以4-氨基-2,2,6,6-四甲基哌啶为初始反应物,先通过Clauson-Kaas反应合成4-吡咯-2,2,6,6-四甲基哌啶(PyTEMP),接着经由3-氯过氧苯甲酸氧化得到电化学活性的4-吡咯-2,2,6,6-四甲基哌啶氮氧化物(PyTEMPO)。核磁共振氢谱和红外光谱证实了PyTEMPO的化学结构。循环伏安测试结果揭示PyTEMPO在水溶液中的氧化还原反应的平衡电位(E0)为0.75V(vs.SHE),与pH无关。动力学研究显示在5个不同支持电解质中,PyTEMPO在Na2SO4溶液中的电子传递速率常数最高,为3.58×10-4cm/s。此外,在NaCl中的电化学稳定性最高,经100次循环伏安(CV)循环后峰电流保持率约为93.0%。
4-Pyrrolyl-2,2,6,6-tetramethylpiperidine (PyTEMP) was firstly synthesized by Clauson Kaas reaction with 4-amino-2,2,6,6-tetramethylpiperidine as the initial reactant,and 4-pyrrolyl-2,2,6,6-tetramethylpiperidine-l-oxyl (PyTEMPO) was then obtained by an oxidation reaction using 3-chloroperoxybenzoic acid as the oxidizer.The chemical structure of PyTEMPO was confirmed by 1H NMR and FT-IR spectra.The cyclic voltammetry results showed that the equilibrium potential (E0) of PyTEMPO in aqueous solution was 0.75V (vs.SHE),and independent of pH.The kinetic studies indicated that PyTEMPO possessed a highest electron transfer rate constant (k0) in Na2SO4,which was about 3.58×10-4cm/s.In addition,PyTEMPO displayed the highest electrochemical stability in NaCl with the peak current retention rate of 93.0% after 100 CV cycles.
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