4-羟基嘧啶、S-甲基-2-硫代尿嘧啶和 2-硫代尿嘧啶中的互变异构现象。

Tautomerism in 4-hydroxypyrimidine, S-methyl-2-thiouracil, and 2-thiouracil.

机构信息

Departamento de Química da Universidade de Coimbra, 3004-535 Coimbra, Portugal.

出版信息

J Phys Chem A. 2010 Dec 9;114(48):12725-30. doi: 10.1021/jp106883s. Epub 2010 Nov 8.

Abstract

The keto-enol tautomerism of 4-hydroxypyrimidine and of the related molecules S-methyl-2-thiouracil and 2-thiouracil has been investigated using synchrotron-based techniques. The populations of the constituent tautomers and thermodynamic parameters have been obtained by analysis of core-level photoemission spectra. The effect of substituents on the stability of tautomers has been revealed. Attaching additional OH (or SH) groups to the aromatic ring stabilizes the dioxo (or oxo-thione) forms. However, substitution of hydrogen in position 2 by an S-CH(3) group (that is, in going from 4-hydroxypyrimidine to S-methyl-2-thiouracil) does not significantly affect the tautomeric equilibrium.

摘要

使用基于同步加速器的技术研究了 4-羟基嘧啶和相关分子 S-甲基-2-硫代尿嘧啶和 2-硫代尿嘧啶的酮烯醇互变异构现象。通过分析芯层光电子能谱获得了组成互变异构体的种群和热力学参数。揭示了取代基对互变异构体稳定性的影响。在芳环上附加额外的 OH（或 SH）基团会稳定二氧（或氧代硫）形式。然而，用 S-CH(3)基团（即从 4-羟基嘧啶到 S-甲基-2-硫代尿嘧啶）取代 2 位上的氢不会显著影响互变异构平衡。