ChemInform Abstract: INTRAMOLECULAR HYDROGEN BONDING IN MONOANIONS AND SOLVATION OF DIANIONS OF AROMATIC DICARBOXYLIC ACIDS IN ACETONITRILE AND DIMETHYL SULFOXIDE

1977 ◽  
Vol 8 (9) ◽  
pp. no-no
Author(s):  
I. M. KOLTHOFF ◽  
M. K. JUN. CHANTOONI
Keyword(s):  
Hydrogen Bonding ◽  
Dimethyl Sulfoxide ◽  
Dicarboxylic Acids ◽  
Intramolecular Hydrogen Bonding ◽  
Aromatic Dicarboxylic Acids ◽  
Intramolecular Hydrogen

scholarly journals Intramolecular Hydrogen Bonding as a Factor in Determining the K1/K2 Ratios of Dicarboxylic Acids.

1963 ◽  
Vol 17 ◽  
pp. 1552-1562 ◽  
Author(s):  
Lennart Eberson ◽  
Ingemar Wadsö ◽  
Bengt Lindberg ◽  
Hans Meier ◽  
Jon Munch-Petersen
Keyword(s):  
Hydrogen Bonding ◽  
Dicarboxylic Acids ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

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.

Intramolecular Hydrogen Bonding in Dimethyl Sulfoxide Solutions of Glucose and Polyglucoses

1971 ◽  
Vol 41 (4) ◽  
pp. 326-330 ◽  
Author(s):  
K.K. Ghosh ◽  
R.D. Gilbert
Keyword(s):  
Hydrogen Bonding ◽  
Dimethyl Sulfoxide ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

Intramolecular hydrogen bonding in some ortho-substituted N-methyl,N-benzyl and N-aryl-4-nitroanilines: a proton magnetic resonance study

1982 ◽  
Vol 35 (12) ◽  
pp. 2497 ◽  
Author(s):  
JFK Wilshire
Keyword(s):  
Hydrogen Bonding ◽  
Dimethyl Sulfoxide ◽  
Long Range ◽  
Chloroform Solution ◽  
Intramolecular Hydrogen Bonding ◽  
Hydrogen Bond Strength ◽  
Dimethyl Sulfoxide Solution ◽  
Proton Magnetic Resonance Study ◽  
Electron Withdrawing Group ◽  
Intramolecular Hydrogen

1H n.m.r. spectra of a wide variety of N-methyl, N-benzyl and N-aryl 2-substituted 4-nitroanilines, where the 2-substituent is an electron-withdrawing group, namely acetyl, cyano, formyl or methoxy-carbonyl, reveal that long-range coupling (5J 0.65-0.70 Hz) occurs between the NH proton and the 5-proton of the nitroaryl ring in (D)chloroform solution; coupling is absent when the 2-substituent is trifluoromethyl. However, for some compounds (the nature of the 2-substituent is critical), NH,H5 coupling is absent in (D6)dimethyl sulfoxide solution. An examination of these phenomena leads to the conclusion (a) that intramolecular hydrogen bonding occurs between the NH group and the 2-substituent and (b) that, for these N,2-substituted 4-nitroanilines, the intramolecular hydrogen bond strength decreases in the following order: NH...COOCH3>NH...NO2≈NH...COCH3>NH...CHO>NH...CN A parallel study involving some N-methyl 4-substituted 2-nitroanilines where the 4-substituent is an electron-donating group, namely t-butyl, methyl and methoxy, revealed long-range NH,H5 coupling in both (D)chloroform and (D6)dimethyl sulfoxide solution; when the substituent is dimethylamino, NH,H5 coupling could not be detected in either solvent.

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