Chapter 4 : Stereochemistry B.sc 1st Year Page : 4 Organic Chemistry
Racemic mixture or Racemic modification
Racemic mixture or racemic modification is an equimolar mixture of two enantiomer. Since it contains equa number of dextro rotatory (+) and levorotatory (-) isomer, the optical rotation is zero. Racemic modifications are usually denoted by prefixing (dl) or (+).
Racemization :
Racemization is the process of producing a racemic mixture starting with one of the pure enantiomer or an achiral molecule. The brominating of n-butane can yield a mixture of 2-bromobutane.
Other example is following hydrolysis reaction :
Inversion of Configuration :
The process of conversion of one enantiomer into another is called emersion of configuration’. If a (+) isomer is converted into its (-) isomer via one or more steps such process involved in inversion of configuration or another compound of opposite optical rotation.
For example, conversion of chloromethane into methanol proceeds via Sn2 mechanism shows an inversion configuration.
Retention :
A process of conversion of one compound into another with the same configuration is called ‘retention’. For example retention and inversion of configuration in nucleophilic substitution exactions. For example, reaction of tertiary butyl bromide with OH-ion results in retention as well as emersion of configuration. As it follows SN1 mechanism.
Walden Inversion:
