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Kinetic and thermodynamic effects on intramolecular aromatic substitution in meta and para substituted benzalacetones
Author(s) -
Schaldach Bernd,
Grotemeyer Barbara,
Grotemeyer Jürgen,
Grützmacher HansFriedrich
Publication year - 1981
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.1210160911
Subject(s) - intramolecular force , substituent , chemistry , substitution (logic) , kinetic energy , electrophilic aromatic substitution , computational chemistry , substitution reaction , aromaticity , medicinal chemistry , stereochemistry , organic chemistry , molecule , physics , quantum mechanics , computer science , programming language
meta and para substituted benzalacetones lose the substituents after electron impact in a multi‐step intramolecular aromatic substitution. The differences in the relative abundances of the benzopyrylium ions thus formed are not determined by the activation energies for the substituent losses but depend on a delicate balance between the thermodynamic stability of the intermediates involved and the rates of several H‐shifts within the intermediates (kinetic stability). The consequences for the analytical utility of intramolecular aromatic substitution are discussed briefly.