Static relative permittivities ( r ) of water + propane-1,2-diol and water + propane-1,3-diol were measured at four mole fractions under pressures up to 300 MPa at 298.15 K. A Tait-type equation was used to represent r with pressure (P) for each composition. Values of (∂ ln r /∂P) T and r -2 (∂ r /∂P) T at 0.1 MPa for both aqueous propanediol systems were determined by use of the static relative permittivity at 0.1 MPa, r (0.1 MPa), and the Tait-type parameters, A and B. Values of (∂ ln r /∂P) T and the isothermal compressibility (κ T ) at 0.1 MPa over the entire composition range are compared for both aqueous propanediol systems. A relationship between (∂ ln r /∂P) T and κ T at 0.1 MPa was derived from the density dependence of r . Furthermore, composition dependence of r -2 (∂ r /∂P) T at 0.1 MPa was examined for the present systems.

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Static relative permittivities εr of water + butane-1,2-diol, water + butane-1,3-diol, and water + butane-1,4-diol in the liquid phase were determined from capacitance measurements over the entire composition range under pressures up to 300 MPa at 298.15 K. The Tait-type equation is applied to represent the pressure dependence of εr for each solution. The Tait-type parameters, A and B, are determined from the nonweighted least-squares method. The composition dependence of εr(0.1), (∂ ln εr/∂P) T , and εr -2(∂εr/∂P) T values at 0.1 MPa for the three binary aqueous butanediol mixtures are compared.

Static relative permittivities er of propan-2-ol, butan-2-ol, pentan-2-ol, and octan-2-ol were measured under high pressures up to 300 MPa at 298.15 K. Pressure dependence of Cr values was fitted to the Tait-type equation. The Kirkwood correlation factor g is determined for each alkan-2-ol as a function of pressure from the present Cr data and the literature density data under high pressure. Pressure dependence of g value is made a comparison among alkan-2-ols and effects of bulky alkyl substituents on molecular structure of alkan-2-ols are discussed.[static relative permittivity, alkan-2-ols, Tait-type equation, Kirkwood correlation factor, hydrogen bonding]

Static relative permittivities, r , were measured for 2-methyl-1-propanol, 2-methyl-1-butanol, 2-methyl-1-pentanol, and 2-methyl-1-hexanol under pressures up to 300 MPa at 298.15 K. Values of r increase with pressure for each 2-methyl-1-alkanol and are well-fitted with the Tait-type equation. In addition, a good correlation equation of static relative permittivities, r (P, n), for 2-methyl-1-alkanols with pressure P and the number n in H(CH 2 ) n-2 CH(CH 3 )CH 2 OH (n ) 3 to 6) is given.