Etude par spectrométrie infrarouge de la complexation entre les N,N-diméthyl-N′-phénylformamidines et quelques donneurs de proton

1975 ◽  
Vol 53 (4) ◽  
pp. 604-609 ◽  
Author(s):  
J. Vaes ◽  
F. Foubert ◽  
Th. Zeegers-Huyskens
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Stability Constant ◽  
Amino Nitrogen ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Acid Base ◽  
Imino Nitrogen ◽  
Stability Constants Of Complexes ◽  
The Stability

The stability constants of complexes formed between ethanol and phenols with some N,N-dimethyl-N′-phenylformamidine derivatives are determined by i.r. spectrometry. The application of the Hammett relation shows the existence, in addition to the first degree terms depending on the substitution parameters of the proton donor (∑σa) and the proton acceptor (∑σb), of a crossed term depending on the ∑σa∑σb product. The different parameters are discussed as a function of the acid–base properties of the molecules. The results suggest that the formation of the hydrogen bond takes place on the imino nitrogen atom. The stability constant of the complexes of 2:1 stoichiometry is calculated; in this complex the second molecule of phenol seems to be preferentially bonded to the oxygen atom of the first molecule rather than to the amino nitrogen atom.

Dipolar and calorimetric study of the complexes between N,N-dimethyl-N′-phenylformamidines and phenols

1976 ◽  
Vol 54 (4) ◽  
pp. 610-616 ◽  
Author(s):  
Alfred F. Foubert ◽  
Pierre L. Huyskens
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Electron Pair ◽  
Dipole Moments ◽  
Phenyl Group ◽  
Ion Pair ◽  
Proton Donor ◽  
Pair Type ◽  
Calorimetric Study ◽  
Imino Nitrogen

The dipole moments µb of N,N-dimethyl-N′-phenylformamidine and its 4-methylphenyl and 4-chorophenyl derivatives and the dipole moments µab of some 20 complexes of these bases with phenols were determined in cyclohexane at 298 K. Assuming the additivity of the bond moments, the angles αb between µb and the axis C1C4 phenyl group were computed for the three bases. Dipole increments [Formula: see text] were then computed assuming the hydrogen bond involved the electron pair of the sp2 hybridized imino nitrogen atom. The variation of the Δµ computed in this way with the complexation enthalpy ΔHab is described by the same curve as that for the systems phenols–anilines and phenols–pyridines. This is not the case when other structures are chosen for computing Δµ and this provides evidence for the 'imino' structure of the complexes. For a given amidine, the dipole increment increases when the proton donor becomes more acidic. The derivative d Δµ/dpKa here is of the order of −0.5 D per pKa unit whereas this value is only −0.2 for the pyridines. The absolute values of Δµ are also greater for the amidines. This can be ascribed in part to a higher proportion of H-bonds of the ion pair type [Formula: see text] when the amidine is complexed by the same phenol as the pyridines.

On the potential role of the amino nitrogen atom as a hydrogen bond acceptor in macromolecules

1998 ◽  
Vol 279 (5) ◽  
pp. 1123-1136 ◽  
Author(s):  
Ben Luisi ◽  
Modesto Orozco ◽  
Jiri Sponer ◽  
Francisco J Luque ◽  
Zippora Shakked
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Potential Role ◽  
Amino Nitrogen ◽  
Hydrogen Bond Acceptor ◽  
Amino Nitrogen Atom

scholarly journals Does the Intramolecular Hydrogen Bond Affect the Spectroscopic Properties of Bicyclic Diazole Heterocycles?

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Paweł Misiak ◽  
Alina T. Dubis ◽  
Andrzej Łapiński
Keyword(s):  
Hydrogen Bond ◽  
Quantum Theory ◽  
Intramolecular Hydrogen Bond ◽  
Natural Bond Orbital ◽  
Spectroscopic Properties ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Nbo Method ◽  
Acceptor Group ◽  
Intramolecular Hydrogen

The formation of an intramolecular hydrogen bond in pyrrolo[1,2-a]pyrazin-1(2H)-one bicyclic diazoles was analyzed, and the influence of N-substitution on HB formation is discussed in this study. B3LYP/aug-cc-pVDZ calculations were performed for the diazole, and the quantum theory of atoms in molecules (QTAIM) approach as well as the natural bond orbital (NBO) method was applied to analyze the strength of this interaction. It was found that the intramolecular hydrogen bond that closes an extra ring between the C=O proton acceptor group and the CH proton donor, that is, C=O⋯H–C, influences the spectroscopic properties of pyrrolopyrazine bicyclic diazoles, particularly the carbonyl frequencies. The influence of N-substitution on the aromaticity of heterocyclic rings is also discussed in this report.

