The Vapor Pressures and Activity Coefficients of Aqueous Solutions of Perchloric Acid at 25°<sup>1</sup>

Pearce, J. N.; Nelson, Arthur F.

doi:10.1021/ja01335a004

Cited by 23 publications

(15 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although these curves are similar in appearance they diverge by up t o 1.7 H A units. We have also checked the water activity dependence of the HR function using published data for sulfuric, perchloric, and nitric acids (12,13) and find again that similar but clearly separate curves result for each acid. I t is therefore apparent that although acidity functions in general are strongly dependent on a , ,~ of the medium, the unique character of the Ho-a,,, relationship for different acids must a t least be partly fortuitous.…”

Section: Indicator Pi< Valuesmentioning

confidence: 64%

THE H_A ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

Yates¹,

Riordan²

1965

Can. J. Chem.

View full text Add to dashboard Cite

Values of the HI, acidity function have been determined for 0-35% hydrochloric acid using a set of amide indicators. T h e indicator pK values agree with those previously obtained in sulfuric acid. T h e HA scale decreases less steeply than Ho in t h e high concentration region, but the difference between the two functions is less marked than in sulfuric acid. The reasons for this are discussed. T h e values of H:i have been combined with available rate and water activity data to obtain information about the mechanism of amide hydrolysis. Eleven sets of rate data, consisting of 64 rate constants obtained under a variety of experimental couditions, give similar hydration parameters for this reaction. T h e temperature dependence of hydration parameters is discussed.

show abstract

Section: Indicator Pi< Valuesmentioning

confidence: 64%

THE H_A ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

Yates¹,

Riordan²

1965

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…p 0 H 2 O , calculated in this work and determined earlier [2, [4][5][6][7][8] are plotted against analytical concentrations in mole fraction in Fig. 1.…”

Section: Resultsmentioning

confidence: 93%

“…Namely, they were carried out at 25°C by isopiestic [4][5][6] and dynamic [7] methods. In addition, measurements were carried out at 0°C by isopiestic [8] and at 50°C by psychrometric [8] methods, as well as at 0, 10, 20, 30, 40 and 50°C by the static [2] method.…”

Section: Resultsmentioning

confidence: 99%

The Water Activity and Free Water Mole Fraction in Perchloric Acid

Карелин

Tarasenko

2015

J Solution Chem

View full text Add to dashboard Cite

show abstract

“…However, the points for the three individual acids fall (very accurately, correlation coefficients 0.9990 in HCl, 0.9994 in HClO 4 , 0.9994 in H 2 SO 4 ) on slightly different lines, which undoubtedly reflects the fact that the water activities for the three acids are not known equally well. Water activities in the aqueous sulfuric acid medium [ 50 ] are very accurately known [ 51 ], but this is not the case for HCl [ 52 – 54 ] and, particularly, HClO 4 [ 55 – 58 ]. All of the plots fit the appropriate lines more closely than was previously found by treating the process as a traditional A1 reaction [ 48 ].…”

Section: Resultsmentioning

confidence: 99%

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

Cox

2011

IJMS

View full text Add to dashboard Cite

If a species does not have a finite lifetime in the reaction medium, it cannot be a mechanistic intermediate. This principle was first enunciated by Jencks, as the concept of an enforced mechanism. For instance, neither primary nor secondary carbocations have long enough lifetimes to exist in an aqueous medium, so SN1 reactions involving these substrates are not possible, and an SN2 mechanism is enforced. Only tertiary carbocations and those stabilized by resonance (benzyl cations, acylium ions) are stable enough to be reaction intermediates. More importantly, it is now known that neither H3O+ nor HO− exist as such in dilute aqueous solution. Several recent high-level calculations on large proton clusters are unable to localize the positive charge; it is found to be simply “on the cluster” as a whole. The lifetime of any ionized water species is exceedingly short, a few molecular vibrations at most; the best experimental study, using modern IR instrumentation, has the most probable hydrated proton structure as H13O6+, but only an estimated quarter of the protons are present even in this form at any given instant. Thanks to the Grotthuss mechanism of chain transfer along hydrogen bonds, in reality a proton or a hydroxide ion is simply instantly available anywhere it is needed for reaction. Important mechanistic consequences result. Any charged oxygen species (e.g., a tetrahedral intermediate) is also not going to exist long enough to be a reaction intermediate, unless the charge is stabilized in some way, usually by resonance. General acid catalysis is the rule in reactions in concentrated aqueous acids. The Grotthuss mechanism also means that reactions involving neutral water are favored; the solvent is already highly structured, so the entropy involved in bringing several solvent molecules to the reaction center is unimportant. Examples are given.

show abstract

The Vapor Pressures and Activity Coefficients of Aqueous Solutions of Perchloric Acid at 25°¹

Cited by 23 publications

References 1 publication

THE H_A ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

THE H_A ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

The Water Activity and Free Water Mole Fraction in Perchloric Acid

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

Contact Info

Product

Resources

About

The Vapor Pressures and Activity Coefficients of Aqueous Solutions of Perchloric Acid at 25°1

Cited by 23 publications

References 1 publication

THE HA ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

THE HA ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

The Water Activity and Free Water Mole Fraction in Perchloric Acid

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

Contact Info

Product

Resources

About

The Vapor Pressures and Activity Coefficients of Aqueous Solutions of Perchloric Acid at 25°¹

THE H_A ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

THE H_A ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID