Molecular-Scale Mechanism of Sequential Reaction of Oxalic Acid with SO₃: Potential Participator in Atmospheric Aerosol Nucleation

Abstract

Recent research has shown the almost barrierless cycloaddition reaction of the carboxylic acid with one SO3 to form products with group of −OSO3H, which can form stable clusters with the nucleation precursors through hydrogen bonds (Science201534958). Oxalic acid (OA), the simplest and prevalent dicarboxylic acid, was selected as an example to clarify the possibility to react with two SO3 sequentially and the nucleation potential of products. The results indicate that OA can sequentially react with two SO3 through low reaction barriers to form the primary product (oxalic sulfuric anhydride (OSA)) and the secondary product (oxalic disulfuric anhydride (ODSA)). Interactions between atmospheric nucleation precursors and OSA, ODSA, or OA are in the order of ODSA > OSA > OA through evaluating the stability of generated clusters by the topological, thermodynamics, and kinetic analysis, which implies generated products could be nucleation stabilizers with nucleation potential positively correlating with the number of −OSO3H. This reaction mechanism contributes to a comprehensive understanding of the reactivity of dicarboxylic acid in the polluted environment as well as the role of products in organosulfur chemistry and, to some extent, help to explain the missing sources of new particle formation.

Reaction of SO3 with HONO2 and Implications for Sulfur Partitioning in the Atmosphere

“…Typically, the concentration of OH is 10 4 to 10 6 molecules cm –3 and the concentration of SO 3 can also reach 10 6 molecules cm –3 in the troposphere. − Therefore, the SO 3 + HONO 2 reaction should be competitive with OH + HONO 2 . Although these similar reactions such as SO 3 with organic acids have been reported in the literature, − their quantitative kinetics are still unknown; this leads to the fact that these reactions have not been put forward and identified as an important sink for organic acids in the atmosphere.…”

Determination of the influence of water on the SO3 + CH3OH reaction in the gas phase and at the air–water interface

“…For example, with the participation of interfacial water molecules, HCOOH can react with SO 3 at the air-water interface to form the SO 3 -COOH À Á Á ÁH 3 O + ion pair. 24 This mechanism differs from the fact that HCOOH in the gas-phase [25][26][27][28] acts as a catalyst for the H 2 SO 4 formation or as a reactant for the HCOOSO 3 H formation. However, the reaction mechanism between SO 3 and CH 3 OH at the air-water interface has not been reported.…”

Hydrogen-Bonding Interactions of Malic Acid with Common Atmospheric Bases

“…The role of organic compounds in NPF formation has been the subject of various theoretical and experimental investigations in the past few years. − Several monocarboxylic compounds like benzoic acid, − formic acid, − methanesulfonic acid, − lactic acid, and dicarboxylic ones such as oxalic acids, ,,− maleic acids, , succinic acid, ,, malonic acid, , and phthalic acid, investigated by theoretical quantum-chemical procedures, have been found to contribute significantly to the nucleation process. Interactions of organic acids and naturally occurring amines were found to be important for the nucleation process under different atmospheric conditions. − Amines are derivatives of NH 3 and are abundantly present in the atmosphere.…”