Calorimetric investigations on association in ternary systems. Part 2.—Thermodynamic functions of complex formation of pentahalogenobenzoic acids and 1,1-dinitroethane with proton acceptors

Abstract

Enthalpies of complex formation (ΔH) by hydrogen bonding of pentachlorobenzoic (PClHBz) and pentafluorobenzoic (PFHBz) acids with a number of proton acceptors in CCl₄ have been determined.

A calorimetric method of determining equilibrium constants and enthalpies of formation of hydrogen-bonded complexes which are in equilibrium with proton transfer complexes is described. The K and ΔH values of complex formation of a C—H acid (1,1-dinitroethane) with a number of proton acceptors are determined. The results obtained both by the calorimetric method and by infrared spectroscopy are compared with those obtained by the use of the i.r. method only. The ΔH values of complex formation are discussed as a function of their acidity, dipole moments and the Gutmann's donor numbers of the investigated substances.