The heat of hydration of the proton in the gas and liquid phases

Librovich, N. B.; Кислина, И. С.; Tarakanova, E. G.

doi:10.1134/s1990793109010217

Cited by 3 publications

(8 citation statements)

References 13 publications

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“…Ideas regarding the existence of Н + (Н 2 О) 6 hexahydrate in aqueous acid with a well‐defined boundary of positive charge delocalization largely coincides with the results of N. B. Librovich and G. V. Yukhnevich et al Their spectral measurements and ab initio calculations for Н 3 О + (Н 2 О) n hydrates at n = 0 to 4 have shown that Н 9 О 4 + possesses a stable structure with a linear symmetrical Н‐bond. The symmetrical hydrogen bond is several times stronger than ordinary hydrogen bonds and has a spectrum with a continuous absorption in the IR region.…”

Section: Proton Aciditysupporting

confidence: 84%

“…Н 5 О 2 + ions tend to form the second coordination sphere of a proton, ie, 4 hydrogen bonds with a strength of 15.7 kcal⋅mol −1 , which is 2 to 3 times greater than the strength of Н‐bonds in liquid water . The average energy of molecular attachment to the third hydration shell is 9 kcal⋅mol −1 , ie, only 1.5 times greater than the bond energy of water dimer.…”

Section: Proton Aciditymentioning

confidence: 99%

“…By summarizing the viewpoints of their predecessors and of their own, the authors of other works set forth the following important proposition:…”

Section: Proton Aciditymentioning

confidence: 99%

“…The increase of water content in the solution causes not only the ordinary hydration of Н 3 О + but also a chemical reaction with water, accompanied by rearrangement of bonds and formation of a symmetric ion Н 5 О 2 + . Dilution causes the hydration shell of the proton to change from an ion contact pair to a solvate‐separated one in which the anion is always outside of the shell limits.…”

Section: Proton Aciditymentioning

confidence: 99%

“…The role of specific acid catalysis in the reactivity of the compounds should not be underestimated. The possibility of specific solvation of the reagent depends on the profoundness of our ideas about the actual acidity of the medium and the correctness of its quantitative description, which in turn is determined by the level of contemporary notions about the state of the solvated proton in aqueous acidic solutions …”

Section: Introductionmentioning

confidence: 99%

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Solvated proton as the main reagent and a catalyst in the single-stage aromatic sulfonation and protodesulfonation of sulfonic acids

2017

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This review is devoted to the critical analysis of the existing contradictory ideas about kinetic description and the mechanisms of electrophilic aromatic substitution (EAS), ie, reversible arene sulfonation and hydrolysis (protodesulfonation) of arenesulfonic acids. Contemporary scientific and educational literature contains prevailing, widespread points of view on the multistage nature processes of the EAS that proceed via πand σ-complexes and are accompanied by arenium ion formation. This interpretation does not account for determining influence of the medium, and the process accompanies the loss of aromaticity. The review presents an alternative point of view: These processes proceed via singlestage and the same transition state. To substantiate this position, we reviewed in detail the contemporary ideas on the solvated proton structure, the limits of applicability of acidity function Н о and excess acidity Х scales, and the experimental solubility data of arenesulfonic acid hydrates in sulfuric acid. This solubility depends on the medium acidity (h o ), which provides the formation of 3 conjugated types of hydrates: anionic (АrSO 3 − ·H 2 O), hydroxonium-arene sulfonated (АrSO 3 − ·H 3 O + ), and the hydroxonium complex with the H-form of АrSO 3 Н·H 3 O + acid. In sulfuric acid solutions with an excess of water, irreversible hydrolysis proceeds with the participation of ArSO 3 − ·H 3 O + . However, protodesulfonation becomes reversible and proceeds with the participation of ArSO 3 Н·H 3 O + in solutions with an excess of sulfuric acid. A conclusion has been made about determining the role of the hydrated proton environment by means the formation of a cyclic transition state. An alternative 2-stage mechanism of EAS is logically and energetically unsubstantiated and, therefore, should be rejected.

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Section: Proton Aciditysupporting

confidence: 84%

Section: Proton Aciditymentioning

confidence: 99%

“…By summarizing the viewpoints of their predecessors and of their own, the authors of other works set forth the following important proposition:…”

Section: Proton Aciditymentioning

confidence: 99%

Section: Proton Aciditymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%