Speed of sound and isentropic compressibility of binary mixtures containing alkyl acetate or ethyl alkanoate, or ethyl bromo-alkanoate with hexane.

Isentropic compressibilities ics, excess isentropic compressibilities kappa (E)(S) have been determined from measurements of speeds of sound u and densities rho of eleven binary mixtures of alkyl acetate, or ethyl alkanoate, or ethyl bromoalkanoate with hexane at 303.15 K. Variable degree of polynomials were fitted to results. The values of kappa (E)(S) regularly decrease with number of carbon atoms of the alkanoate going from positive values for methyl acetate + hexane to negative values for dodecyl acetate + hexane. The values of kappa (E)(S) for all four-ethyl bromoalkanoate mixtures are highly negative and their magnitude depends on the type of bromoester and the position of Br- atom in ethyl bromoalkanoates. The experimental speeds of sound have been analyzed in terms of collision factor theory (CFT), free length theory (FLT) and Prigogine-Flory-Patterson statistical theory (PFPT) of solutions. (C) 2001 Elsevier Science B.V. All rights reserved.