Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto, Portugal.
J Phys Chem B. 2011 May 5;115(17):4939-48. doi: 10.1021/jp200670s. Epub 2011 Apr 8.
In the present work, the values of the standard (p(o) = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, of 1,2-diaminobenzene, 1,3-diaminobenzene, and 1,4-diaminobenzene are reported as 86.6 ± 1.6, 89.6 ± 1.6, and 99.7 ± 1.7 kJ·mol⁻¹, respectively. These values were derived from experimental thermodynamic parameters, namely the standard (p(o) = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, Δf H(m)(o)(cr), at T = 298.15 K, obtained from the standard molar enthalpies of combustion, Δ(c) H(m)(o), measured by static bomb combustion calorimetry, and the standard molar enthalpies of sublimation, at T = 298.15 K, derived from the temperature-vapor pressure dependence, determined by the Knudsen mass loss effusion method. The results were compared with estimates obtained by standard ab initio molecular calculations at the G3(MP2)//B3LYP level. Experimental and calculated data are in very good agreement and show that the 1,2-diaminobenzene is, thermodynamically, the most stable isomer. Finally, proton and electron affinities, basicities and adiabatic ionization enthalpies were also computed at the same level.
在本工作中，报道了 1,2-二氨基苯、1,3-二氨基苯和 1,4-二氨基苯在气态下标准（p(o) = 0.1 MPa）摩尔生成焓，在 T = 298.15 K 时分别为 86.6 ± 1.6、89.6 ± 1.6 和 99.7 ± 1.7 kJ·mol⁻¹。这些值是从实验热力学参数中得出的，即标准（p(o) = 0.1 MPa）摩尔生成焓，在 T = 298.15 K 时的晶相，Δf H(m)(o)(cr)，由静态弹燃烧量热法测量的标准摩尔燃烧焓，Δ(c) H(m)(o)，以及标准摩尔升华焓，在 T = 298.15 K 时，由克努森质量损失扩散法确定的温度-蒸气压关系推导出。结果与 G3(MP2)//B3LYP 水平的标准从头算分子计算的估算值进行了比较。实验和计算数据非常吻合，表明 1,2-二氨基苯在热力学上是最稳定的异构体。最后，在相同水平上还计算了质子亲和能、电子亲和能、碱度和绝热电离焓。
