Substituent effects in keto-enol tautomerism. Part 3.1 influence of substitution on the equilibrium composition of of β-dicarbonyl compounds
作者:M. Bassetti、G. Cerichelli、B. Floris
DOI:10.1016/s0040-4020(88)90039-7
日期:1988.1
effect, and substituent parameters, representing the variation produced by the substituent, have been calculated. Equilibrium enthalpy and entropy have been obtained in the range of temperature 20–60°C. A correlation between enolic 1JCH= coupling constants and equilibrium free energies in DMSO is discussed in terms of substituent effects on the energy of the enol.
酮-烯醇互变异构的烯醇含量和平衡自由能已在40°C下在氘代氯仿和二甲基亚砜-d 6(DMSO)中通过1 H nmr测定了一系列的1,3-二酮。已经研究了含有甲基,苯基,叔丁基,2-噻吩基,三氟甲基和乙氧基的化合物。DMSO中的平衡自由能以线性加和效应为特征,并且已经计算出代表由取代基产生的变化的取代基参数。在20–60°C的温度范围内获得了平衡的焓和熵。根据取代基对烯醇能量的影响,讨论了烯丙基1J CH =耦合常数与DMSO中的平衡自由能之间的相关性。