M. Ashraf Uddin

Excess molar volumes and viscosities of some alkanols with cumene

Densities, ρ, viscosities, η, of the systems, cumene + 1-propanol, +2-propanol, +1-butanol and +t-butanol, have been determined from 303.15 to 323.15 K, with an interval of 5 K. Excess molar volumes, , and excess viscosities, ηE, have been calculated from density and viscosity data. ρ, , η and ηE of the systems have been plotted against the mole fraction of alcohols. Some of these properties and their excess values have been represented satisfactorily by appropriate polynomials. For the systems, cumene + 1-propanol and cumene + 1-butanol, are both positive and negative, but for the systems, cumene + 2-propanol and cumene + t-butanol, positive have been observed for the whole range of composition. The observed volumetric and viscometric properties have been explained by the concepts: (a) dissociation of alkanols in cumene-rich region, (b) partial accommodation of cumene into interstitial positions of 1-alkanols in alkanol-rich region, (c) donor–acceptor interaction between alkanols and cumene and (d) steric hindrance of branched alkanols.

Viscosity of the systems m-xylene, +1-propanol, +2-propanol, +1-butanol, +t-butanol

Viscosities, η, of the systems, m-xylene, +1-propanol, +2-propanol, +1-butanol and +t-butanol have been measured for the whole range of composition at 303.15, 308.15, 313.15, 318.15 and 323.15 K. The variation of viscosities has been plotted against mole fraction of alkanols. Viscosities have been found to increase slowly up to a considerable concentration of alkanols, followed by a rapid rise of viscosities at higher concentrations. The slow rise of viscosity is attributed to dissociation of alkanols in m-xylene, while the rapid rise of viscosity is ascribed to self-association of alkanols. Excess viscosities, ηE, have been plotted as a function of mole fraction of alkanols. The curves show negative values for the whole range of composition, with minima occurring in alkanol-rich region. η and ηE have been fitted to appropriate polynomial equations. The study shows the effect of branching and chain length of alkanols on η and ηE.

Excess molar volumes of the systems m-xylene + 1-propanol, +2-propanol, +1-butanol, +2-methyl-2-propanol

Densities, ρ, of the systems m-xylene + 1-propanol, + 2-propanol, + 1-butanol and + 2-methyl-2-propanol have been determined from 303.15 to 323.15 K with an interval of 5 K. Excess molar volumes, , have been calculated from density data. ρ and have been fitted to appropriate polynomial equations and plotted against mole fraction of alkanols. For the systems, m-xylene + 1-propanol and m-xylene + 1-butanol, sigmoid type of curves have been observed, but for the systems, m-xylene + 2-propanol and m-xylene + 2-methyl-2-propanol, positive have been observed for the whole range of composition. The observed volumetric properties have been explained by the concepts: (a) dissociation of alkanols in m-xylene-rich region, (b) partial accommodation of m-xylene into interstitial positions of 1-alkanols in alkanol-rich region, (c) donor–acceptor interaction between alkanols and m-xylene and (d) steric hindrance of branched alkanols.