Intramolecular hydrogen bonds and the orientation of amino groupsin o-phenylenediamines

1967 ◽  
Vol 45 (19) ◽  
pp. 2135-2141 ◽  
Author(s):  
P. J. Krueger
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Absorption ◽  
Substituent Effect ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Amino Groups ◽  
Intramolecular Hydrogen Bonds ◽  
Infrared Absorption Spectra ◽  
Intramolecular Hydrogen

The infrared absorption spectra of partially deuterated o-phenylenediamine and 4,5-di-methyl-, 4-methyl-, and 4-chloro-o-phenylenediamine in dilute CCl4 solution show double intramolecular [Formula: see text] hydrogen bonds in which the two NHD groups are equivalent and each group acts as both a proton donor and a proton acceptor. The ring substituent effect on this interaction in these compounds is small. In 4-methoxy-o-phenylenediamine, the amino groups are not equivalent, but double intramolecular hydrogen bonds are still present. In 4-nitro-o-phenylenediamine, only one intramolecular [Formula: see text] hydrogen bond appears to exist. The effect of N-substitution on some of these observations is discussed.

scholarly journals Protolytic properties of the structurally rigid analogs of 2,6-distyrylpyridine. Widening the pH sensitivity range by the photochemical E→Z isomerisation and introduction of substituents capable to protolytic interactions

2010 ◽  
Vol 8 (4) ◽  
pp. 766-782
Author(s):  
Oleksiy Grygorovych ◽  
Oleksiy Nevskii ◽  
Sofia Moskalenko ◽  
Vasyl Pivovarenko ◽  
Andrey Doroshenko
Keyword(s):  
Full Range ◽  
Proton Donor ◽  
Ph Sensitivity ◽  
Proton Acceptor ◽  
Acid Base ◽  
Multi Stage ◽  
Protolytic Interactions ◽  
Pyridine Nitrogen ◽  
Sensitivity Range ◽  
Wide Range

AbstractProtolytic interactions in the series of prospective fluorescent ratiometric wide-range pH indicators — structurally rigid analogs of 2,6-distyrylpyridine — (3E,5E)-3,5-dibenzylidene-8-phenyl-1,2,3,5,6,7-hexahydrodicyclopentano[b,e]pyridine — were investigated. The pyridine nitrogen atom basicity in these compounds is significantly lower in comparison with that of unsubstituted heterocycle and 2,6-distyrylpyridine. The photochemical E→Z photoisomerization and the side benzene rings substituents influence on the acid-base equilibria were studied. The complex multi-stage mechanism of the acid-base interactions of the polysubstituted compounds was elucidated. The most significant spectral effects were typical to the N,N-dialkylamino substituted compounds of the investigated series. The widest pH sensitivity interval covering nearly the full range of 0–14 units was demonstrated for compounds with both proton donor and proton acceptor substituents.

Civil Partnerships: Lewis Acid–Base Reactions

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Boron Trifluoride ◽  
Proton Transfer Reaction ◽  
Proton Donor ◽  
Ammonia Molecule ◽  
Proton Acceptor ◽  
Acid Base ◽  
Molecular Events ◽  
Acids And Bases ◽  
Insight Into

One of the most remarkable chemists of the twentieth century, Gilbert Lewis (1875–1946), who died in a rather peculiar event involving cyanide (which will figure further in this account) took the story of acids and bases that I described in Reaction 2, extended its reach, and thereby captured a further huge swathe of chemical countryside. As I remarked in that section, chemists seek patterns of behaviour, partly because it systematizes their subject but also because it gives insight into the molecular events accompanying a reaction. Lewis contributed greatly to this enlargement of chemistry’s vision, as I shall unfold in this section. I explained in Reaction 2 how Lowry and Brønsted had extended Arrhenius’s vision of acids and bases by proposing that all reactions between acids and bases involve the transfer of a proton (a hydrogen ion, H+) from the acid, the proton donor, to the base, the proton acceptor. For instance, hydrochloric acid, HCl, can provide a proton that sticks to an ammonia molecule, NH3, 1, converting it into NH4+, 2. The Lowry–Brønsted account of an acid–base reaction involves a proton as an essential part of the definition: if protons aren’t around, then Lowry and Brønsted are silent on whether a substance is an acid or a base. There are, however, many reactions that resemble acid–base reactions but in which no protons are transferred. I will give what might seem to be a rather esoteric example, but it makes the point in a simple and direct way, so please bear with me; you will soon see the relevance of this presentation to everyday life. The esoteric example I have in mind is a reaction in which a boron trifluoride molecule, BF3, 3, sticks to an ammonia molecule to form NH3BF3, 4. This reaction clearly resembles the proton transfer reaction in which H+ attaches to NH3 to form NH4+, but with BF3 playing the role of H+. Lewis brought these aspects together in a very simple idea in 1923, at about the same time as Lowry and Brønsted made their proposals. A base, he proposed, is any species that can use two of its electrons to attach to an incoming species.

