Influence of the acidity on the kinetics of diphenylamine oxidation by peroxodisulfate anions

1993 ◽  
Vol 71 (2) ◽  
pp. 167-174 ◽  
Author(s):  
M. Balón ◽  
P. Guardado ◽  
C. Carmona ◽  
J. Hidalgo ◽  
M. A. Munoz
Keyword(s):  
Acetic Acid ◽  
Decomposition Products ◽  
Kinetic Rate ◽  
Rate Law ◽  
Rate Determining Step ◽  
Water Media ◽  
Acid Catalyzed ◽  
Radical Traps ◽  
Kinetics Of ◽  
Acetic Acid Acetate

A kinetic study is reported on the oxidation of diphenylamine (DPA) by peroxodisulfate (PDS) anions in H2SO4 and buffered acetic acid – acetate 20% v/v methanol–water media. The primary detectable product of the reaction is N-phenyl-p-benzoquinoneimine (PBQ), which undergoes acid-catalyzed hydrolysis giving different decomposition products. At pH > 4 (acetic acid – acetate buffers) the hydrolytic decomposition is very slow and it does not interfere with PBQ formation, but in H2SO4 media of pH < 2.5, PBQ decomposes as it is formed. In these media, the reaction obeys the kinetic rate law:[Formula: see text]a, the kinetic parameter, being acid dependent. Neither radical promoters (Ag+) nor radical traps (allyl alcohol) influence the reaction rate. In acetic acid – acetate buffers of pH > 4 the kinetic rate law is simple: first order in each one of the reactants, and acid independent. These results have been interpreted by assuming the formation, in a preequilibrium step, of an N-diphenylhydroxylamine-O-sulfonate intermediate, which further rearranges to yield PBQ. The rate-determining step of the reaction changes with the protonation state of the intermediate, whose protonation pKa has been kinetically estimated as 2.4.

Kinetics of the acid-catalyzed isomerization of phenylbutenes in glacial acetic acid

1972 ◽  
Vol 94 (4) ◽  
pp. 1247-1249 ◽  
Author(s):  
R. S. Schwartz ◽  
H. Yokokawa ◽  
E. W. Graham
Keyword(s):  
Acetic Acid ◽  
Glacial Acetic Acid ◽  
Acid Catalyzed ◽  
Kinetics Of

Kinetics of the addition of acids to olefins with and without boron fluoride catalysis

1967 ◽  
Vol 45 (1) ◽  
pp. 11-16 ◽  
Author(s):  
G. A. Latrèmouille ◽  
A. M. Eastham
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Apparent Activation Energy ◽  
Trifluoroacetic Acid ◽  
Similar Rate ◽  
Ethylene Dichloride ◽  
Kcal Mole ◽  
Rate Law ◽  
Boron Fluoride ◽  
Kinetics Of

Isobutene reacts readily with excess trifluoroacetic acid in ethylene dichloride solution at ordinary temperatures to give t-butyl trifluoroacetate. The rate of the reaction is given, within the range of the experiments, by the expression d[ester]/dt = k[acid]2[olefin], and the apparent activation energy is about 6 kcal/mole. The rate of addition is markedly dependent on the strength of the reacting acid and is drastically reduced in the presence of mildly basic materials, such as dioxane. The boron fluoride catalyzed addition of acetic acid to 2-butene can be considered to follow a similar rate law, i.e. d[ester]/dt = k[acid·BF3]2[olefin], but only if some assumptions are made about the position of the equilibrium [Formula: see text]since only the 1:1 complex is reactive.

The kinetics of isomerization of allylbenzene homogeneously catalysed by palladium(II) in acetic acid

1973 ◽  
Vol 26 (12) ◽  
pp. 2635 ◽  
Author(s):  
BI Cruikshank ◽  
NR Davies
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Experimental Evidence ◽  
Active Catalyst ◽  
Bimolecular Reaction ◽  
Equilibrium System ◽  
Constant Concentration ◽  
First Order ◽  
Rate Determining Step ◽  
Kinetics Of

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.

Palladium(II) Catalyzed Exchange Reactions. XI. Vinyl Propionate Exchange with Acetic Acid Catalyzed by Palladium(II) Acetate

1975 ◽  
Vol 53 (15) ◽  
pp. 2223-2231 ◽  
Author(s):  
Raj N. Pandey ◽  
Patrick M. Henry
Keyword(s):  
Acetic Acid ◽  
Sodium Acetate ◽  
Exchange Reactions ◽  
Free System ◽  
Acetate Concentration ◽  
Rate Expression ◽  
Π Complex ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Vinyl Propionate

The kinetics of the palladium(II) acetate catalyzed exchange of vinyl propionate with acetic acid solvent to give vinyl acetate has been studied in the sodium acetate concentration range from 0 to 1 M. The exchange rate first sharply increases as [NaOAc] increases, reaches a maximum at about 0.2 M and then gradually decreases as the sodium acetate concentration is in-creased to 1.0 M. Using previous results on the equilibrium between palladium(II) acetate and sodium acetate in acetic acid it can be shown that the rate expression for exchange is: rate = (ko + kt[Pd3(OAc)6] + kd[Na2Pd2(OAc)6]) [CH2=CHO2CC2H5] where ko = 2 × 10−4 s−1, kt = 0.045 M−1 s−1, and kd = 0.089 M−1 s−1. A monomeric palladium(II) species, Na2Pd(OAc)4, formed at high [NaOAc] is unreactive. Since the rate expression does not contain a term in [NaOAc], the sodium acetate serves only to convert one palladium(II) species to another. The lack of a [NaOAc] term in the rate expression for the Na2Pd2(OAc)6 catalyzed reaction is believed to result from cancellation of an inhibitory term for π-complex formation by a catalytic term in [NaOAc] in the rate determining conversion of π -complex to σ-complex (acetoxypalladation). Stereochemical studies indicate that acetoxypalladation is nonstereospecific. This result is expected since in the chloride free system acetate is both a ligand and a reactant. Thus it can attack from both inside and outside the coordination sphere of Pd(II).

Reaction kinetics of the esterification reaction between ethanol and acetic acid catalyzed by Keggin heteropolyacids

2013 ◽  
Vol 111 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Xiufeng Lu ◽  
Hengbo Yin ◽  
Lingqin Shen ◽  
Yonghai Feng ◽  
Aili Wang ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Reaction Kinetics ◽  
Esterification Reaction ◽  
Keggin Heteropolyacids ◽  
Acid Catalyzed ◽  
Kinetics Of

Kinetics and mechanism of dehydrochlorination of N-aryl-C-ethoxycarbonylformohydrazidoyl chlorides

1986 ◽  
Vol 64 (5) ◽  
pp. 871-875 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Hassan A. Albar
Keyword(s):  
Rate Constants ◽  
Water Solution ◽  
Chloride Ion ◽  
Order Conditions ◽  
Rate Law ◽  
First Order ◽  
Rate Determining Step ◽  
Pseudo First Order ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of triethylamine (TEA) catalyzed deydrochlorination of a series of N-aryl-C-ethoxycarbonylformohydrazidoyl chlorides 1a–m have been studied under pseudo-first-order conditions in 4:1 (v/v) dioxane–water solution at 30 °C. For all compounds studied, the kinetics followed the rate law: kobs = k2 (TEA). The values of the overall second-order rate constants for the studied compounds were correlated by the equation: log k2 = 0.533σ−-0.218. The results are compatible with a mechanism involving a fast reversible deprotonation step leading to the anion of 1, followed by rate-determining step involving the loss of the chloride ion from the anion. The reaction constants of these two steps were estimated to be 0.845 and −0.312, respectively.

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