Intensities of Infrared Bands in Solution. I. Benzene Solutions

Publisher Website
Google Scholar
Abstract
It is shown that the molar extinction coefficients of band maxima of infrared ``inactive'' fundamentals of benzene in solution are markedly sensitive to the nature of the solvent. CS2, C6H5Br, C6H5Cl, and C5H6N enhance the inactive benzene fundamentals while CCl4, cyclohexane, and several normal paraffins diminish the extinction coefficients. The extinction coefficients are shown to change linearly with solvent concentration for C6H6–CCl4 and C6H6–CS2 solutions. The intensity changes in solution are shown to correlate with an approximate calculation of intermolecular dispersion forces between benzene and solvent molecules. The inactive fundamentals of several methylene halides also exhibit this ``solution sensitivity.'' The technique of enhancing inactive fundamentals in solutions is shown to be useful for the purpose of identification of these fundamentals in infrared spectra.