核磁COLOC技术在一类多取代苯结构鉴定中的应用一类多取代苯结构的COLOC鉴定

通过非环前体的分子内成环反应,可合成一类多取代苯,对这类产物进行结构鉴定,有助于了解整个反应历程和机理。但取代基增多,势必导致各结构因素变得复杂,难以从各芳碳的经验计算式去推测各取代基所处的相对位置,而以一般的光、波谱方法也较难获得这类结构信息。实验表明,核磁COLOC技术是确定这类产物各取代基相对位置较为合适的方法,本文以NMR技术对这类产物进行了结构鉴定,并讨论了COLOC技术在确定其各取代基相对位置中的作用;同时通过对产物的结构确认,讨论了产物取代基间的相互作用所导致其芳碳化学位移实测值与经验计算值之间的差异,以及含氟基团对邻位芳碳的碳氟间三键偶合作用。

THE STRUCTURAL DETERMINATION OF A FEW POLYSUBSTITUTED BENZENE DERIVATIVES BY COLOC TECHNIQUE

Ploy-substituted benzene can be simply synthesized via acyclic precursor through intramolecular witting reaction.But the relative situation between each o f the substituents can not be easily confirmed by the empirical calculation of chemical shift of aromatic carbon through normal 1D NMR experiments.2D COLOC NMR technique is an efficient method to determine the location of each substituent of poly-substituted benzene,This paper deals with the application of COLOC to the structural identification.The difference between the calculated and the measured chemical shift of each aromatic carbon and the ³J_CF coupling constants were discussed.