Solvent effects on the conformations of ortho-substituted acetanilides

1968 ◽  
Vol 46 (15) ◽  
pp. 2589-2592 ◽  
Author(s):  
Ian D. Rae
Keyword(s):  
Hydrogen Bond ◽  
Carbonyl Group ◽  
Aromatic Ring ◽  
Solvent Effects ◽  
Ortho Position ◽  
Polar Solvents ◽  
Amide Carbonyl ◽  
Amide Carbonyl Group ◽  
Intramolecular Hydrogen ◽  
Deshielding Effect

In acetanilides bearing nitro, halogen, alkoxyl, or carboxyl substituents in the ortho position, the intramolecular hydrogen bond is disrupted by polar solvents and the acetamido group adopts a position out of the plane of the aromatic ring. These changes are studied by means of changes in the deshielding effect of the amide carbonyl group on the remaining ortho proton.

Solvent effects on the tautomeric equilibrium of 2,4-pentanedione

1982 ◽  
Vol 60 (10) ◽  
pp. 1178-1182 ◽  
Author(s):  
J. N. Spencer ◽  
Eric S. Holmboe ◽  
Mindy R. Kirshenbaum ◽  
Daniel W. Firth ◽  
Patricia B. Pinto
Keyword(s):  
Hydrogen Bond ◽  
Solvent Effects ◽  
Tautomeric Equilibrium ◽  
Spectroscopic Techniques ◽  
Hydrogen Bond Formation ◽  
Entropy Changes ◽  
Tautomeric Forms ◽  
Self Association ◽  
Enol Tautomer ◽  
Intramolecular Hydrogen

The influence of solvent on the equilibrium position of the tautomeric forms of 2,4-pentanedione was studied by calorimetric and nmr spectroscopic techniques. For solvents such as CCl4 and cyclohexane the intramolecular bond of the enol form persists and bulk solvent effects account for the equilibrium enol–keto content. In solvents such as DMSO, disruption of the intramolecular bond occurs and the percentage of enol falls due to unfavorable entropy changes. The enol intramolecular bond is disrupted by the solvents water and methanol. Enol hydrogen bond formation through self-association and with the solvent accounts for the entropy changes upon enolization in these solvents. The thermodynamic parameters for enolization in neat 2,4-pentanedione are rationalized by the disruption of the enol intramolecular hydrogen bond through consequent polymerization of the enol tautomer.

Hydrogen bonding, configuration and conformation of substituted α-oxo oximes and hydrazones

1979 ◽  
Vol 44 (8) ◽  
pp. 2494-2506 ◽  
Author(s):  
Otto Exner ◽  
Jorga Smolíková ◽  
Václav Jehlička ◽  
Ahmad S. Shawali
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Intramolecular Hydrogen Bond ◽  
Benzene Solution ◽  
Dipole Moments ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Configuration And Conformation

Substituted 2-bromo-1-phenylglyoxal 2-phenylhydrazones IIIa-f exist in tetrachloromethane or benzene solutions prevailingly in E-configuration and in conformation A with an intramolecular hydrogen bond. The latter was evidenced by the N-H valence frequency at 3 290 cm-1 and by 1H NMR shifts with reference to derivatives without a carbonyl group - α-chlorobenzaldehyde phenylhydrazones V. From dipole moments of IIIa-d, measured in benzene solution, the contribution of the hydrogen bond (μH) was evaluated to 17 . 10-30 C m. This quantity is twice larger than in any other reported compound but the direction of the vector is as usual: approximately from H to N. In structurally similar derivatives of hydroxylamine, substituted 2-phenylglyoxylhydroximoyl chlorides IVa-d, no intramolecular hydrogen bond was detected; the dipole moments found were interpreted in terms of the Z-configuration and the prevailing conformation G.

Synthesis and conformation of some 6-aminomethyluracil amides

1990 ◽  
Vol 55 (11) ◽  
pp. 2731-2737 ◽  
Author(s):  
Ivan Stibor ◽  
David Šaman ◽  
Pavel Fiedler
Keyword(s):  
Hydrogen Bond ◽  
Ir Spectroscopy ◽  
Intramolecular Hydrogen Bond ◽  
Amide Carbonyl ◽  
Intramolecular Hydrogen

Three model amides (I-III) derived from 6-(N-alkylaminomethyl)-uracil and arylcarboxylic acids were synthesized and their conformation in solution studied. The 7-membered intramolecular hydrogen bond between amide carbonyl and H-N1 of uracil nucleus was proved to exist in solution of all three compounds using NMR and IR spectroscopy.

