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Thermodynamic Study of Hydrogen Bonding to Chloride Ions S. Y. Lam, C. Louis, and R. L. Benoit* Contributionfrom the Dgpartment de Chimie, Universitg de Montrgal, Montreal, Quebec, H3C 3 V I , Canada. Received May 15, I975
Abstract: The equilibrium constants, K ,and enthalpy changes, AHr(l), for the 1:l association reaction between chloride ion and a variety of proton donors, HR, have been determined at 3OoC in sulfolane. Thermodynamic data for the association of CI- with substituted acetic acids as H R were also obtained at 25OC in acetonitrile, dimethylformamide, and dimethyl sulfoxide. The experimental methods used involved solubility and vapor-pressure measurements, proton N M R , and calorimetry. The order of increasing donor strength of H R based on AHf(l) (kcal mol-') i n sulfolane is HCCI3 (-2.1) < HOH (-2.6) < H C H 3 0 HCH3C02 (-3.2) < H C s H s 0 (-3.6) < HCOzH HCF3C02 (-4.0)
