Densities of aqueous solutions of the chiral (racemic, with the enantiomer ratio of 1:1) 2-monomethylglycoluril (MMGU) and 2,4,6-trimethylglycoluril (TriMGU) have been measured using an Anton Paar DMA 5000 M densimeter. All density experiments have been performed with a precision of 0.025 kg·m^–3 in the temperature range between 278.15 and 318.15 K (with a step of 10 K) at a pressure of (99.6 ± 0.08) kPa. The solute molality is in the range from 0.032 to 0.523 mol·(kg H₂O)⁻¹, respectively. The temperature-dependent standard (apparent at infinite dilution) molar volumes and expansibilities of MMGU and TriMGU in water have been derived from the density data. The molar volumetric characteristics for MMGU or TriMGU as a solute in the aqueous medium have been discussed within the scope of comparative analysis including the previously obtained similar quantities for the chiral 2,6-dimethyglycoluril (trans-DMGU).

中文翻译：

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环境压力下278.15至318.15 K之间的水中手性N-甲基取代的甘脲的标准体积特性

已使用Anton Paar DMA 5000 M密度计测量了手性（外消旋，对映体比例为1：1）2-单甲基甘脲（MMGU）和2,4,6-三甲基甘脲（TriMGU）水溶液的密度。在（99.6±0.08）kPa的压力下，所有密度实验均在278.15至318.15 K（步长为10 K）之间的温度范围内以0.025 kg·m ^–3的精度进行。溶质摩尔浓度为0.032〜0.523mol·（kg H ₂ O）^-1， 分别。温度相关的标准品（无限稀释时的表观浓度）的摩尔体积和MMGU和TriMGU在水中的扩展性已从密度数据中得出。MMGU或TriMGU作为水介质中的溶质的摩尔体积特性已在比较分析的范围内进行了讨论，其中包括先前获得的手性2,6-二甲基甘脲（反式-DMGU）的相似量。