Bis(2-[alpha-hydroxyethyl]benzimidazolato)copper(II) anchored onto chloromethylated polystyrene for the biomimetic oxidative coupling of 2-aminophenol to 2-aminophenoxazine-3-one
Title | Bis(2-[alpha-hydroxyethyl]benzimidazolato)copper(II) anchored onto chloromethylated polystyrene for the biomimetic oxidative coupling of 2-aminophenol to 2-aminophenoxazine-3-one |
Publication Type | Journal Article |
Year of Publication | 2005 |
Authors | Maurya, MR, Sikarwar, S, Joseph, T, Halligudi, SB |
Journal | Journal of Molecular Catalysis A - Chemical |
Volume | 236 |
Issue | 1-2 |
Pagination | 132-138 |
Date Published | JUL |
Type of Article | Article |
ISSN | 1381-1169 |
Keywords | 2-aminophenol, 2-aminophenoxazine-3-one, bis(2-[alpha-hydroxyethyl]benzimidazolato)copper(II), chloromethylated polystyrene, oxidative coupling |
Abstract | 2-(alpha-Hydroxyethyl)benzimidazole (Hhebmz) has been covalently anchored to chloromethylated polystyrene cross-linked with 5% divinylbenzene. This polymer-anchored chelating resin reacts with cupric acetate in presence of Hhebmz to give polymer-anchored copper(II) complex PS-[Cu(hebmz)(2)]. Elemental analyses, FT-IR, electronic, scanning electron micrographs (SEM) and TGA-DTA pattern have been used to characterize the complex. Oxidative coupling of 2-aminophenol (OAP) to 2-aminophenoxazine-3-one (APX) catalyzed by PS-[Cu(hebmz)(2)] in presence of air at 70 degrees C in DMF gave 62% substrate conversion over a period of 8 h. Kinetics of the above reaction indicated that the rate of oxidative coupling of OAP has a first order dependence with respect to substrate, catalyst and air pressure (dissolved O-2) concentrations in the range of conditions evaluated. Based on these observations, a plausible mechanism for the above reaction has been proposed. From, the study on the effect of temperature on the rates of oxidative coupling, an activation energy 34.2 kcal/degree mole was evaluated from Arrhenius plot of -ln rate versus 1/T. Enthalpy, entropy and free energy were calculated using standard thermodynamic equations for the above reaction. (c) 2005 Elsevier B.V. All rights reserved. |
DOI | 10.1016/j.molcata.2005.02.034 |
Type of Journal (Indian or Foreign) | Foreign |
Impact Factor (IF) | 3.958 |