作者:Ahmad S. Shawali、Nagwa M. S. Harb、Khadiga O. Badahdah
DOI:10.1002/jhet.5570220555
日期:1985.9
The spectra (1H nmr, ir and uv) of a series of 3-arylazo-4-hydroxycoumarins 1a-m indicate that such compounds exist predominantly in the keto hydrazone form 1A both in solid state and in solution. The acid dissociation constants of the series studied were determined spectrophotometrically in 80 vol% ethanol-water mixture at 27° and ionic strength of 0.1. The results of the correlations of these constants
一系列3-芳基偶氮-4-羟基香豆素1a-m的光谱(1 H nmr,ir和uv)表明,此类化合物主要以固态和溶液形式以酮to形式1A存在。在27%的离子强度和0.1的离子强度下,在80%体积的乙醇-水混合物中用分光光度法测定了所研究系列的酸解离常数。通过Hammett和Yukawa-Tsuno方程对这些常数进行相关的结果排除了与1A平衡的羟基偶氮形式1B的存在与光谱数据一致。此外,HMO方法已用于研究此类化合物中的互变异构现象。结果也与光谱和线性自由能相关性完全一致,,形式1A最稳定。进一步表明,分子间和分子内氢键均有利于t互变异构体。