Mechanistic Aspects of Charge-remote Fragmentation in Saturated and Mono-unsaturated Fatty Acid Derivatives. Evidence for Homolytic Cleavage

✍ Scribed by Magda Claeys; Libérata Nizigiyimana; Hilde Van den Heuvel; Peter J. Derrick

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 483 KB
• Volume: 10
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(199605)10:7<770::aid-rcm575>3.0.co;2-d

✦ Synopsis

The high-energy collision-induced dissociation (CJD) of [M+Li]+ ions of n-butyl ester derivatives of palmitic acid and oleic acid as well as 9,9-*H,-palmitic acid and ll,ll-2H,-oleic acid has been studied in order to obtain information on the charge-remote fragmentation mechanism of saturated and mono-unsaturated fatty acid ions containing a stable charge centre. The results obtained in the present study indicate that homolytic cleavage reactions, involving C-I3 cleavage as an initial rate-determining step, operate during the charge-remote fragmentation observed for high-energy CJD of [M+Li]+ ions of n-butyl palmitate and correspond to a major fragmentation route. With respect to the charge-remote fragmentation of n-butyl oleate, our ZH-labelling results point to the same mechanism, involving an initial C-I3 cleavage at allylic positions, for the formations of ions corresponding to a formal homo-allylic cleavage, and are also consistent with a direct allylic C-C cleavage for the formation of ions due to a formal allylic C-C cleavage. These results, however, do not exclude the possibility of other minor homolytic fragmentation pathways for the formation of ions involving formal allylic and homoallylic cleavages.