二甲基姜黄素酮-烯醇互变异构化的NMR研究

NMR studies on keto-enol tautomerism of dimethylcurcumin

采用核磁共振(NMR)技术研究了二甲基姜黄素酮-烯醇互变异构体系在Benzene-d_6,CD_2Cl_2,CDCl_3,Acetone-d6,DMSO-d6等不同溶剂中的主要存在形式及其相互间平衡关系,根据平衡反应在不同溶剂中的ΔrGm、不同温度下的ΔrHm与ΔrSm值对其异构化过程的原因进行了阐述.结果表明:二甲基姜黄素在不同溶剂中主要以烯醇式结构存在,温度和溶剂极性的改变只促使其发生微弱的酮-烯醇式异构化转变,主要是因为烯醇式结构含有的分子内氢键使β-二酮形成了稳定的类似六元环状的结构.

The structure of dimethylcurcumin and keto-enol equilibrium relationship in different sol-vents are investigated by using NMR techniques. And the reason of the keto-enol isomerization process is explained according to the values of △rGmθ,△rGmθ,and △rGmθ The results show that thedimethylcurcumin exists in the form of enol in different solutions. Its main structure is less affected by the solvent polarity and temperature, which is attributed to that intramolecular hydrogen bond contained in the enol structure makes the β-diketon structure form a stable similar six membered ring.