Chemical properties of trihexyl(tetradecyl)phosphonium chloride and bis(2,4,4-trimethylpentyl)phosphinic acid mixtures: Interaction study by FT-IR and NMR spectroscopies

FT-IR, 31P and 1H NMR spectra of binary Cyanex 272-Cyphos IL 101 mixtures have been recorded at room temperature in the whole range of Cyphos IL 101 molar fraction (x2) in order to investigate the interactions. In agreement with a previous study based on the analysis of the variation of rheological properties of this mixture against the molar fraction of Cyphos IL 101, the present study confirms that (i) for 0 < x2 ≤ 0.3, Cyphos IL 101 may mainly exist as solvent separated ion-pairs such as chloride anions and phosphonium cations separated by Cyanex 272 molecules (Cl−/HL/P+ where HL and P+ represent the protonated Cyanex 272 molecule and the Cyphos IL 101 cation, respectively), (ii) for 0.3 < x2 < 0.6, Cyphos IL 101 may exist predominantly as contact ion-pairs solvated by Cyanex 272 molecules ([Cl−/P+]/HL) and finally (iii) for x2 ≥ 0.6, the contact ion-pairs of Cyphos IL 101 solvated by Cyanex 272 (L−/P+ where L− represents deprotonated Cyanex 272 molecules) start to dissociate to form the contact ion-pairs.