1H NMR studies of solvent and substituent effects on strong intramolecular hydrogen bonds

1981 ◽  
Vol 15 (1) ◽  
pp. 78-82 ◽  
Author(s):  
Bogumił Brzezinski ◽  
Miroslaw Szafran
Keyword(s):  
Hydrogen Bonds ◽  
1H Nmr ◽  
Substituent Effects ◽  
Nmr Studies ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

scholarly journals A 1H-NMR and MD study of intramolecular hydrogen bonds in methyl β-cellobioside

1992 ◽  
Vol 230 (1) ◽  
pp. 41-61 ◽  
Author(s):  
Bas R. Leeflang ◽  
Johannes F.G. Vliegenthart ◽  
Loes M.J. Kroon-Batenburg ◽  
Bouke P. van Eijck ◽  
Jan Kroon
Keyword(s):  
Hydrogen Bonds ◽  
1H Nmr ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Synthesis of 4-Aryl-3(5)-(2-hydroxyphenyl)pyrazoles by Reaction of Isoflavones and their 4-Thio Analogues with Hydrazine Derivatives

2007 ◽  
Vol 60 (12) ◽  
pp. 905 ◽  
Author(s):  
Albert Lévai ◽  
Artur M. S. Silva ◽  
José A. S. Cavaleiro ◽  
José Elguero ◽  
Ibon Alkorta ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Hydrazine Hydrate ◽  
1H Nmr ◽  
Theoretical Calculations ◽  
Intramolecular Hydrogen Bonds ◽  
Nmr Study ◽  
Intramolecular Hydrogen ◽  
New Compounds

4-Aryl-3(5)-2-(hydroxyphenyl)pyrazoles have been prepared by the reaction of isoflavones and their 4-thio analogues with hydrazine hydrate and phenylhydrazine in hot pyridine. The reaction mechanism for the formation of these pyrazoles is discussed. All the new compounds have been fully characterized by NMR spectroscopy. In [D6]DMSO, a 1H NMR study allows observation of the presence of both pyrazole annular tautomers, due to the presence of intramolecular hydrogen bonds in each tautomer (OH···N and NH···O). Theoretical calculations have been carried out on tautomers and conformers of compounds 20 (3(5)-(2-hydroxy-4-methoxyphenyl)-5(3)-methyl-4-phenylpyrazole) and 21 (3(5)-(2-hydroxy-4-methoxyphenyl)-4-(2-methoxyphenyl)-5(3)-methylpyrazole), including the absolute shieldings (GIAO/B3 LYP/6–311++G**) of 21.

Dissolution of Cellulose and Synthesis of Cellulose-Graft-Poly (L-Lactide) via Ring-Opening Polymerization in an Ionic Liquid

2012 ◽  
Vol 476-478 ◽  
pp. 1897-1900 ◽  
Author(s):  
Shu Xiao ◽  
Lin Dai ◽  
Jing He
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonds ◽  
1H Nmr ◽  
Ring Opening ◽  
Graft Copolymerization ◽  
Ring Opening Polymerization ◽  
Intramolecular Hydrogen Bonds ◽  
Ft Ir ◽  
Intramolecular Hydrogen ◽  
Organic Catalyst

Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) with L-lactide. The best synthetic condition of the cellulose-graft-poly (L-) (cellulose-g-PLLA) was that cellulose 0.6g, L-lactide 5.34g and 4-dimethylaminopyri lactide dine (DMAP) as an organic catalyst 0.69g reacted for 12 hours at 80°C. The synthesized AmimCl and cellulose graft copolymers were characterized by FT-IR, 1H-NMR, GPC, TG and WAXD. The results indicated that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the grafting rate of the polymer reached 4.44, which was higher than that reported in AmimCl with Sn(oct)2 as a catalyst.

scholarly journals A hemicryptophane with a triple-stranded helical structure

2018 ◽  
Vol 14 ◽  
pp. 1885-1889 ◽  
Author(s):  
Augustin Long ◽  
Olivier Perraud ◽  
Erwann Jeanneau ◽  
Christophe Aronica ◽  
Jean-Pierre Dutasta ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonds ◽  
Helical Structure ◽  
Aromatic Rings ◽  
Nmr Studies ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
H Nmr ◽  
Amine Groups ◽  
Intramolecular Hydrogen

A hemicryptophane cage bearing amine and amide functions in its three linkers was synthesized in five steps. The X-ray molecular structure of the cage shows a triple-stranded helical arrangement of the linkers stabilized by intramolecular hydrogen bonds between amide and amine groups. The chirality of the cyclotriveratrylene unit controls the propeller arrangement of the three aromatic rings in the opposite part of the cage. 1H NMR studies suggest that this structure is retained in solution.

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