Notes was contaminated with the meso cis isomer or that partial loss of optical configuration is involved in the (R)-(+)-pulegone -(R)-(+)-5 transformation, perhaps in the dehydration of 1,3-dimethylcyclohexanol to dimethylcyclohexene.

No abstract

It is shown that a correlation of some property, reactivity or biological activity with pure parameters can also be carried out with composite parameters to produce a model with comparable statistics. Modified composite electrical effect parameters can be obtained from known composite electrical effect parameters by means of an algorithm such asin which X is the modified composite electrical effect parameter (MCEEP), X the original composite electrical effect parameter, c a constant and m an exponent. MCEEPs were calculated from this equation with c equal to 2 and m ranging from À4 to 4 when X is m or p , and from À2 to 2 when it is þ p . They were used to model 10 sets of chemical reactivities that had previously been correlated with the pure parameters l , d and e , which represent the localized (field), intrinsic delocalized (resonance) and electronic demand sensitivity electrical effects, respectively. In most cases both the pure and the modified composite parameters give comparable fits to the data as measured by the values of 100R 2 , in accord with the prediction. The composition of the MCEEPs was a linear function of m. The advantage in using pure parameters is that they are readily interpretable. Correlations with composite parameters can be interpreted only if their composition has been determined. These results provide an understanding of the way in which topological parameters work.