images [identical physical and chemical properties]
- E and Z isomers
- Isomerism
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