Beschreibung:
<jats:title>Abstract</jats:title><jats:p>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 <jats:italic>n</jats:italic>‐butanal, <jats:disp-formula>
</jats:disp-formula> in contrast to a previous conclusion. The most favorable geometry for departure of the C<jats:sub>2</jats:sub>H<jats:sub>4</jats:sub> 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 <jats:italic>n</jats:italic>‐butanal ion is stepwise. The RRKM calculations predict competition of H exchange with decomposition up to much higher energies than actually occurs.</jats:p>