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 |
| |
Authors: | Kanawati Basem Joniec Seweryn Winterhalter Richard Moortgat Geert K |
| |
Institution: | Max-Planck Institute for Chemistry, Atmospheric Chemistry Division, PO Box 3060, D-55020 Mainz, Germany. kanawati.b@gmail.com |
| |
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: | |
本文献已被 PubMed 等数据库收录! |
|