Calculated results indicate that the formation of products including hydrocarbon radicals and CO2 molecule is energetically favored. The rate of decomposition increases with the number of carbon in non-cyclic saturated acyloxy radicals. Calculated enthalpies and Gibbs free energies of reactions well agree with experimental values. This study is a contribution to the understanding of the reaction mechanism of decomposition of acyloxy radicals in atmosphere and combustion chemistry. | Vietnam Journal of Science and Technology 55 (6A) (2017) 105-111 THEORETICAL STUDY ON THE REACTION MECHANISM OF CO2 FORMATION FROM ACYLOXY RADICALS Nguyen Thi Minh Hue1, * Pham Tho Hoan2, Vu Hoang Phuong3, Nguyen Trong Nghia4, Ngo Tuan Cuong1, * 1 Faculty of Chemistry and Center for Computational Science, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Ha Noi, Viet Nam 2 Faculty of Information Technology and Center for Computational Science, Hanoi National University of Education,136 Xuan Thuy, Cau Giay, Ha Noi, Viet Nam 3 Sao Do University, 24 Thai Hoc 2, Chi Linh, Hai Duong, Viet Nam 4 School of Chemical Engineering, Hanoi University of Science and Technology, 1 Dai Co Viet, Ha Noi, Viet Nam * Email: Received: 15 June 2017; Accepted for publication: 21 December 2017 ABSTRACT The decomposition mechanism of acyloxy radicals has been studied by the Density Functional Theory (DFT) using B3LYP functional in conjunction with the 6-311++G(d,p) and 6-311++G(3df,2p) basis sets. The potential energy profiles for reaction systems were generally established. Calculated results indicate that the formation of products including hydrocarbon radicals and CO2 molecule is energetically favored. The rate of decomposition increases with the number of carbon in non-cyclic saturated acyloxy radicals. Calculated enthalpies and Gibbs free energies of reactions well agree with experimental values. This study is a contribution to the understanding of the reaction mechanism of decomposition of acyloxy radicals in atmosphere and combustion chemistry. Keywords: reaction mechanism, acyloxy radical, density functional theory. 1. INTRODUCTION In chemical reactions of organic compounds free radicals play a crucial role [1-3]. They are involved in almost every reactions in fuel systems, and in the earth’s atmosphere. In particular, reactions of the free acyloxyl radical RCOO has attracted much attention from both theoretical and experimental .