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Theoretical Studies on Mechanism and Rate Constant of Gas Phase Hydrolysis of Glyoxal Catalyzed by Sulfuric Acid
Ming-qiang Huang1,2,3, Shun-you Caia1,2, Ying-min Liao3, Wei-xiong Zhao4, Chang-jin Hu4, Zhen-ya Wang4, Wei-jun Zhang4
1.College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000, China;2.Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Zhangzhou 363000, China;3.Department of Environmental Science and Engineering, College of Tan Kah Kee, Xiamen University, Zhangzhou 363105, China;4.Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Abstract:
The gas phase hydration of glyoxal (HCOCHO) in the presence of sulfuric acid (H2SO4) were studied by the high-level quantum chemical calculations with M06-2X and CCSD(T) theoretical methods and the conventional transition state theory (CTST). The mechanism and rate constant of the ve di erent reaction paths are consid-ered corresponding to HCOCHO+H2O, HCOCHO+H2O H2O, HCOCHO H2O+H2O, HCOCHO+H2O H2SO4 and HCOCHO H2O+H2SO4. Results show that H2SO4 has a strong catalytic ability, which can signi cantly reduce the energy barrier for the hydration reaction of glyoxal. The energy barrier of hydrolysis of glyoxal in gas phase is lowered to 7.08 kcal/mol from 37.15 kcal/mol relative to pre-reactive complexes at the CCSD(T)/6-311++G(3df, 3pd)//M06-2X/6-311++G(3df, 3pd) level of theory. The rate constant of the H2SO4 catalyzed hydrolysis of glyoxal is 1.34×10-11cm3/(molecule s), about 1013 higher than that involving catalysis by an equal number of water molecules, and is greater than the reaction rate of glyoxal reaction with OH radicals of 1.10×10-11cm3/(molecule s) at the room temperature, indicating that the gas phase hydrolysis of glyoxal of H2SO4 catalyst is feasible and could compete with the reaction glyoxal+OH under certain atmospheric condi-tions. This study may provide useful information on understanding the mechanistic features of inorganic acid-catalyzed hydration of glyoxal for the formation of oligomer
Key words:  Glyoxal  Hydrolysis  Sulfuric acid  Acid-catalyzed mechanism
FundProject:This work is supported by the National Natural Sci-ence Foundation of China (No.41575118, No.41305109, No.21502086, No.41575126, No.41330424, and No.41127001), the Outstanding Youth Science Founda-tion of Fujian Province of China (No.2015J06009), and the Natural Science Foundation of Fujian Province of China (No.2015J05028). The author thanks professors W. T. Duncan, R. L. Bell, and T. N. Truong for providing TheRate programme through Internet.
硫酸催化乙二醛气体相水化反应机理和速率常数理论计算研究
黄明强1,2,3, 蔡顺有1,2, 廖颖敏3, 赵卫雄4, 胡长进4, 王振亚4, 张为俊4
1.闽南师范大学化学与环境学院, 漳州 363000;2.福建省现代分离分析科学与技术重点实验室, 漳州 363000;3.厦门大学嘉庚学院环境科学与工程系, 漳州 363105;4.中国科学院安徽光学精密机械研究所大气物理化学实验室, 合肥 230031
摘要:
采用M06-2X和CCSD(T)高阶量化计算和传统过渡态理论研究硫酸催化乙二醛气体相水化反应.对HCOCHO+H2O, HCOCHO+H2O+H2O, HCOCHO+H2O+H2O, HCOCHO+H2O...H2SO4和HCOCHO+H2O+H2SO4五个路径的反应机理和速率常数进行了研究.计算结果表明硫酸具有较强的催化能力,能显著减小乙二醛水化反应的能垒,在CCSD(T)/6-311++G(3df,3pd)//M06-2X/6-311++G(3df,3pd)理论水平,当硫酸分子参与乙二醛水化反应时,反应能垒从37.15 kcal/mol减少至7.08 kcal/mol.在室温条件下,硫酸催化乙二醛水化反应的反应速率1.34×10-11 cm3/(molecule.s),是等量水分子参与乙二醛水化反应的速率的1012倍,大于乙二醛与OH自由基反应的反应速率1.10×10-11 cm3/(molecule.s).这表明大气条件下,硫酸催化乙二醛水化反应可以发生,同乙二醛与OH自由基反应相竞争.
关键词:  乙二醛  水化  硫酸  酸催化机理
DOI:10.1063/1674-0068/29/cjcp1509193
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