The Brønsted relation – recent developments

Kresge, A. J.

doi:10.1039/cs9730200475

Cited by 175 publications

(120 citation statements)

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“…Alternatively we may use the best available pKBH+ values for the esters (see Calculations) and see how well the data obey the Marcus equation for mechanism [13]. When the data are plotted in this way, the points fall in reasonable accord with eq.…”

Section: I Imentioning

confidence: 55%

“…The difficulty with process [13] was that the best available values for the pKBH+ values of carbonyl compounds led to some points falling in impossible regions, corresponding to rate constants exceeding the relaxation rate for water (1); this was not compelling because there is considerable uncertainty concerning the true pKBH+ values for simple carbony1 compounds, and recent values for acetone have varied from -2.72 (16) to -5.37 (17). Only for the more negative values of the pKBH+ for acetone and other simple carbonyl compounds do the points fall in forbidden regions.…”

Section: I Imentioning

confidence: 99%

“…Other investigations, to be reported separately, [13], with specific acid catalysis. The line is the best fit by least squares, and looks much better than for mechanism [14].…”

Section: I Imentioning

confidence: 99%

“…Acid catalyzed hydrolysis of esters poses a problem, since there are two mechanisms which both lead to plausible fits of data to the Marcus equation with the limited set of data initially available (1), namely specific acid catalyzed6 addition of water in which water adds to the protonated ester to give the protonated form of the tetrahedral intermediate, process [13], or general acid catalyzed6 addition of water, with hydronium ion acting as general acid, so that water plus hydronium ion combines with the ester to give the protonated tetrahedral intermediate, process [l4].…”

Section: I Imentioning

confidence: 99%

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Effect of the acyl substituent on the equilibrium constant for hydration of esters

Guthrie¹,

Cullimore²

1980

Can. J. Chem.

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Can. J. Chem. 58, 1281 (1980). Heats of hydrolysis have been measured for the trimethyl orthoesters of isobutyric, propionic, benzoic, methoxyacetic, chloroacetic, and cyanoacetic acids using aqueous acid with an organic cosolvent where necessary, and of the corresponding esters in alkaline solution. Solubilities or free energies of transfer from gas to aqueous solution have been measured. permitting calculation of the free energies of formation of the aqueous orthoesters, and by methods which we have published previously, calculation of the free energies of formation of the covalent hydrates of the esters, and the free energy changes for hydration of these esters.Using estimated pKa values equilibrium constants were calculated for the addition of hydroxide to the esters. The data are ingood agreement with the appropriate Marcus equation relating rate and equilibrium constants with a value forb of 8.99 f 0.17. This line was used to estimate the equilibrium constant for addition of hydroxide, and thence of water, to some additional esters where only the rate constant was available. Rate constants for hydrolysis of methyl esters in aqueous solution at 25°C were calculated from literature data, correcting for the effect of other conditions as necessary. From the equilibrium constants for addition of water we could estimate the rate constants for uncatalyzed hydrolysis; for the cases where this rate constant has been measured, the agreement was satisfactory. For acid catalyzed hydrolysis the data permit a test of the two alternative mechanisms considered previously, namely specific acid catalysis and general acid catalysis with hydronium ion acting as a general acid. For esters the mechanism is clearly specific acid catalysis, but for aldehydes and ketones it appears very likely that the mechanism is general acid catalysis.J. PETER GUTHRIE et PATRICIA A. CULLIMORE. Can. J. Chem. 58, 1281 (1980). On a mesure les chaleurs d'hydrolyse des orthoesters trimethyliques des acides isobutyrique, propionique, benzoique, methoxyacetique, chloroacetique et cyanacttique en utilisant une solution aqueuse acide avec un cosolvant organique lorsque cela s'avkre necessaire; on a aussi mesure les chaleurs d'hydrolyse des esters correspondants en solution basique. On a mesure les solubilites ou les energies libresde transfertde la phase gazeuse a la solution aqueuse ce qui a permisde calculerles energies libres de formation des orthoesters aqueux et de calculer, au moyen de methodes publiees anterieurement, les energies libres de formation des hydrates covalents des esters et les changements d'energie libre d'hydratation de ces esters.On a calcule les constantes d'equilibre de la reaction d'addition de I'hydroxyde sur les esters en utilisant les valeurs approximatives du pKa. Les donnees sont en parfait accord avec I'equation appropriee de Marcus reliant la vitesse et les constantes d'equilibre avec une valeur de b = 8.99 f 0.17. Cette donnee est utiliste pour evaluer la constante d'equilibre de la reaction d'addition d'hydroxyde et pa...

