Long-Lasting Antioxidant Protection: A Regenerable BHA Analogue
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- 作者：Henrik Johansson ; David Shanks ; Lars Engman ; Riccardo Amorati ; Gian Franco Pedulli ; Luca Valgimigli
- 刊名：Journal of Organic Chemistry
- 出版年：2010
- 出版时间：November 19, 2010
- 年：2010
- 卷：75
- 期：22
- 页码：7535-7541
- 全文大小：859K
- 年卷期：v.75,no.22(November 19, 2010)
- ISSN：1520-6904
文摘
Introduction of an octyltelluro group ortho to the phenolic moiety in 3-tert-butyl-4-hydroxyanisole (BHA) was found to significantly improve the antioxidant characteristics of the material. In contrast to BHA and the corresponding ortho-substituted octylthio- (9c) and octylseleno (9b) derivatives, the organotellurium 9a was regenerable when assayed for its capacity to inhibit azo-initiated peroxidation of linoleic acid in a chlorobenzene/water two-phase system containing N-acetylcysteine as a stoichiometric reducing agent, and peroxyl radicals were quenched more efficiently than with α-tocopherol. In the homogeneous phase, inhibition of styrene autoxidation occurred with a rate constant kinh as large as 1 × 107 M−1 s−1 but with a low (n = 0.4) stoichiometric factor. Evans−Polanij plots of log (kinh) versus BDE(O−H), which are usually linear for phenols with similar steric crowding reacting by H-atom transfer, revealed that compound 9a was more than 2 orders of magnitude more reactive than expected. Although further mechanistic investigations are needed, it seems that the ortho-arrangement of an alkyltelluro group and hydroxyl should be considered a privileged structure for phenolic antioxidants.