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Substituent Effects in Chain‐Breaking Aryltellurophenol Antioxidants
Author(s) -
Poon Jiafei,
Yan Jiajie,
Jorner Kjell,
Ottosson Henrik,
Donau Carsten,
Singh Vijay P.,
Gates Paul J.,
Engman Lars
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201704811
Subject(s) - chemistry , substituent , radical , dissociation (chemistry) , thiol , photochemistry , antioxidant , aqueous solution , molecule , aqueous two phase system , quenching (fluorescence) , organic chemistry , medicinal chemistry , fluorescence , physics , quantum mechanics
2‐Aryltellurophenols substituted in the aryltelluro or phenolic parts of the molecule were prepared by lithiation of the corresponding tetrahydropyran‐protected 2‐bromophenol, followed by reaction with a suitable diaryl ditelluride then deprotection. In a two‐phase system containing N ‐acetylcysteine as a co‐antioxidant in the aqueous phase, all of the compounds quenched lipid peroxyl radicals more efficiently than α‐tocopherol, with three to five‐fold longer inhibition times. Thus, these compounds offer better and longer‐lasting antioxidant protection than recently prepared alkyltellurophenols. Compounds with electron‐donating para substituents in the aryltelluro or phenolic part of the molecule showed the best results. The mechanism for quenching peroxyl radicals was considered and discussed with respect to the calculated O−H bond‐dissociation energies, deuterium‐labelling experiments and studies of thiol consumption in the aqueous phase.