Abstract 5-(Diethylammoniothio)-1,3-dimethylbarbituric acid ( 8 ) was obtained in good yield from the reaction of 5-bromo-1,3-dimethylbarbituric acid ( 5 ) and 1,3-diethylthiourea. The obtained product has been characterized using different techniques including single-crystal X-ray diffraction, FTIR, MS and NMR spectroscopy. For this reaction, a detailed computational study of the reaction steps has been performed using density functional theory (DFT). Both thermodynamic and kinetic parameters were calculated. Step B is the most favorable reaction with an activation energy of 33 kJ mol −1 using the solvation model that based on the solvent model density (SMD) calculated at B3LYP/6-31G(d). Graphic abstract The rate-determining step of the most plausible mechanism involves the formation of C-S bond via proton transfer to oxygen (intramolecular attraction) with an activation barrier of 33 kJ mol-1 using the solvation model that based on density (SMD) solvent model calculated at B3LYP/6-31G(d).

中文翻译：

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了解 5-(Diethylammoniothio)-1,3-二甲基巴比妥酸的形成：晶体结构和 DFT 研究

摘要 5-溴-1,3-二甲基巴比妥酸(5)与1,3-二乙基硫脲反应以良好的收率得到5-(二乙基氨硫基)-1,3-二甲基巴比妥酸(8)。所得产物已使用不同的技术进行表征，包括单晶 X 射线衍射、FTIR、MS 和 NMR 光谱。对于该反应，使用密度泛函理论 (DFT) 对反应步骤进行了详细的计算研究。计算了热力学和动力学参数。步骤 B 是最有利的反应，使用基于 B3LYP/6-31G(d) 计算的溶剂模型密度 (SMD) 的溶剂化模型，活化能为 33 kJ mol -1。