Enthalpy hydrogen-bond dependent scales

In the course of this study, the authors determined /Lvalues for dibenzyl, methyl phenyl, methyl p-nitrophenyl, di-p-tolyl, di-isopropyl and tetramethylene sulphoxides and for diethyl, dipropyl and dibutyl sulphites. The /Lscales are applied to the various reactions or the spectral measurements. The /Lscales have been divided into either family-dependent (FD) types, which means two or more compounds can share the same /Lscale, family-independent (FI) types. Consequently, a variety of /Lscales are now available for various families of the bases, including 29 aldehydes and ketones, 17 carboxylic amides and ureas, 14 carboxylic acids esters, 4 acyl halides, 5 nitriles, 10 ethers, 16 phosphine oxides, 12 sulphinyl compounds, 15 pyridines and pyrimidines, 16 sp3 hybridized amines and 10 alcohols. The enthalpies of formation of the hydrogen bond of 4-fluorophenol with both sulphoxides and phosphine oxides and related derivatives fit the empirical equation 18, where the standard deviation is y = 0.983. Several averaged scales are shown in Table 1588. 

Chemometricians may be able to construct many kinds of data matrices Ifom the Lewis basicity scales in this book. For example, matrices might refer to a given family of bases (e.g. nitriles), or a given property (e.g. complexation enthalpies), or a given type of complex (e.g. hydrogen-bonded complexes), or a combination of families, properties and types of complexes. The analysis of judiciously constructed matrices by appropriate chemometric methods should enable the intrinsic fundamental effects in the data matrix to be extracted and used to predict the Lewis basicity and many basicity-dependent properties. 

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