【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^-11cm³/（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^-11cm³/（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.更多还原

【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 five different reaction paths are considered 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 significantly 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^-11 cm³/（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 l.10×10^-11 cm³/（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 conditions.This study may provide useful information on understanding the mechanistic features of inorganic acid-catalyzed hydration of glyoxal for the formation of oligomer.更多还原