Borderline Cases of Asymmetric Transformation

It is obvious from the above that there is no clear-cut distinction between first-order asymmetric transformations, second-order asymmetric transformations, and the process of resolution by salt formation. An acid so optically stable that it does not undergo configurative inversion within the accessible range of experimental conditions will show straightforward resolution but an acid with a marked temperature coefficient of optical inversion might be made to show all three variations of the phenomenon under a ppropriate temperature conditions. 

Kuhn himself recognized the possibility that borderline cases, neither erster Art nor zweiter Art, might exist. Jamison and Turner (54) consider Kuhn s insistence—that an asymmetric transformation is of the second order only if the labile system shows a detectable optical activity after removal of the stable directing system— to be an immaterial and arbitrary distinction  

Jamison and Turner regard this as the essential criterion. 

Read and McMath (122) prepared (—)-hydroxyhydrindaminechloro-bromomethanesulfonate, and observed a marked mutarotation in acetone solution. The salt of the (-f) base showed a corresponding mutarotation in the opposite sense. The authors calculated that the following equilibrium had been set up  

Despite intensive effort, however, they were unable to remove the base in such a way as to liberate an optically active acid, so that, in the narrow sense of Kuhn s original definition, this would have to be classed as a first-order transformation. 

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