Self-association and stereochemistry study of 2-methylthio-, 2-dimethylaminocyclohexanone oximes and the parent cyclohexanone oxime

Abstract

X-ray diffraction analyses of 2-substituted cyclohexanone oximes C5H9(X)C=NOH [X = SMe (1), NMe2 (2)] and of the parent compound [X = H (3)] showed that their cyclohexyl rings are in a slightly distorted chair conformation. These compounds assume in the solid state the (E) configuration bearing the 2-substituents in the axial conformation. Compounds (1) and (2) exist as dimeric and polymeric hydrogen-bond associates, respectively. Low-temperature X-ray analysis of the cyclohexanone oxime (3) showed that the molecules are associated forming two independent trimers. The dimer in (1) and the trimer in (3) are built up via [O-H...N=C] hydrogen bonds, while the polymer of (2) is via the [OH...NMe2] hydrogen bond. The comparative IR nu(OH) and nu(C=N) analysis of the title compounds, in the solid state and in CCl4 solution, fully supports the nature of the associates for (1)-(3) obtained by X-ray diffraction. The IR azomethyne frequency shift analysis (Deltanu(C=N)) also suggests the occurrence of the pi(C=N)/sigma*(C-X) orbital interaction which stabilizes the axial conformations of (1) and (2).

Comprehensive Vibrational Spectroscopic Characterization of Nylon‐6 Precursors for Precise Tracking of the Beckmann Rearrangement

“…), and the infrared and Raman spectra of cyclohexanone oxime and ϵ caprolactam (supported by density functional theory (DFT) calculations) have been reported as part of the measurement of thermodynamic properties (heats of sublimation and vaporization, and the standard entropy) in the ideal gas state . Infrared spectroscopy has also been used to study hydrogen bonding in cyclohexanone oxime, both in solution and in the solid state . Nonetheless, vibrational spectra have been assigned using normal coordinate analysis and DFT, invoking the isolated molecule approximation so that hydrogen bonding is omitted or only treated empirically – even when the experimental data is for the solid state.…”

Thermodynamics of Cyclohexanone Oxime

“…The calculated IR intensity of these modes is rather high (Table 10), but no high-intensity band is observed in the wavenumber range of (400 to 500) cm -1 . The possible cause of this fact is the absence of the CHO molecules without a hydrogen bond both in the crystal 22 and in the CCl 4 solution. Therefore, for these modes, the calculated values of the frequencies were used.…”

Microwave spectrum, molecular structure, and theoretical calculation of cyclohexanone oxime (chair form)

“…The infrared spectroscopic study of cyclohexanone oxime showed to be a trimer in the solid state and a dimmer in CCl 4 solution observing the OH stretching vibrational modes of the free and associated forms [9]. 13 C NMR spectroscopic study [10] of cyclohexanone oxime showed the 13 C chemical shifts of 160.…”