Étude par spectrométrie raman laser de l'extraction liquide-liquide du FeCl3 par le chlorhydrate de trilaurylamine

Raman spectra of aqueous 1 M chloroferrate(III) solutions indicate the presence of FeCl₃ and FeCl₄^- in proportion to the hydrochloric acid concentration, but FeCl₄^- is only present in solutions of acidity higher than 5 M HCl. The liquid-liquid extraction of the aqueous chloroferrate phases ( 1 M HCl) by trilaurylamine hydrochloride in cyclohexane, shows that iron(III) is extracted only in its FeCl₄^- form, even though this species does not appear in the aqueous solutions. A quantitative spectroscopic study of the organic phases by means of the v₁ line of FeCl₄^- at 332 cm^-1 leads to the following conclusions: (a) the plot of the scattering coefficient of the 332 cm^-1 line versus iron(III) concentration shows the presence of two complex species in the organic phase; (b) the distribution curves of the complex species could be calculated. On the basis of the Raman results, an ion-pair type compound is proposed for the two complexes.