Thermodynamics of semiquinone disproportionation in aqueous buffer
Thermodynamics of semiquinone disproportionation in aqueous buffer
复制标题
DOI：
10.1039/ft9969204965
复制
发表时间：
1996-12-21
期刊：
影响因子：
--
通讯作者：
Guevara, N
中科院分区：
文献类型：
--
作者：
Alegria, AE;Lopez, M;Guevara, N
本文测定了1，4-苯醌（BQ）、1，4-萘醌（NQ）、2-甲基苯醌（MBQ）、甲萘醌（MNQ）、萘茜素（NZQ）和醌茜（QNZ）等半醌类化合物的反硝化反应的热力学参数K_disp、Δ H度和Δ S度。观察到较小的反硝化常数，K-disp时，除了一个稠合的苯环的半醌结构。负熵和正熵控制着反应平衡。在NQ（.-）中的5和8位添加OH基团可能是由于分子内氢键作用，使双羟化平衡转移到半醌上。
The thermodynamic parameters, K-disp, Delta H degrees and Delta S degrees, controlling the disproportionation of semiquinones derived from 1,4-benzoquinone (BQ), 1,4-naphthoquinone (NQ), 2-methylbenzoquinone (MBQ), menadione (MNQ), naphthazarin (NZQ) and quinizarin (QNZ), have been determined. Smaller disproportionation constants, K-disp, are observed upon addition of a fused benzene ring to the semiquinone structure. Negative enthalpies and positive entropies of disproportionation govern the disproportionation equilibria. Addition of OH groups to the 5 and 8 positions in NQ(.-) displaces the disproportionation equilibrium to the semiquinone probably due to intramolecular hydrogen bonding.