Unit 4.1 - Stereoisomerism (PhysicsandMaths) Flashcards
what are stereoisomers
compounds with same structural formula with different spatial arrangement of atoms
How is stereoisomerism different to structural isomerism
structural isomers = same molecular formula, different structural formula
stereo isomers =same molecular formula, same structural formula, different spatial arrangement
2 main types of stereoisomerism
- optical isomerism
- E-Z isomerism
what is E-Z isomerism
occurs due to restricted rotation around C=C ∴ if both C=C have different groups attached to them, different isomers produced
what is an E-isomer
- high priority groups are diagonally across from each other
what is a Z isomer
- high priority groups are on the zame zide
how do you determine priority of the groups in E-Z
on each carbon, atom with higher atomic number gets higher priority
what is optical isomerism
type of stereoisomerism
- optical isomers have same structure but are non-superimposable mirror images of eachother
what is a chiral centre
carbon with four different groups attached to it
why is a chiral centre required for optical isomerism
chiral centre has 4 different groups attached to it
groups can be attached in different ways to give 2 different ways = optical isomers
what is an enantiomer
two different molecules which are non-superimposable mirror images of each other and arise from optical isomerism
(another name for an optical isomer)
explain the optical activity of optical isomers
optical isomers are optically active ∴ rotate plane polarised light
how does optical activity differ for a pair of entantomers
2 enantiomers will rotate plane polarised light in opposite directions
what is a racemic mixture
a mixture which contains equal quantities of each enantiomer of an optically active compound
why is optical isomerism a problem for the drug industry
often, only 1 enantiomer is effective due to an enzyme’s active site being 3D.
A reaction can be modified to produce a single enantiomer but it is difficult and expensive
