Assay of sulphur compounds with 1-chlorobenzotriazole

A simple but accurate potentiometric method for the estimation of certain sulphur containing organic compounds has been developed, based on their oxidation with 1-chlorobenzotriazole. A back-titration procedure can also be used. The nature of oxidation in different media is discussed and the oxidation products have been identified.     

A one-pot oxidation/allylation/oxidation sequence for the preparation of β,γ-unsaturated ketones directly from primary alcohols

A one-pot oxidation/allylation/oxidation procedure has been developed for the conversion of primary alcohols into β,γ-unsaturated ketones. The methodology has been applied to a range of alcohols, and in some cases, isomerisation to produce the corresponding α,β-unsaturated ketones has been carried out.     

Further electrochemical investigations of the oxidation of 1-phenylpyrazolidin-3-ones at high pH

The oxidation mechanism at pH 14 for a number of 1-phenylpyrazolidin-3-ones substituted in the 4 position of the heterocyclic ring has been investigated with electrochemical techniques. A general oxidation mechanism, resulting in the formation of a radical species and short-lived pyrazolinone tautomers has been postulated.     

Ti-STT: a new zeotype shape selective oxidation catalyst

A new zeotype titanium silicate oxidation catalyst with the STT topology has been synthesized from direct synthesis. Ti-STT has a microporous structure with small pore openings, allowing shape selective oxidation catalysis. The isomorphous substitution of Si by Ti in the framework has been confirmed by Raman, FT-IR, UV-VIS and XANES spectroscopies.     

Kinetics of oxidation of some disaccharides in ammoniacal medium

Kinetics of oxidation of lactose, maltose, cellobiose and melibiose has been studied by hexacyanoferrate(III) in the presence of ammonia. A general mechanism involving the formation of intermediate enodiol anion has been suggested. The effects of dielectric constant and salts have been studied in detail. The oxidation products have been characterised by descending paper chromatography. Compensation effects have been observed.     

Electrocatalytic Oxidation of Ethylene Glycol on Dispersed Pt: Determination of the Reaction Products

Comparative studies of electrocatalytic ethylene glycol oxidation on bulk and dispersed Pt in acidic aqueous solutions have been performed. A quantitative method has been developed to determine all organic oxidation products using high-performance liquid chromatography with appropriate derivatising reagents.     

Estimation of thiosemicarbazide with chloramine-T

A rapid and accurate method for the estimation of thiosemicarbazide in aqueous solution has been developed based on its oxidation with chloramine-T at room temperature and pH 4. The effect of such variables as pH, mode of addition of reagents and concentration of chloride ion on the extent of oxidation has been studied.     

Nanosecond redox equilibrium method for determining oxidation potentials in organic media

A general, nanosecond equilibrium method is described for determining thermodynamically meaningful oxidation potentials in organic media for compounds that form highly reactive cation radicals upon one-electron oxidation. The method provides oxidation potentials with unusually high precision and accuracy. Redox ladders have been constructed of appropriate reference compounds in dichloromethane and in acetonitrile that can be used to set up electron-transfer equilibria with compounds with unknown oxidation potentials. The method has been successfully applied to determining equilibrium oxidation potentials for a series of aryl-alkylcyclopropanes, whose oxidation potentials were imprecisely known previously. Structure-property trends for oxidation potentials of the cyclopropanes are discussed.     

Inhibition Effect of {Cationic Surfactant-Ascorbic Acid} Premicellar Aggregation on the Rate of Hexacyanoferrate(III) Oxidation of Ascorbic Acid: A Kinetic Study

The kinetics of oxidation of ascorbic acid by acidic hexacyanoferrate(III) have been investigated in presence of cationic surfactant viz. cetyltrimethylammonium bromide (CTAB). An inhibition effect of CTAB (below its critical micelle concentration) on the rate of oxidation has been observed. The spectrophotometric and kinetic data support a 1:1 premicellar association between substrate and surfactant. A mechanism has been proposed and a rate law consistent with kinetic results has been derived.     

A study of the reaction of oxygen with graphite: model chemistry

A considerable amount of research has been directed towards the mechanism of oxidation of graphite as a model reaction system and because of its industrial importance. A number of recent studies have been concerned with ab initio molecular orbital calculations on graphite including model chemistry and the reactions with molecular oxygen. This study is concerned with oxidation steps involving the attachment of molecular oxygen to the graphene, the formation of carbon monoxide and, in particular, the subsequent oxidation reactions.     

In Process Citation

The electrochemical oxidation of khelline and amikhelline (chromone derivatives) has been performed by cyclic voltammetry at carbon-paste and polymeric carbon electrodes. The mechanism of oxidation of the two compounds at various pH values has been deduced. The detection limit is 8 x 10(-7)M. A constant-current coulometrie procedure is also described, based on the oxidation of the two chromones with vanadium(V) and backtitration of the excess of oxidant with iron(II).     

Estimation of mercaptans with 1-chlorobenzotriazole

A simple but accurate potentiometric method for the estimations of mercaptans in 0.01M perchloric acid has been developed, based on their oxidation with 1-Chlorobenzotriazole. Quantitative oxidation solely to the disulphide stage is ensured by using critical amounts of methanol, acetonitrile and potassium iodide. Chloride, mercury(II) and copper(II) interfere. A back-titration procedure can also be used. The oxidation products have been identified.     

