Acid ionization constants of 4-substituted phenols in methanol + water mixtures
Acid ionization constants of 4-substituted phenols in methanol + water mixtures
复制标题
甲醇-水混合物中 4-取代酚的酸电离常数
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
C. H. Rochester
中科院分区：
文献类型：
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作者：
G. H. Parsons;C. H. Rochester
4-叔丁基苯酚、4-甲基苯酚、苯酚、4-溴苯酚、4-甲酰基苯酚和4-硝基苯酚在甲醇+水混合物中的pKa值在10-90 wt.使用组合的玻璃和银/银氯化物电极系统通过电位测定法确定了%甲醇组成范围。对于所有的溶剂组合物，pKa值与Hammett ρσ关系雅阁，ρ在ca处最大。60- 70wt. %甲醇。ρ随溶剂组成的变化可间接归因于体相溶剂结构对苯氧阴离子溶剂化自由能的影响。介质对pKa的总影响被认为是静电和非静电贡献的总和。对影响后者的一些因素作了简要的讨论。
The pKa values of 4-t-butylphenol, 4-methylphenol, phenol, 4-bromophenol, 4-formylphenol and 4-nitrophenol in methanol + water mixtures in the 10–90 wt. % methanol composition range have been determined potentiometrically using a combined glass and silver/silver chloride electrode system. The pKa values are in accord with the Hammett ρσ relationship for all solvent compositions with a maximum value of ρ at ca. 60–70 wt. % methanol. The variation of ρ with solvent composition is indirectly attributed to the influence of bulk solvent structure on the free energies of solvation of phenoxide anions. The total medium effects on pKa are considered to be the sum of both electrostatic and nonelectrostatic contributions. Some factors influencing the latter are briefly discussed.