High-precision densitometry and high-accuracy refractometry measurements of extremely dilute solutions of the thiophene-2- (TCPH), pyrrole-2- (PCPH) and furan-2-carboxaldehyde-phenylhydrazone (FCPH) compounds in acetonitrile have been obtained at 293.15 K. The partial molar volumes V 2^∞ of each compound at infinite dilution were determined. The apparent molar refraction of these solutes at infinite dilution at 293.15 K has been experimentally determined within the Kohner-Geffcken-Grunwald-Haley approximation. The volumetric and refractometric results were interpreted in terms of the Pauling electronegativity and intrinsic molar volume of the heteroatom, and the aromaticity of the heterocyclic rings. The experimental results indicate that solute-solute interactions are negligible within the concentration range studied. Theoretical calculations at the DFT-B3LYP/6−311++G(3d,3p) level of molecular volumes support the interpretation that the volumetric contribution from the solute-solvent interactions to the limiting partial molar volumes of solutes are very small and thus solute molecules are isolated in this medium.
在 293.15 K 的温度下,对
噻吩-2-(
TCPH)、
吡咯-2-(PCPH)和
呋喃-2-甲醛苯腙(FCPH)化合物在
乙腈中的极稀释溶液进行了高精度密度测量和高精度折射测量。根据 Kohner-Geffcken-Grunwald-Haley 近似法,实验测定了这些溶质在 293.15 K 时无限稀释时的表观摩尔折射率。根据杂原子的鲍林电负性和固有摩尔体积以及杂环的芳香性解释了体积测定法和折射测定法的结果。实验结果表明,在所研究的浓度范围内,溶质与溶质之间的相互作用可以忽略不计。DFT-B3LYP/6-311++G(3d,3p) 级别的分子体积理论计算支持这样的解释,即溶质-溶剂相互作用对溶质极限部分摩尔体积的体积贡献非常小,因此溶质分子在这种介质中是孤立的。