Ab initio and RRKM evidence that the McLafferty rearrangement of ionized n-butanal is stepwise

✍ Scribed by Charles E. Hudson; Lawrence L. Griffin; David J. McAdoo

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 468 KB
• Volume: 24
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210241003

✦ Synopsis

Hartree

-Fock calculations with geometry optimization at a series of C(2)-C(3) distances predict a negligible reverse critical energy for the second step of the McLafferty rearrangement of ionized n-butanal, 'CH,CH,CH,CH=OH+ + 'CHICH,-OH+ + CH,=CH, in contrast to a previous conclusion. The most favorable geometry for departure of the C,H, has a dihedral angle of about 90" between the parting fragments. RRKM calculations were used to estimate rates of reactions associated with the McLafferty rearrangement. These calculations indicate that the McLafferty rearrangement of the n-butanal ion is stepwise. The RRKM calculations predict competition of H exchange with decomposition up to much higher energies than actually occurs.