Vibrational and NMR spectra of alkali metal salts of 3-amino-, 3-hydroxy- and 3-halogenobenzoic acids

The alkali metal series (Li→Na→K→Rb→Cs) of 3-amino-, 3-hydroxy- and 3-halogenobenzoates were studied. The FT-IR and FT-Raman spectra of lithium, sodium, potassium, rubidium and cesium salts were recorded, assigned, analyzed and compared. The electronic and NMR (1H and 13C) spectra were recorded and analyzed too. The wavenumbers of the bands are different in the series Li→Cs in the case of all studied acids. The influence of various substituents: amino, hydroxyl and halogen groups on the electronic charge distribution in studied compounds were investigated. The wavenumbers of the aromatic ring bands change toward the series of studied substituents. Most of them increase in the series I→NH2→OH (18a in IR and Raman spectra, 18b in IR spectra, 19a and 6a in IR spectra). The magnitudes of separation between wavenumbers due to asymmetrical and symmetrical stretching vibration of COO− group increases in the series H→NH2→I→OH for potassium, sodium and rubidium.