α-异噁唑偶氮基-β-二酮类衍生物及其互变异构体的光谱

Spectroscopy of α-Isoxazoleazoxyl-β-Diketone Derivatives and Their Tautomers

研究了5种新型的具有不同结构的α异唑偶氮基β二酮类衍生物的红外光谱和紫外光谱,讨论了它们的酮式烯醇式以及偶氮式腙式之间的互变异构化现象。结果表明,所有化合物无论以固体形式或在溶液中均以腙式二酮体和偶氮式烯醇体的混合形式存在。各化合物的紫外吸收谱均呈双峰状,峰值分别处于246～262nm和326～339nm之间,其中,高波长吸收峰的强度明显高于低波长吸收峰强度,说明了各化合物中偶氮式烯醇体形式均多于腙式二酮体形式,其原因是由于各化合物中偶氮式烯醇体的异构体较多,且易以分子内氢键形式形成六元环,有利于结构稳定。

In this paper, the IR and UV-Vis spectroscopy of five novel α-isoxazoleazoxyl-β-diketone derivatives with different ~structures have been studied, and their keto-enol and azo-hydrazone tautomeric phenomena have been discussed. It was found that all compounds, which are in the solid or in the solution, exist in the form of hydrazodiketo and azoenol isomers. The authors can also see that there are two absorption bands which are in the range 246-262 nm and 326-339 nm, respectively, for all compounds in the UV spectra, and the intensities of long wavelength absorption bands which are attributed to azoenol forms are stronger than short wavelength absorption bands which are attributed to hydrazodiketo forms. This shows that the quantities of azoenol forms in the compounds are more than hydrazodiketo forms, and it may be due to that the varieties of the azoenol isomers can easily form six-membered rings structure in the form of intramolecular hydrogen bonding, and make chemical structures more stable.