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合成了一系列六氢吡啶酰胺化合物以研究酰胺键的双键性质.采用1H及13CNMR技术确证了不同取代的酰胺化合物中酰胺键的双键性质.进一步采用变温核磁共振技术对2-(3,5-dinitrophenyl)-1-(piperidin-1-yl)ethanone(化合物1)进行了1H及13CNMR研究.结果表明,在20℃(293 K)时,a,b及c,d上的氢和碳原子具有不同的化学位移,且距酰胺键越近,化学位移的差异越大.随着温度的升高,两种异构体的转换速率增加,酰胺双键的性质越来越不明显,导致化学位移的差异逐渐减小,直至融合为一个峰.经计算,在融合温度下两种异构体的相互转换的速率常数是380s-1,能垒约为67kJ·mol-1.
A series of hexahydropylamide compounds were synthesized to study the double bond nature of the amide bond. The double bond properties of the amide bond in different substituted amide compounds were confirmed by 1H and 13CNMR techniques. The 2- (3, 1H-NMR and 13CNMR studies of 5-dinitrophenyl-1- (piperidin-1-yl) ethanone showed that the hydrogen and carbon of a, b and c, d at 20 ℃ Atoms with different chemical shifts, and closer to the amide bond, the greater the chemical shift differences.With the temperature increases, the conversion rate of the two isomers increases, the nature of the amide double bond more and more obvious, resulting in The difference of chemical shift gradually decreases until it reaches a peak, and the conversion rate constant of the two isomers at the fusion temperature is 380 s-1 and the energy barrier is about 67 kJ · mol -1.