A modification of Trouton's rule

Abstract

Trouton's rule is modified to allow for the fact that the entropy of vaporization is generally a function of the Guldberg ratio and the parachor‐critical volume ratio. The medification has the advantage that it is applicable to non‐associated substances of low boiling‐point, and furnishes a rational basis for their classification into normal and abnormal liquids. Moreover, a high value of the medified ratio is diagnostic of association in the liquid state.

DFT calculations in solution systems: solvation energy, dispersion energy and entropy

“…Table 5 shows the entropy of vaporization S vap of some organic compouds calculated using eqn (20). 26,140,142…”

“…According to the Trouton rule 26,27 and its modifications, [139][140][141][142][143][144][145] the entropy difference between the gas phase and solution is ca. 21.0 cal mol À1 K À1 for most organic materials, which is expressed in modern terms as follows 146 DH vap…”

“…Table 5 shows the entropy of vaporization S vap of some organic compouds calculated using eqn (20). 26,140,142 For single-molecule reactions, the calculation error of entropy can be offset because the number of molecules does not change. However, for bimolecular reactions (A + B-AB), the activation entropy in the liquid phase is ca.…”

Molecular interpretation of Trouton’s and Hildebrand’s rules for the entropy of vaporization of a liquid

“…The prediction of either entropy change, however, is another matter. A variety of quantities on which the entropy changes might depend have been proposed: DH ;pp b [7], the critical temperature and volume [8,9], the sum of atomic number [10], T b [11], molecular mass [11], molecular volume [12][13][14][15][16], symmetry number [17], number of torsions [17], the extent of planarity [17], or type of functional group [18]. None of these, though, have had a firm enough combination of simplicity, accuracy, and a sound theoretical basis to surpass Hildebrand's rule let alone Trouton's rule.…”