EI fragmentation of E,Z-3-iodo-2-alkenoic acids and methyl E,Z-3-iodo-2-alkenoates

✍ Scribed by J. C. Herrera; N. A. Urdaneta

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 148 KB
• Volume: 12
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19980731)12:14<955::aid-rcm267>3.0.co;2-7

✦ Synopsis

The electron ionization mass spectra of some E,Z-3-iodo-2-alkenoic acids and methyl E,Z-3-iodo-2alkenoates were investigated. A semi-empirical method was used to examine the thermochemical and molecular properties of the species. Two fragmentation paths of the molecular ions are determined by the geometry of the carbon-carbon double bond: (i) heterolytic loss of I Á radical, and (ii) a rearrangement that produces [M À C n H 2n ] Á ions. The E-compounds show less stabilized molecular ions, preference to lose I Á , and little tendency for the rearrangement. A favourable critical energy (E o ), in the C-I bond dissociation of the E-compounds, is required to observe the configuration effect. A mechanism for the formation of [M À C n H 2n ] Á ions is proposed.