The von Auwers' boiling point rule. A new approach

Substructural Analysis Techniques for Empirical Structure-Property Correlation. Application to Stereochemically Related Molecular Properties

“…These results are generally in accord with the findings of previous workers. 23 The contributions for equatorial and axial methyl groups, and for the gem and ortho methyl groups, are similar to those of Kellie and Riddell. Significant contributions were also found for some meta and para related groups.…”

“…Values were available for a set of 60 cyclohexane and dioxane derivatives. 23 This property depends upon intermolecular effects and upon stereochemistry. In this case, equatorial and axial substitution affects conformation and hence boiling point.…”

“…The values are broadly in agreement with those of the original investigators. 23 The difference between contribution to boiling point of equatorial and axial groups for 2-and 4-substituents is noteworthy. Not surprisingly, therefore, the simple correlation using only the number of methyls, and not indicating position, is significantly worse than the best regression: R = 0.859, r = 8.28, df = 29, F = 81.64.…”

“…The data set used comprised 29 methyl cyclohexanes and 31 methyl derivatives of 1,3-dioxane, for which correlations of structural features with boiling point had been described. 23 These structures were encoded in WLN, according to the tentative rules for describing cis-trans isomerism in such systems. Since these compounds are known to exist exclusively in the chair form,24 and since only one type of substituent is present, it is straightforward to determine algorithmically the most stable conformation from the principles of conformational analysis24 using the stereochemical information from WLN.…”

Conformational analysis of substituted 1,2-oxathiane 2-oxides by 13C and 1H nuclear magnetic resonance spectroscopy

“…If 9 were to adopt a twist shape then all the I3C shifts would be expected to go upfield (21) and such a trend is not observed.…”