The mechanism of formaldehyde loss from the oxonium ions CH3CH2CH2CHO+CH3 and CH3CH2CH2CH2+OCH2

Abstract

In contrast to CH₃CH₂(CH₃)CO⁺CH₃ and (CH₃)₂CHCHO⁺CH₃, which in slow dissociations lose mainly CH₃OH, metastable CH₃CH₂CH₂CHO⁺CH₃ exples predominantly CH₂O by isomerising to CH₃CH₂CH₂CH₂⁺OCH₂, probably via two 1,2-H shifts and a subsequent 1,5-H shift; CH₃CH₂CH₂⁺OCH₂ undergoes limited interconversion with CH₃⁺CHCH₂CH₂OCH₃, prior to CH₂O elimination, via a 1,5-H shift.