Abstract
The dissociative photoionization of energy-selected cis-1-bromopropene, trans-1-bromopropene, 2-bromopropene, 3-bromopropene (allyl bromide) and bromocyclopropane was investigated by imaging photoelectron photoion coincidence (iPEPICO) spectroscopy. Br loss was the only dissociation channel observed in the measured energy range. Cis-1-bromopropene, trans-1-bromopropene and 2-bromopropene cations are metastable at the 0K appearance energy of Br loss, whereas allyl bromide and bromocyclopropane cations dissociate quickly. The experimental onsets, supported by ab initio calculations, show that allyl bromide, cis- and trans-1-bromopropene, and bromocyclopropane dissociatively photoionize by Br loss to form the allyl cation, CH2CHCH2+. Due to the high barrier between the 2- and 3-bromopropene cations, the 2-bromopropene cation dissociates into the other, less stable C3H5+ isomer, the 2-propenyl cation, CH3CCH2+. The 0K appearance energy of the allyl cation from the cis- and trans-1-bromopropenes, allyl bromide and bromocyclopropane was determined to be 10.581±0.014eV, 10.561±0.012eV, 10.522±0.005eV and 10.211±0.005eV, respectively. Similarly, the 0K appearance energy of the 2-propenyl cation from 2-bromopropene was determined to be 10.930±0.015eV. Using a mixed theoretical and experimental thermochemical network, the 0K heats of formation of cis-1-bromopropene, trans-2-bromopropene, allyl bromide, 2-bromopropene, and bromocyclopropane were determined as 64.7±2.9, 66.4±2.8, 70.3±2.6, 58.5±2.9, and 104.3±4kJmol−1, respectively.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
