Intramolecular Hydrogen Bonding Facilitates Electrocatalytic Reduction of Nitrite in Aqueous Solutions

2019 ◽  
Vol 58 (14) ◽  
pp. 9443-9451 ◽  
Author(s):  
Song Xu ◽  
Hyuk-Yong Kwon ◽  
Daniel C. Ashley ◽  
Chun-Hsing Chen ◽  
Elena Jakubikova ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Aqueous Solutions ◽  
Intramolecular Hydrogen Bonding ◽  
Electrocatalytic Reduction ◽  
Intramolecular Hydrogen

scholarly journals Kinetics and Mechanisms of the Chromium(III) Reactions with 2,4- and 2,5-Dihydroxybenzoic Acids in Weak Acidic Aqueous Solutions

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Kimon Zavitsanos ◽  
Athinoula L. Petrou
Keyword(s):  
Hydrogen Bonding ◽  
Aqueous Solutions ◽  
Activation Parameters ◽  
Intramolecular Hydrogen Bonding ◽  
Dihydroxybenzoic Acid ◽  
Proton Release ◽  
Second Stage ◽  
Ph Decrease ◽  
Intramolecular Hydrogen ◽  
Two Stages

The reactions of 2,4- and 2,5-dihydroxybenzoic acids (dihydroxybenzoic acid, DHBA) with chromium(III) in weak acidic aqueous solutions have been shown to take place in at least two stages. The first stage of the reactions has an observed rate constantk1(obs)=k1[DHBA]+Cand the corresponding activation parameters areΔH1(2,4)≠=49,5 kJ/mol−1,ΔS1(2,4)≠=−103,7J mol−1K−1,ΔH1(2,5)≠=60,3 kJ/mol−1, andΔS1(2,5)≠=−68,0 J mol−1K−1. These are composite activation parameters and the breaking of the strong intramolecular hydrogen bonding in the two ligands is suggested to be the first step of the (composite) first stage of the reactions. The second stage is ligand concentration independent and is thus attributed to a chelation process. The corresponding activation parameters areΔH2(2,4)≠=45,13 kJ/mol−1,ΔS2(2,4)≠=−185,9 J mol−1K−1,ΔH2(2,5)≠=54,55 kJ/mol−1, andΔS2(2,5)≠=−154,8 J mol−1K−1. The activation parameters support an associative mechanism for the second stage of the reactions. The various substitution processes are accompanied by proton release, resulting in pH decrease.

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

Seven-Membered Intramolecular Hydrogen Bonding of Phenols: Database Analysis and Phloroglucinol Model Compounds

2012 ◽  
Vol 2012 (24) ◽  
pp. 4483-4492 ◽  
Author(s):  
Ronald K. Castellano ◽  
Yan Li ◽  
Edwin A. Homan ◽  
Andrew J. Lampkins ◽  
Iris V. Marín ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Model Compounds ◽  
Database Analysis ◽  
Intramolecular Hydrogen

scholarly journals NMR of Natural Products as Potential Drugs

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3763
Author(s):  
Poul Erik Hansen
Keyword(s):  
Natural Products ◽  
Hydrogen Bonding ◽  
Density Functional ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Density Functional Theory Calculations ◽  
Intramolecular Hydrogen Bonding ◽  
Chemical Equilibria ◽  
Nmr Techniques ◽  
Intramolecular Hydrogen

This review outlines methods to investigate the structure of natural products with emphasis on intramolecular hydrogen bonding, tautomerism and ionic structures using NMR techniques. The focus is on 1H chemical shifts, isotope effects on chemical shifts and diffusion ordered spectroscopy. In addition, density functional theory calculations are performed to support NMR results. The review demonstrates how hydrogen bonding may lead to specific structures and how chemical equilibria, as well as tautomeric equilibria and ionic structures, can be detected. All these features are important for biological activity and a prerequisite for correct docking experiments and future use as drugs.

Intramolecular hydrogen bonding guides a cationic amphiphilic organocatalyst to highly stereoselective aldol reactions in water

RSC Advances ◽  
2015 ◽  
Vol 5 (77) ◽  
pp. 62331-62335 ◽  
Author(s):  
Ángel M. Valdivielso ◽  
Alba Catot ◽  
Ignacio Alfonso ◽  
Ciril Jimeno
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Structural Motif ◽  
Aldol Reactions ◽  
Asymmetric Aldol ◽  
Neutral Ph ◽  
Intramolecular Hydrogen

A novel amphiphilic acylguanidine organocatalyst using intramolecular hydrogen bonding as a key structural motif is efficient for asymmetric aldol reactions of ketones in water at neutral pH.

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