The monomer [math] dimer equilibria and thermodynamic functions in heptafluorobutanic acid

¹ Department of Physics, Indian institute of Technology, Kanpur 208 016, Inde.
² Department of Physics, Banaras Hindu University, Varanasi 221 005, Inde.

Résumé

Spectres IR et Raman (liquide pur et solution dans CC1₄) de l'acide heptafluorobutanoique. Influence des concentrations et température sur les spectres des solutions, établissement d’une corrélation directe entre l'équilibre monomère-dimère et le degré de liaison hydrogène. Les solutions diluées présentent des bandes d'élongation d'O — H et de C = 0 du monomère et du dimère cyclique. Les données des solutions permettent de calculer la constante d'équilibre K_md', l'énergie libre, l'entropie et l’enthalpie de formation du dimère.

Abstract

This paper reports the infrared and Raman spectra of heptafluorobutanic acid (HFBA) in the pure liquid and the CC1₄ solution. The spectra in solution were measured as a function of concentration and temperature, and a direct correlation was obtained between the monomer [math] dimer equilibria and the nature and extent of hydrogen bonding. Bands due to the 0 — H and C = 0 stretching vibrations of monomer and cyclic-dimer were observed in the spectra of dilute solutions. In addition, the equilibrium constant K_md', free energy ΔG^O_T, entropy ΔS⁰, and enthalpy of dimer formation ΔH^O were calculated using the data in solution.