Efficient synthesis of N-butadiene substituted oxindole derivatives

2018 ◽  
Vol 5 (23) ◽  
pp. 3460-3463
Author(s):  
Chao Li ◽  
Wei-Huan Li ◽  
Lin Dong
Keyword(s):  
Carbonyl Group ◽  
Efficient Method ◽  
Efficient Synthesis ◽  
Amide Carbonyl ◽  
Amide Carbonyl Group

A novel rhodium(iii)-catalyzed amide carbonyl group directed alkenylation reaction between oxindoles and alkenes has been reported, which provides an efficient method for the synthesis of valuable and versatile functionalized N-(2E,4Z)-butadiene substituted oxindole derivatives.

Deoxygenative Hydroboration of Carboxamides: A Versatile and Selective Synthetic Approach to Amines

2021 ◽  
Author(s):  
Andrey Y. Khalimon
Keyword(s):  
Carbonyl Group ◽  
Thermodynamic Stability ◽  
Synthetic Approach ◽  
Amide Carbonyl ◽  
Amide Carbonyl Group ◽  
High Thermodynamic Stability

Deoxygenative reduction of amides is considered as an attractive method for preparation of synthetically valuable amines. However, the low electrophilicity of the amide carbonyl group, high thermodynamic stability and kinetic...

scholarly journals Enzymatically-stable oxetane-based dipeptide hydrogels

2018 ◽  
Vol 54 (14) ◽  
pp. 1793-1796 ◽  
Author(s):  
Laura McDougall ◽  
Emily R. Draper ◽  
Jonathan D. Beadle ◽  
Michael Shipman ◽  
Piotr Raubo ◽  
...  
Keyword(s):  
Carbonyl Group ◽  
Amide Carbonyl ◽  
Amide Carbonyl Group ◽  
Oxetane Ring

A new Fmoc-protected dipeptide incorporating an oxetane ring as a surrogate for the amide carbonyl group is an effective gelator.

Reduction of amide carbonyl group and formation of modified amino acids and dipeptides

2015 ◽  
Vol 56 (16) ◽  
pp. 2062-2066 ◽  
Author(s):  
M.L. Di Gioia ◽  
E.L. Belsito ◽  
A. Leggio ◽  
V. Leotta ◽  
E. Romio ◽  
...  
Keyword(s):  
Amino Acids ◽  
Carbonyl Group ◽  
Amide Carbonyl ◽  
Amide Carbonyl Group

scholarly journals Hydroquinone-Based Anion Receptors for Redox-Switchable Chloride Binding

Chemistry ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 80-88 ◽  
Author(s):  
Daniel A. McNaughton ◽  
Xiaochen Fu ◽  
William Lewis ◽  
Deanna M. D’Alessandro ◽  
Philip A. Gale
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Binding Mode ◽  
Chloride Binding ◽  
Binding Studies ◽  
Secondary Interaction ◽  
Amide Carbonyl ◽  
Internal Hydrogen Bond ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonding Site

A series of chloride receptors has been synthesized containing an amide hydrogen bonding site and a hydroquinone motif. It was anticipated that oxidation of the hydroquinone unit to quinone would greatly the diminish chloride binding affinity of these receptors. A conformational switch is promoted in the quinone form through the formation of an intramolecular hydrogen bond between the amide and the quinone carbonyl, which blocks the amide binding site. The reversibility of this oxidation process highlighted the potential of these systems for use as redox-switchable receptors. 1H-NMR binding studies confirmed stronger binding capabilities of the hydroquinone form compared to the quinone; however, X-ray crystal structures of the free hydroquinone receptors revealed the presence of an analogous inhibiting intramolecular hydrogen bond in this state of the receptor. Binding studies also revealed interesting and contrasting trends in chloride affinity when comparing the two switch states, which is dictated by a secondary interaction in the binding mode between the amide carbonyl and the hydroquinone/quinone couple. Additionally, the electrochemical properties of the systems have been explored using cyclic voltammetry and it was observed that the reduction potential of the system was directly related to the expected strength of the internal hydrogen bond.

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