Density measurements under pressure for the binary system 1-propanol plus toluene

The density of the binary system composed of 1-propanol and toluene has been measured under pressure using a vibrating-tube densimeter. The measurements have been performed for four different compositions as well as the pure compounds at four temperatures in the range of (303.15 to 333.15) K and seven isobars up to 30 MPa.

The uncertainty of the reported densities is less than 0.05%. The measured data has been used to study the influence of temperature, pressure, and composition on the isothermal compressibility and the isobaric thermal expansivity as well as the excess molar volume, which shows a complex sigmoid behavior involving both positive and negative values.

This complex behavior has been interpreted as the result of changes in the free volume due to volume expansion and compressibility as a result of the breaking of hydrogen bonds of the self-associating alcohol molecules but also due to the electron donor- acceptor-type formation of hydrogen bonding between the hydroxyl group of 1-propanol and the pi electrons of toluene because aromatic hydrocarbons can act as electron donors.