Acetoxylation by aryliodoso acetates. II. Kinetics of the reaction of phenyliodoso acetate with aceto-p-toluidide

1958 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
WD Johnson ◽  
NV Riggs

The reaction of phenyliodoso acetate and aceto-p-toluidide in acetic acid is first order in each reactant and measured rates fit the Arrhenius equation in the temperature range 15-45 �C. Addition of water to the solvent markedly accelerates the reaction, whereas addition of benzene lowers the rate and acetic anhydride has little effect. A polar transition state is indicated.

1973 ◽  
Vol 26 (4) ◽  
pp. 761 ◽  
Author(s):  
DA Kairaitis ◽  
VR Stimson ◽  
JW Tilley

Acetic acid catalyses the decomposition of 2,2-dimethoxypropane into methyl isopropenyl ether and methanol in the temperature range 314- 400�. The reaction is first order in the pressure of each reactant, and the variation of rate with temperature is given by the Arrhenius equation: ������������ k2 = 1012.90�0.15exp(-30830�420/1.987T) s-1 ml mol-1 The reaction is believed to be homogeneous and molecular. This is the first example of this series where the catalyst has been other than a hydrogen halide.


1931 ◽  
Vol 5 (6) ◽  
pp. 636-647 ◽  
Author(s):  
C. C. Coffin

The decomposition represented by the general equation[Formula: see text]has been found to take place according to the monomolecular law. In the case of the several homologous esters already investigated at pressures above 10 cm. of mercury the reaction is entirely homogeneous, is uninfluenced by the presence of inert gases and obeys the Arrhenius equation. This paper describes the experimental method and deals with the decomposition of ethylidene diacetate to acetaldehyde and acetic anhydride at temperatures of 220° to 268 °C. and at initial pressures of 11 to 46 cm. of mercury. The heat of activation is 32900 cal./mol and the velocity constants (sec−1) are given by the equation, ln [Formula: see text]. The theoretical significance of the data is discussed.


2012 ◽  
Vol 581-582 ◽  
pp. 694-697
Author(s):  
Yong Yao ◽  
De Li Luo ◽  
Zhi Yong Huang ◽  
Jiang Feng Song

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.


2003 ◽  
Vol 58 (8) ◽  
pp. 787-794 ◽  
Author(s):  
B.Thimme Gowda ◽  
K. L. Jayalakshmi ◽  
K. Jyothi

In an effort to introduce N,N-dichloroarylsulphonamides of different oxidising strengths, four mono- and five di-substituted N,N-dichlorobenzenesulphonamides are prepared, characterised and employed as oxidants for studying the kinetics of oxidation of dimethyl sulphoxide (DMSO) in 50% aqueous acetic acid. The reactions show first order kinetics in [oxidant], fractional to first order in [DMSO] and nearly zero order in [H+]. Increase in ionic strength of the medium slightly increases the rates, while decrease in dielectric constant of the medium decreases the rates. The results along with those of the oxidation of DMSO by N,N-dichlorobenzenesulphonamide and N,N-dichloro-4- methylbenzenesulphonamide have been analysed. Effective oxidising species of the oxidants employed in the present oxidations is Cl+ in different forms, released from the oxidants. Therefore the introduction of different substituent groups into the benzene ring of the oxidant is expected to affect the ability of the reagent to release Cl+ and hence its capacity to oxidise the substrate. Significant changes in the kinetic and thermodynamic data are observed in the present investigations with change of substituent in the benzene ring. The electron releasing groups such as CH3 inhibit the ease with which Cl+ is released from the oxidant, while electron-withdrawing groups such as Cl enhance this ability. The Hammett equation, log kobs = −3.19 + 1.05 σ , is found to be valid for oxidations by all the p-substituted N,N-dichlorobenzenesulphonamides. The substituent effect on the energy of activation, Ea and log A for the oxidations is also analysed. The enthalpies and free energies of activation correlate with an isokinetic temperature of 320 K.


