季戊四醇双缩苯乙二酮异构体的NMR研究

Isomers of Pentaerythritol Diacetals:NMR Spectroscopy and Theoretical Computation

合成并利用1H NMR表征了3,3′-二甲基-3,3′-二苯基-2,2′,4,4′-四氧杂螺[5,5]十一烷(简称季戊四醇双缩苯乙二酮),用Gaussian03软件中B3LYP/6-311+g*对化合物进行势能扫描,得到4种稳定结构.用B3LYP/6-311++g**方法预测季戊四醇双缩苯乙二酮异构体的氢化学位移,得到的最稳态结构的氢化学位移与实验值偏差较小,并用CHK文件生成了异构体电子云密度等高线图,其电子云密度图说明静电屏蔽作用与氢质子化学位移的变化一致.

The compound 3,3-dimethyl-3,3′-dibenzyl-2,2′,4,4′-tetraoxaspiro undecane was synthesized.1H NMR spectroscopy and theoretical computation was used to characterize the hydrogen atoms in the compound.With Gaussian03 software package,the results of potential energy scanning revealed that four possible conformations existed for the undecane.The 1H chemical shifts of the four possible isomers were calculated under B3LYP/6-311＋ ＋g ＊ ＊ level.The isomer showed the smallest difference between the theoretical results and experimental results was considered to be the correct conformation.The electron density maps of different isomers were drawn from its CHK files,which revealed electrostatic shielding that was consistent with the change of 1H chemical shift.