5-取代巴比妥酸酮-烯醇互变异构体的测定

DETERMINNATION OF KETO-ENOL TAUTOMERS OF 5-MONOSUBSTITUTED BARBITURIC ACID

5-取代巴比妥酸在DMSO溶液中呈现酮-烯醇互变。在常温下可用核磁共振氢谱对两种异构体的相对含量进行测定,用碳-13谱进行佐证。测定结果表明,在DMSO溶液中以酮式弄构体为主,在碱催化下几乎全为烯醇式异构体。

5-Monosubstituted barbituric acid exhibits keto-enol tautomerism in DMSO solution.The relative quantities of the two tautomers can be measured by ~1H-NMR under room temperature,and the ^(13)C-NMR spectrum of them peovides a qualitative elaboration.The results show that the keto-form of 5-monosubs tituted barbituric acid is predominant in DMSO solution and it converts into enol-form by basic catalysis.