The kinetics of proton and deuteron transfer from 4-nitrophenylnitromethane and l-(4-nitrophenyl)-l-nitroethane to 2,7-dimethoxy-l,8-bis(dimethylamino)naphthalene in acetonitrile solvent

1981 ◽  
Vol 59 (21) ◽  
pp. 3034-3038 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Przemyslaw Pruszynski
Keyword(s):  
Isotope Effect ◽  
Reaction Rate ◽  
Significant Contribution ◽  
Reaction Parameters ◽  
Deuterium Isotope Effect ◽  
First Order ◽  
Enthalpy Of Activation ◽  
Deuteron Transfer ◽  
Slow Dissociation ◽  
Kinetics Of

4-Nitrophenylnitromethane reacts with 2,7-dimethoxy-1,8-bis(dimethylamino)naphthalene in acetonitrile in a bimolecular proton transfer, which shows a primary deuterium isotope effect, kH/kD = 12.2 at 25 °C. The large isotope effect on the enthalpy of activation, (ΔHD≠ – ΔHH≠) = 4.6 ± 0.3 kcal mol−1 is consistent with a significant contribution of proton tunnelling to the reaction rate of the protium substrate.The analogous reaction of 1-(4-nitrophenyl)-1-nitroethane with the same base in acetonitrile gives contrasting kinetics and reaction parameters. The reaction is first order, showing no dependence on base concentration. While the isotope effect kH/kD = 9.3 at 25 °C, the enthalpy of activation difference (ΔHD≠ – ΔHH≠) is only 0.5 ± 0.1 kcal mol−1. It is concluded that the 1-(4-nitrophenyl)-1-nitroethane undergoes a slow dissociation, with a very small dissociation constant, followed by a fast association with the base to yield the carbanion ion-pair.

The kinetics of proton and deuteron transfer from 1-(4-nitrophenyl)-1-nitroethane to1,8-diazabicyclo[5.4.0]undec-7-ene in aprotic solvents

1982 ◽  
Vol 60 (13) ◽  
pp. 1692-1695 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Przemyslaw Pruszynski
Keyword(s):  
Energy Barrier ◽  
Reaction Rate ◽  
Significant Contribution ◽  
Transfer Reaction ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Proton Transfer Reaction ◽  
Potential Energy Barrier ◽  
Deuteron Transfer ◽  
Kinetics Of

1-(4-Nitrophenyl)-1-nitroethane reacts with the base1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in both acetonitrile and toluene solvents in a normal second-order proton-transfer reaction, in contrast to its behaviour with the base 2,7-dimethoxy-1,8-bis(dimethylamino)naphthalene in acetonitrile.The primary isotope effect, kHlkD = 12.0 at 25° in toluene is very similar to that observed by other workers for the reaction of 4-nitrophenylnitromethane with DBU under the same conditions. In acetonitrile solvent a kHlkD ratio of 7.8 was found at 25 °C. The isotope effects on the activation parameters for the reaction in both solvents indicate that tunnelling of the proton through the potential energy barrier makes a significant contribution to the reaction rate.

THE KINETICS OF THE INHIBITED AUTOXIDATION OF TETRALIN

1964 ◽  
Vol 42 (10) ◽  
pp. 2324-2333 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Isotope Effect ◽  
Chain Transfer ◽  
Square Root ◽  
Deuterium Isotope Effect ◽  
First Order ◽  
Oxidation Rates ◽  
First Order Kinetics ◽  
A Value ◽  
Root Relation ◽  
Kinetics Of

The kinetics of the inhibition of the autoxidation of tetralin by 2,6-di-t-butyl-4-methylphenol, phenol, and 4-methoxyphenol have been investigated at 65 °C. The highly hindered 2,6-di-t-butyl-4-methylphenol follows simple first order kinetics and exhibits a normal deuterium isotope effect (kH/kD = 10). The kinetics with phenol are complicated by the fact that the phenoxy radical can abstract a hydrogen atom from both tetralin and its hydroperoxide. This leads to oxidation rates which are inversely proportional to the square root of the phenol concentration. The deuterium isotope effect has about the value to be expected in view of this square root relation. The kinetics with 4-methoxyphenol result from chain transfer and from chain termination by the coupling of 4-methoxyphenoxy radicals. The isotope effect varies between zero and a value that approaches the upper limit of about 10 at low inhibitor concentrations.

scholarly journals The kinetics and mechanism of the ligand substitution reaction of aquapentacyanoruthenate(II) with d-penicillamine in aqueous medium

2020 ◽  
pp. 174751982096101
Author(s):  
Rupal Yadav ◽  
Radhey Mohan Naik
Keyword(s):  
Aqueous Medium ◽  
Reaction Rate ◽  
Electronic Effect ◽  
Ligand Substitution ◽  
Order Conditions ◽  
Reaction Parameters ◽  
First Order ◽  
Coloured Complex ◽  
Kinetics Of ◽  
Ligand Substitution Reaction

The kinetics of the formation of the light orange–coloured complex [Ru(CN)5D-PA]3− are studied spectrophotometrically through substitution of a coordinated H2O molecule in aquapentacyanoruthenate(II) [Ru(CN)5OH2]3− by interaction with D-penicillamine [D-PA] in aqueous medium at 490 nm (λmax of [Ru(CN)5D-PA]3−). The reaction is monitored under pseudo-first-order conditions, taking [D-PA] in excess over [Ru(CN)5OH23−]. The effects of various reaction parameters on the rate of the reaction are investigated. Experimental observations reveal that the variation in [D-PA] obeyed the first-order rate law while it is found to be invariant with [Ru(CN)5OH23−] in the whole experimental range. With ionic strength variation, as the reaction advances a decrease in the reaction rate is noticed. The product stoichiometry is assigned as 1:1. The ease of substitution at an H2O molecule in [Ru(CN)5OH23−] is considered on the basis of the electronic effect generated through interactions of the M–OH2 bond. A provisional mechanism based on the calculated results is proposed based on the slowest step of the reaction.

