INDEXES Bond dissociation energy

Physical Properties. Properties of some alkyl peroxyesters are Hsted in Table 13 and the properties of some alkyl areneperoxysulfonates are given in Table 14. Mass spectra (226), total energies, and dipole moments (227) oxygen—oxygen bond-dissociation energies (44,228) and boiling points, melting points, densities, and refractive indexes (44,168,213) have been reported for a variety of tert-huty peroxycarboxylates. 

The BDB variant of BP was used to predict the density, viscosity, and refractive index of ternary and quaternary liquid systems based on training data from binary systems.Performance was acceptable, although a theoretical equation gave better predictions in a number of cases. BDB has also been applied to the prediction of bond dissociation energies. ... 

Bond energy term values do not bear a simple relation to bond dissociation energies, and are not necessarily numerically identical with them on the contrary, the two measures often differ by substantial amounts. The widespread acceptance of E values as an index of bond strength continues nonetheless, largely as a matter of expediency due to the lack of more direct information. 

Figure 6.15 Correlation between the bond dissociation energies of C-H bonds in CH3R molecules and the electrophilicity indexes of the corresponding CHjR radicals.

In Fig. 21.1 the dissociation energy of the weakest bond of the same polymers, supplemented with the data of a number of radical initiators (peroxides and azo compounds) is plotted against the most characteristic index of the heat resistance, viz. the temperature of "half decomposition" (Ta4/2). The relationship is evident, though not sufficiently accurate for a reliable estimate of T yi-... 

It is convenient to first establish some definitions, and these are listed in Table 6.2. As discussed in Chapter 5, as an adsorbate approaches a surface, changes occur in the potential energy of the system and one must relate this energy, Epot, to the distance, r, from the surface. It is certainly anticipated that the migration and dissociation of an adsorbate, X, on the surface involve changes in the coordination mode, Mn — X, and the M-X distance, r, where M is a metal atom and n is the coordination number. Assuming quasi-spherical interactions, a two-center M-A bond index, x, in the form of Pauling s bond order [23], is defined as... 

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