Abstract

The acidity constants of a number of guaiacyl phenols simulating structural fragments of natural lignins in the electronically excited state in water–N,N-dimethylformamide mixtures are determined by fluorescence spectroscopy using the Förster cycle. The differentiating effect of an aprotic solvent on the acidity of phenols is shown. It is found that the pK_a values in the excited state are associated with the properties of para-substituents with respect to the phenolic hydroxyl group. The highest capacity for acid ionization during photoexcitation is exhibited by compounds containing an electron-withdrawing carbonyl group.

中文翻译：

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水-N，N-二甲基甲酰胺混合物中电子激发态木质素模型化合物的酸度常数

摘要

在水– N，N-二甲基甲酰胺混合物中，模拟电子激发态的天然木质素结构片段的一些愈创木酚酚的酸度常数通过Förster循环荧光光谱法测定。显示了非质子溶剂对酚酸度的区分作用。发现在激发态的p K _a值与相对于酚羟基的对位取代基的性质有关。包含吸电子羰基的化合物在光激发过程中具有最高的酸离子化能力。