Question

Define ‘Racemization’.

Answer 1

Hint: Racemisation is the process when the enantiomer is converted into a racemic mixture (by chemical reaction) or when one pure form( which is optically active ) of an enantiomer is converted into equal proportion of both enantiomers, forming a racemate.

Complete step by step solution:
Racemization is a thermodynamically supported process and it proceeds spontaneously if a convenient pathway is available for the interconversion of the enantiomers. It can be reversible as it is a reversible process because mechanism of racemisation must be operated from either of the enantiomers.
Properties of Racemization –
∎ Racemization takes place in SN1 reaction because in SN1 reaction nucleophile attacks from both sides.
∎ Racemization can be done by mixing to equal quantities of enantiomers ( a pair of molecules that are mirrors of each other).
∎ It converts an optically active compound to an optically inactive compound.
∎ Racemic mixture contains equal amounts of (+) and (-) forms .
Example : Example of racemic mixtures are ibuprofen, thalidomide. Racemic acid which is a form of tartaric acid is an mixture of two enantiomers (which are optically active in different directions)

Note: Now we know about racemization that is mixing to equal quantities of enantiomers .This can be done by heat, chemical reaction etc. When (R)-3-phenyl-2-butanone is added in aqueous ethanol that contains NaOH or HCl a racemate is formed .This can convert a optically active form of compound to optically inactive form. Racemic mixtures have no optical activity since its enantiomers have equal and opposite specific optical rotations.