Angioblastic meningioma

Sarada, P; Khan, Md. Abu Hadi Noor Ali; Gs, Kumari; Cc, Reddy; Dinakar, I

doi:10.1007/bf02749274

Cited by 5 publications

(6 citation statements)

References 6 publications

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“…Similar observations have been noted for the substrates like hexitols [14], methanol [3,4] and formic acid [7b]. (19) The catalytic efficiency of PA arises from the enhancement of the reduction potential of the couple Cr(VI)/Cr(IV) through the stabilisation of Cr(IV) which participates in the rate determining step (eqn 16 scheme 3). The cationic surfactant N-cetylpyridinium chloride (CPC) inhibits the reaction (both catalysed and uncatalysed paths) while the anionic surfactant sodium dodecyl sulfate (SDS) catalyses the reactions followed by retardation (both catalysed and uncatalysed paths).…”

Section: Resultssupporting

confidence: 66%

Micellar Effects on the Reactions of Chromium(VI) Oxidation of Lactic Acid and Malic Acid in the Presence and Absence of Picolinic Acid in Aqueous Acid Media

Saha¹,

Islam²,

Das³

2006

BioInorganic Reaction Mechanisms

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Section: Resultssupporting

confidence: 66%

Micellar Effects on the Reactions of Chromium(VI) Oxidation of Lactic Acid and Malic Acid in the Presence and Absence of Picolinic Acid in Aqueous Acid Media

Saha¹,

Islam²,

Das³

2006

BioInorganic Reaction Mechanisms

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“…This observation is similar to that observed by Bunton and Cerichelli [33] in the oxidation of ferrocene by Fe(III) salts in the presence of cationic cetyl trimethyl ammonium bromide. Similar observations have also been noted by Panigrahi and Sahu [34] in the oxidation of acetophenone by Ce(IV) and by Sarada and Reddy [35] in the oxalic acid catalyzed oxidation of aromatic azo compounds by Cr(VI) in the presence of SDS. The neutral triol is likely preferably partitioned in the micellar phase and the kinetically active H 2 CrO 4 species [36] may remain concentrated in the stern layer of the micellar phase [37].…”

Section: Ch(oh)c H(oh) Which Initiates Polymerization Of Acrylonitsupporting

confidence: 78%

“…This helps a larger number of data to come under the purview of analysis. Although equation (26) was originally developed for micelle-catalyzed reactions showing a maximum rate followed by inhibition, the model has been applied for different work[34,35, 40] to explain the miceller effect in which the reaction is inhibited or catalyzed by the micelle over the whole range as observed in the present system. By using equation (26), i.e., the plot of log P versuslog[D] T , parameters n, log[D] 50 (where log[D] 50 represents the concentration of surfactant required for half-maximum catalysis or inhibition) and log K D have been determined (table 2).…”

mentioning

confidence: 99%

Micellar catalysis on picolinic acid promoted hexavalent chromium oxidation of glycerol

Ghosh

Basu

Saha

et al. 2012

Journal of Coordination Chemistry

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Under pseudo-first-order conditions, monomeric Cr(VI) was found to be kinetically active in the absence of picolinic acid (PA), whereas in the PA-promoted path, the Cr(VI)-PA complex undergoes nucleophilic attack by the substrate to form a ternary complex which subsequently experiences redox decomposition, leading to glyceraldehydes and Cr(IV)-PA complex. The uncatalyzed path shows a second-order dependence on [H þ ], whereas the PA-catalyzed path shows zero-order dependence on [H þ ]. Both the uncatalyzed and PA-catalyzed path show a first-order dependence on [glycerol] T and [Cr(VI)] T . The PA-catalyzed path is first order in [PA] T . All these observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant cetyl pyridinium chloride (CPC) and anionic surfactant sodium dodecyl sulfate (SDS) on the PA-catalyzed path have been studied. CPC inhibits, whereas SDS accelerates the reaction. Here, SDS is a catalyst for glyceraldehydes production and at the same time reduction of carcinogenic hexavalent chromium to nontoxic trivalent chromium. The reaction proceeds simultaneously in both aqueous and micellar phase. Micellar effects have been explained by considering the preferential partitioning of reactants between the micellar and aqueous phase. The Menger-Portnoy model, Piszkiewicz cooperative model, and pseudo-phase ion exchange model have been tested to explain the observed micellar effect.

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“…The observation is similar to that observed by Bunton and Cerichelli [41] in the oxidation of ferrocene by Fe III salts in the presence of the cationic surfactant cetyltrimethyl ammonium bromide (CTAB). Similar observations have also been noted by Panigrahi et al [42] in the oxidation of acetophenone by Ce IV , by Reddi et al [43] in the oxalic acid-catalysed oxidation of aromatic azo-compounds by Cr VI in the presence of the surfactant sodium dodecyl sulfate (SDS). In the uncatalysed path, the neutral Cr VI -substrate ester formed [cf.…”

Section: Effect Of Cpcsupporting

confidence: 74%

Kinetic and Mechanistic Aspects of the Chromic Acid Oxidation of D-Galactose in the Presence and Absence of Picolinic Acid Catalyst in Aqueous Micellar Acid Media

Das

Islam

Das

et al. 2010

Progress in Reaction Kinetics and Mechanism

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The kinetics and mechanism of the chromic acid oxidation of D-galactose in the presence and absence of picolinic acid (PA) in aqueous acid media have been determined under the conditions, ½D À galactose T 4½Cr VI T at different temperatures. Under the kinetic conditions, HCrO 4 À has been found kinetically active in the absence of PA while in the PA catalysed path, a Cr VI -PA complex has been established as the active oxidant. In the PA-catalysed path, the Cr VI -PA complex receives a nucleophilic attack by the substrate to form a ternary complex which subsequently undergoes a redox decomposition through a two-electron transfer leading to a lactone (oxidised product) and a Cr IV -PA complex. Then the Cr IV -PA complex participates further in the oxidation of D-galactose and ultimately is converted into a Cr III -PA complex. In the uncatalysed path, a Cr VI -substrate ester experiences an acid catalysed redox decomposition (2e-transfer) at the ratedetermining step. The uncatalysed path shows a second-order dependence on [H þ ]. Under the experimental conditions, both paths show first-order dependences on [D-galactose] T and [Cr VI ] T . The PA-catalysed path is first-order in [PA] T . These observations remain unaltered in the presence of externally added surfactants. The effect of surfactants like N-cetylpyridinium chloride (CPC, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant), on both the uncatalysed and PA-catalysed paths have been studied. CPC retards both the uncatalysed and PA-catalysed path, while SDS accelerates the reactions. The observed micellar effects have been explained by considering the hydrophobic and electrostatic interactions between the reactants and surfactants.

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Angioblastic meningioma

Cited by 5 publications

References 6 publications

Micellar Effects on the Reactions of Chromium(VI) Oxidation of Lactic Acid and Malic Acid in the Presence and Absence of Picolinic Acid in Aqueous Acid Media

Micellar Effects on the Reactions of Chromium(VI) Oxidation of Lactic Acid and Malic Acid in the Presence and Absence of Picolinic Acid in Aqueous Acid Media

Micellar catalysis on picolinic acid promoted hexavalent chromium oxidation of glycerol

Kinetic and Mechanistic Aspects of the Chromic Acid Oxidation of D-Galactose in the Presence and Absence of Picolinic Acid Catalyst in Aqueous Micellar Acid Media

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