Optical Isomerism Flashcards
Define stereoisomers
Stereoisomers are molecules that have the same structural formula but have the atoms arranged differently in space
What are the two types of stereo isomerism?
Geometrical (E/Z) isomerism and Optical isomerism
What is a chiral centre?
Has four different atoms or groups of atoms attached to it
What is an enantiomer?
Compounds with a chiral centre exists as two optical isomers known as enantiomers
Enantiomers are non-superimposable, true or false?
True
Define non-superimposable?
something cannot be rotated or placed on top of another object without some points not matching.
How could you distinguish between separate samples of the two enantiomers
Plane polarised light rotates each enantiomers either clockwise or anticlockwise so the enantiomers are optically active
Why does the reaction produce a racemic mixture?
The planar carbonyl group can be attacked from either side with equal probability
Explain Net Optical activity
Let’s suppose that in a solution, there is 20% of the enantiomer which rotates the plane polarised light clockwise and 80% of the enantiomer which rotates the plane of polarised light anticlockwise
There is an uneven mixture of each enantiomer, so the reaction mixture is said to be optically active
The net effect is that the plane of polarised light will be rotated anticlockwise
Define a racemic mixture
A racemic mixture (or racemate) is a mixture in which there are equal amounts of enantiomers present in the solution
A racemic mixture is optically inactive, true or false? Explain your reasoning.
True
A racemic mixture is optically inactive as the enantiomers will cancel out each others effect and the plane of polarised light will not change
Explain how a structural feature of the enzyme enables it to catalyse the hydrolysis of isomer G but not the hydrolysis of isomer F
Enzyme has an active site and the correct stereochemistry
How many isomers are represented by the formula C5H12?
3
