Infrared Absorption Spectra of the Alcohols, Two Acids, and Their Solutions in Carbon Tetrachloride

Abstract

The paper describes the absorption spectra of the first eight alcohols of the aliphatic series and of formic and acetic acids in the regions extending from 0.9 to 2.2μ and from 2.0 to 4.0μ. The absorptions of the pure liquids are compared with their absorptions in carbon tetrachloride solutions. For methyl and ethyl alcohols and the two acids comparisons are also made with their vapor spectra. In every case solution in carbon tetrachloride modifies the bands characteristic of the hydroxyl group and leaves unchanged the hydrocarbon bands. The modifications are attributed to polymers or lattice structures which are partially destroyed in the solutions. Four bands near 0.96, 1.40, 1.89 and 2.1μ for the alcohols and one near 1.40μ for the acids which are present in the solution spectra are attributed to single molecules. Each of them in the solution spectra is accompanied by a broad almost continuous region of absorption on its long wave-length side, attributed to polymers, which grows stronger with increasing concentration until in the pure liquid it practically replaces the sharper bands predominating in the solution. The bands of the single molecules can still be detected, however, in each of the pure liquid alcohols. Comparison is made with the spectrum of aniline whose behavior near 1.4μ is peculiar.