Activation parameters and kinetic isotope effect in the system tropaeolin O-OH?

1978 ◽  
Vol 10 (4) ◽  
pp. 407-415 ◽  
Author(s):  
Berta Perlmutter-Hayman ◽  
Ruth Shinar
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Activation Parameters ◽  
Kinetic Isotope

Aspects of the hydrolysis of formamide: revisitation of the water reaction and determination of the solvent deuterium kinetic isotope effect in base

2002 ◽  
Vol 80 (10) ◽  
pp. 1343-1350 ◽  
Author(s):  
H Slebocka-Tilk ◽  
F Sauriol ◽  
Martine Monette ◽  
R S Brown
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Base Hydrolysis ◽  
Kinetic Isotope ◽  
Acid And Base ◽  
Acid Reaction ◽  
Ph Range ◽  
Hydrolysis Of

A study of the hydrolysis of formamide is reported with the aims of isolating the water reaction for hydrolysis from the acid and base hydrolysis terms and determining the solvent deuterium kinetic isotope effect (dkie) on base-catalyzed hydrolysis. Respective activation parameters (ΔH‡ and ΔS‡) of (17.0 ± 0.4) kcal mol–1 and (–18.8 ± 1.3) cal mol–1 K–1 for the acid reaction and (17.9 ± 0.2) kcal mol–1 and (–11.1 ± 0.5) cal mol–1 K–1 for the base reaction were determined from Eyring plots of the second-order rate constants over the range of 27–120°C. Kinetic studies at the minima of the pH/rate profiles in the pH range from 5.6 to 6.2 in MES buffers at 56°C, and in the pH range of 4.25–6.87 in acetate and phosphate buffers at 120°C are reported. At 56°C the available data fit the expression k56obs = 0.00303[H3O+] + 0.032[HO–] + (3.6 ± 0.1) × 10–9, while at 120°C the data fit k120obs = (0.15 ± 0.02)[H3O+] + (3.20 ± 0.24)[HO–] + (1.09 ± 0.29) × 10–6. Preliminary experimental estimates of Ea (ln A) of 22.5 kcal mol–1 (15.03) for the water rate constant (kw) are calculated from an Arrhenius plot of the 56 and 120°C data giving an estimated kw of 1.1 × 10–10 s–1 (t1/2 = 199 years) at 25°C. Solvent dkie values of kOH/kOD = 1.15 and 0.77 ± 0.06 were determined at [OL–] = 0.075 and 1.47 M, respectively. The inverse value is determined under conditions where the the first step of the reaction dominates and is analyzed in terms of a rate-limiting attack of OL–.Key words: formamide, activation parameters, water reaction, acid and base hydrolysis, solvent kinetic isotope effect.

scholarly journals The Mechanism of RuO4-Mediated Oxidations of Saturated Hydrocarbons. Reactivity, Kinetic Isotope Effect and Activation Parameters.

1992 ◽  
Vol 46 ◽  
pp. 644-649 ◽  
Author(s):  
Jan M. Bakke ◽  
Donald Bethell ◽  
Niels Harrit ◽  
Arne Holm ◽  
P. Spielbüchler ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Activation Parameters ◽  
Saturated Hydrocarbons ◽  
Kinetic Isotope

scholarly journals Kinetics and Mechanism of the Oxidation of α-Hydroxy Carboxylic Acids by Bromine

1973 ◽  
Vol 28 (7-8) ◽  
pp. 450-453 ◽  
Author(s):  
Kalyan K. Banerji
Keyword(s):  
Isotope Effect ◽  
Hydroxy Acid ◽  
Kinetic Isotope Effect ◽  
Activation Parameters ◽  
Probable Mechanism ◽  
Molecular Bromine ◽  
Solvent Isotope Effect ◽  
First Order ◽  
Kinetic Isotope ◽  
Solvent Isotope

The oxidation of glycollic, lactic, u-hydroxybutyric, and 2-phenyllactic acids by aqueous bromine has been studied. The reaction is of first order with respect to the oxidant and the anion of the hydroxy acid respectively. The active oxidising species is molecular bromine. The oxidation of α,α-dideuterioglycollic acid indicated a kinetic isotope effect, kH/kD=4.62 at 25°C. The reaction does not show any appreciable solvent isotope effect. The activation parameters arc evaluated. A probable mechanism has been suggested.

The Kinetics of the Oxidation of Acetaldehyde by Acid Permanganate

1972 ◽  
Vol 27 (7) ◽  
pp. 772-774 ◽  
Author(s):  
K. K. Banerji
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Activation Parameters ◽  
Hydrogen Ion ◽  
First Order ◽  
Hydride Ion ◽  
Kinetic Isotope ◽  
Kinetics Of

The kinetics of the oxidation of aceltaldehyde by acid permanganate has been studied. The reaction is of first order with respect to the aldehyde, the oxidant and hydrogen ion individually. The oxidation does not induce polymerisation of acrylonitrile and show a kinetic isotope effect (kH/kD= 6.1). The activation parameters for the oxidation and enolisation reactions have been evaluated. The rate of enolisation, under similar conditions, is less than that of oxidation. A mechanism involving the transfer of a hydride ion from the aldehyde hydrate to the oxidant has been suggested.

Deuterium isotope exchange between molecular hydrogen and cyclopentylamine1

1981 ◽  
Vol 59 (15) ◽  
pp. 2386-2390 ◽  
Author(s):  
E. Allan Symons ◽  
Michel J. Clermont
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Activation Parameters ◽  
Hydrogen Gas ◽  
Gas Solubility ◽  
Constant Ratio ◽  
Nonpolar Solvents ◽  
Solution Exchange ◽  
Kinetic Isotope ◽  
Rate Constant Ratio

Over the temperature range −68 to −10 °C the ability of the alkali metal cyclopentylamide salts to catalyze deuterium exchange between D2 and cyclopentylamine (CPA) is in the order [Formula: see text] The rate constant ratio at −68 °C for CsCPA/LiCPA is > 103. The measured Arrhenius activation parameters and kinetic isotope effect data are only slightly different for the Li and Na salts. The in-solution exchange reaction is so fast for the KCPA and CsCPA catalysts that rate constants independent of mass transfer could not be measured for them in the stirred gas/liquid reactor even at −68 °C.The gas solubility isotope effect, sie = [D2]/[H2], has been determined in CPA over the range −50 to +25 °C. From the values obtained (e.g. 1.08 at 25 °C, 1.10 at −25 °C) and the limited literature data available it appears that the sie for hydrogen gas may be greater for polar than for nonpolar solvents.

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