Halogen compounds correlation table

The correlation table for halogen compounds is in Appendix 2, Table A2.13. 

Halogenated phenols correlate well with Hammett s constant (a). Figure 6.24 shows the linear trend of the c values of 3-chlorophenol, 4-chlorophenol, 3,4-dichlorophenol, and 3,5-dichlorophenol with respect to their first-order reaction rate constants. Aromatic compounds with substituents in the meta and para positions have pronounced steric differences and result in a well-defined trend. Table 6.9 summarizes all the QSAR models discussed above. 

The two other methods suggested by Deverell - the "T " and the "6 vs. T2" methods in the abbreviated terminology of Table 6.1 - have some attractive features. There are indications of a correlation between quadrupolar coupling constants and shielding values for halide nuclei in covalent halogen compounds (cf. Subsection 3.1.3) - corre-... 

Halogens are important since these elements form compounds with the vast majority of the other elements in the periodic table. By means of easy concepts such as the pseudohalogen concept, correlation between structure, bonding and properties can be predicted for unknown compounds. 

While the boiling points of chloro- and bromomethanes always increase according to the number of halogen atoms, this correlation does not exist in the case of fluoromethanes. The bp increases from CH4 to CH2F2 and then decreases until CF4 (Table 1.4). Indeed, a parallelism exists between boiling points and dipolar moments. A partially fluorinated compound will exhibit nonnegligible intermolecular interactions according to the importance of the dipolar moment (Table 1.5). ... 

Returning to the statistics for dipole moment in Table 6.8, the group of 265 compounds containing oxygen (but no other heteroatom except halogen) shows the lowest correlations between the semiempirical methods and B3LYP (AMI R2 = 0.776, PM3 R2 = 0.701, PM5 R2 = 0.726) except for PM5 with a still slightly lower R2 value for the 42 compounds with phosphorus or sulfur atoms or both (0.716). Moreover, with both AMI and PM3 the 276 non-aromatic compounds yield lower correlation coefficients than the 331 aromatic compounds (AMI 0.763 vs. 0.859, PM3 0.731 vs. 0.801). 

Fig. 2. Re-establishment of Hammett correlation for halogen-substituted phenols in the reaction with polyvinyl acetate radical. The straight line represents the Hammett equation found for 26 compounds (No. 12 in Table 3). Key o non-halogen substituted phenols including 2,6-dimethylphenols, excluding 2,6-t-Bu2-4-substituted-phenols halogen-substituted phenols.

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