6533b822fe1ef96bd127d66c
RESEARCH PRODUCT
The identification of vicinally substituted cyclohexane isomers in their mixtures by 1H and 13C NMR spectroscopy.
Erkki KolehmainenAlexander B. TerentievTamara T. VasilievaReijo KauppinenTapio NevalainenKatri Laihiasubject
Addition reactionCarbon IsotopesMagnetic Resonance SpectroscopyCyclohexaneStereochemistryCyclohexeneMolecular ConformationStereoisomerismStereoisomerismBenzoyl peroxideNuclear magnetic resonance spectroscopyTritiumMedicinal chemistryAtomic and Molecular Physics and OpticsAnalytical Chemistrychemistry.chemical_compoundchemistryCyclohexanesmedicineMolecular orbitalInstrumentationSpectroscopyCis–trans isomerismmedicine.drugdescription
The radical addition reactions of organobromine compounds, XBr (X = CH2COOMe, PhCH2, CHBr2 and CCl3) with cyclohexene afforded mixtures of cis/trans isomer pairs of 1-X-2-Br-cyclohexanes. In addition to benzyl benzoyloxy derivatives are formed also, when benzoyl peroxide is used as an initiator. Owing to the great difficulties in separating these cis/trans isomer pairs, they are identified directly in their mixtures by NMR spectroscopy. In addition to one-dimensional (ID) 1H, proton decoupled 13C and DEPT-135, also two-dimensional (2D) 13C-13C INADEQUATE as well as 1H-13C HMQC experiments have been used in assigning the signals of each compound in their mixtures. The identification of each isomer was based on comparison of experimental 3J(H,H) coupling constants with theoretical ones based on the well-known Karplus type relationship. The more stable conformation for each isomer was estimated using the semiempirical AM1 molecular orbital method. The calculations support the isomer pair elucidations.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2000-05-04 | Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy |