Correlation Analysis of Acidity and Basicity: From the Solution to the Gas Phase

Gal, Jean‐François; Maria, Pierre‐Charles

doi:10.1002/9780470171967.ch6

Cited by 63 publications

(9 citation statements)

References 236 publications

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“…However, in the second half of the 20th century MS techniques reached a level of development such as the determination of the energy of formation of ions, as well as the quantitative studies of kinetics and thermodynamics of gas-phase proton-transfer reactions became possible. 123−126,136−138,180−185 Thanks to this evolution, relative acidities and basicities could be experimentally determined 74,75,84,[92][93][94][95][96][97]144,145,151 and gas-phase acidity and basicity scales established. 39…”

Section: Absolute Acid−base Strengthmentioning

confidence: 99%

Enhanced Basicity of Push–Pull Nitrogen Bases in the Gas Phase

2016

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Nitrogen bases containing one or more pushing amino-group(s) directly linked to a pulling cyano, imino, or phosphoimino group, as well as those in which the pushing and pulling moieties are separated by a conjugated spacer (C═X), where X is CH or N, display an exceptionally strong basicity. The n-π conjugation between the pushing and pulling groups in such systems lowers the basicity of the pushing amino-group(s) and increases the basicity of the pulling cyano, imino, or phosphoimino group. In the gas phase, most of the so-called push-pull nitrogen bases exhibit a very high basicity. This paper presents an analysis of the exceptional gas-phase basicity, mostly in terms of experimental data, in relation with structure and conjugation of various subfamilies of push-pull nitrogen bases: nitriles, azoles, azines, amidines, guanidines, vinamidines, biguanides, and phosphazenes. The strong basicity of biomolecules containing a push-pull nitrogen substructure, such as bioamines, amino acids, and peptides containing push-pull side chains, nucleobases, and their nucleosides and nucleotides, is also analyzed. Progress and perspectives of experimental determinations of GBs and PAs of highly basic compounds, termed as "superbases", are presented and benchmarked on the basis of theoretical calculations on existing or hypothetical molecules.

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Section: Absolute Acid−base Strengthmentioning

confidence: 99%

Enhanced Basicity of Push–Pull Nitrogen Bases in the Gas Phase

2016

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“…At variance with solution chemistry where it is often difficult to separate solvent and substituent effects, gas‐phase chemistry allows the understanding of intrinsic reactivity. Substituent effect on thermochemical properties of gaseous cations and anions has been consequently a subject of intense interest for a long time (Taft & Topsom, 1987; Gal & Maria, 1990; Chuchani et al, 1999). The substituent effects are generally interpreted by the combination of terms taking into account (i) the electrostatic effects (field/inductive, polarizability) and (ii) the resonance of π electrons.…”

Section: Structural and Energetic Aspects Of The Protonationmentioning

confidence: 99%

Gas‐phase basicities of polyfunctional molecules. Part 1: Theory and methods

Bouchoux

2007

Mass Spectrometry Reviews

116

197

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The experimental and theoretical methods of determination of gas-phase basicities, proton affinities and protonation entropies are presented in a tutorial form. Particularities and limitations of these methods when applied to polyfunctional molecules are emphasized. Structural effects during the protonation process in the gas-phase and their consequences on the corresponding thermochemistry are reviewed and classified. The role of the nature of the basic site (protonation on non-bonded electron pairs or on p-electron systems) and of substituent effects (electrostatic and resonance) are first examined. Then, linear correlations observed between gas-phase basicities and ionization energies or substituent constants are recalled. Hydrogen bonding plays a special part in proton transfer reactions and in the protonation characteristics of polyfunctional molecules. A survey of the main properties of intermolecular and intramolecular hydrogen bonding in both neutral and protonated species is proposed. Consequences on the protonation thermochemistry, particularly of polyfunctional molecules are discussed. Finally, chemical reactions which may potentially occur inside protonated clusters during the measurement of gas-phase basicities or inside a protonated polyfunctional molecule is examined. Examples of bond dissociations with hydride or alkyl migrations, proton transport catalysis, tautomerization, cyclization, ring opening and nucleophilic substitution are presented to illustrate the potentially complex chemistry that may accompany the protonation of polyfunctional molecules. # 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:775-835, 2007

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“…This led us to undertake quantum mechanical ''QM'' studies on substituted R-BTPs to investigate the intrinsic effect of their R para -pyridine substituent (R = NMe 2 , NH 2 , OMe, C 6 H 5 , t Butyl, Me, H, F, Cl) in the gas phase. As a reference, we consider the protonation of R-pyr analogues in the pyridine series, well documented by experiment in the gas phase and in aqueous solution 13,14 and by simulations. [15][16][17] Solvation effects play a major role in proton transfer, reactivity and complexation equilibria.…”

Section: Introductionmentioning

confidence: 99%

“…[15][16][17] Solvation effects play a major role in proton transfer, reactivity and complexation equilibria. 13,18,19 When used as extractant molecules, BTPs are solubilized in the organic phase, in equilibrium with acidic aqueous solutions. This medium is more polar than an organic phase based on e.g.…”

Section: Introductionmentioning

confidence: 99%

Substituent effects on BTP's basicity and complexation properties with Ln^IIIlanthanide ions

et al. 2011

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Correlation Analysis of Acidity and Basicity: From the Solution to the Gas Phase

Cited by 63 publications

References 236 publications

Enhanced Basicity of Push–Pull Nitrogen Bases in the Gas Phase

Enhanced Basicity of Push–Pull Nitrogen Bases in the Gas Phase

Gas‐phase basicities of polyfunctional molecules. Part 1: Theory and methods

Substituent effects on BTP's basicity and complexation properties with Ln^IIIlanthanide ions

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Correlation Analysis of Acidity and Basicity: From the Solution to the Gas Phase

Cited by 63 publications

References 236 publications

Enhanced Basicity of Push–Pull Nitrogen Bases in the Gas Phase

Enhanced Basicity of Push–Pull Nitrogen Bases in the Gas Phase

Gas‐phase basicities of polyfunctional molecules. Part 1: Theory and methods

Substituent effects on BTP's basicity and complexation properties with LnIIIlanthanide ions

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Product

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Substituent effects on BTP's basicity and complexation properties with Ln^IIIlanthanide ions