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The study of C 1 C 3 monosubstituted alkyl benzenes by the inverse convolution of first differential ionization efficiency curves
Author(s) -
Selim Ezzat T. M.,
Helal A. I.
Publication year - 1982
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.1210171102
Subject(s) - ion , ionization , benzene , chemistry , photoionization , electron ionization , alkyl , toluene , standard enthalpy of formation , analytical chemistry (journal) , organic chemistry
The electron impact ionization efficiency curves for the parent ions and the [C 7 H 7 ] + fragment ion formed from monosubstituted alkyl benzenes (RCH 3 n ‐C 3 H 7 ) have been studied by applying the inverse convolution technique of Vogt and Pascual to the first derivative ionization efficiency curves of the ions. Ionization and appearance energies measured for the ions at threshold are in good agreement with recently published photoionization values. Structures in the ionization efficiency curves (higher energy processes) are also reported for about 4 e V above threshold. The heats of formation calculated for [C 7 H 7 ] + fragment ions obtained from toluene and ethyl benzene at threshold are equal to 864 and 865 kJ mol −1 respectively, and are consistent with the tropylium structure. However, for the [C 7 H 7 ] + fragment ion obtained from n ‐propyl benzene at threshold the calculated heat of formation is equal to 923 kJ mol −1 and probably corresponds to a benzyl structure.