Nonlinear Hammett Relationships in the Reaction of Peroxomonosulfate Anion (HOOSO3-) with meta- and para-Substituted Anilines in Alkaline Medium

2001 ◽  
Vol 66 (6) ◽  
pp. 897-911 ◽  
Author(s):  
Subbiah Meenakshisundaram ◽  
Ramanathan Sockalingam
Keyword(s):  
Nitrogen Atom ◽  
Equilibrium Constant ◽  
Rate Equation ◽  
Kinetic Data ◽  
Formation Constant ◽  
Order Rate Constant ◽  
Reactive Intermediate ◽  
Substituted Anilines ◽  
Experimental Conditions ◽  
First Order

The HOOSO3- oxidation of eleven meta- and para-substituted anilines to the corresponding nitrosobenzenes at pH ≈ 11 was characterized by the rate equation v = kK[OX][An]/(1 + K[An]). Formation constant of the reactive intermediate and its rate of decomposition were evaluated separately for ascertaining the structure-reactivity relationships. Under the experimental conditions the dianion, -O-O-SO3- is probably the effective electrophile. Kinetic data can be rationalized by a bimolecular process which involves the attack of nucleophilic nitrogen atom on the peroxidic oxygen. The highlight of the study is the opposite curvatures observed in the nonlinear Hammett plots of first-order rate constant k and the "equilibrium" constant K, being concave downward and upward, respectively.

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.

Bond Scission in Sulfur Compounds. Part X. The Hydrazinolysis of Methyl p-Nitrophenyl Sulfate

1975 ◽  
Vol 53 (9) ◽  
pp. 1275-1280 ◽  
Author(s):  
Erwin Buncel ◽  
Claudio Chuaqui
Keyword(s):  
Kinetic Data ◽  
Order Rate Constant ◽  
Rate Data ◽  
Sulfate Ion ◽  
First Order ◽  
Nucleophilic Displacement ◽  
Bond Scission ◽  
Different Types ◽  
Acid Catalyzed ◽  
Pseudo First Order

Reaction of methyl p-nitrophenyl sulfate with the hydrazine – hydrazine hydrochloride system in methanol gives rise to different types of behavior depending on the state of ionization of the reagent. For the H2NNH2/H2NNH3+ combination the observed reaction is conversion of methyl p-nitrophenyl sulfate to p-nitrophenyl sulfate ion (alkyl–oxygen scission). For the H2NNH3+/+H3NNH3+ combination, or with +H3NNH3+ alone, one observes the consecutive processes methyl p-nitrophenyl sulfate → p-nitrophenyl sulfate ion → p-nitrophenol (alkyl–oxygen followed by sulphur–oxygen scission). For the alkyl–oxygen scission process, i.e. nucleophilic displacement on the alkyl carbon, the observed pseudo first-order rate constant is given by the contributions of several nucleophilic species; [Formula: see text] A method for the dissection of kobs into the constituent terms is given. The sulphur–oxygen scission process is an acid catalyzed reaction and the measured kinetic data have been utilized for the derivation of the pKa of +H3NNH3+ in methanol. Rate data for the conversion of sodium p-nitrophenyl sulfate to p-nitrophenol in methanol containing HCl have also been determined in this connection.

scholarly journals Oxidation of deuteroferrihaem by hydrogen peroxide

1973 ◽  
Vol 135 (2) ◽  
pp. 361-365 ◽  
Author(s):  
Peter Jones ◽  
Kenneth Prudhoe ◽  
Terrence Robson
Keyword(s):  
Mass Spectrometry ◽  
Kinetic Data ◽  
Preceding Paper ◽  
Catalytic Decomposition ◽  
Order Rate Constant ◽  
Bile Pigment ◽  
Pigment Formation ◽  
Kinetic Spectrophotometry ◽  
First Order ◽  
Constant Ph

1. The oxidation of deuteroferrihaem by H2O2 to bile pigment and CO was studied both by stopped-flow kinetic spectrophotometry and mass spectrometry, at 25°C, I=0.1m. 2. Spectrophotometric studies imply that, at constant pH, the rate of bile pigment formation is first-order with respect to [H2O2] and also proportional to [deuteroferrihaem monomer]. The effect of pH on the apparent second-order rate constant suggests that acid-ionization of deuteroferrihaem monomer is important in the reaction mechanism. 3. The relative rates of formation of O2 (from catalytic decomposition of H2O2) and CO (from oxidation of ferrihaem) have been measured by mass spectrometry. The results are in excellent agreement with those obtained by combining kinetic data for catalytic decomposition (Jones et al., 1973, preceding paper) with the spectrophotometric results for deuteroferrihaem oxidation.

SECOND-ORDER UNIMOLECULAR KINETICS IN THE THERMAL DECOMPOSITION OF HYDROGEN PEROXIDE VAPOR

1958 ◽  
Vol 36 (9) ◽  
pp. 1308-1319 ◽  
Author(s):  
W. Forst
Keyword(s):  
Hydrogen Peroxide ◽  
Thermal Decomposition ◽  
Initial Pressure ◽  
Critical Energy ◽  
Order Rate Constant ◽  
Second Order ◽  
Static Method ◽  
Experimental Conditions ◽  
First Order ◽  
Hydrogen Peroxide Vapor

The thermal decomposition of hydrogen peroxide vapor has been reinvestigated by the static method as a function of initial pressure at pressures up to 22 mm Hg, and in the presence of inert gas (helium, oxygen, and water) up to 100 mm Hg. In each case the apparent first-order rate constant increased linearly with pressure. It is demonstrated that under the present experimental conditions the pyrolysis of hydrogen peroxide shows behavior typical of an elementary unimolecular reaction in its low-pressure, second-order region. The reaction was accompanied by a heterogeneous decomposition which in the presence of foreign gas became inhibited. Helium was used as inhibitor over the temperature range 430–470 °C, which permitted calculating the activation energy for activation with peroxide and with helium. The results can be satisfactorily accounted for by assuming a critical energy of 47–50 kcal and five effective classical oscillators for activation with peroxide and three with helium, provided deactivation occurs on every collision. Kinetic evidence against this assumption is briefly discussed.

