Thermodynamic studies of hydrogen bonding and proton transfer between weak acids and bases in nonaqueous solvents as a model for acid-base reactions in proteins

The aim of the present paper is an analysis of the hydrogen bond properties for the acid-base systems depending on the ability to the proton transfer in the formulation of the Brönsted approach. After definition of the proton transfer equilibrium expressed by using the equation log KPT=ξΔpKN, various examples of different physical properties, such as dipole moments, IR spectra, and nuclear magnetic resonances, are presented which correlate with the ΔpKN value. In such a way, a critical state of hydrogen bonding can be defined that corresponds to the potential of the proton motion for either single minimum or double minimum with low barrier. A particular attention in this paper found electronic spectra which have not been analysed so far and the quantitative analysis of the vibrational polarizability which can reach very high values of the order of electronic polarizability.

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Proton transfer and hydrogen bonding in the organic solid state: a combined XRD/XPS/ssNMR study of 17 organic acid–base complexes

Physical Chemistry Chemical Physics ◽

10.1039/c3cp53907e ◽

2014 ◽

Vol 16 (3) ◽

pp. 1150-1160 ◽

Cited By ~ 79

Author(s):

Joanna S. Stevens ◽

Stephen J. Byard ◽

Colin C. Seaton ◽

Ghazala Sadiq ◽

Roger J. Davey ◽

...

Keyword(s):

Hydrogen Bonding ◽

Solid State ◽

Proton Transfer ◽

Organic Acid ◽

Acid Base ◽

Organic Solid ◽

Organic Solid State

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A simple theoretical, quantitative approach to help understand the titration of weak acids and bases

Chemistry Teacher International ◽

10.1515/cti-2021-0021 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Miguel Arocena

Keyword(s):

Undergraduate Students ◽

Weak Acid ◽

Quantitative Approach ◽

Weak Acids ◽

Weak Base ◽

Acid Base ◽

Buffer Solution ◽

Strong Base ◽

Acids And Bases ◽

Quantitative Treatment

Abstract What happens at the very beginning of the titration of a weak acid or base is a question sometimes asked by undergraduate students when introduced to the concept of buffer solution. To attempt to answer this question, a simple quantitative approach is developed, which also allows explaining more general properties of the weak acid or weak base titration process, while serving as well as an introduction to the theoretical, quantitative treatment of this subject. Using this approach, it can be shown that, at the beginning of the titration, the reaction between a weak acid (base) and a strong base (acid) does not occur on a one to one ratio when very small amounts of the strong base (acid) are added.

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Supramolecular association in proton-transfer adducts containing benzamidinium cations. II. Concomitant polymorphs of the molecular salt of 2,6-dimethoxybenzoic acid with benzamidine

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s010827011204067x ◽

2012 ◽

Vol 68 (11) ◽

pp. o447-o451 ◽

Cited By ~ 6

Author(s):

Simona Irrera ◽

Giancarlo Ortaggi ◽

Gustavo Portalone

Keyword(s):

Hydrogen Bonding ◽

Proton Transfer ◽

Water Solution ◽

Asymmetric Unit ◽

Acid Base ◽

Space Group ◽

One Dimensional ◽

Carboxylate Groups ◽

Molecular Components ◽

Molecular Salt

Two concomitant polymorphs of the molecular salt formed by 2,6-dimethoxybenzoic acid, C9H10O4(Dmb), with benzamidine, C7H8N2(benzenecarboximidamide, Benzam) from water solution have been identified. Benzamidinidium 2,6-dimethoxybenzoate, C7H9N2+·C9H9O4−(BenzamH+·Dmb−), was obtained through protonation at the imino N atom of Benzam as a result of proton transfer from the acidic hydroxy group of Dmb. In the monoclinic polymorph, (I) (space groupP21/n), the asymmetric unit consists of two Dmb−anions and two monoprotonated BenzamH+cations. In the orthorhombic polymorph, (II) (space groupP212121), one Dmb−anion and one BenzamH+cation constitute the asymmetric unit. In both polymorphic salts, the amidinium fragments and carboxylate groups are completely delocalized. This delocalization favours the aggregation of the molecular components of these acid–base complexes into nonplanar dimers with anR22(8) graph-set motifviaN+—H...O−charge-assisted hydrogen bonding. Both the monoclinic and orthorhombic forms exhibit one-dimensional isostructurality, as the crystal structures feature identical hydrogen-bonding motifs consisting of dimers and catemers.

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