Basicity proton affinity

Nucleophilicity. A distinction is usually made between nucleophilicity and Lowry-Bronsted basicity [213]. The latter involves specifically reaction at a proton which is complexed to a Lewis base (usually H2O), while the former refers to reactivity at centers other than H. Linear correlations have been shown for gas-phase basicity (proton affinity) and nucleophilicity of nitrogen bases toward CH3I in solution [214] where the solvent is not strongly involved in charge dispersal. In each case, reaction of the base/nucleophile... 

Understanding the behavior of organic bases in solution requires some knowledge of their gas phase (intrinsic) basicities (proton affinities (PA)). These can be determined by ICR methods or by variable-temperature pulsed high-pressure mass spectrometry. Both methods afford basicities (termed thermodynamic vs. kinetic basicity), which have been compared in (91JOC179). 

TABLE 14. Gas phase basicities, proton affinities and hydride affinities for cations... 

In order to understand the difference in basicity, proton affinity and stability of complexes of N, on the one hand, and As, Sb and Bi on the other, we discuss the stability of ammonium vs arsonium chloride. Using a simple Bom-Haber approach as described in Reference 34 we can estimate the heat of reactions 28-31 AH°) as summarized in Table 1. All data were estimated as illustrated in Schemes 1-5. 

Gas-Phase Basicities, Proton Affinities, and Adiabatic and Vertical Ionization Potenhals of Compounds of N, O, P, and S with Various Hybridizations at 25°C ... 

Gas-Phase Basicities, Proton Affinities, and Derived Inductive and Resonance Effects for... 

Thus, the relationship between the gas-phase basicity, proton affinity and entropy of protonation is given by... 

The results of these recent experimental proton transfer equilibrium studies indicated that portions of the 1984 gas-phase basicity/proton affinity scale were constricted. For example, in the 1984 scale the difference between the proton affinities of isobutene and ammonia was given as 33.5 kj moH, while according to the newer results, this interval is actually about 50 kJ moH. Also, these experimental results indicated that the portion of the 1984 scale representing gas-phase basicities/proton affinities higher than that of ammonia (a portion of the scale that was not anchored by data for a primary standard) was seriously constricted. 

Yassin, F. H. Marynick, D. S. Computational estimates of the gas-phase basicities, proton affinities and ionization potentials of the six isomers of... 

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