Spectroscopic Evidence for Hydrogen Bonds: Comparison of Proton-Attracting Properties of Liquids. III

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Abstract
This is the third paper of a series in which the proton‐attracting powers of different liquids are compared by a measurement of the perturbation they produce on the OD vibrational band of CH3OD. Data showing the absorption of the OD group of CH3OD in seventy‐seven different solvents are given in the present paper, in a table listing positions of the band and shifts from the position of the unperturbed OD absorption band. Ketones, aldehydes, organic and inorganic esters, ethers, nitriles, amines, glycols, amides and a few other types of compounds were studied. Many interesting variations due to differences in structure were detected. With certain exceptions a linear relation was found to exist between the logarithms of the basicity constants of the solvents as measured in water solution and the shifts they cause in the OD band. A close correlation was observed between the effects of these solvents on the OD band of heavy methyl alcohol and their solubilities and heats of mixing with certain other compounds. No correlation was evident between the absorption data and the dielectric constants and dipole moments of the solvents. A relationship was found to exist between the proton‐acceptor power of a given atom and the electro‐negativities of the atoms adjacent to it in the molecule.