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- W2331248051 abstract "[Manuscript received November 5, 19501. The diastereoisomeric acetals derived &om (&)-camphor and (-)-butane2,3-diol have been completely separated by gas-liquid chromatography,l but our attempts to apply such acetalization to the optical resolution of other cyclic ketones were unsuccessful. We now describe a simple procedure suitable for the g.1.c. separation of many asymmetric acyclic, monocyclic, and steroidal ketones. The method depends on the formation of diastereoisomeric hydrazones separable by g.1.c. The reagent 2,2,2-trifluoroethyl-1-phenylhydrazine is readily prepared from the commerically available 2,2,2-trifluoroacetophenone and the (+) enantiomer can be obtained optically pure by fractional crystallization of the diastereoisomeric hydrazones derived from 5cc-androstan-17-one, followed by acid hydrolysis. To establish the utility of the gas chromatographic method for the determination of optical purity of asymmetric ketones, it is essential to show that the steric purity of the ketone is retained during hydrazone formation. Since monocyclic ketones, such as (I), (2), (3), (7), and (9) (Table 1) are difficult to prepare and to maintain in an optically pure form, this check was done by condensing 2,6,6-trideutero-2-methylcyclohexanone (2) with the reagent. By a mass spectrometric examination of the resulting hydrazone, it was shown that approximately 30% of the deuterium label had been lost during the condensation reaction. One must conclude that some racemization of the ketone by either enolization or carbanion formation had occurred under our reaction conditions. However, sterically pure hydrazones were obtained from the optically pure ketones (5), (ll), (20), and (21), which are sterically more hindered, and from all ketones which have an asymmetric tertiary cc carbon atom" @default.
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- W2331248051 date "1971-01-01" @default.
- W2331248051 modified "2023-10-18" @default.
- W2331248051 title "The use of (+)-2,2,2-Trifluoro-1-phenylethylhydrazine in the optical analysis of asymmetric ketones by gas chromatography" @default.
- W2331248051 doi "https://doi.org/10.1071/ch9711103" @default.
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