Theoretical study on atmospheric gaseous reactions of glyoxal with sulfuric acid and ammonia

Abstract

The reaction mechanisms and rate constants of the gaseous reactions of glyoxal with H2SO4, NH3-catalyzed glyoxal with H2SO4, glyoxal with NH3, and H2SO4-catalyzed glyoxal with NH3 are studied detailedly using M06-2X followed by CCSD(T) calculations and conventional transition state theory in current study. The results show that NH3 has a certain catalytic ability to reduce the barrier for reaction of glyoxal with H2SO4, and increases their rate constant by 103 times to 2.66 × 10-15 cm3 molecule-1 s−1 under atmospheric condition ·NH3 can facilitate the formation of organosulfates at high concentration and low temperature. H2SO4 has a strong catalytic ability, significantly reduces the barrier of glyoxal with NH3, and increases their rate constant to 4.52 × 10-12 cm3 molecule-1 s−1, which is slightly less than the rate coefficient of OH radicals and glyoxal. These provide the basis for clarifying the characteristic mechanism of gaseous reaction of glyoxal to form organosulfates and carbinolamine.