Oxidative Regeneration of Carbonyl Compounds from Oximes by Pyridinium Fluorochromate: A Kinetic and Mechanistic Study

Abstract

The oxidative deoximination of several aldoximes and ketoximes by pyridinium fluorochromate, in dimethyl sulphoxide, exhibited a first order dependence on pyridinium fluorochromate. A Michaelis-Menten type kinetics was observed with respect to oximes. The oxidation of ketoximes is slower than that of aldoximes. The rates of oxidation of aldoximes correlated well in terms of Pavelich-Taft dual substituentparameter equation. The low positive value of polar reaction constant indicated a nucleophilic attack by a chromate-oxygen on the carbon. The reaction is subjected to steric hindrance by the alkyl groups. The reaction of acetaldoxime has been studied in 19 different organic solvents. The solvent effect has been analyzed by multiparametric equations. A mechanism involving the formation of a cyclic intermediate, in the rate-determining step is suggested.

Kinetics and Mechanism of Oxidation of Aliphatic Secondary Alcohols by Benzimidazolium Fluorochromate in Dimethyl Sulphoxide Solvent

“…All the studies were done at a constant temperature 16,17 (± 0.1 K), and up to the 80% of reaction was observed by observing the decrease in the concentration of BIFC spectrophotometrically at a wavelength of 364 nm. Linear least squares method was used for the calculations of pseudofirst-order rate constant and a graph between log [BIFC] versus time was plotted.…”

“…= -1.76(± 0.16) ∑σ* -2.14 (15) r 2 =0.9509; sd = 0.19; n = 8; ψ = 0.22; T = 298 K log k 2 = -1.34(± 0.99) ∑Es -2.82 (16) r 2 = 0.2324; sd = 0.76; n = 8; ψ = 0.92; T = 298 K Therefore, the rates were correlated in terms of Pavelich-Taftʼs dual substituent-parameter equation 38 (17).log k = ρ*∑σ* + δ ∑Es + log k 0(17) …”

New organic ionic plastic crystals utilizing the morpholinium cation

“…1). The morpholinium cation has been of interest for ionic liquid crystals, 28 gas separation 29 catalyst for organic synthesis, 30 corrosion inhibitors and electrochemical applications. 31 An advantage of using this cation for synthesis is that the cost of 4-methylmorpholine as a cation source is more economical than 4-methylpyrrolidine and 4-methylpiperidine.…”

Assay of Some Antimalarial Drugs in Pure Form and in Their Pharmaceutical Preparations with Pyridinium Fluorochromate Reagent

“…A variety of compounds containing chromium(VI) have proved to be versatile reagents capable of oxidizing almost every oxidizable functional group 1 . Extensive work has led to the development of a good number of such oxidants like Collins reagent 2 , chromium trioxide-3,5-dimethylpyrazole complex 3 , pyridinium chlorochromate 4 , pyridinium dichromate 5 , 2,2'bipyridinium chlorochromate 6 , pyridinium fluorochromate 7,8 , quinolinium fluorochromate 9 , quinolinium chlorochromate 10 , 3,5-dimethylpyrazolium fluorochromate 11 , 2,6-dicarboxypyridinium chlorochromate 12,13 , N-methylpiperidinium chlorochromate 14 , tetramethylammonium fluorochromate 15 and benzyltrimethylammonium fluorochromate 16 .…”

“…Industrial demands have led many workers to search for more ideal oxidants with a number of specifications including lower cost, higher yields, better selectivity, milder neutral conditions, easier preparations, high solubility, less toxicity and short reaction times. Among the above mentioned reagents [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] , pyridinium fluorochromate (PFC) has an edge over others for rendering higher yields in neutral conditions. In the present manuscript we have taken pyridinium fluorochromate as an oxidizing reagent which has been synthesized in the laboratory 17 .…”