Infrared Spectra of Aluminum Hydroxide Chlorides

Abstract

Infrared spectra of aluminum chloride and aluminum hydroxide chloride solute species were determined using a Fourier transform infrared spectrometer. The solutions which were examined contained: aluminum chloride; an aluminum hydroxide chloride with an OH/A1 ratio of 2.4, prepared by dissolving freshly prepared aluminum hydroxide gel in an aluminum chloride solution; and an aluminum hydroxide chloride with an OH/A1 ratio of 2.5, prepared by reacting aluminum metal with an AlCl₃ solution. Significant differences in the infrared spectra were observed. All solute spectra contained bands in the 2500 to 3100 cm⁻¹ region for the stretch of water coordinated to aluminum, with the bands for aluminum chloride solutions most intense. In the bending region for Al—O—H, bands were observed at 970 to 1080 cm⁻¹. The polymeric solute species also had absorption bands, although at different frequencies, in the OH stretch region, 3300 to 3700 cm⁻¹, and in the frequency region from 600 to 800 cm⁻¹.