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Section: I Imentioning

confidence: 55%

Section: I Imentioning

confidence: 99%

“…Other investigations, to be reported separately, [13], with specific acid catalysis. The line is the best fit by least squares, and looks much better than for mechanism [14].…”

Section: I Imentioning

confidence: 99%

Section: I Imentioning

confidence: 99%

See 2 more Smart Citations

Effect of the acyl substituent on the equilibrium constant for hydration of esters

Guthrie¹,

Cullimore²

1980

Can. J. Chem.

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“…Such mechanisms have been shown to be important in exchange reactions that can be followed by nrnr, and in carbinolamine forming processes. As I stated above, my examination of the E2 reaction, combined with a common organic prejudice that proton transfer along a preformed hydrogen bond should be very easy (24,42,43,102,(105)(106)(107), led me to expect a small intrinsic barrier for "fast" proton transfers. ow ever examination of the classic data from Eigen (108) on such proton transfers, interpreted in terms of the classic Eigen mechanism, with a chemical step preceded and followed by diffusional steps, showed that application of Marcus theory to the chemical step required a barrier of 4-5 kcallmol.…”

Section: Conjecture 2: Multidimensional Marcusmentioning

confidence: 99%

1995 Syntex Award Lecture Correlation and prediction of rate constants for organic reactions

Guthrie¹

1996

Can. J. Chem.

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Abstract:Marcus theory provides a framework for correlating rate and equilibrium constants, and thus the possibility of predicting rate from structure. This had been successful for a number of simple reactions, including the addition of hydroxide to carbonyl compounds, enolate formation from carbonyl compounds, and aldol addition and elimination reactions. The theory can be extended, as Multidimensional Marcus Theory, to cover concerted reactions such as E2 eliminations, the water-mediated proton switch, or the breakdown of the tetrahedral intermediate in amide hydrolysis. We have now found that Marcus theory can be applied not only to inter-molecular reactions but also to intra-molecular reactions. This is illustrated for aldol condensation and esterllactone formation.Key words: Marcus theory, concerted reactions, intramolecular reactions, aldol condensation, ester formation, proton transfer.Resume : La thCorie de Marcus offre un s y s t h e pour Ctablir des corrClations entre les constantes de vitesse et dlCquilibre et, de ce fait, la possibilitC de faire des pridictions relatives aux vitesses ii partir des structures. Cette approche a Ct C couronnke de succks pour un certain nombre de rCactions simples, y compris l'addition de l'ion hydroxyde ii des composks carbonylks, la formation d'Cnolates 5 partir de composCs carbonylks et les rkactions d'addition et d'klimination aldoliques. On a ktendue la thiorie, sous la forme de la thCorie multidimensionnelle de Marcus, pour couvrir les rCactions concertkes, comme les Climinations E2, 1'Cchange de protons avec l'eau comme mCdiateur ou 1adCpyramidalisation de l'intermkdiaire tCtraCdrique lors de l'hydrolyse des amides. On a trouvC que la thCorie de Marcus peut &tre appliquCe, non seulement aux rCactions inter~nolCculaires mais aussi aux rCactions intramolCculaires. On illustre ce point par la condensation aldolique et le formation d'esterllactone.

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Rapid Marcus Curvature Due to Extremely Strong Solvational Imbalances inthe Deprotonation of a Trinitrobenzylic Carbon Acid by Oximate Bases

Terrier¹,

Moutiers²,

Pelet

et al. 1999

Eur. J. Org. Chem.

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The Brønsted relation – recent developments

Abstract: This is the range over which dG* is a single-valued function of dG" and therefore the range

Cited by 175 publications

References 1 publication

Effect of the acyl substituent on the equilibrium constant for hydration of esters

Effect of the acyl substituent on the equilibrium constant for hydration of esters

1995 Syntex Award Lecture Correlation and prediction of rate constants for organic reactions

Rapid Marcus Curvature Due to Extremely Strong Solvational Imbalances inthe Deprotonation of a Trinitrobenzylic Carbon Acid by Oximate Bases

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