Refractions, atomic and group

From the atomic and group refractions in Table 5.19, the molar refraction is computed as follows ... 

Rc=0 = O-S-ficarbon + ketonicoxygen and so on. The imperfect additivity of the earlier atomic and structural refractivities is, of course, carried over to bond refractivities by such derivations. The bond refractions of Denbigh or Vogel depend directly upon molecular refractions determined by experiment fundamentally the value found for the methylene group in a homologous series can be written as f CHa = i c—c + 2-RC—h and, correspondingly, the molecular refraction for any n-alkane is... 

Batsanov SS (2003) On the covalent refractions of metals. Russ 1 Phys Chem 77 1374-1376 Noorizadeh S, Parhizgar M (2005) The atomic and group compressibility. 1 Mol Struct Theochem 725 23-26... 

Prentiss, S. W. The reactivity of atoms and groups in organic compounds. IX. The vapor pressures, densities and refractive indices of certain binary mixtures J. Am. Chem. Soc. 1929,51, 2825-2832... 

Polar interactions, which result from dispersion forces (van der Waals interactions) are best described by molar refractiv-ity MR, which is a refractive index-corrected molar volume. Thus, it has also been used to describe steric features of substituents. Like log P, MR is an additive constitutive molecular property which can be calculated from atom and group contributions. " ... 

Uric acid is odourless in spite of three carbonyl groups, four trivalent nitrogen atoms and a double bond, and that it is similarly colourless in spite of four chromophores. Measurements of its refractive and dispersive properties indicate that it is a saturated body which suggests that molecular attraction exists between the various groups. 

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