ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Mechanistic insights into the reaction of CF3CCl3 with SO3: Theory and experiment
Zhi-Zheng Liu, Zhi-Rong Chen, Hong Yin, and Shen-Feng Yuan
Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou, 310027 China
Abstract: Reaction mechanism of 1,1,1-trifluorotrichloroethane (CF3CCl3) and sulphur trioxide (SO3) in the presence of mercury salts (Hg2SO4 and HgSO4) was studied applying the density functional theory (DFT) at the UB3LYP/6-31+G(d,p) level. It was found that this reaction
occurs in the free radical chain path as follows: mercury(I) sulphate free radical is generated by heat, causing CF3CCl3 to produce the CF3CCl2 free radical which reacts with SO3 leading to the formation of CF3CCl2OSO2 decomposing into CF3COCl and SO2Cl. The SO2Cl free radical triggers CF3CCl3 to regenerate CF3CCl2 which recycles the free radical growth reaction. This elementary reaction has the highest energy barrier and it is therefore
the rate control step of the whole reaction path. Experiment data can confirm the existence of the mercury(I) salt free radical
and the free radical initiation stage. So, mercury salts play the role of initiators not that of catalysts. The results agree
well with our hypothesis.
Keywords: reaction mechanism – mercury salts – density functional theory – free radical chain
Full paper is available at www.springerlink.com.
Chemical Papers 66 (11) 1059–1064 (2012)