Standard volumetric characteristics of N-dimethyl-substituted bicyclic bisureas (glycolurils) in water at T= (278.15 to 318.15) K and p ~ 0.1 MPa

Standard Volumetric Properties of Chiral N-Methyl-Substituted Glycolurils in Water between 278.15 and 318.15 K at Ambient Pressure

“…15, 288.15, 298.15, 308.15, and 318.15) K and p = (99.6 ± 0.8) kPa are reported here. Recently, 7 we have already analyzed the temperature-dependent behavior of standard (apparent or partial at infinite dilution) molar volumes V However, such characteristics for MMGU and TriMGU were not studied. Of particular value are data for MMGU, given the fact of very low solubility of this glycoluril derivative in water.…”

“…It may be connected with the different ability of stereochemically distinguishable molecular forms of a glycoluril molecule to hydrogen bonding with water at the expense of proton-acceptor (C = O) groups and proton-donor (N−H and HC−CH) moieties. [6][7][8]32,37,38 One can assume that V 2 o (T) for the chiral (racemic) glycoluril derivatives being studied here, similarly to Nmethyl-substituted acyclic ureas, is influenced by the following: 7,34 (i) an intrinsic contribution from each CH 3 group, (ii) a hydrophobic contribution caused by a molecule sequential methylation, (iii) a hindrance for hydrogen bonding due to an N-methylated position, and a possible decrease in ability to form CO•••H bonds as well. According to the trend of sequential increase in V 2 o expressed by eq 3, the first two of the mentioned effects are to be perhaps most important in the case considered here.…”

“…30,31 The E p,2 o values were computed by differentiating the temperature dependence of V 2 o . For this purpose, the nonlinear V 2 o vs T functions were approximated by the equation 7,21,32,38 V…”

“…From a purely thermodynamic viewpoint, such glycoluril derivatives exhibit a number of interesting features as solutes in aqueous media. − These features are caused by the molecular structure peculiarities of each of them. ,,− In Figure (panels a to c ), the simplified structures of MMGU, trans -DMGU, and TriMGU molecules are depicted.…”

“…To fill this gap, the new results of densimetric measurements for aqueous solutions of MMGU and TriMGU at T = (278.15, 288.15, 298.15, 308.15, and 318.15) K and p = (99.6 ± 0.8) kPa are reported here. Recently, we have already analyzed the temperature-dependent behavior of standard (apparent or partial at infinite dilution) molar volumes V 2 o and expansibilities E p ,2 o = (∂ V 2 o /∂ T ) p for trans- DMGU as a solute in water. However, such characteristics for MMGU and TriMGU were not studied.…”