Abstract:

Infrared spectra of 1,2-ethanediol, 1,2-propanediol, 1,4- butanediol and 1,6-hexanediol in CCl_4 were determined in the presence of an aprotic solvent B. The cooperative effects of intraand intermolecular hydrogen bonds for the diols were quantitatively discussed by analyzing these IR spectra. The results indicated that the formation of intramolecular hydrogen bonds in diols had definitely strengthened the intermolecular hydrogen bonds of the naked OH groups with basic solvents, in addition, for 1,2-ethanediol and 1,2-Propanediol the formation constants of the diol intramolecular associates and those of intermolecular associates between diol intramolecular species and B were also estimated. Compared with the inter molecular formation constants of the correspondent monoalkanols with B, K_B of diols were much higher. The fact also showed that the intramolecular hydrogen bonds polarize the naked hydroxy group, strengthening the O-H…B hydrogen bonds.

Key words: Infrared spectrum, Cooperative effect, Intramolecular association, Intermolecular association