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Year 2007, Month 10 (Section Full Articles, Page 1996)

Temperature effect on the volume properties of a bisurea aqueous solutions

E. V. Ivanov, V. K. Abrosimov, N. G. Ivanova, and E. Yu. Lebedeva

The densities of aqueous solutions of bisurea (2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7dione) were measured using a vibrating-tube densimeter at 288.15, 298.15, 308.15, and 318.15 K in the concentration range up to ~3•10^–3 moles of solute (1000 g of H₂O)^–1 with the error at most ±5•10^–6 g cm^–3 (reproducibility up to 2•10^–6 g cm^–3). The limiting partial molar volume and expansibility of bisurea in water were calculated. The bicyclic molecules under study form in aqueous solution H-bonded hydrate complexes with rather high structure-packing density. These complexes are more subjected to the destroying effect of temperature than the corresponding urea complexes. The hydration of bisurea weakens with the temperature increase.

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