A novel use of the recyclable polymer-supported IBX: an efficient chemoselective and regioselective oxidation of phenolic compounds. The case of hydroxytyrosol derivatives.

A useful and novel application of polymer-supported IBX for the chemoselective and regioselective oxidation of phenolic compounds has been described. Hydroxytyrosol and carboxymethylated hydroxytyrosol have been prepared in good conversions and yields under green chemistry conditions in the presence of dimethyl carbonate as the solvent. Polymer-supported reagent has been recovered by simple filtration, regenerated and reused for more cycles of oxidation reactions without loss of efficiency.     

Kinetics and mechanism of oxidation of S2O 32? by potassium bis (tellurato) cuprate(III)

The kinetics of oxidation of sodium thiosulphate by potassiumbis(tellurato) cuprate(III) in an alkaline medium has been reported. The reaction is first order in [S₂O ₃ ²⁻ ] but zero order in copper(III). Hydroxide ions are found to retard the oxidation rate. A rate expression rationalising the kinetic data has been derived. Sodium tetrathionate has been found to be the product of oxidation.     

Highly diastereoselective oxidation of 2-amino-2-deoxy-1-thio-beta-D-glucopyranosides: synthesis of imino sulfinylglycosides

A synthetic route to imino thioglycosides and to imino sulfinylglycosides has been developed. A detailed study on the diastereoselective oxidation of 2-amino-2-deoxy-1-thio-beta-D-glucopyranosides is reported. It has been shown that the stereochemical outcome of the oxidation is highly dependent on the protective group of the amine function. While the oxidation of iminothioglycosides is slightly diastereoselective (up to 30% de in favor of the R(S) sulfoxide), a single isomer is obtained in the case of tetrachlorophthalimido derivatives. The absolute configuration of the sulfinyl glycoside was ascertained by NMR analysis using our recent model on the basis of the exo-anomeric effect corroborated by X-ray crystallography.     

Kinetics and mechanism of the oxidation of α-amino acids by n-bromoacetamide

The kinetics of the oxidation of eight α-amino adds by N-bromoacltanude have been studied in aqueous perchloric acid solution. The main products of the oxidation are the corresponding carbonyl compounds. The reaction is of first order with respect to the oxidant and the amino acid. The rate of oxidation decreases linearly with an increase in hydrogen ion concentration. The rate is decreased by the addition of acetamide. The oxidation of deuteriated glycine indicated the absence of a primary kinetic isotope effect. The reaction rate has been determined at different temperatures and activation parameters have been calculated. Hypobromous add has been postulated as the reactive oxidizing species. A rate-determining reaction of the neutral amino add and hypobromous add to give an N-bromo derivative has been proposed. The slow step is followed by a fast decomposition of the N-bromo derivative to yield the ultimate product.     

Kinetics and mechanism of oxidation of phenylhydrazine and P-bromophenylhydrazine by hexacyanoferrate(III) in acidic medium

Kietics of oxidation of phenylhydrazine and p-bromophenylhydrazine by hexacyanoferrate(III) in acidic medium have been studied. The reactions follow similar kinetics, being first order with respect to both hydrazine and exacyanoferrate(III) and inverse first order with respect to the hydrogen ion. Addition of hexacyanoferrate(II) has no retarding effect on the rate of oxidation. The effects of varying ionic strength, dielectric constant, and temperature on the reaction rates have been investigated. A plausible mechanism has been proposed to account for the experimental results. Benzene and bromobenzene have been identified as the oxidation products.     

Prospects for Using Photocatalytic Air Cleaning Technology to Provide Safety of Sevoflurane Application to Parturition Anesthesia in Obstetric Hospitals

The product composition of photocatalytic oxidation of vaporized sevoflurane, a next-generation fluorinated inhalation anesthetic, has been studied. It has been found that the final products of oxidation are carbon dioxide and hydrogen fluoride. The possibility of complete chemical absorption of the evolved hydrogen fluoride by a lime absorber during the course of the photocatalytic reaction has been shown. A safe scheme for using photocatalysis is recommended for purifying air to remove vapors of halogen-containing anesthetics under medical hospital conditions.     

Comparative studies of reactions of commercial polymers with molecular oxygen,singlet oxygen,atomic oxygen and ozone—I. Reactions with cis-1,4-polybutadiene

The oxidation of cis-1,4-polybutadiene by molecular oxygen, singlet oxygen, atomic oxygen and ozone has been studied using u.v. and i.r. spectroscopic methods. Some possible implications of the results of oxidation in the presence of singlet oxygen (parallel free radical oxidation) and atomic oxygen (formation of NO₂ and its reaction with polymer) are discussed. Chain scission was observed during all types of oxidation. A new mechanism involving opening of double bonds and formation of biradicals has been considered in detail.     

Highly efficient aerobic oxidation of oximes to carbonyl compounds catalyzed by metalloporphyrins in the presence of benzaldehyde

Highly efficient oxidation of oximes to carbonyl compounds by molecular oxygen with benzaldehyde as an oxygen acceptor in the presence of metalloporphyrins has been reported. The simple structural manganese porphyrin showed an excellent activity for the oxidative deoximation reactions of various oximes. Moreover, different factors influencing oximes oxidation, that is, catalyst, solvent, and temperature, have been investigated. A possible mechanism for the deoximation reaction has been proposed.