Effects of hydrogen bonding and homoconjugation on the titration curves of a synthetic polynuclear phenolic compound in non-aqueous solvents

1969 ◽  
Vol 47 (12) ◽  
pp. 2323-2326 ◽  
Author(s):  
S. K. Chatterjee
Keyword(s):  
Hydrogen Bonding ◽  
Phenolic Compound ◽  
Sharp Increase ◽  
Intramolecular Hydrogen Bonding ◽  
Straight Chain ◽  
Oh Groups ◽  
Titration Curves ◽  
Intramolecular Hydrogen

A straight chain polynuclear phenolic compound containing 9 phenolic nuclei has been synthesized and titrated in several non-aqueous solvents. In some of the solvents, a stepwise neutralization of OH groups in the compound has been observed. Some of the OH groups in the compound have a hyperacid character, and a sharp increase in conductance was observed as these OH groups are neutralized by the base. Some of these features have been discussed in terms of intramolecular hydrogen bonding and homoconjugation between the acid and its anion.

scholarly journals A simple and effective preparation of quercetin pentamethyl ether from quercetin

2018 ◽  
Vol 14 ◽  
pp. 3112-3121 ◽  
Author(s):  
Jin Tatsuzaki ◽  
Tomohiko Ohwada ◽  
Yuko Otani ◽  
Reiko Inagi ◽  
Tsutomu Ishikawa
Keyword(s):  
Hydrogen Bonding ◽  
Dimethyl Sulfoxide ◽  
Room Temperature ◽  
Computational Study ◽  
Dimethyl Sulfate ◽  
Intramolecular Hydrogen Bonding ◽  
Single Product ◽  
Oh Groups ◽  
Methylation Product ◽  
Intramolecular Hydrogen

Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per-O-methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. When methyl iodide was used in place of dimethyl sulfate, the C-methylation product 6-methylquercetin pentamethyl ether was also formed. A computational study provided a rationale for the experimental results.

scholarly journals 4,4′-(4,5-Dimethyl-1,2-phenylene)bis(2-methylbut-3-yn-2-ol): structural variation in vicinal dialkynols

2012 ◽  
Vol 68 (4) ◽  
pp. o179-o182
Author(s):  
Marcus R. Bond ◽  
Bruce A. Hathaway ◽  
Uriah J. Kilgore
Keyword(s):  
Hydrogen Bonding ◽  
Double Layer ◽  
Title Compound ◽  
Structural Variation ◽  
Intramolecular Hydrogen Bonding ◽  
Molecular Plane ◽  
Oh Groups ◽  
Compound C ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The structure of the title compound, C18H22O2, contains two non-equivalent molecules which differ primarily in the location of the –OH groups on opposite sides or on the same side of the molecular plane. Inversion-symmetric pairs of molecules form intermolecular O—H...O hydrogen-bonded tetrameric synthons that link non-equivalent molecules into an approximately square double layer parallel to (\overline{1}02). Recently reported fluorinated analogues [Kane, Meyers, Yu, Gerken & Etzkorn (2011).Eur. J. Org. Chem.pp. 2969–2980] have significantly different structures of varying complexity that incorporate intramolecular hydrogen bonding and suggest that further study of structureversussubstituents in vicinal dialkynols could be fruitful.

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

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

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.

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