17.1.1 ISOMERISM
27 September 2021
19:45
Structural isomerism is when compounds have the same molecular formula but
different structural formula.
Chain - Different arrangement of C skeleton.
Position - Same functional group attached to a different part of the C chain.
Functional group - Different functional groups.
Stereoisomerism - Same structural formula but atoms have different special
arrangements.
17.1.2 E/Z ISOMERISM
27 September 2021
20:08
Stereoisomerism - Molecules with the same molecular and structural formula have a
different spatial arrangement of bonds.
E/Z isomerism - Occurs when there's restricted rotation about a bond and also
different groups are attached to the C atoms at each end of the bond.
Look at the atoms bonded with each C atom of the C=C double bond.
The atom with the highest atomic number is the priority group.
If the 2 groups have the same atom bonded to the C atom, the next bonded
atom is taken into account.
- If no priority groups, no geometric isomerism.
If the priority groups on the 2 C atoms are:
Opposite - E - Trans-
Same side - Z - Cis-
, 17.1.3 CHIRALITY & OPTICAL ISOMERISM
27 September 2021
20:09
Chiral molecule - Cannot be superimposed on its mirror image.
The chiral C centre has 4 different groups attached to it.
Asymmetric.
Optical isomers - Chiral molecules and its non-superimposable images.
Enantiomers.
Plane-polarised light has a single wavelength and vibrates in one direction.
The plane of polarisation of plane-polarised monochromatic light can be rotated by
optical isomers.
Both enantiomers rotate the plane in opposite directions.
Racemic Mixture - Equal amounts of the two enantiomers of a chiral compound, so
doesn't rotate plane polarised light.
27 September 2021
19:45
Structural isomerism is when compounds have the same molecular formula but
different structural formula.
Chain - Different arrangement of C skeleton.
Position - Same functional group attached to a different part of the C chain.
Functional group - Different functional groups.
Stereoisomerism - Same structural formula but atoms have different special
arrangements.
17.1.2 E/Z ISOMERISM
27 September 2021
20:08
Stereoisomerism - Molecules with the same molecular and structural formula have a
different spatial arrangement of bonds.
E/Z isomerism - Occurs when there's restricted rotation about a bond and also
different groups are attached to the C atoms at each end of the bond.
Look at the atoms bonded with each C atom of the C=C double bond.
The atom with the highest atomic number is the priority group.
If the 2 groups have the same atom bonded to the C atom, the next bonded
atom is taken into account.
- If no priority groups, no geometric isomerism.
If the priority groups on the 2 C atoms are:
Opposite - E - Trans-
Same side - Z - Cis-
, 17.1.3 CHIRALITY & OPTICAL ISOMERISM
27 September 2021
20:09
Chiral molecule - Cannot be superimposed on its mirror image.
The chiral C centre has 4 different groups attached to it.
Asymmetric.
Optical isomers - Chiral molecules and its non-superimposable images.
Enantiomers.
Plane-polarised light has a single wavelength and vibrates in one direction.
The plane of polarisation of plane-polarised monochromatic light can be rotated by
optical isomers.
Both enantiomers rotate the plane in opposite directions.
Racemic Mixture - Equal amounts of the two enantiomers of a chiral compound, so
doesn't rotate plane polarised light.
