Hydrogen-Bond Basicity Scales Early Works

2 Hydrogen-Bond Basicity Scales Early Works 

The first set of equilibrium constants for the hydrogen bonding of a large number of diverse Lewis bases to a given hydrogen-bond donor, in the same conditions of temperature and solvent, which should permit the construction of a Lewis basicity scale, refers to phenol at 20 °C in CCI4. The association constants between phenol and about 200 Lewis bases 

The equilibrium constants of reaction 4.2 are found in three papers. The first [10] collects 25 values, called Ki, determined by the IR method, ranging from K =. 9 mol for diphenyl ether to 3600 1 moU for hexamethylphosphoric triamide. The second paper [7] reports 35 new values determined by the F NMR method, ranging fi om 261 1 mol for tetramethylurea to 1.3 1 mol for diethyl sulfide. In the third paper [9], revised values are given for 19 bases and new values for 20 bases. The scale is extended up to Ki = 45701 moU for triphenylarsine oxide. 

In the absence of primary data, a secondary value may be obtained from Equation 4.6  

Few further determinations of equilibrium constants of the complexation of 4-fluorophenol were reported between 1972 and 1988. Then, Laurence, Berthelot and coworkers (University of Nantes) began to extend the p. HB scale systematically to almost 

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