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Energy and substituent effects on the mass spectra of substituted benzophenones
Author(s) -
Einolf Noel,
Munson Burnaby
Publication year - 1971
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210050406
Subject(s) - ion , chemistry , substituent , mass spectrum , spectral line , electron ionization , analytical chemistry (journal) , reaction rate constant , medicinal chemistry , physics , kinetics , organic chemistry , ionization , quantum mechanics , astronomy
For two competing decompositions of the same molecular ion to give products [A 1 + ] and [A 2 + ], the ratio [A 1 + ]/[A 2 + ], is equal to the ratio of rate constants for the formation of the stable ions. Thr ratios, [Y C 7 H 4 O + ]/[C 7 H 5 O + ], were determined for several benzophenones for electron energies from 15 to 70 eV. Plots of log [Y C 7 H 4 O + ]/[C 7 H 5 O + ] vs.[ω + ] gave good straight lines at all energies. Similar correlations have been reported for log [Y C 7 H 6 + ]/[C 7 H 7 + ] from substituted diphenyl ethanes and are also true for substituted acetophenones, log [YøCO + ]/[CH 3 CO + ]. A few charge exchange data were obtained which showed the same general trend as the electron‐impact data and emphasize the contribution of low energy ions in the 70 eV mass spectra. Relatively poor correlations were obtained for the [Y C 6 H 4 + ] and [C 6 H 5 + ] ions that are formed by both one‐step and two‐step decompositions.