Kinetics of Proton Transfer Reactions of Carbon Acids. IV. Primary Deuterium Isotope Effect in the Reaction of Di-(4-nitrophenyl)methane-d2 with t-Butoxide

1974 ◽  
Vol 52 (4) ◽  
pp. 592-596 ◽  
Author(s):  
Jae-Hang Kim ◽  
Kenneth T. Leffek
Keyword(s):  
Proton Transfer ◽  
Isotope Effect ◽  
Activation Parameters ◽  
Proton Transfer Reaction ◽  
Transfer Reactions ◽  
Deuterium Isotope Effect ◽  
Enthalpy Of Activation ◽  
Proton Transfer Reactions ◽  
Carbon Acids ◽  
Kinetics Of

The primary deuterium isotope effect has been measured for the proton transfer reaction from di-(4-nitrophenyl)methane to t-butoxide ion in a solvent consisting of 10% v/v toluene in t-butanol at a series of temperatures between 20 and 45 °C. The isotopic rate ratio, kH/kD, is 7.3 at 25 °C. The activation parameters showed an enthalpy of activation difference (ΔHD≠ − ΔHH≠) of only ca. [Formula: see text] kcal mol−1 and an entropy isotope effect (ΔSD≠ − ΔSH≠) of −2.4 cal mol−1 deg−1. The latter indicates, according to the theory of Bell, that tunnelling of the proton through the energy barrier is unimportant in this reaction. This result is compared to other reactions in the literature, in which tunnelling has been postulated to occur.

Oxidation of Hydrocarbons. VII. Kinetics of the Oxidation of Naphthalenes by Ruthenium Tetroxide

1975 ◽  
Vol 53 (19) ◽  
pp. 2865-2868 ◽  
Author(s):  
Udo A. Spitzer ◽  
Donald G. Lee
Keyword(s):  
Isotope Effect ◽  
Bond Cleavage ◽  
Initial Reaction ◽  
Second Order Reaction ◽  
Deuterium Isotope Effect ◽  
Ruthenium Tetroxide ◽  
First Order ◽  
Oxidation Of Hydrocarbons ◽  
Inverse Isotope Effect ◽  
Kinetics Of

The kinetics of the oxidation of naphthalene by ruthenium tetroxide have been investigated. When the reaction was monitored using an absorption band at 385 nm it was possible to detect two processes; the first, a rapid second-order reaction which yielded a ruthenium(VI) moiety, was followed by a much slower first-order decomposition of this intermediate. The initial reaction exhibited an inverse isotope effect when naphthalene-d8 was used as a substrate and was accelerated by the introduction of electron donating substituents. The decomposition of the intermediate was not sensitive to the presence of substituents, but involved carbon–hydrogen bond cleavage as indicated by the occurrence of a primary deuterium isotope effect.

The kinetics of the decarboxylation of β-resorcylic acid in catechol

1976 ◽  
Vol 29 (2) ◽  
pp. 443 ◽  
Author(s):  
MA Haleem ◽  
MA Hakeem
Keyword(s):  
Rate Equation ◽  
Kinetic Data ◽  
Reaction Rate ◽  
Complex Mechanism ◽  
First Order ◽  
Absolute Reaction Rate ◽  
First Time ◽  
Kinetics Of ◽  
Absolute Reaction ◽  
Reaction Rate Equation

Kinetic data are reported for the decarboxylation of β-resorcylic acid in resorcinol and catechol for the first time. The reaction is first order. The observation supports the view that the decomposition proceeds through an intermediate complex mechanism. The parameters of the absolute reaction rate equation are calculated.

Study on Kinetics of Reaction between ZrNi5 and Water Vapor

2012 ◽  
Vol 581-582 ◽  
pp. 694-697
Author(s):  
Yong Yao ◽  
De Li Luo ◽  
Zhi Yong Huang ◽  
Jiang Feng Song
Keyword(s):  
Water Vapor ◽  
Reaction Rate ◽  
Arrhenius Equation ◽  
Tritiated Water ◽  
First Order ◽  
Order Chemical Reaction ◽  
First Order Chemical Reaction ◽  
Kinetics Of Reaction ◽  
Reaction Activation Energy ◽  
Kinetics Of

In order to evaluate the feasibility of tritium recovery from tritiated water by thermochemical decomposition using ZrNi5, the kinetics of reaction between ZrNi5 and water vapor was studied by thermogravimetric method in the temperature range from 673K to 823K. The result shows that reaction rate increased significantly with the increasing of temperature and H2O concentration; the reaction mechanism for ZrNi5 can be described by the first-order chemical reaction, and the reaction is first order for H2O concentration. The reaction activation energy of ZrNi5 is 55.8kJ/mol calculated from the Arrhenius equation.

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