Effect of changing pH upon the kinetic 13C-isotope effect in the decarboxylation of 4-methoxyanthranilic acid

1968 ◽  
Vol 46 (4) ◽  
pp. 563-566 ◽  
Author(s):  
G. E. Dunn ◽  
John Buccini
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Isotope Effect ◽  
Aromatic Ring ◽  
Kinetic Isotope Effect ◽  
13C Isotope ◽  
Kinetic Isotope ◽  
The One

The 13C-carboxyl kinetic isotope effect on decarboxylation of 4-methoxyanthranilic acid has been determined in aqueous solutions of ionic strength 0.50 at 60 °C. The isotope effect, 100(k12/k13 −1), is found to be 4.2% at pH −0.3, 1.4% at pH 1.3, and zero at pH 4.0. This information makes it possible to decide between two mechanisms previously proposed in favor of the one in which both anion and neutral acid are protonated at carbon-1 of the aromatic ring but only the protonated anion decarboxylates.

Is There a Deuterium Kinetic Isotope Effect in the One-Electron Transfer from 1-Benzyl-1,4-dihydronicotinamide to 9-Fluorenylidenemalononitrile?

2000 ◽  
Vol 65 (21) ◽  
pp. 7213-7214 ◽  
Author(s):  
Agnès Anne ◽  
Jacques Moiroux ◽  
Jean-Michel Savéant
Keyword(s):  
Electron Transfer ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
The One

Kinetic Isotope Effect for γ-Radiolytic Reduction of Divalent Lead in Aqueous Solutions

1994 ◽  
Vol 4 (4) ◽  
pp. 124-125
Author(s):  
Aleksandr Yu. Garnov ◽  
Sergey I. Nikitenko ◽  
Arkadii A. Lukonin ◽  
Boris G. Ershov
Keyword(s):  
Aqueous Solutions ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
Radiolytic Reduction

Kinetic evidence for the importance of solvent-separated ion pairs during the solvolyses of adamantylideneadamantyl derivatives

2004 ◽  
Vol 82 (9) ◽  
pp. 1336-1340
Author(s):  
Xicai Huang ◽  
Andrew J Bennet
Keyword(s):  
Ionic Strength ◽  
Transition State ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Kinetic Isotope Effects ◽  
Ion Pair ◽  
Salt Effects ◽  
Kinetic Isotope

The aqueous ethanolysis reactions of adamantylideneadamantyl tosylate, -bromide, and -iodide (1-OTs, 1-Br and 1-I) were monitored as a function of ionic strength. Special salt effects are observed during the solvolyses of both homoallylic halides, but not in the case of the tosylate 1-OTs. The measured α-secondary deuterium kinetic isotope effects for the solvolysis of 1-Br in 80:20 and 60:40 v/v ethanol–water mixtures at 25 °C are 1.110 ± 0.018 and 1.146 ± 0.009, respectively. The above results are consistent with the homoallylic halides reacting via a virtual transition state in which both formation and dissociation of a solvent-separated ion pair are partially rate-determining. While the corresponding transition state for adamantylideneadamantyl tosylate involves formation of the solvent-separated ion pair.Key words: salt effects, kinetic isotope effect, internal return, solvolysis, ion pairs.

scholarly journals Kinetics and Mechanism of the Decarboxylation of Pyrrole-2-carboxylic Acid in Aqueous Solution

1971 ◽  
Vol 49 (7) ◽  
pp. 1032-1035 ◽  
Author(s):  
G. E. Dunn ◽  
Gordon K. J . Lee
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Carboxylic Acid ◽  
Isotope Effect ◽  
Anthranilic Acid ◽  
Kinetic Isotope Effect ◽  
Pyrrole Ring ◽  
First Order ◽  
Kinetic Isotope ◽  
Ph Range

The decarboxylation of pyrrole-2-carboxylic acid in aqueous buffers at 50° and ionic strength 1.0 has been found to be first order with respect to substrate at a fixed pH. As the pH is decreased, the rate constant increases slightly in the pH range 3–1, then rises rapidly from pH 1 to 10 M HCl. The 13C-carboxyl kinetic isotope effect is 2.8% in 4 M HClO4 and negligible at pH ~ 3. These observations can be accounted for by a mechanism, previously proposed for the decarboxylation of anthranilic acid, in which the species undergoing decarboxylation is the carboxylate ion protonated at the 2-position of the pyrrole ring. This intermediate can be formed both by ring-protonation of the carboxylate anion and by ionization of the ring-protonated acid. At low acidities ring-protonation is rate determining, but at higher acidities the rate of protonation exceeds that of decarboxylation.

Kinetic Isotope Effect for Hydrogen Abstraction by•OH Radicals from Normal and Carbon-Deuterated Ethyl Alcohol and Methylamine in Aqueous Solutions†

2003 ◽  
Vol 107 (30) ◽  
pp. 7268-7276 ◽  
Author(s):  
Marija Bonifačić ◽  
David A. Armstrong ◽  
Igor Štefanić ◽  
Klaus-Dieter Asmus
Keyword(s):  
Aqueous Solutions ◽  
Isotope Effect ◽  
Ethyl Alcohol ◽  
Kinetic Isotope Effect ◽  
Hydrogen Abstraction ◽  
Oh Radicals ◽  
Kinetic Isotope

The influence of H/D kinetic isotope effect on radiation-induced transformations of hydroxyl-containing compounds in aqueous solutions

2020 ◽  
Vol 54 (10) ◽  
pp. 732-744
Author(s):  
Palina S. Nepachalovich ◽  
Oleg I. Shadyro ◽  
Andrei V. Bekish ◽  
Vadim V. Shmanai
Keyword(s):  
Aqueous Solutions ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
Radiation Induced

H/D Kinetic Isotope Effect as a Tool to Elucidate the Reaction Mechanism of Methyl Radicals with Glycine in Aqueous Solutions

2013 ◽  
Vol 117 (51) ◽  
pp. 13996-13998 ◽  
Author(s):  
Guy Yardeni ◽  
Israel Zilbermann ◽  
Eric Maimon ◽  
Lioubov Kats ◽  
Ronen Bar-Ziv ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Methyl Radicals ◽  
Kinetic Isotope
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