An Investigation of Structure of Intermediate Ions from Several Substituted Alkyl Benzoates by the ortho Effect and Kinetic Energy Release

Abstract

Single and double hydrogen atom transfers in reactions (1) and (2) are found in the mass spectra of n-propyl and n-butyl benzoates, and n-propyl and n-butyl p-hydroxy-benzoates. In contrast, only single hydrogen atom transfer is found in the mass spectra of n-propyl and n-bulyl salicylates and it is concluded that the hydrogen bond prevents the second hydrogen atom transfer. The kinetic energy release for the loss of water from the m/z 138 ion[C7H6O3]+ produced from ethyl and higher alkyl salicylates by a McLafferty rearrangement was nearly equal to that from the molecular ion of salicylic acid (m/z 138). The kinetic energy release for the loss of water from the m/z 137 ion[C7H7NO2]+ from ethyl o-aminobenzoate was also equal to that from the molecular ion of o-amino benzoic acid (m/z 137). However, the corresponding kinetic energy release from the m/z 136 ion[C8H8O2]+ from ethyl o-methylbenzoate was somewhat higher than that from the molecular ion of o-methyl benzoic acid (m/z 136).