Substituent Effects in Chain‐Breaking Aryltellurophenol Antioxidants

• Published in: Chemistry : a European journal Vol. 24; no. 14; pp. 3520 - 3527
• Main Authors: Poon, Jia‐fei, Yan, Jiajie, Jorner, Kjell, Ottosson, Henrik, Donau, Carsten, Singh, Vijay P., Gates, Paul J., Engman, Lars
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 07.03.2018; Wiley Subscription Services, Inc
• Subjects: Acetylcysteine; Antioxidants; aryltellurophenols; Chemistry; Chemistry with specialization in Organic Chemistry; Chemistry, Multidisciplinary; Deuterium; Hydrogen bonds; Kemi med inriktning mot organisk kemi; Labeling; lipid peroxidation; Peroxyl radicals; Phenolic compounds; Phenols; Physical Sciences; Radicals; Science & Technology; substituent effects; tellurium; Tocopherol; TOCOPHEROL; antioxidants; aryltellurophenols; AUTOXIDATION; KINETICS; tellurium; REACTIVITY; substituent effects; lipid peroxidation; DERIVATIVES; KEY; chain-breaking antioxidant aryltellurophenol lipid peroxidation substituent effect BDE-OH
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.201704811

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. Make a change: Aryltellurophenols outperform α‐tocopherol in catalytic trapping of lipid peroxyl radicals in a two‐phase system. Compounds with electron‐donating substituents in the aryltelluro or phenolic part of the molecule (see figure) showed the best results.