Conformational dissymmetry model

These considerations, thus, lay the groundwork for tests among several semi-empirical approaches to the estimation of optical rotation of bond systems regarded as helices. Should it be necessary to use Eq. (lb) rather than (la), then a sweeping reassessment of the use of the helical conductor model will be required. However that test turns out, a test between that model and the simple conformational dissymmetry model becomes possible on the basis of the material shown in Table 1. At this point it should be said that our calculations on twistane 16> support the helical conductor model but that the results obtained by Pino and his co-workers 17 18> on the chiroptical properties of isotactic polymers prepared from chiral a-olefins support the conformational dissymmetry model. [We are not able, at present anyhow, to account for their results with the helical conductor model]. 

Rotivity contributions for some common conformational units were calculated by the use of equation 12 and are compared with those used with the empirical Conformational Dissymmetry Model (Table 13). 

In the original Conformational Dissymmetry Model (above), the digauche conformations 20c and 21 were considered to be forbidden all others were equally allowed . It would be more realistic to consider that conformers are neither forbidden nor allowed. 

To apply the Conformational Dissymmetry Model to 31, the bond angle and torsion angle corrections of the Helix Model are required ... 

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