Further Studies on a Site-specific Hydrogen Transfer Observed in Electron Capture Negative Ion Chemical Ionization Mass Spectrometry of Hydroxyamine Pentafluoropropionate Derivatives

Article abstract of DOI:10.1002/oms.1210201002

Further studies have demonstrated that the site-specific hydrogen transfer process involved in the formation of the m/z 145 anion of β-hydroxyamine pentafluoropropionate (PFP) derivatives observed under electron capture negative ion chemical ionization conditions occurs when the two functional groups are separated by up to five carbon atoms.Deuterium labelling has established that the site specificity, transfer of a hydrogen atom from the carbon adjacent to nitrogen to the OPFP group, is maintained in 4-amino-butan-1-ol-N,O-(PFP)2.The corresponding PFP derivatives of the N-methylaminoalkanol- (PFP)2 derivatives lack the m/z 145 species with m/z 163, ^-, being the base anion.Substitution of alkyl groups on the carbon adjacent to oxygen results in a diminution of the ion intensity at m/z 145 with a marked increase in the intensity of m/z 144.The formation of the m/z 145 and 144 anions is proposed to proceed through the intervention of a fluoride ion-molecule complex as outlined in Scheme 1 with the product ion distribution dependent on which of the two pathways is preferred.