Acidity function for carbon bases in aqueous sulfuric and perchloric acids

Reagan, Morris T.

doi:10.1021/ja01048a018

Cited by 22 publications

(7 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With the acyclic analogue PhCH=C(SMe),, the exchange was only 3-fold as rapid as the hydrolysis under similar conditions, although the kinetic reversibility of the protonation in terms of k2/kPl (0.36) was greater in mostly aqueous solutions (2 Stability and reactivity The equilibrium constants K1 for protonation of the double bond refer to carbon basicity. Similar determinations of which we are aware are those with 1,l-diarylethylenes (6,11) and enarnines of propiophenone (12). The most basic is the enarnine (log K1 = 10) (12).…”

Section: Isotope Exchangesupporting

confidence: 55%

“…[6]). The deuterated substrate is more reactive owing to the secondary kinetic isotope effects and for some other reasons (2).…”

Section: Low Acidity Regionmentioning

confidence: 99%

“…A sample of 30 pL of a stock solution of the substrate in acetonitrile was introduced from a microsyringe into 3.0 mL of acid solution, which was thermally equilibrated in a quartz cuvette, and time-dependent absorbance change was recorded. The absorbance was extrapolated to the time of mixing by a pseudo-first-order plot to obtain A', and Am was read after 6 …”

Section: Equilibrium Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Acid-catalyzed hydrolysis of 2-methylene-1,3-dithiolane. 2. Remarkable effects of β substitution on reversibility of the carbon protonation

Okuyama¹,

Toyoda²,

Fueno³

1986

Can. J. Chem.

View full text Add to dashboard Cite

This paper is dedicated to Professor Arthur N . Bourns TADASHI OKUYAMA, MASAYOSHI TOYODA, and TAKAYUKI FUENO. Can. J. Chem. 64, 11 16 (1986).Hydrolyses of Zethylidene-( l b ) , 2-isopropylidene-( l c ) , and 2-benzylidene-l,3-dithiolane ( I d ) were kinetically investigated in aqueous solution. All the individual rate constants involved in this three-step reaction were evaluated. Initial carbon protonation is only partially reversible (k2/k-1 = 1.33,0.68, and 1.02 for l b , l c , and Id, respectively) at higher pH, while the protonation becomes completely reversible below pH 2 where the thud step is rate determining. Complete H-D isotopeexchange at the P-carbon of l b and Id was observed in deuterium media before appreciable hydrolysis took place. It was demonstrated that reversion from the tetrahedral intermediate 3 to 1 occurs extensively during the reaction in the latter acidity range. Relative stabilities and reactivities of the olefinic substrates 1 are discussed. que, au cours de la rCaction, la transformation de l'intenntdiaire tCtraidrique 3 en 1 ne se produit que dans le dernier intervalle de pH. On discute des stabilitCs et des rtactivitts relatives des substrats olCfiniques 1.[Traduit par la revue]

show abstract

Section: Isotope Exchangesupporting

confidence: 55%

“…[6]). The deuterated substrate is more reactive owing to the secondary kinetic isotope effects and for some other reasons (2).…”

Section: Low Acidity Regionmentioning

confidence: 99%

Section: Equilibrium Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Acid-catalyzed hydrolysis of 2-methylene-1,3-dithiolane. 2. Remarkable effects of β substitution on reversibility of the carbon protonation

Okuyama¹,

Toyoda²,

Fueno³

1986

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…It is therefore not surprising that, in due time, several acidity functions were measured using as bases N,N‐dialkyl nitroanilines (H o ”’), triaryl carbenium ions (H R ), amides (H A ), and so on leading to the widespread belief in an “acidity function failure” . This “failure” also was exaggerated, as the definition of the functions, with γ B /γ BH + constant within a family of structurally similar bases, was clear and correct.…”

Section: Hammett's Acidity Functionmentioning

confidence: 99%

Beyond pH

Scorrano¹,

O'Ferrall

2013

J of Physical Organic Chem

View full text Add to dashboard Cite

pH is one of the few chemical quantities known also to the lay public. However, when we use acid solution more concentrated than 1 M, very few chemists are aware of how to define the activity of the proton under such conditions. In this review, we will describe the scientific efforts to understand in a comprehensible way the behavior of organic compounds in moderately concentrated aqueous solutions. In the second part of the past century, it became clear that, since increasing the aqueous acid concentration, we must decrease the concentration of water, protonation of weak bases is always accompanied by a change in solvating ability of the medium. As a consequence, the description of the protonation equilibria must be made either by the pK in water and by the solvent effect on the equilibrium. We will show that treatments by Bunnett and Olsen, Marziano, and Cox and Yates all give the same results, although on a slightly different scale. It is possible to classify organic ions solvation abilities in the scale oxonium ammonium > sulphonium > carbenium. The same scale is obtained by evaluating the energetics of transfer of the same ions from gas phase to water. More recently, it has become possible to calculate the energetic of ion solvation, obtaining the same scale described above for the experimental data.

show abstract

“…The fact that this reaction, under conditions of both low and high acidity, appears to be first o d e r with respect to the Hammett acidity function, ho, may be fortuitous. There is evidence that the protonation of arenes does not follow this function (7), and while little is known about the protonation behavior of oxy anions there is no reason to suspect that such a reaction would follow a simple Hammett acidity relationship (Id). In fact it has been discovered that this function is completely satisfactory only for reactions which involve protonation of primary amines; even the protonation of tertiary amines does not conform exactly (8).…”

Section: \ Imentioning

confidence: 99%