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The substituent effect on the single and double hydrogen atom transfer reactions in para ‐substituted benzoic acid isobutyl esters
Author(s) -
Tobita Seiji,
Tajima Susumu,
Tsuchiya Toshikazu
Publication year - 1984
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.1210190707
Subject(s) - chemistry , hydrogen atom , substituent , benzoic acid , hydrogen , ion , electron transfer , photochemistry , atom (system on chip) , medicinal chemistry , organic chemistry , alkyl , computer science , embedded system
Abstract The substituent effect on the single and double hydrogen atom transfer reactions in para ‐substituted benzoic acid isobutyl esters has been investigated by electron impact mass spectrometry. Electron‐donating substituents favour formation of the [MC 4 H 8 ] + ˙ ion generated by single hydrogen atom transfer reaction (McLafferty rearrangement), whereas electron‐withdrawing substituents favour formation of the [MC 4 H 7 ] + ion generated by double hydrogen atom transfer reaction. In the case of the latter compounds, the m / z 56 ([C 4 H 8 ] + ˙) ion, which is generated by single hydrogen atom transfer reaction with charge migration, is very intense, while in the former compounds, the m / z 56 ion is very weak. These observations can be reasonably explained on thermochemical grounds based on the sum of the standard heats of formation of the fragments.