Effect of substituents at the proton-donor nitrogen atom on an intramolecular hydrogen bond of type NH...O

1974 ◽  
Vol 15 (3) ◽  
pp. 353-356
Author(s):  
L. N. Kurkovaskaya ◽  
I. L. Radushnova ◽  
N. N. Shapet'ko ◽  
S. M. Kvitko ◽  
Yu. S. Andreichikov ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Intramolecular Hydrogen Bond ◽  
Proton Donor ◽  
Effect Of Substituents ◽  
Donor Nitrogen Atom ◽  
Donor Nitrogen ◽  
Intramolecular Hydrogen

Equilibrium studies of triphenyltin(IV) complexes with glycine, glycyl-glycine, and glycyl-glycyl-glycine in different aqueous solutions of ethanol

2010 ◽  
Vol 88 (9) ◽  
pp. 877-885 ◽  
Author(s):  
Morteza Jabbari ◽  
Farrokh Gharib
Keyword(s):  
Hydrogen Bond ◽  
Stability Constant ◽  
Formation Constants ◽  
Least Squares Regression ◽  
Hydrogen Bond Donor ◽  
Equilibrium Studies ◽  
Hydrogen Bond Acceptor ◽  
Complex Species ◽  
The Stability ◽  
Glycyl Glycine

The protonation equilibria of glycine (gly), glycyl-glycine (gly-gly), and glycyl-glycyl-glycine (gly-gly-gly) and their formation constants with triphenyltin(IV) chloride were studied over a wide pH range (pH 1–11), using a combination of spectrophotometric and potentiometric methods at constant temperature (25 °C), different ethanol–water mixtures (50%–80%, v/v), and constant ionic strength (0.1 mol dm–3 NaClO4). Least-squares regression calculations are consistent with the formation of ph3SnHL+, ph3SnL, and ph3SnH–1L– complex species, where L– represents the fully dissociated form of each ligand. The stability constant of the formed complexes in different media were analyzed in terms of Kamlet, Abboud, and Taft (KAT) parameters. Single-parameter correlations of the stability constants versus α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity), and for π* (dipolarity/polarizability) are relatively poor in all solutions, but multi-parameter correlations represent significant improvements with regard to the single- and dual-parameter models. Linear correlation is observed when the experimental logβxyz values are plotted versus the calculated ones, while all the KAT parameters are considered. Also, the stability constant values of the formed complexes are determined in zero percent of organic solvent using the Yasuda–Shedlovsky extrapolation approach. Finally, the results are discussed in terms of the effect of solvent on complexation.

Acid-Base Disorders

2017 ◽  
Author(s):  
Herbert Chen ◽  
Jason Primus ◽  
Colin Martin
Keyword(s):  
Metabolic Alkalosis ◽  
Respiratory Acidosis ◽  
Respiratory Alkalosis ◽  
Proton Donor ◽  
The Body ◽  
Proton Acceptor ◽  
Acid Base ◽  
Mixed Acid ◽  
Organ Systems ◽  
Homeostatic Mechanisms

This review is a summary of the acid-base physiology that is essential to understanding acid-base pathophysiology. An acid is defined as a proton donor; a base is defined as a proton acceptor. The body fluids are composed of acids and bases, which are tightly regulated by our organ systems, specifically the respiratory system and kidneys. Derangements in the body’s acid-base homeostatic mechanisms or overloading the capacity of the body’s ability to respond can lead to acid-base disorders. These include acidosis and alkalosis, which can be further classified into respiratory, metabolic, or mixed disorders. The approach to these disorders is to stabilize the patient, focusing on respiratory and circulatory status and treating the underlying cause of the acid-base derangement. This review contains 4 highly rendered figures, 2 tables, and 26 references. Key words: acid-base disorders, acid-base homeostasis, acid-base physiology, acidemia, alkalemia, metabolic acidosis, metabolic alkalosis, mixed acid-base disorders, respiratory acidosis, respiratory alkalosis 

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