Spectral properties and intramolecular hydrogen bonding in 1-methyl(phenyl)-4(5)-substituted 6-oxo-1H-pyridazin-4(5)-ols

1980 ◽  
Vol 45 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Štefan Kováč ◽  
Václav Konečný
Keyword(s):  
Hydrogen Bonding ◽  
Spectral Data ◽  
Spectral Properties ◽  
Intramolecular Hydrogen Bonding ◽  
H Nmr ◽  
Substituent Constants ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bondings ◽  
Methyl Phenyl

Infrared, ultraviolet and 1H-NMR spectral data of 53 1-methyl(phenyl)-4(5)-substituted 6-oxo-1H-pyridazin-4(5)-ols are listed. Intramolecular hydrogen bondings are discussed; relatively strong hydrogen bondings OH...S were found, which are comparable in terms of strength with those of OH...O=C. Wavenumbers of ν(C=O) and ν(O-H) bands linearly correlated with substituent constants σ*, σR and σF.

scholarly journals Microwave-Assisted Synthesis of Mono- and Disubstituted 4-Hydroxyacetophenone Derivatives via Mannich Reaction: Synthesis, XRD and HS-Analysis

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 590 ◽  
Author(s):  
Ghadah Aljohani ◽  
Musa Said ◽  
Dieter Lentz ◽  
Norazah Basar ◽  
Arwa Albar ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Chair Conformation ◽  
Mannich Bases ◽  
Secondary Amines ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Regioselective Substitution ◽  
Intramolecular Hydrogen ◽  
Methyl Phenyl

An efficient microwave-assisted one-step synthetic route toward Mannich bases is developed from 4-hydroxyacetophenone and different secondary amines in quantitative yields, via a regioselective substitution reaction. The reaction takes a short time and is non-catalyzed and reproducible on a gram scale. The environmentally benign methodology provides a novel alternative, to the conventional methodologies, for the synthesis of mono- and disubstituted Mannich bases of 4-hydroxyacetophenone. All compounds were well-characterized by FT-IR, 1H NMR, 13C NMR, and mass spectrometry. The structures of 1-{4-hydroxy-3-[(morpholin-4-yl)methyl]phenyl}ethan-1-one (2a) and 1-{4-hydroxy-3-[(pyrrolidin-1-yl)methyl]phenyl}ethan-1-one (3a) were determined by single crystal X-ray crystallography. Compound 2a and 3a crystallize in monoclinic, P21/n, and orthorhombic, Pbca, respectively. The most characteristic features of the molecular structure of 2a is that the morpholine fragment adopts a chair conformation with strong intramolecular hydrogen bonding. Compound 3a exhibits intermolecular hydrogen bonding, too. Furthermore, the computed Hirshfeld surface analysis confirms H-bonds and π–π stack interactions obtained by XRD packing analyses.

scholarly journals Multicentered hydrogen bonding in 1-[(1-deoxy-β-D-fructopyranos-1-yl)azaniumyl]cyclopentanecarboxylate (`D-fructose-cycloleucine')

2019 ◽  
Vol 75 (8) ◽  
pp. 1096-1101 ◽  
Author(s):  
Valeri V. Mossine ◽  
Charles L. Barnes ◽  
Thomas P. Mawhinney
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Slow Rotation ◽  
H Nmr ◽  
Compound C ◽  
Nmr Data ◽  
Cyclopentane Ring ◽  
Intramolecular Hydrogen ◽  
Hydroxy Groups

The title compound, C12H21NO7, (I), is conformationally unstable; the predominant form present in its solution is the β-pyranose form (74.3%), followed by the β- and α-furanoses (12.1 and 10.2%, respectively), α-pyranose (3.4%), and traces of the acyclic carbohydrate tautomer. In the crystalline state, the carbohydrate part of (I) adopts the 2 C 5 β-pyranose conformation, and the amino acid portion exists as a zwitterion, with the side chain cyclopentane ring assuming the E 9 envelope conformation. All heteroatoms are involved in hydrogen bonding that forms a system of antiparallel infinite chains of fused R 3 3(6) and R 3 3(8) rings. The molecule features extensive intramolecular hydrogen bonding, which is uniquely multicentered and involves the carboxylate, ammonium and carbohydrate hydroxy groups. In contrast, the contribution of intermolecular O...H/H...O contacts to the Hirshfeld surface is relatively low (38.4%), as compared to structures of other D-fructose-amino acids. The 1H NMR data suggest a slow rotation around the C1—C2 bond in (I), indicating that the intramolecular heteroatom contacts survive in aqueous solution of the molecule as well.

Synthesis and spectroscopic study of aminals derived from 8-aminoquinoline

1982 ◽  
Vol 60 (13) ◽  
pp. 1775-1779 ◽  
Author(s):  
Juana Bellanato ◽  
Enrique Galvez ◽  
Rosario Escobar ◽  
Jose Manuel Cano-Pavon
Keyword(s):  
Hydrogen Bonding ◽  
Schiff Base ◽  
Spectroscopic Study ◽  
Mass Spectra ◽  
Intramolecular Hydrogen Bonding ◽  
H Nmr ◽  
Intramolecular Hydrogen

Treating 8-aminoquinoline with di-2-pyridyl ketone, pyridine-2-carboxaldehyde, or 6-methylpyridine-2-carboxaldehyde leads to the formation of the corresponding aminal instead of the expected Schiff base. The ir, 1H nmr, and mass spectra of these compounds are described and discussed.Infrared and 1H nmr analyses indicate that these aminals enjoy intramolecular hydrogen bonding. This effect is considered to contribute significantly to their unusual stability.

