CF sub(3)I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 118; no. 10; pp. 1918 - 1926-1918-1926
• Main Authors: Hu, Yingjie, Wu, Taiping, Liu, Weizhou, Zhang, Liyang, Pan, Renming
• Format: Journal Article
• Language: English
• Published: 03.03.2014
• Subjects: Activated carbon; Density functional theory; Dimerization; Fluorine; Fluorometers; Graphite; Iodine; Synthesis (chemistry)
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp410133v

A revised reaction mechanism of CF sub(3)I synthesis catalyzed by activated carbon is investigated with quantum chemistry methods using density functional theory (DFT). The adsorption configurations of possible intermediates are carefully examined. The reaction pathway and related transition states are also analyzed. According to our calculations, first, the dehydrofluorination of CHF sub(3) is catalyzed by -COOH groups, which possesses the highest barrier and is accordingly identified as the rate-determining step. Second, the difluorocarbene disproportionation over graphite (001) surface proceeds instead of dimerization. The next reaction steps involving the association of fluoromethine and trifluoromethyl, the fluorine abstractions between intermediates and the iodine abstractions by the desorbed CF sub(3) and CF sub(2)CF sub(3) from molecular iodine are also feasible over graphite (001) surfaces. It is also found that the coke deposition in experiments is due to the fluorine abstraction from fluoromethine. This revised mechanism is in agreement with available experimental data and our theoretical computations.