Kinetics of halogen substituted aniline transformation in anaerobic estuarine sediment

1996 ◽  
Vol 34 (7-8) ◽  
pp. 37-43 ◽  
Author(s):  
Sridhar Susarla ◽  
Shigeki Masunaga ◽  
Yoshitaka Yonezawa
Keyword(s):  
Rate Constant ◽  
Halogen Bond ◽  
Order Rate Constant ◽  
Quantitative Structure Activity Relationship ◽  
Estuarine Sediment ◽  
Substituted Anilines ◽  
First Order ◽  
The Relationship ◽  
Steric Constant ◽  
Kinetics Of

The kinetics of halogen substituted anilines were examined in estuarine sediment collected from Tsurumi river, Japan. Aniline was substituted with F, Cl, Br and I groups at meta or para positions on the aromatic ring. The transformation of all the compounds followed a first-order reaction kinetics with rate constants for the disappearance ranging between 0.002 to 0.006 day−1 or half lives between 108 and 669 days. Results indicated that para substituted anilines transformed two to four times faster compared to meta substituted ones. The rate of transformation followed the order: I > Br > Cl > F. A quantitative structure-activity relationship was evaluated relating the first-order rate constant in sediment with several readily available molecular descriptors: carbon-halogen bond strength, Hammett sigma constants, Taft steric constant, and Lipophilic constant. In addition octanol/water partition coefficients and solubility were included in the correlation. The relationship obtained was only significant between the rate constant and lipophilic constant.

scholarly journals Fragmentation of Chitosan by Acids

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Mohammad Reza Kasaai ◽  
Joseph Arul ◽  
Gérard Charlet
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Kinetic Data ◽  
Chemical Structure ◽  
Size Exclusion ◽  
Experimental Conditions ◽  
First Order ◽  
H Nmr ◽  
Exclusion Chromatography ◽  
Kinetics Of

Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by1H NMR spectroscopy and elemental analysis. The kinetic data indicates that the reaction was of first order. The results of polydispersity and the DA suggest that the selected experimental conditions (temperature and concentration of acid) were appropriate to obtain the fragments having the polydispersity and the DA similar to or slightly different from those of the original one. A procedure to estimate molecular weight of fragments as well as the number of chain scissions of the fragments under the experimental conditions was also proposed.

THE MONO-OXALATO COMPLEXES OF IRON(III): PART II. KINETICS OF FORMATION

1965 ◽  
Vol 43 (10) ◽  
pp. 2763-2771 ◽  
Author(s):  
R. F. Bauer ◽  
W. MacF. Smith
Keyword(s):  
Rate Constant ◽  
Order Rate Constant ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Experimental Conditions ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Independent Path ◽  
Kinetics Of ◽  
Oxalato Complexes

The kinetics of the formation of the mono-oxalato complexes of iron (III) have been examined spectrophotometrically over the range of temperatures 5 to 25 °C in an aqueous medium of ionic strength 0.50 and the range of hydrogen ion concentrations 0.03 to 0.45 M. The kinetic-ally significant paths under the conditions studied involve reactions first order in iron (III) and in bioxalate but there appears to be some decrease in the second order rate constant with increase in hydrogen ion concentration at the highest acidities and at the highest temperatures. Although there is no significant contribution to the rate by an acid-independent path first order in free oxalate under the experimental conditions, the possibility of the rate constant for such a path being greater than that first order in bioxalate is not precluded.

The thermal decomposition of azobenzene

1983 ◽  
Vol 61 (8) ◽  
pp. 1712-1718 ◽  
Author(s):  
Donald Barton ◽  
Michael Hodgett ◽  
Paul Skirving ◽  
Michael Whelton ◽  
Keith Winter ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Equilibrium Constant ◽  
Trans Isomer ◽  
Rate Constant ◽  
Volume Ratio ◽  
Order Rate Constant ◽  
Small Concentration ◽  
First Order ◽  
Temperature Range ◽  
Cis Isomer

The rate of nitrogen formation during the thermal decomposition of azobenzene in static and stirred-flow systems was measured over the temperature range of 368.9 °C to 437.4 °C. The first order rate constant was found to be given by the expression[Formula: see text]A consideration of the equilibrium constant between cis-azobenzene and trans-azobenzenc, and the rate of attainment of equilibrium, leads to the conclusion that a small concentration of cis-azobenzene is always present, at equilibrium with the trans isomer. Since the cis isomer is likely to be more reactive than the trans isomer the rate constant cannot be ascribed to the trans isomer alone. No effect of variation of surface-to-volume ratio could be detected. Some preliminary experiments in which toluene and ethylene were employed as additives indicated that these did not affect the rate of formation of nitrogen. Nevertheless, because of a certain amount of scatter in the results, a small effect could not be excluded. There were at least nine products, in addition to nitrogen.

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