2,2,6,6-Tetramethyl-4-oxo-piperidyl-radikal | 38951-80-3

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 哌啶类
• 英文名称: 2,2,6,6-Tetramethyl-4-oxo-piperidyl-radikal
• CAS: 38951-80-3
• 化学式: C₉H₁₆NO
• 分子量: 154.232
• InChiKey: TZTCHDTXXNFICW-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  0.5
• 重原子数：
  11
• 可旋转键数：
  0
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.89
• 拓扑面积：
  18.1
• 氢给体数：
  0
• 氢受体数：
  1

反应信息

• 作为产物：
  描述：

  四甲基哌啶酮 、 二苯甲酮 以 苯 为溶剂， 生成 2,2,6,6-Tetramethyl-4-oxo-piperidyl-radikal 、 羟基-二苯基-甲基
  参考文献：
  名称：

  One-Electron Oxidation of Sterically Hindered Amines to Nitroxyl Radicals:  Intermediate Amine Radical Cations, Aminyl, α-Aminoalkyl, and Aminylperoxyl Radicals

  摘要：

  Sterically hindered amines (2,2,6,6-tetramethyl-substituted piperidines) are easily oxidized (i) by electron transfer to parent cations in n-butyl chloride solution, (ii) by the sulfate radical anion in aqueous solution, and (iii) by sensitized electron transfer to carbonyl triplets. In nonpolar surroundings in the nanosecond time range, the radical cations of the tertiary piperidines have been directly observed by optical spectroscopy to exhibit absorption maxima below lambda = 300 nm and; around 550 nm. Subsequently, they deprotonate to alpha-alkylamine radicals, which are also the first observable products of oxidation with sulfate radical anions in water. In the case of secondary piperidines, the amine radical cations deprotonate to aminyl radicals in times < 10 ns. The triplet-sensitized electron transfer to the benzophenone as well as cyclohexanone triplet results in amine-derived and ketyl-type radicals formed at a nearly diffusion-controlled rate, which suggests an electron- and subsequent proton-transfer mechanism. In the presence. of oxygen, the amine-derived radicals are oxidized to nitroxyl radicals by different pathways for secondary and tertiary piperidines. For the reaction of the nitroxyl radicals with other radicals, rate constants are found to be quite similar (about 5 x 10(8) M-1 s(-1)) for several alkyl radicals and for the tert-butyloxyl radical and less than 10(5) M-1 s(-1) for alkylperoxyl radicals. Because of the minor importance of radical reactions with the sterically hindered amines (HALS), the antioxidant effect of these compounds ought to be explained by oxidation, primarily via cationic and subsequently radical intermediates to the persistent nitroxyl radicals, which scavenge other radicals very efficiently.

  DOI：

  10.1021/jp980089j

文献信息

• One-Electron Oxidation of Sterically Hindered Amines to Nitroxyl Radicals:  Intermediate Amine Radical Cations, Aminyl, α-Aminoalkyl, and Aminylperoxyl Radicals
  作者：O. Brede、D. Beckert、C. Windolph、H. A. Göttinger

  DOI：10.1021/jp980089j

  日期：1998.2.1

  Sterically hindered amines (2,2,6,6-tetramethyl-substituted piperidines) are easily oxidized (i) by electron transfer to parent cations in n-butyl chloride solution, (ii) by the sulfate radical anion in aqueous solution, and (iii) by sensitized electron transfer to carbonyl triplets. In nonpolar surroundings in the nanosecond time range, the radical cations of the tertiary piperidines have been directly observed by optical spectroscopy to exhibit absorption maxima below lambda = 300 nm and; around 550 nm. Subsequently, they deprotonate to alpha-alkylamine radicals, which are also the first observable products of oxidation with sulfate radical anions in water. In the case of secondary piperidines, the amine radical cations deprotonate to aminyl radicals in times < 10 ns. The triplet-sensitized electron transfer to the benzophenone as well as cyclohexanone triplet results in amine-derived and ketyl-type radicals formed at a nearly diffusion-controlled rate, which suggests an electron- and subsequent proton-transfer mechanism. In the presence. of oxygen, the amine-derived radicals are oxidized to nitroxyl radicals by different pathways for secondary and tertiary piperidines. For the reaction of the nitroxyl radicals with other radicals, rate constants are found to be quite similar (about 5 x 10(8) M-1 s(-1)) for several alkyl radicals and for the tert-butyloxyl radical and less than 10(5) M-1 s(-1) for alkylperoxyl radicals. Because of the minor importance of radical reactions with the sterically hindered amines (HALS), the antioxidant effect of these compounds ought to be explained by oxidation, primarily via cationic and subsequently radical intermediates to the persistent nitroxyl radicals, which scavenge other radicals very efficiently.