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Raman spectra of formamide (FA) and tetrahydrofuran (THF) mixtures at different compositions were obtained. The appearance of new bands at 897 and 1612 cm −1 , whose intensities show large dependence on the FA concentration, are assigned to an FA-THF adduct. This assignment is supported by the Lewis acid-base theory, where the two H-bond donor sites of FA and the strong donor character of THF became the environment propitious for the donor-acceptor reaction. Quantitative measurements performed in the band envelope at ∼915 cm −1 allowed to determine the stoichiometry of the Lewis acid-base adduct. The experimental evidence of the 2 : 1 FA-THF adduct is presented for the first time using Raman spectroscopy and our results show an excellent agreement with similar systems. The present work also shows hydrogen interactions which can be involved in systems containing peptide groups and constituents of nucleic acids.

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Raman spectra of aqueous halate and oxyacids HXO 3 (X = Cl, Br) solutions were obtained. Integrated Raman intensity measurements of the 804 and 933 cm −1 bands of HBrO 3 and HClO 3 in aqueous solutions, respectively, allowed the determination of the degree of dissociation of these acids in the molarity range studied. The results show that these acids are almost completely dissociated until the maximum concentration studied. In addition, we observed that bromic and chloric acid solutions with concentrations ≥3.2 and 2.5 mol L −1 , respectively, decompose to bromine and chlorine at room temperature. The trend of the Raman specific intensities of the halate ions (BrO 3 − > ClO 3 − ) bands in aqueous solutions is discussed and compared with that observed by other workers who considered the contributions of the isotropic and anisotropic components of the polarizability tensor. Measurements of the Raman line broadening of the same bands gave values of 2.6 × 10 11 L mol −1 s −1 for the second-order rate constant of the reaction between H + and BrO 3 − and 3.4 × 10 11 L mol −1 s −1 for the reaction between H + and CIO 3 − .