scholarly journals CONTRIBUTION CONCERNING THE PROBLEM OF THE INTRAMOLECULAR HYDROGEN BONDS IN ORTHO HALOPHENOLS

1963 ◽  
Vol 41 (9) ◽  
pp. 2240-2244 ◽  
Author(s):  
Henriette Bourassa-Bataille ◽  
P. Sauvageau ◽  
C. Sandorfy
Keyword(s):  
Carbon Tetrachloride ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Alternative Methods ◽  
Intramolecular Hydrogen Bonds ◽  
Oh Groups ◽  
Integrated Intensities ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The infrared spectra of the four ortho halophenols were measured in carbon tetrachloride solutions containing variable amounts of ether. The integrated intensities of the stretching band corresponding to the intermolecularly hydrogen-bonded OH groups were determined and plotted against ether concentration. From the curves obtained in this manner it was possible to deduce the relative strengths of the intramolecular hydrogen bonds which are present in these molecules. They are, in order of increasing strength: F < I < Br < Cl. This result is compared to others, published in the literature, obtained using alternative methods.

NUCLEAR SHIELDING PARAMETERS FOR PROTONS IN HYDROGEN BONDS: II. CORRELATION OF CHEMICAL SHIFTS IN INTRAMOLECULAR HYDROGEN BONDS WITH INFRARED STRETCHING FREQUENCIES

1960 ◽  
Vol 38 (8) ◽  
pp. 1249-1254 ◽  
Author(s):  
L. W. Reeves ◽  
E. A. Allan ◽  
K. O. Strømme
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Infinite Dilution ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonds ◽  
A Value ◽  
Nuclear Shielding ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

Nuclear shielding parameters have been obtained for 24 intramolecularly hydrogen-bonded phenols and naphthols. The shielding parameters are corrected for large diamagnetic anisotropies and a value ΔσOH obtained which represents the change in shielding parameter in parts per million with reference to the infinite dilution chemical shift of phenol, α-naphthol, or β-naphthol. These values of ΔσOH are approximately proportional to the change ΔvOH in the OH stretching frequency on formation of the hydrogen bond.

Solvent effects on the infrared spectra of anilines. VII. 2-Substituted 4-nitroanilines

1970 ◽  
Vol 23 (5) ◽  
pp. 947 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Solvent Effects ◽  
Intermolecular Hydrogen Bond ◽  
Lone Pair ◽  
Acceptor Molecule ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen ◽  
Ortho Substituent

Measurements of N-H stretching frequencies of 4-nitroanilines in the presence of hydrogen bond acceptors show that the ease of forming a second intermolecular hydrogen bond in the presence of an ortho substituent decreases in the order hydrogen > methyl > bromo, methoxyl > nitro. This order demonstrates the importance of repulsions between lone pair orbitals on the ortho substituent and the acceptor molecule. Weak intramolecular hydrogen bonds are detected in 2-iodo- and 2-bromo-aniline, and such bonds can be strengthened by introduction of a 4-nitro substituent.

Intramolecular hydrogen bonds in ethylenediamines and otheraliphatic diamines

1967 ◽  
Vol 45 (19) ◽  
pp. 2143-2149 ◽  
Author(s):  
P. J. Krueger
Keyword(s):  
Hydrogen Bonds ◽  
Chain Length ◽  
Band Intensity ◽  
Intramolecular Hydrogen Bonds ◽  
Intensity Measurements ◽  
Methylene Chain ◽  
Aliphatic Diamines ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The fundamental NH stretching bands of 22 aliphatic diamines have been investigated in dilute C2Cl4 solution.N,N′-Dimethyl-1,3-propanediamine and N,N′-dimethyl- and N,N,N′-trimethyl-ethylenediamine exist predominantly in an intramolecularly hydrogen bonded conformation. Such bonding also exists in N-methyl- and N,N -dimethyl-ethylenediamine, in N-methyl- and N,N-dimethyl-1,3-propanediamine, and in amines of the type H2N(CH2-CH2NH)xCH2CH2NH2. For all of the diamines investigated, intramolecular NH···N bonding disappears sharply when the intervening methylene chain length exceeds three units. Integrated band intensity measurements for primary aliphatic diamines H2N(CH2)nNH2 over the range n = 2–12 suggest that intramolecular hydrogen bonds may also play an important role in the conformation of ethylenediamine and 1,3-diaminopropane.

