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《Chinese Journal of Magnetic Resonance》 2008-03
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Isomerization of the Amide Bond in Piperidin Amides Studied by Variable-temperature NMR Spectroscopy

QIAO Rui-rui,SUN Jing,YANG Chun-hui,XIAO Qiang,CUI Yu-xin(State Key Laboratory of Natural and Biomimetic Drugs,School of Pharmaceutical Sciences,Peking University,Beijing 100083,China)  
A series of amides of piperidin were synthesized and used for studies on the partial double-bond feature of the amide bonds.1H and 13C NMR spectra of 2-(3,5-dinitrophenyl)-1-(piperidin-1-yl) ethanone(compound 1) were acquired at various temperatures.The results showed that the C-N bond of the piperidin amides exhibited partially double-bond character at 20 ℃(293 K),suggesting that the chemical shifts of a and b,c and d in compound 1 were very different due to the two rotameric states.With increasing temperature,the two peaks of non-equivalent-CH2-groups collapsed into one peak due to the fast rotation of the C-N bond.The rate constant for the dynamic process detected for compound 1 was 380 s-1,and the free energy of activation for compound 1 at coalescence temperature(343 K) was 67 kJ·mol-1.
【CateGory Index】: O626.321
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1 LI Ying-jun~1, WANG Ying~1, JIN Kun~2, PENG Qin-ji~2, LIU Su-na~1, ZHANG Zhi-guang~1 (1College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029, China; 2State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China);NMR Study on 5-2-Furfuraldehyde Hydrazones[J];Chinese Journal of Magnetic Resonance;2005-01
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【Secondary Citations】
Chinese Journal Full-text Database 1 Hits
1 XIAO Wen\+\{a,b\}, LU Zhonglin\+\{a,b\}, SU Chengyong\+a, LIU Hanqin\+a, and KANG Beisheng\+\{a,*\} (\+aSchool of Chemistry and Chemical Engineering, Zhongshan University,Guangzhou 510275; \{\}\+bState Key Laboratory of Organometallic Chemistry, Shangh;NMR STUDIES ON 4,5-DIAZAFLUORENE-9-ONE 2-NAPHTHOYLHYDRAZONE (HL) AND ITS COMPLEX PbL_2[J];CHINESE JOURNAL OF MAGNETIC RESONANCE;2000-04
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