| Title: | Mass spectrometric characterization of 4-oxopentanoic acid and gas-phase ion fragmentation mechanisms studied using a triple quadrupole and time-of-flight analyzer hybrid system and density functional theory |
| Author(s): | Kanawati B; Joniec S; Winterhalter R; Moortgat GK; |
| Address: | "Max-Planck Institute for Chemistry, Atmospheric Chemistry Division, PO Box 3060, D-55020 Mainz, Germany. kanawati.b@gmail.com" |
| Journal Title: | Rapid Commun Mass Spectrom |
| ISSN/ISBN: | 0951-4198 (Print) 0951-4198 (Linking) |
| Abstract: | "4-Oxopentanoic acid was characterized experimentally by electrospray ionization using a triple quadrupole and time-of-flight analyzer hybrid system. This compound was chosen as a model substance for small organic compounds bearing an acetyl and a carboxyl group. Collision-induced dissociation experiments at different activation energies were performed to elucidate possible fragmentation pathways. These pathways were also studied on the theoretical level using density functional theory (DFT) B3LYP/6-311++G(3df,3pd)//B3LYP/6-31+G(d)+ZPVE calculations. CO2 ejection from the [M-H](-) anion of 4-oxopentanoic acid was observed and the fragmentation pathway studied by DFT reveals a new concerted mechanism for CO2 elimination accompanied by an intramolecular proton transfer within a pentagonal transition state structure. Successive elimination of water and CO from the [M-H](-) anion of 4-oxopentanoic acid was also observed. A rearrangement in the primary deprotonated ketene anion produced after water elimination was found on the theoretical level and leads to CO elimination from the primary product anion [M-H-H2O](-). Energy diagrams along the reaction coordinates of the fragmentation pathways are presented and discussed in detail. Mulliken charge distributions of some important structures are presented" |
| Keywords: | "Anions/chemistry Carbon Dioxide/chemistry Ethylenes/chemistry Hot Temperature Hydroxides/chemistry Keto Acids/*chemistry Ketones/chemistry Mass Spectrometry/*methods Methanol/chemistry Models, Molecular Pentanoic Acids/*chemistry Solvents/chemistry Spectr;" |
| Notes: | "MedlineKanawati, Basem Joniec, Seweryn Winterhalter, Richard Moortgat, Geert K eng Research Support, Non-U.S. Gov't England 2008/06/20 Rapid Commun Mass Spectrom. 2008 Jul; 22(14):2269-79. doi: 10.1002/rcm.3611" |
