Impact of Fluorinated Cobalt(II) Phthalocyanine Catalysts on Aerobic Thiol Oxidation Kinetics

• Published in: Chemical engineering communications Vol. 203; no. 6; pp. 714 - 723
• Main Authors: Reid, Nellone, Barat, Robert
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 02.06.2016; Taylor & Francis Ltd
• Subjects: Batch reactors; Binding; Catalysis; Catalysts; Chemical engineering; Disulfides; Gas sweetening; Kinetics; Multiphase reactors; Oxidation; Reaction kinetics; Substrates; Thiols
• ISSN: 0098-6445; 1563-5201
• DOI: 10.1080/00986445.2015.1067802

Kinetic studies were conducted for the aerobic oxidation of 2-mercaptoethanol (2-ME) and 4-fluorobenzenethiol (4-FBT) catalyzed by cobalt(II) phthalocyanines: H 16 PcCo, F 16 PcCo, and F 64 PcCo, each exhibiting a metal center subject to increasing Lewis acidity and steric hindrance. The experiments were performed in a reaction-limited, isothermal, bench-scale, batch reactor, with thiol concentrations measured using GC/FID. Conversions of 2-ME to 2-hydroxyethyl disulfide and 4-FBT to 4-fluorophenyl disulfide in excess of 90% were achieved. Kinetic analyses suggest that the substrate binding and electron transfer are directly related to the Lewis acidity and steric bulkiness of catalyst molecules. Substrate binding was found to be the slow step for thiol oxidations catalyzed by H 16 PcCo. The rate-determining step for thiol oxidations, catalyzed by F 16 PcCo and F 64 PcCo, is the expulsion of the thiyl radical (RS * ) from the catalyst molecule.