Williams Leodrina L, Webster Richard D
Research School of Chemistry, Australian National University, Canberra ACT 0200, Australia.
J Am Chem Soc. 2004 Oct 6;126(39):12441-50. doi: 10.1021/ja046648j.
Alpha-tocopherol (alpha-TOH) can be electrochemically oxidized in CH(3)CN containing Bu(4)NPF(6) in a chemically reversible two-electron/one-proton (ECE) process to form the phenoxonium cation (alpha-TO(+)) that is stable for at least several hours at 243 K. In the presence of up to approximately 1% CF(3)SO(3)H, alpha-TO(+) exists in equilibrium with the alpha-tocopherol cation radical (alpha-TOH(+)()), whereas at concentrations between approximately 1-3% CF(3)SO(3)H the electrochemical oxidation of alpha-TOH occurs by close to one-electron to form alpha-TOH(+)().alpha-TOH(+)(*) can be further oxidized in a one-electron process to form the alpha-tocopherol dication (alpha-TOH(2+)). The identity and stability of the phenolic cationic compounds were determined by a combination of electrochemical (cyclic voltammetry and controlled potential electrolysis) and in situ spectroscopic (UV-vis-NIR, FTIR, EPR, and NMR) analysis.
α-生育酚（α-TOH）在含有四丁基六氟磷酸铵（Bu(4)NPF(6)）的乙腈（CH(3)CN）中可通过化学可逆的双电子/单质子（ECE）过程进行电化学氧化，形成苯氧鎓阳离子（α-TO(+)），该阳离子在243 K下至少可稳定存在数小时。在存在高达约1%的三氟甲磺酸（CF(3)SO(3)H）时，α-TO(+)与α-生育酚阳离子自由基（α-TOH(+)()）处于平衡状态，而在约1 - 3% CF(3)SO(3)H的浓度范围内，α-TOH的电化学氧化通过近单电子过程发生，形成α-TOH(+)()。α-TOH(+)(*)可通过单电子过程进一步氧化形成α-生育酚二价阳离子（α-TOH(2+)）。酚类阳离子化合物的特性和稳定性通过电化学（循环伏安法和控制电位电解）和原位光谱（紫外可见近红外光谱、傅里叶变换红外光谱、电子顺磁共振光谱和核磁共振光谱）分析相结合的方法来确定。
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