Comparative Study on the Oxidation Kinetics of Structural Isomers by Acidified N-Bromo-Benzenesulfonamide: A Mechanistic Determination

Autor: Shubha Jayachamarajapura Pranesh, Sushma Nurani Viswanathan, Puttaswamy Swamy
Rok vydání: 2019
Předmět:
Zdroj: Chemistry Africa. 2:435-441
ISSN: 2522-5766
2522-5758
DOI: 10.1007/s42250-019-00068-9
Popis: A comparative study on the oxidation kinetics of potent antihistamines promethazine hydrochloride(PRM1) and promazine hydrochloride (PRM2)—structural isomers by sodium N-bromo-benzene-sulphonamide (bromamine-B or BAB) was carried out in acidic medium (HClO4) at 303 K. The reactions follow identical kinetics, which area fractional order dependence on acid concentration and first-order each on [oxidant]o, and [substrate]. The rate of reaction observed with dielectric constant of the medium which shows inverse proportionality and the reaction is performed by adding methanol. Effect of p-benzenesulfonamide, halide ion and ionic strength on the reaction rate has been investigated. The activation parameters were calculated by varying the temperature range. The reaction stochiometry was found to be 1:1 and the products obtained by the oxidation (promethazine S-oxide and promazine S-oxide) were identified by spectral analysis. Under similar experimental conditions, the rate of oxidation of promethazine hydrochloride is nearly 1.3 times more than the rate of oxidation of promazine hydrochloride. The difference in the acidic nature of nitrogen which is attached to the different carbon atoms accounts for the rate difference of PRM1 and PRM2. The rate law and a plausible mechanism are derived for the obtained experimental results.
Databáze: OpenAIRE
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