Electron and proton magnetic resonance spectroscopic investigation of anthracene oxidation
Mohamed A. Morsy,
Abdel-Nasser M. Kawde,
Muhammad Kamran,
Thomas F. Garrison,
Wissam Iali,
Salman S. Alharthi
Affiliations
Mohamed A. Morsy
Chemistry Department, College of Chemicals and Materials, King Fahd University of Petroleum & Minerals, P.O. Box 1624, Dhahran 31261, Saudi Arabia; Corresponding author.
Abdel-Nasser M. Kawde
Department of Chemistry, College of Sciences, Research Institute of Sciences and Engineering, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates
Muhammad Kamran
Chemistry Department, College of Chemicals and Materials, King Fahd University of Petroleum & Minerals, P.O. Box 1624, Dhahran 31261, Saudi Arabia
Thomas F. Garrison
Chemistry Department, College of Chemicals and Materials, King Fahd University of Petroleum & Minerals, P.O. Box 1624, Dhahran 31261, Saudi Arabia
Wissam Iali
Chemistry Department, College of Chemicals and Materials, King Fahd University of Petroleum & Minerals, P.O. Box 1624, Dhahran 31261, Saudi Arabia
Salman S. Alharthi
Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
The work reports a method for monitoring anthracene radical-mediated oxidation reactions using electron paramagnetic resonance (EPR) spectroscopy. The formation of anthracene dimer product was well-defined using 1H-NMR and 1H–1H correlation spectroscopy (COSY). Unrestricted 3-21G/B3LYP DFT was used to estimate radical hyperfine spacing (hfs), then to identify the characteristic EPR-spin transitions of anthracene radical intermediate. A detailed investigation of an anthracene oxidation reaction and its possible reaction mechanism in concentrated sulphuric acid is conducted as a model system for polyaromatic hydrocarbons. Peak-to-peak (p2p) intensities of selected EPR-spectral lines were used to evaluate anthracene's oxidation kinetic model. The findings showed that radical intermediate formation is a unimolecular autocatalytic process, dimerization is a pseudo-zero-order reaction, and the latter is the rate-determining step with a half-life of 48 ± 2 min at 25.0 °C.
