Mixture of enantiomers
In stereochemistry, mixtures of enantiomers are mixtures of two enantiomers :
- if the mass ratio of the enantiomers is 1: 1, the mixture of enantiomers is called a racemate
- if the mass ratio of the enantiomers is different from 1: 1, this mixture of substances is called a non-racemic mixture of enantiomers.
Emergence
Non-racemic mixtures of enantiomers can arise from racemates if, in the event of an incomplete kinetic resolution - for example under the influence of enzymes such as a lipase - one of the enantiomers is preferentially broken down ; then - if the conversion is not complete - a non-racemic mixture of enantiomers remains. Such kinetic resolution processes can occur in organisms or in the environment. There are also technical processes which are based on the use of kinetic racemate resolution, for example the industrial production of ( S ) - methionine from ( RS ) - N - acetyl methionine.
Even with enantioselective syntheses , non-racemic mixtures of enantiomers are often formed, since such syntheses are generally not enantiospecific.
Chromatography
Non-racemic mixtures of enantiomers can sometimes be separated chromatographically on an achiral stationary phase .
Individual evidence
- ↑ Jürgen Martens and Ravi Bhushan: Resolution of Enantiomers with Achiral Phase Chromatography. In: Journal of Liquid Chromatography . 15 ( 1992 ) 1-27. doi: 10.1080 / 10826079208018806 .
- ↑ Renato Baciocchia, Gianmarco Zenonib, Marco Mazzottic and Massimo Morbidelli: Separation of binaphthol enantiomers through achiral chromatography . In: Journal of Chromatography A , 944 ( 2002 ) 225-240, doi: 10.1016 / S0021-9673 (01) 01366-8 .