Kinetics and mechanisms of mercuration of aliphatic carboxylic acids

1965 ◽  
Vol 18 (3) ◽  
pp. 305 ◽  
Author(s):  
W Kitching ◽  
PR Wells
Keyword(s):  
Acetic Acid ◽  
Propionic Acid ◽  
Perchloric Acid ◽  
Mercuric Acetate ◽  
First Order ◽  
Mercuric Nitrate ◽  
Catalysed Reaction ◽  
Aqueous Conditions ◽  
Aliphatic Carboxylic Acids ◽  
Kinetics Of

The kinetics of the mercuration of acetic acid by mercuric acetate under anhydrous and aqueous conditions have been studied. The reaction is first order in mercuric acetate and possibly first order in acetic acid. Radicals are not involved. The reaction is insensitive to added salts and is not catalysed by acetate. Enol or carbanion intermediates are excluded by the absence of H-D exchange. A four-centre (SF2) mechanism is suggested. The reaction is accelerated by perchloric acid and this is attributed to mercuration by acetoxymercuric perchlorate probably in the form of an ion pair. Mercuric perchlorate and mercuric nitrate are more effective mercurating agents than mercuric acetate. Although the perchloric acid catalysed reaction may follow the SE2 mechanism an SF2 pathway is preferred. Propionic acid is mercurated exclusively at the α-carbon atom and trimethylacetic acid is unreactive. Acetic acid is 2.7 times as reactive as propionic acid. Optically active methylethylacetic acid appears to be mercurated stereospecifically.

Kinetics and Mechanism of Oxidation of Dimethyl Sulphoxide by Mono- and Di-Substituted N,N-Dichlorobenzenesulphonamides in Aqueous Acetic Acid

2003 ◽  
Vol 58 (8) ◽  
pp. 787-794 ◽  
Author(s):  
B.Thimme Gowda ◽  
K. L. Jayalakshmi ◽  
K. Jyothi
Keyword(s):  
Acetic Acid ◽  
Benzene Ring ◽  
Dimethyl Sulphoxide ◽  
Aqueous Acetic Acid ◽  
Isokinetic Temperature ◽  
Free Energies ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

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.

scholarly journals Kinetic Evidence of a Common Mechanism in the Oxidation by Chromium(vi) Complexes: Oxidation of Benzyl Alcohol

2000 ◽  
Vol 2000 (3) ◽  
pp. 114-115 ◽  
Author(s):  
Chockalingam Karunakaran ◽  
Sadasivam Suresh
Keyword(s):  
Acetic Acid ◽  
Benzyl Alcohol ◽  
Perchloric Acid ◽  
Mineral Acid ◽  
Common Mechanism ◽  
Aqueous Acetic Acid ◽  
First Order ◽  
Chromium Vi ◽  
Oxidation Of Benzyl Alcohol

The oxidation of benzyl alcohol by dichromate and seven chromium(VI) complexes in aqueous acetic acid in the presence of perchloric acid is first order each in the oxidants, the alcohol and the mineral acid. The oxidation conforms to the isokinetic and Exner relationships and follows a common mechanism.

Studies on the oxidative degradation of paracetamol by a μ-oxo-diiron(III) complex

2020 ◽  
Vol 98 (2) ◽  
pp. 98-105
Author(s):  
Bula Singh ◽  
Ranendu Sekhar Das
Keyword(s):  
Acetic Acid ◽  
Oxidative Degradation ◽  
Active Role ◽  
Order Reaction ◽  
Proton Abstraction ◽  
First Order ◽  
Initial Activation ◽  
Reaction Media ◽  
Kinetics Of ◽  
Reactivity Order

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.

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.

Equilibrium and Kinetics of Reactive Extraction of Propionic Acid Using Aliquat 336 and Tri-n-Butyl Phosphate in n-Hexanol

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Dr. Kailas L. Wasewar ◽  
Amit Keshav ◽  
Shri Chand
Keyword(s):  
Propionic Acid ◽  
Acid Concentration ◽  
Fermentation Broth ◽  
Reactive Extraction ◽  
Acid Extraction ◽  
Aliquat 336 ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pharmaceutical Industries ◽  
Kinetics Of

Recovery of propionic acid from different sources, like aqueous streams or from fermentation broth, is important in view of its wide usage in food, chemical and pharmaceutical industries. Reactive extraction is an emerging separation technique having numerous advantages like high selectivity and recovery. Effect of acid concentration, extractant concentration, pH, temperature and kinetics are the important steps in the reactive extraction. Equilibrium of propionic acid extraction using tri-n-butyl phosphate (TBP) and Aliquat 336 in n-hexanol respectively was carried out to find the better extractant out of the two for extraction of propionic acid. Aliquat 336 was found to be better than TBP with Ks = 2.2119 m3/kmol, thus indicating good complexation between it and the acid. The kinetics of extraction of the acid using Aliquat 336 in a stirred cell was investigated. The reaction was found to be first order in acid concentration and zero order in Aliquat 336 concentration. The reaction was found to be fast pseudo first order reaction occurring in the diffusion film and was found to be independent of hydrodynamics conditions. Rate constant was evaluated to be 163.398 1/s.

scholarly journals OXIDATION OF BENZALDEHYDE BY QUINOXALINIUM DICHROMATE

2016 ◽  
Vol 12 (9) ◽  
pp. 4396-4403 ◽  
Author(s):  
K Anbarasu ◽  
N. GEETHA
Keyword(s):  
Acetic Acid ◽  
Perchloric Acid ◽  
Reaction Rate ◽  
Sodium Perchlorate ◽  
Activation Parameters ◽  
Probable Mechanism ◽  
Water Medium ◽  
First Order ◽  
Rate Of Reaction ◽  
Acetic Acid Water

The kinetics and mechanism of oxidation of benzaldehyde by quinoxalinium dichromate has been studied in the presence of perchloric acid in 70 % acetic acid - water medium. The reaction follows first order with respect to benzaldehyde, quinoxalinium dichromate and fractional order with respect to perchloric acid. There is no effect on the reaction rate with increase in ionic strength of the medium by adding sodium perchlorate. The rate of reaction increases with increase in the percentage of acetic acid. The reaction does not induce the polymerization with acrylonitrile. The rate of reaction decreases with increase in the concentration of manganoussulphate. The thermodynamic and activation parameters have been calculated and a probable mechanism has been proposed.

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