2020 ◽  
Vol 98 (2) ◽  
pp. 98-105
Author(s):  
Bula Singh ◽  
Ranendu Sekhar Das

In higher organisms, metalloenzymes like cytochrome P450, containing a Fe(III) metal center, play an active role in metabolism of paracetamol (APAP). Here, we have chosen a mimicking μ-oxo-diiron complex, [Fe(III)2(μ-O)(phen)4(H2O)2]4+ (1, phen = 1,10-phenanthroline), to study spectrophotometrically the kinetics of the redox interactions with APAP. In acidic buffer media (pH = 3.4–5.1), APAP quantitatively reduces 1 following first-order reaction kinetics. Each molecule of 1 accepts two electrons from APAP and is reduced to ferroin [Fe(phen)3]2+. On oxidation, APAP produces N-acetyl-p-benzoquinone imine (NAPQI), which on hydrolysis results in a mixture of benzoquinone, quinone oxime, acetamide, and acetic acid. In reaction media due to successive deprotonations, 1 exists in equilibrium with the species [Fe(III)2(μ-O)(phen)4(H2O)(OH)]3+ (1a) and [Fe(III)2(μ-O)(phen)4(OH)2]2+ (1b) (pKa = 3.71 and 5.28, respectively). The kinetic analyses suggest for an unusual reactivity order as 1 < 1a ≫ 1b. The mechanistic possibilities suggest that although 1 is reduced by concerted electron transfer (ET) – proton transfer (PT) mechanism, 1a and 1b may be reduced by a concerted PT–ET mechanism where a slow proton-abstraction step is followed by a rapid ET process. It seems that the initial activation of the bridging μ-oxo group by a proton-abstraction results in the higher reactivity of 1a.


1973 ◽  
Vol 26 (12) ◽  
pp. 2635 ◽  
Author(s):  
BI Cruikshank ◽  
NR Davies

The changes in the kinetics observed during the isomerization of allylbenzene catalysed by palladium(II) are interpreted in terms of the slow formation of a hydrido complex of palladium(II) which subsequently attains a constant concentration in an equilibrium system. The kinetics during these phases are shown to be consistent with first-order dependence on the concentration of an active catalyst formed in a bimolecular reaction from a mononuclear palladium(II) complex and with a regenerative hydrido-π-alkene-σ-alkyl mechanism of isomerization. The hypothesis that a further stage in the kinetics reflects a change in the rate determining step to one involving alkene displacement from the catalyst is supported by the experimental evidence. The concentration of active catalyst is shown not to fall appreciably until all the allylbenzene has undergone isomerization, but thereafter there is a slow reduction of catalytic activity which is not completely restored by the addition of further allylbenzene. It is suggested that the slow formation of a π-allylic complex is responsible.


2015 ◽  
Vol 62 (2) ◽  
pp. 38-42
Author(s):  
Stankovičová M. ◽  
Miháliková V. ◽  
Mezovský Ľ. ◽  
Lašáková A. ◽  
Medlenová V. ◽  
...  

AbstractIn present work, we have studied kinetics of alkaline hydrolysis of 14 compounds, which are phenylcarbamic acid derivatives with integrated N-phenylpiperazine moiety in the structure. The compounds possessed moderate antiarrhythmic and antimycobacterial activity. Their hydrolysis was carried out in an aqueous medium ethanol sodium hydroxide solution. The course of the hydrolysis was observed spectrophotometrically in visible as well as in ultraviolet regions. The pseudo-first order rate constants were calculated at several temperatures. The values of the activation energy EAwere determined by the Arrhenius equation. The rate of hydrolysis of the compounds under the study increase with the increase in temperature and it has been differentiated according to the substitution of N-phenylpiperazine as well as to the alkoxy substitution on phenyl ring.


1971 ◽  
Vol 49 (10) ◽  
pp. 1683-1687 ◽  
Author(s):  
R. C. Turner ◽  
Wan Sulaiman

The effect of varying 8-quinolinol and acetate concentration on the rate of decomposition of poly-nuclear hydroxyaluminum cations was studied. It was found that the concentration of the undissociated 8-quinolinol and acetic acid molecules determined the magnitude of the first order rate constant for the decomposition of the polynuclear hydroxyaluminum cations, except when the acetate concentrations were relatively high. With high acetate concentrations, it appeared that polynuclear acetate species were involved in the reactions. An empirical equation was developed showing the effect of 8-quinolinol and acetic acid molecule concentrations on the pseudo first order rate constant for the decomposition reaction.


1971 ◽  
Vol 26 (1) ◽  
pp. 30-31 ◽  
Author(s):  
K. K. Banerji ◽  
P. Nath ◽  
G. V. Bakore

The oxidation of methyl n-propyl ketone by Mn (III) sulphate in aq. acetic acid is first order with respect to the ketone and Mn (III). The rate is independent of acidity and solvent composition. The activation parameters for oxidation and enolisation were evaluated. Oxidation is faster than enolisation under similar conditions. A mechanism involving an attack on the keto-form by Mn (III) is proposed.


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