Abstract The standard (po =0.1 MPa) molar enthalpies of formation of orotic and isoorotic acids, in the crystalline phase, were derived from the respective standard massic energies of combustion measured by static bomb combustion calorimetry, in oxygen, at T =298.15 K, as ‒821.7 ± 1.1 kJ mol−1 and ‒838.3 ± 1.9 kJ mol−1, respectively. The molecular structure and conformational behaviour of orotic and isoorotic acids were studied by theoretical calculations and the standard gas-phase molar enthalpies of formation were derived using an appropriate set of working reactions. Sublimation enthalpies, at the reference temperature T = 298.15 K, were estimated from difference between crystalline and gaseous enthalpies of formation and from statistically-based interaction indices derived from molecular surface electrostatic potentials.

中文翻译：

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尿嘧啶衍生物的能量表征：乳清酸和异乳清酸

摘要 乳清酸和异乳清酸在结晶相中的标准 (po = 0.1 MPa) 摩尔生成焓来自通过静态弹式燃烧量热法测量的各自标准燃烧质量，在氧气中，T = 298.15 K，分别为 ‒821.7 ± 1.1 kJ mol-1 和 ‒838.3 ± 1.9 kJ mol-1。通过理论计算研究了乳清酸和异乳清酸的分子结构和构象行为，并使用一组适当的工作反应推导出标准气相摩尔生成焓。在参考温度 T = 298.15 K 下，升华焓是根据结晶和气态形成焓之间的差异以及从分子表面静电势得出的基于统计的相互作用指数估计的。