Volumetric properties of some asymmetrically methyl-N-substituted thioureas in water between (278.15 and 318.15) K at ambient pressure

Densities of dilute aqueous solutions of 1-monomethyl-2-thiourea and 1,1,3-trimethyl-2-thiourea have been measured using an Anton Paar DMA 5000 M vibrating-tube densimeter. The apparent molar volumes and expansibilities (down to infinite dilution) have been calculated from the obtained density data. The experiments have been performed in the temperature range between (278.15 and 318.15) K, with a step of 10 K, at p similar to 0.1 MPa. The influence of a nature of methyl-N-sited substituents on the structure-packing properties of aqueous thioureas has been discussed. A possibility to estimate the standard (limiting apparent or partial) molar volumes for asymmetrically substituted 1,1-dimethyl-2-thiourea in water has been considered, too. (C) 2014 Elsevier B.V. All rights reserved.