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Published June 29, 2006 | metadata_only
Journal Article

Cluster Phase Chemistry: Gas-Phase Reactions of Anionic Sodium Salts of Dicarboxylic Acid Clusters with Water Molecules


A homologous series of anionic gas-phase clusters of dicarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) generated via electrospray ionization (ESI) are investigated using collision-induced dissociation (CID). Sodiated clusters with the composition (Na+)2n+1(dicarboxylate2-)n+1 for singly charged anionic clusters, where n = 1−4, are observed as major gas-phase species. Isolation of the clusters followed by CID results mainly in sequential loss of disodium dicarboxylate moieties for the clusters of succinic acid, glutaric acid, and adipic acid (C4−C6). However, all oxalate (C2) and malonate (C3) clusters and dimers (n = 1) of succinate (C4) and glutarate (C5) exhibit more complex chemistry initiated by collision of the activated cluster with water molecules. For example, with water addition, malonate clusters dissociate to yield sodium acetate, carbon dioxide, and sodium hydroxide. More generally, water molecules serve as proton donors for reacting dicarboxylate anions in the cluster and introduce energetically favorable dissociation pathways not otherwise available. Density functional theory (DFT) calculations of the binding energy of the cluster correlate well with the cluster phase reactions of oxalate and malonate clusters. Clusters of larger dicarboxylate ions (C4−C6) are more weakly bound, facilitating the sequential loss of disodium dicarboxylate moieties. The more strongly bound small dicarboxylate anions (oxalate and malonate) preferentially react with water molecules rather than dissociate to lose disodium dicarboxylate monomers when collisionally activated. Implications of these results for the atmospheric aerosol chemistry of dicarboxylic acids are discussed.

Additional Information

© 2006 American Chemical Society. Received 17 October 2005. Published online 3 June 2006. Published in print 1 June 2006. The research described in this paper was carried out at the Beckman Institute and Jet Propulsion Laboratory of the California Institute of Technology. We appreciate the support provided by the Mass Spectrometry Resource Center in the Beckman Institute, California Institute of Technology. Partial support was also provided by the National Science Foundation (NSF) under grant no. CHE-0416381. We greatly appreciate the support and critical discussion of Drs. Isik Kanik, Luther W. Beegle, Paul V. Johnson, and Charles P. Malone at Jet Propulsion Laboratory, California Institute of Technology.

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August 19, 2023
August 19, 2023