title: Acid-base equilibria in nonpolar media. 4. Extension of the self-consistent basicity scale in THF medium. Gas-phase basicities of phosphazenes.
abstract: Eleven new phenyl-substituted phosphazenes (P1-, P3-, and P4-bases) have been synthesized by the Staudinger or the Kirsanov reactions. The UV-vis spectrophotometric titration method was used to establish the relative basicity of them, and to extend the ion-pair basicity scale for THF medium. These measurements together with our previous work give a continuous basicity scale in THF ranging from 2.6 (2-MeO-pyridine) to 26.6 (2-Cl-C6H4P4(pyrr) phosphazene) in pKalpha units: that is for 24 orders of magnitude and containing 58 compounds (pyridines, anilines, amines, guanidines, amidines, phosphazenes). Ion-pair formation was taken into account by using the Fuoss equation. DeltapKip values of some phosphazene indicators estimated earlier by the 13C NMR method were revised. For some of the phosphazenes gas-phase basicities were measured.
authors.affiliation: Department of Chemistry, University of Tartu, Jakobi 2, 51014 Tartu, Estonia.
authors.forename: Ivari
authors.initials: I
authors.lastname: Kaljurand
authors.forename: Toomas
authors.initials: T
authors.lastname: Rodima
authors.forename: Aino
authors.initials: A
authors.lastname: Pihl
authors.forename: Vahur
authors.initials: V
authors.lastname: Mäemets
authors.forename: Ivo
authors.initials: I
authors.lastname: Leito
authors.forename: Ilmar A
authors.initials: IA
authors.lastname: Koppel
authors.forename: Masaaki
authors.initials: M
authors.lastname: Mishima