Solvent Influence on the Transformation of Intramolecular Hydrogen Bonds in 2-Hydroxy-5-Methyl-3-Nitroacetophenone

Konopacka, Aleksandra; Filarowski, Aleksander; Pawełka, Z.

doi:10.1007/s10953-005-6257-4

Cited by 12 publications

(7 citation statements)

References 31 publications

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“…[21][22][23] Note that this last value is much closer to the calculated dipole moment of 6.13 D. Dielectrometric titration of 5 with [D 6 ]DMSO did not show any variation in the dipole moment, which suggests no complex formation with the external base.…”

Section: Dielectrometrysupporting

confidence: 63%

Enol Forms of 1,3‐Indanedione, Their Stabilization by Strong Hydrogen Bonding, and Zwitterion‐Assisted Interconversion

et al. 2010

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By analyzing NMR spectroscopic data, and supported by IR, UV/Vis, Raman, dielectrometry, and DFT techniques, a comprehensive study of the 1:2 adducts of picolinaldehyde and 1,3‐indanediones is presented. The parent indanedione derivative 5 exists in an equilibrium between all‐keto and enol forms, the latter being stabilized by an intramolecularO–H···N hydrogen bond. Only the all‐keto form was observed in the 5,6‐dimethoxy compound 6, whereas solely the enol tautomer was observed with its 5,6‐dichloro analogue 7. Polar solvents and low temperatures shift the equilibrium towards the enol tautomer in 5. The structure of adduct 8, formed with isonicotinaldehyde, prevents the formation of intramolecular O–H···N hydrogen bonds and thus it exists in the all‐keto form in low polar solvents. However, in DMSO solutions it adopts a zwitterionic form with a strong anionic O–···H···O hydrogen bond. Thus, the enol form in indanedione adducts was unequivocally characterized in solution and the factors that determine the keto–enol tautomerism, namely electronic effects, solvent, temperature, and intramolecular hydrogen bonds, have been methodically studied by spectroscopic and quantum mechanical methods.

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Section: Dielectrometrysupporting

confidence: 63%

Enol Forms of 1,3‐Indanedione, Their Stabilization by Strong Hydrogen Bonding, and Zwitterion‐Assisted Interconversion

et al. 2010

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“…It is noteworthy that the stretching vibration of the carbonyl group (ν (C = O)) was the most sensitive to the conformational equilibrium [ 30 , 31 ]. According to IR and Raman spectra measured in the solid state ( Figure S7, SM ), only one band was observed in the 1800–1600 cm −1 range at 1650 cm −1 and was assigned to ν (C = O) mode (PED analysis, Table S2, SM ).…”

Section: Resultsmentioning

confidence: 99%

Polymorphism and Conformational Equilibrium of Nitro-Acetophenone in Solid State and under Matrix Conditions

et al. 2021

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Conformational and polymorphic states in the nitro-derivative of o-hydroxy acetophenone have been studied by experimental and theoretical methods. The potential energy curves for the rotation of the nitro group and isomerization of the hydroxyl group have been calculated by density functional theory (DFT) to estimate the barriers of the conformational changes. Two polymorphic forms of the studied compound were obtained by the slow and fast evaporation of polar and non-polar solutions, respectively. Both of the polymorphs were investigated by Infrared-Red (IR) and Raman spectroscopy, Incoherent Inelastic Neutron Scattering (IINS), X-ray diffraction, nuclear quadrupole resonance spectroscopy (NQR), differential scanning calorimetry (DSC) and density functional theory (DFT) methods. In one of the polymorphs, the existence of a phase transition was shown. The position of the nitro group and its impact on the crystal cell of the studied compound were analyzed. The conformational equilibrium determined by the reorientation of the hydroxyl group was observed under argon matrix isolation. An analysis of vibrational spectra was achieved for the interpretation of conformational equilibrium. The infrared spectra were measured in a wide temperature range to reveal the spectral bands that were the most sensitive to the phase transition and conformational equilibrium. The results showed the interrelations between intramolecular processes and macroscopic phenomena in the studied compound.

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“…The phenomenon of competition between two hydrogen bonds within one molecule is an interesting point to consider [109,110]. The competitive equilibrium between the O–H···O 2 N– and O–H···O=C hydrogen bonds in 5-methyl-3-nitro-2-hydroxyacetophenone ( 11 ) (Figure 13) by infrared spectroscopy and quantum-mechanical calculations is studied in [91,110].…”

Section: Equilibrium Between Different Intra-/intra-molecular Hydrmentioning

confidence: 99%

Some Brief Notes on Theoretical and Experimental Investigations of Intramolecular Hydrogen Bonding

et al. 2016

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Abstract:A review of selected literature data related to intramolecular hydrogen bonding in ortho-hydroxyaryl Schiff bases, ortho-hydroxyaryl ketones, ortho-hydroxyaryl amides, proton sponges and ortho-hydroxyaryl Mannich bases is presented. The paper reports on the application of experimental spectroscopic measurements (IR and NMR) and quantum-mechanical calculations for investigations of the proton transfer processes, the potential energy curves, tautomeric equilibrium, aromaticity etc. Finally, the equilibrium between the intra-and inter-molecular hydrogen bonds in amides is discussed.

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Solvent Influence on the Transformation of Intramolecular Hydrogen Bonds in 2-Hydroxy-5-Methyl-3-Nitroacetophenone

Cited by 12 publications

References 31 publications

Enol Forms of 1,3‐Indanedione, Their Stabilization by Strong Hydrogen Bonding, and Zwitterion‐Assisted Interconversion

Enol Forms of 1,3‐Indanedione, Their Stabilization by Strong Hydrogen Bonding, and Zwitterion‐Assisted Interconversion

Polymorphism and Conformational Equilibrium of Nitro-Acetophenone in Solid State and under Matrix Conditions

Some Brief Notes on Theoretical and Experimental Investigations of Intramolecular Hydrogen Bonding

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