摘要
测定了meso和dl 2,3-二氰基-2,3-二(p-X苯基)丁二酸二乙酯(X=OCH_3,CH_3,H,Cl,NO_2)的~1H NMR谱及X为CH_3相应二乙酯的~1H Noesy谱。在meso和dl异构体中,苯环m-~1H的化学位移与p-X的Hammett基团常数σ呈线性关系,c^1H的化学位移仅受分子构型的影响,;△δdl-meso为负值,乙氧基中CH_2和CH_3的质子化学位移也只受分子构型的影响,△δdl-meso均为正值。
The 3H NMR spectra of mesa and dl diethyl 2.3-dicyano-2. 3-di(p-X phenyl)succi-nates(X = OCH3, CH3, H, Cl, NO2) and 1H Noesy spectra of meso and dl isomers of the diethyl ester with X = CH3 were determined by using Bruker Am 400 MHz superconducting NMR spectrometry. The corresponding proton of the substituent groups attached to the two central carbon atoms in the molecules are chemical shift equivalence. The average difference between o-1H absorptions of phenyl in the dl-isomers and that in meso-isomers was found to be △δdl-meso= -120. 1 ± 6.1 Hz. All of the meso-isomers, then, have, methylene (ABX3 system) and methyl in the ethoxy at upfield positions, and all of the dl-isorners have that at downfield positions, △δdl-meso= 53. 3 ± 5. 9 Hz and△δdl-meso= 53. 5 ± 5. 4 Hz for A and B protons in the methyienes, and △δdl-meso=39. 3 + 3. 5 Hz for protons in the methyls. △δdl-meso is the mark of influence of molecular configuration on the chemical shift.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
1991年第12期1627-1630,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金
关键词
丁二酸二乙酯
NMR
化学位移
1H NMR spectra. Chemical shift, Molecular configuration, Diethyl 2, 3-dicyano-2,3-bis(p-substituted phenyDsuccinates (Y, X)
