chloramine-T In Presence Research Articles

English

English

Rhodium(III) Catalyzed and Uncatalyzed Kinetic Spectrophotometric Oxidation of Amodiaquine Hydrochloride With Chloramine-T in Presence of Alkaline Buffer: A Mechanistic Chemistry

Amodiaquine hydrochloride (AQ) is a 4-aminoquinoline derivative commonly used to prevent and treat malaria. Sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) is a well-known oxidizing agent. In rhodium(III) chloride (Rh(III)) catalyzed oxidation, the rate law is -d[CAT] / dt = k [CAT]o [AQ]o [OH–]–x [Rh(III)]y and it takes the form -d[CAT]/dt = k [CAT]o[AQ]o[OH–]–x for uncatalyzed reaction, where x and y are less than unity. The rate constants revealed that the Rh(III) catalyzed reactions are about five fold faster than the uncatalyzed reactions. The catalytic constant (KC) and activation parameters with respect to Rh(III) catalyst have been deduced.

Mechanistic aspects for the oxidation of sunset yellow dye by chloramine-T in presence of perchloric acid and in sodium hydroxide medium catalyzed by Os(VIII): A spectrophotometric kinetic approach

The kinetics of oxidation of sunset yellow (SY) by sodium- N-chloro- p-toluenesulfonamide or chloramine-T (CAT) was studied spectrophotometrically in HClO 4 and NaOH media with Os(VIII) as a catalyst in the latter medium at 298 K and 303 K, respectively. In acid medium, the experimental rate law is −d[CAT]/d t = k[CAT] 0[SY] 0[HClO 4] −0.46. Alkali accelerates the rate of reaction and the rate law takes the form −d[CAT]/d t = k[CAT] 0[SY] 0[NaOH] 0.23[OsO 4] 0.84. The solvent isotope effect was studied using D 2O. Benzenesulfonic acid and 1,2-naphthoquinone-6-sulfonic acid were characterized as the oxidation products of SY. Under identical set of experimental conditions in alkaline medium, Os(VIII) catalyzed reaction is about seven-fold faster than the uncatalyzed reaction. Activation parameters for the overall reaction and also with respect to catalyst have been evaluated. The observed results have been explained by plausible mechanisms and the related rate laws have been deduced.

A new approach for the transformation of alkenes to pyrrolines via aziridine intermediates

Alkenes (1) reacts with chloramine-T in presence of the catalyst silver nitrate to afford aziridines (2). The aziridines underwent ring expansion with the acrylo nitrile or ethyl acrylate (3) in the presence of solid sodium hydroxide to form pyrrolines (4) in 40–58% yield.

Kinetics and mechanism of Os(VIII)-catalysed oxidation of some substituted trans-cinnamic acids by chloramine-T in alkaline medium — A non-linear Hammett plot

The kinetics and mechanism of Os(VIII) catalysed oxidation of some substituted trans-cinnamic acids by chloramine-T in presence of alkaline medium has been investigated. The order with respect to [CAT] is zero and is [OsO] one. The reaction is fractional order in [substrate). The rate dependence on [OH] is inverse first order. Both the electron-releasing and withdrawing substituents facilitate the reaction rate. The observed rate constants for substituents are plotted against Hammett constant σ, a non-linear, ‘V’ shaped curve is obtained. The electron-withdrawing substituents fall on one side of the curve having a negative ϱ value, and electron-releasing substituents fall on the otherside with positive ϱ value. The break in the Hammett plot is due to change in the nature of transition state. The mechanism proposed and the derived rate law are in confirmity with the observed results.

Direct spectrophotometric determination of thiocyanate in serum and urine with a continuous-flow analyzer

A spectrophotometric method for the rapid measurement of thiocyanate in serum and urine without separation from interfering substances is described. Thiocyanate reacts immediately with chloramine-T in presence of iron(III) chloride catalyst to give cyanogen chloride, which reacts with a mixture of γ-picoline (4-methylpyridine) and barbituric acid to form a soluble violet—blue product, which is measured at 605 nm. Other components of physiological fluids react more slowly and do not interfere if the reaction time of the chlorinating step is kept very short. The proposed procedure is compared with a highly selective method, based on the oxidation of thiocyanate to cyanide, and good agreement was obtained for both serum and urine. The method is readily adapted to a continuous-flow procedure with a Technicon AutoAnalyzer.

