Quantum-chemical calculations of the methylation of hydroxamic and thiohydroxamic acids with diazomethane

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• 作者：Chung-Yu Yang ; Hui-Lung Chen ; Jia-Jen Ho
• 关键词：Ab initio ; Hydroxamic acid ; Thiohydroxamic acids ; CH₂N₂
• 刊名：Journal of Molecular Structure: THEOCHEM
• 出版年：2006
• 出版时间：11 December 2006
• 年：2006
• 卷：778
• 期：1-3
• 页码：27-34
• 全文大小：333 K

文摘

We made calculations about the methylation of both hydroxamic and thiohydroxamic acids with CH₂N₂. The potential-energy surfaces of several proposed pathways leading to possible site-selective products (N-methylated and O-methylated hydroximates) are presented. Our results agree satisfactorily with an experimental observation by Liguori et al. who found site selectivity in the formation of dimethylated products. Simultaneous deprotonation and methylation occurs in both forms (E and Z) of hydroxamic acid and thiohydroxamic acid, and the net energy barrier via this pathway is the smallest. In most corresponding processes the energy barriers are smaller for thiohydroxamic acid, and the Z-form has an energy barrier smaller than that of the E-form in both hydroxamic and thiohydroxamic acids.