Waals Volume-molar Refraction Relationships

Van der Waals Volume-Molar Refraction Relationships. Bhatnagar et al. [15] have found a significant correlation between Rd and Vv(jw for alkyl halides 

Source Reprinted with permission from Ref. 14. Copyright (1956) American Chemical Society. 

The phenol substituents include alkyl (C1-C4), alkoxy (C1-C5), and a few other groups. However, the effect of the ring position on RD was not evaluated. 

---

Other molecular properties have been also proposed to model the hydrophobic interactions. The parachor, which is related to the surface tension of a compound (139, 140) represents mainly the intermolecular interactions in a liquid. The Hildebrand-Scott solubility parameter, 6, (141) is related to intermolecular van der Waals forces and the closely related molar attraction constant, F, is obtained by multiplying 6 by the molar volume (142). The partition coefficient between two solvents can be obtained from the solubility parameters and the molar volumes of the solute and the solvents (193). This relationship is based on regular solution theory (194) and the assumption that the partial molar volumes of the solute is not different from its molar volume. Recently this has been criticized and a new derivation was proposed (195) in which the partial molar volumes are taken into account. The molar refractivity, MR, is related to dispersion forces and can be obtained as a sum of the partial molar refractivi-ties assigned to atoms and bonds (140, 143). These parameters have been compared (144) to establish their relative applicability to correlations with biological activity. The conclusion was that logP and molecular refractivity were the best parameters. Parameters obtained from high pressure liquid chromatography (144,... 

---