ChemInform Abstract: KINETICS AND MECHANISM OF OXIDATION OF ACETONE, ETHYL METHYL KETONE AND DIETHYL KETONE WITH CHLORAMINE‐T IN HYDROCHLORIC ACID MEDIUM

The kinetics of oxidation of aliphatic ketones (acetone, ethyl methyl ketone and diethyl ketone) by chloramine-T in presence of hydrochloric acid (0.1 to 0.3M) have been investigated at 30 °C. The rate of disappearance of chloramine-T has been found to be first order each with respect to oxidant, ketone and [H+], in the range of the acid concentrations studied. The thermodynamic and kinetic parameters have been evaluated by determining the rate constants at different temperatures. The products of the reaction have been identified as chloroketones by their NMR spectra. The solvent isotope effect has been studied in the case of the oxidation of acetone and ethyl methyl ketone. A mechanism has been proposed.

Kinetics and mechanism of oxidation of acetone, ethyl methyl ketone and diethyl ketone with chloramine-T in hydrochloric acid medium

The kinetics of oxidation of aliphatic ketones (acetone, ethyl methyl ketone and diethyl ketone) by chloramine-T in presence of hydrochloric acid (0.1 to 0.3M) have been investigated at 30 °C. The rate of disappearance of chloramine-T has been found to be first order each with respect to oxidant, ketone and [H+], in the range of the acid concentrations studied. The thermodynamic and kinetic parameters have been evaluated by determining the rate constants at different temperatures. The products of the reaction have been identified as chloroketones by their NMR spectra. The solvent isotope effect has been studied in the case of the oxidation of acetone and ethyl methyl ketone. A mechanism has been proposed.

ChemInform Abstract: KINETICS OF OXIDATION OF ALLYL ALCOHOL BY CHLORAMINE‐T IN HYDROCHLORIC ACID MEDIUM, EFFECT OF HIGH ACID CONCENTRATIONS

The kinetics of oxidation of allyl alcohol by chloramine-T in presence of hydrochloric acid(0.15-0.29M) has been studied. At 0°C the rate is first order with respect to chloramine-T, second order in [H+] and independent of the alcohol concentration. The energy of activation and entropy of activation of the reaction have been found to be 55.6 kJ mol -1 and -153 J K-1 respectively. A mechanism is proposed.

Kinetics of oxidation of allyl alcohol by chloramine-T in hydrochloric acid medium: effect of high acid concentrations

The kinetics of oxidation of allyl alcohol by chloramine-T in presence of hydrochloric acid(0.15-0.29M) has been studied. At 0�C the rate is first order with respect to chloramine-T, second order in [H+] and independent of the alcohol concentration. The energy of activation and entropy of activation of the reaction have been found to be 55.6 kJ mol -1 and -153 J K-1 respectively. A mechanism is proposed.

Kinetics and mechanism of oxidation of allyl alchohol by chloramine-T in hydrochloric acid medium

The kinetics of oxidation of allyl alcohol by chloramine-T in presence of hydrochloric acid (0.04-0.13M ) has been studied at O�C. The reaction shows first-order dependence on chloramine-T and hydrogen ion concentration and is independent of the concentration of alcohol. The energy and entropy of activation of the reaction have been found to be 12.3 kcal mol-1 and -33.2 e.u. respectively.Ionic strength has very little influence on the rate of reaction. A mechanism in terms of a fast interaction between allyl alcohol and hypochlorous acid formed by the hydrolysis of N-chloro-p-toluenesulphonamide in a slow step is proposed.

Iron(II)-chloramine-T reaction

When a large excess of the oxidant is used in the iron(II)—chloramine-T reaction at pH 2·56–5·6 the amount of oxidant consumed is well above the stoichiometric amount required to oxidize iron(II) to iron(III). This has been attributed to the formation and subsequent behaviour of free radicals during the reaction. The formation of free radicals has been experimentally demonstrated. They apparently dimerize to give products of the type RNClNClR (R = CH 3C 6H 4SO 2), which are further oxidized by chloramine-T. The dimerized species liberate iodine very slowly from acidified potassium iodide. This explanation satisfactorily accounts for the observed extent and rate of destruction of excess of chloramine-T in presence of small amounts of Fe(II) or bromide at pH 2·65–4·70. The storage of chloramine-T in metal containers might cause extensive destruction of the oxidant by a similar free radical mechanism and should be avoided.