Hydration Leads to Efficient Reactions of the Carbonate Radical Anion with Hydrogen Chloride in the Gas Phase

Abstract

The carbonate radical anion CO is a key intermediate in tropospheric anion chemistry. Despite its radical character, only a small number of reactions have been reported in the literature. Here we investigate the gas-phase reactions of CO and CO(HO) with HCl under ultrahigh vacuum conditions. Bare CO forms OHCl with a rate constant of 4.2 × 10 cm s, which corresponds to an efficiency of only 0.4%. Hydration accelerates the reaction, and ligand exchange of HO against HCl proceeds with a rate of 2.7 × 10 cm s. Quantum chemical calculations reveal that OHCl is best described as an OH hydrogen bonded to Cl, while the ligand exchange product is Cl(HCO). Under tropospheric conditions, where CO(HO) is the dominant species, Cl(HCO) is efficiently formed. These reactions must be included in models of tropospheric anion chemistry.

Kinetics of the reaction of CO3˙−(H2O)n, n = 0, 1, 2, with nitric acid, a key reaction in tropospheric negative ion chemistry

“…Recent studies in our laboratory reveal that this reaction proceeds via formation of a short lived, very reactive Cl À (OH ) intermediate that reacts fast with a second HCl molecule, producing HCl 2 À and Cl 2 À as final products. 31 The rate of the first step is 4.2 Â 10 À12 cm 3 s À1 , consistent with the upper limit given by Dotan et al 24 Interestingly, hydration dramatically accelerates the rate to 2.7 Â 10 À10 cm 3 s À1 for CO 3 À (H 2 O), resulting in the reactive Cl À (HCO 3 ) radical species. 31 Nitric acid [21][22][23]32 and methane sulfonic acid 20 show efficient reactions with CO 3…”

“…31 The rate of the first step is 4.2 Â 10 À12 cm 3 s À1 , consistent with the upper limit given by Dotan et al 24 Interestingly, hydration dramatically accelerates the rate to 2.7 Â 10 À10 cm 3 s À1 for CO 3 À (H 2 O), resulting in the reactive Cl À (HCO 3 ) radical species. 31 Nitric acid [21][22][23]32 and methane sulfonic acid 20 show efficient reactions with CO 3…”

“…The mechanism of the reaction of HNO 3 with CO 3 À (H 2 O) n , n = 0, 1, 2, is very similar to the previously studied HCl reaction. 31 overall significantly lower than in the flow reactor studies previously reported in the literature, indicating a strong pressure dependence.…”

“…The mechanism of the reaction of HNO 3 with CO 3 À (H 2 O) n , n = 0, 1, 2, is very similar to the previously studied HCl reaction. 31 With bare CO 3 À , the reaction is relatively slow, and the proton-transfer intermediate NO 3 À (OH ) is the unambiguously identified primary product, corresponding to Cl À (OH ) in the HCl reaction. Also NO 3 À is directly formed, but with even lower rate.…”

Simplified Multiple-Well Approach for the Master Equation Modeling of Blackbody Infrared Radiative Dissociation of Hydrated Carbonate Radical Anions

“…BIRD kinetics were measured using a 4.7 Tesla Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR MS) in the temperature range of 250–330 K. The investigated clusters were generated with a gas mixture of O 2 , CO 2 , H 2 O, and the carrier gas He in the hot plasma of a laser vaporization source, followed by supersonic expansion. , The molecular clusters were in the electronic ground state due to the supersonic expansion; their vibrational temperature is below room temperature upon leaving the ion source . The ions were then guided to the ICR cell, where they were mass selected and stored in UHV conditions.…”