The BF3 Affinity Scale Data

Most BF3 affinities in Table 3.3 are primary values measured in dichloromethane. This solvent was chosen because it can dissolve most BF3 complexes, while being rather inert (low hydrogen-bond acidity, Lewis basicity and relative permittivity). Nitrobenzene also exhibits good solvent properties towards BF3 complexes, and some measurements were run on representative bases, in both C6H5NO2 and CH2CI2. A very good linear relationship was observed [5] between the enthalpy changes of reaction 3.4 in dichloromethane and nitrobenzene  

This relation, established for bases 41, 49, 50, 75, 79, 82, 84, 116, 287, 305, 311 and 339 in Table 3.3, covers a wide range of reactivity, about 100 kJ moP, from dimethyl sulfite to 4-dimethylaminopyridine hence it can be safely used for calculating secondary BF3 affinities, as described below. 

In order to minimize the dissociation of weakly stable complexes, some measurements were made on pure bases (bulk liquids). They correspond to reaction  

49 4-Dimethylami nopyridine Five-membered aromatic N-heterocyck 4-Me2NCsH4N 151.55 0.76 [48] 

96 Aliphatic ketones Di-tert-butyl ketone t-BuCO-t-Bu 31.32 0.41 [5] 

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