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Basicity of azoles. 5—Experimental gas phase basicities determined by mass spectrometry towards ab initio calculated protonation energies
Author(s) -
Flammang R.,
Maquestiau A.,
Catalán J.,
Pérez P.,
Elguero J.
Publication year - 1984
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210191208
Subject(s) - protonation , chemistry , ab initio , imidazole , mass spectrometry , molecule , proton affinity , computational chemistry , ab initio quantum chemistry methods , gas phase , indazole , benzimidazole , affinities , ion , stereochemistry , organic chemistry , chromatography
Using Cooks' method, the relative gas phase proton affinities of six azoles (imidazole, benzimidazole, pyrazole, indazole, 1‐methylindazole and 2‐methylindazole) have been determined. Ab initio calculations have been carried out for these six molecules and the corresponding cations, thus allowing the determination of protonation energies. Even the correlation between these quantities (‐log K = 0.438+0.0744δΔ E p ) is far from perfect ( r 2 = 0.863), the order of basicity is the same. Aqueous basicities, p K a values, are totally uncorrelated.