Synthesis and intramolecular hydrogen bonding of syn-9-hydroxy-18-substituted [3.3]metacyclophanes

2012 ◽  
Vol 90 (2) ◽  
pp. 222-229 ◽  
Author(s):  
Kazuya Tazoe ◽  
Xing Feng ◽  
Bigyan Sharma ◽  
Shinpei Miyamoto ◽  
Takehiko Yamato
Keyword(s):  
Hydrogen Bonding ◽  
Coupling Reaction ◽  
Sodium Hydride ◽  
Intramolecular Hydrogen Bonding ◽  
Aromatic Rings ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Low Field ◽  
Field Shift ◽  
Intramolecular Hydrogen

Various anti-9-methoxy[3.3]metacyclophane-2,11-diones are exclusively obtained by the coupling reaction of the corresponding 1,3-bis(bromomethyl)benzenes and 2,6-bis[2-isocyano-2-(tolylsulfonyl)ethyl]-4-tert-butylanisole in dimethylformamide (DMF) with an excess of sodium hydride, from which the corresponding syn-[3.3]metacyclophanes (MCPs) are synthesized via anti/syn-isomerization during the Wolff–Kishner reduction. Demethylation of syn-9-methoxy[3.3]MCPs with BBr3 afforded the corresponding syn-9-hydroxy[3.3]MCPs in good yields. The existence of the strong intramolecular hydrogen bonding between the 9-hydroxy group and the 18-substituents, such as F, OH, and OMe groups at the opposing aromatic rings, are observed in solution and in the solid state. A distinct low-field shift of the phenolic OH proton was observed in the 1H NMR spectrum compared with that of the 18-unsubstituted analog. Furthermore, O–H···F through-space coupling was observed.

Characterization of Hydrogen Bonds in the End-Functionalized Single-Wall Carbon Nanotubes: A DFT Study

NANO ◽  
2015 ◽  
Vol 10 (03) ◽  
pp. 1550036
Author(s):  
Reza Ghafouri ◽  
Fatemeh Ektefa ◽  
Mansour Zahedi
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Bonding ◽  
Computational Study ◽  
Intramolecular Hydrogen Bonding ◽  
Nbo Analysis ◽  
Coupling Constants ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bondings

A systematic computational study is carried out to shed some light on the structure of semiconducting armchair single-wall carbon nanotubes (n, n) SWCNTs, n = 4, 5 and 6, functionalized at the end with carboxyl (– COOH ) and amide (– CONH 2) from the viewpoint of characterizing the intramolecular hydrogen bondings at the B3LYP/6-31++G(d, p) level. Geometry parameters display different types of intramolecular hydrogen bonding possibilities in the considered functionalized SWCNTs. All of the hydrogen bondings are confirmed by natural bonding orbitals (NBO) analysis as well as nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) parameters. Based on NBO analysis, the calculated [Formula: see text] delocalization energies E(2), 1.15 kcal/mol to 7.04 kcal/mol, are in direct relation with the hydrogen bonding strengths. Differences in the chemical shielding principal components of 13 C and 17 O nuclei correlate well with the strengths of the hydrogen bondings. Participating in stronger hydrogen bondings, a larger SWCNT has a decreasing effect on 13 C (= O ) and 17 O isotropic chemical shieldings, σiso, consistent with the NBO analysis. The considerable changes of 13 C /17 O σiso can be interpreted as a result of shielding tensor component orientation. The 13 C (= O ) and 17 O quadrupole coupling constants C Q decrease under the effect of hydrogen bonding while asymmetry parameters ηQ significantly increase, indicating that 17 O ηQ is more sensitive to hydrogen bondings.

Resonance and solvent effects on absorption spectra of 2-nitroaniline derivatives

1976 ◽  
Vol 29 (7) ◽  
pp. 1469 ◽  
Author(s):  
T Yokoyama
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectral Data ◽  
Absorption Spectra ◽  
Long Range ◽  
Solvent Effects ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

Spectral data for N-methyl-2-nitroaniline correlate well with those for N,N-dimethyl-2-nitroaniline in non-hydrogen-bonding, hydrogen-bond-accepting and amphiprotic alcoholic solvents. This same pattern has been reported for N-methyl-2-nitro-p-toluidine. These results indicate that these N-methyl compounds have no hydrogen bonds with any of the solvents studied and intramolecular hydrogen bonding predominates. In the N.M.R. spectra of such amines, long-range coupling between the H5 (ring) and N-H protons is not necessarily evidence for intramolecular hydrogen bonding.� +M substituents at the 4-position increase the twist of the dimethylamino and 2-nitro groups and enhance the C1 → C2 transition, an effect which follows the order of +M abilities of the 4-substituents.

Theoretical study of intramolecular hydrogen bonding and molecular geometry of 2-trifluoromethylphenol

10.1002/jcc.2 ◽  
1996 ◽  
Vol 17 (16) ◽  
pp. 1804-1819 ◽  
Author(s):  
Attila Kov�cs ◽  
Istv�n Kolossv�ry ◽  
G�bor I. Csonka ◽  
Istv�n Hargittai
Keyword(s):  
Hydrogen Bonding ◽  
Theoretical Study ◽  
Molecular Geometry ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen
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