Tautomerization of 2-acetylcyclohexanone. 1. Characterization of keto-enol/enolate equilibria and reaction rates in water
Tautomerization of 2-acetylcyclohexanone. 1. Characterization of keto-enol/enolate equilibria and reaction rates in water
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DOI：
10.1021/jo026629x
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发表时间：
2003-04-04
影响因子：
3.6
通讯作者：
Iglesias, E
中科院分区：
文献类型：
--
作者：
Iglesias, E
研究了不同实验条件下2-乙酰环己酮（ACHE）在水中的酮-烯醇互变异构现象。与以往研究的其他β-二酮相比，乙酰胆碱酯酶体系中的酮-烯醇互变是一个缓慢的过程。在平衡条件下，分析的吸光度读数的乙酰胆碱水溶液产生超过40%的烯醇含量在25 degreesC;然而，在非质子溶剂，如二氧六环，乙酰胆碱几乎完全烯醇化。在碱性介质中，烯醇化物离子是唯一存在的物质; pH对ACHE紫外吸收光谱影响的研究得出ACHE的总pK（a）值为9.85。在非平衡条件下，研究了酮-烯醇在水中的互变异构反应。研究了影响反应的几个因素，包括H+催化、离子强度效应、缓冲催化、氘同位素效应、温度效应和溶剂效应。
The keto-enol tautomerism of 2-acetylcyclohexanone (ACHE) was studied in water under different experimental conditions. By contrast with other previously studied beta-diketones, the keto-enol interconversion in the ACHE system is a slow process. Under equilibrium conditions, the analysis of the absorbance readings of ACHE aqueous solutions yielded more than 40% of enol content at 25 degreesC; nevertheless, in aprotic solvents such as dioxane, ACHE is almost completely enolized. In alkaline medium, the enolate ion is the only existing species; the study of the effect of pH on the UV-absorption spectrum of ACHE yielded a value of 9.85 for the overall pK(a) of ACHE. Under nonequilibrium conditions, the keto-enol tautomerization was studied in water. Several factors affecting the reaction have been investigated, which include H+-catalysis, ionic strength effect, buffer catalysis, deuterium isotope effects, temperature effect, or solvent effects.