Infrared spectra of phenols with intramolecular hydrogen bonds and their reactions with amines

1976 ◽  
Vol 25 (4) ◽  
pp. 1322-1324
Author(s):  
A. E. Lutskii ◽  
T. I. Klepanda ◽  
G. G. Sheina ◽  
L. P. Batrakova
Keyword(s):  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Large perturbations of long-range nJ(1H,1H) and nJ(1H,19F) by the intramolecular hydrogen bonds in 2-mercaptobenzaldehyde, salicylaldehyde, and some derivatives. Reference structures for intramolecular hydrogen bonds

1993 ◽  
Vol 71 (7) ◽  
pp. 960-967 ◽  
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian ◽  
David M. McKinnon ◽  
Perry W. Spevack ◽  
Kerry J. Cox ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Long Range ◽  
Bond Formation ◽  
Coupling Constants ◽  
Hydrogen Bond Formation ◽  
Intramolecular Hydrogen Bonds ◽  
Large Perturbation ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

Precise 1H nuclear magnetic resonance spectral parameters are reported for salicyladehyde and its 3-fluoro and 5-fluoro derivatives in nonpolar solutions. Such data are also given for the 2-mercapto, 2-methylthio, and 2-methoxy derivatives of benzaldehyde. Comparison of the long-range coupling constants in the various compounds and their conformers shows a large perturbation of their magnitudes by hydrogen bond formation. For the salicylaldehyde system, the perturbation is particularly large for couplings involving the aldehyde proton and protons or fluorine nuclei placed ortho to the hydroxyl group. For example, 5Jt (F, CHO) is reduced by about 50%. The perturbation, as expected, is much smaller for coupling constants of nuclei remote from the site of the hydrogen bond. In 2-mercaptobenzaldehyde the long-range coupling constants are also sensitive to hydrogen bond formation, those involving the sulfhydryl proton markedly so compared to the hydroxyl proton in salicylaldehyde. The strength of the [Formula: see text] bond is discussed. It is argued that the reference conformer for the mercapto compound in such a discussion is less easily defined than for salicylaldehyde because [Formula: see text] are similar to [Formula: see text] energies. The experimental data for the CCl4 solutions imply a free energy of formation of the [Formula: see text] bond of 4.8(5) kJ/mol at 300 K. Molecular orbital computations on the four planar conformers of each salicylaldehyde and 2-mercaptobenzaldehyde with the 6-31 G**(5D) basis are reported. For salicylaldehyde, the [Formula: see text] arrangement is taken as the reference conformer, with a computed energy of 25.7 kJ/mol relative to the hydrogen-bonded structure. For 2-mercaptobenzaldehyde, the [Formula: see text] and [Formula: see text] conformers are calculated to be isoenergetic, at 5.1 kJ/mol relative to the hydrogen-bonded conformer. Hence either arrangement serves as a reference structure in computations of the strength of the hydrogen bond. The computations are consistent with the experimental results for solutions of the molecules under discussion. An appendix gives the computed geometries of the eight planar conformers, as well as some atomic charges, allowing a rationalization of the relative energies of the conformers.

scholarly journals The peptideZ-Aib-Aib-Aib-L-Ala-OtBu

2014 ◽  
Vol 70 (4) ◽  
pp. 405-407 ◽  
Author(s):  
Renate Gessmann ◽  
Hans Brückner ◽  
Kyriacos Petratos
Keyword(s):  
Hydrogen Bonds ◽  
Butyl Ester ◽  
Intramolecular Hydrogen Bonds ◽  
Aminoisobutyric Acid ◽  
Left Handed ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The title peptide,N-benzyloxycarbonyl-α-aminoisobutyryl-α-aminoisobutyryl-α-aminoisobutyryl-L-alaninetert-butyl ester orZ-Aib-Aib-Aib-L-Ala-OtBu (Aib is α-aminoisobutyric acid,Zis benzyloxycarbonyl and OtBu indicates thetert-butyl ester), C27H42N4O7, is a left-handed helix with a right-handed conformation in the fourth residue, which is the only chiral residue. There are two 4→1 intramolecular hydrogen bonds in the structure. In the lattice, molecules are hydrogen bonded to form columns along thecaxis.

3,5-Diphenyl-1,2,4-triazin-6(1H)-one: synthesis, and X-ray and DFT-calculated structures

2012 ◽  
Vol 68 (4) ◽  
pp. o149-o151
Author(s):  
Krzysztof Ejsmont ◽  
Agnieszka Kudelko ◽  
Wojciech Zieliński
Keyword(s):  
Hydrogen Bonds ◽  
Density Functional ◽  
Point Group ◽  
Group Symmetry ◽  
Air Oxidation ◽  
Intramolecular Hydrogen Bonds ◽  
Compound C ◽  
Planar Conformation ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The title compound, C15H11N3O, (I), was obtained by the air oxidation of 3,5-diphenyl-4,5-dihydro-1,2,4-triazin-6(1H)-one. In the crystal structure, (I) forms centrosymmetric hydrogen-bonded dimers through pairs of N—H...N hydrogen bonds. The molecular structure of (I) deviates somewhat from planarity in the crystalline state, whereas a density functional theory (DFT) study predicts a completely planar conformation (Cspoint-group symmetry) for the isolated molecule. The solid-state conformation of (I) is stabilized by intramolecular hydrogen bonds,viz.one C—H...O interaction, which forms a six-membered ring, and three C—H...N interactions that each form five-membered rings. To estimate the influence of the intramolecular hydrogen-bonded rings on the aromaticity of the phenyl rings, the HOMA (harmonic oscillator model of aromaticity) descriptor of π-electron delocalization has been calculated for conformations of (I) with and without intramolecular hydrogen bonds. In the planar conformation of (I), the HOMA values for both benzene rings are lower than in hypothetical conformations without intramolecular hydrogen bonds.

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