2-tert-butylsemiquinone radical | 66806-57-3

• 分子结构分类: 有机化合物 - 苯类化合物 - 苯和取代衍生物
• 英文名称: 2-tert-butylsemiquinone radical
• CAS: 66806-57-3
• 化学式: C₁₀H₁₃O₂
• 分子量: 165.212
• InChiKey: LRRVYFBQAFEFFR-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  2.8
• 重原子数：
  12
• 可旋转键数：
  1
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.4
• 拓扑面积：
  21.2
• 氢给体数：
  1
• 氢受体数：
  1

反应信息

• 作为反应物：
  描述：

  2-tert-butylsemiquinone radical 在 2-tert.-Butyl-p-semichinon-radikalanion 作用下， 以 水 为溶剂， 生成 叔丁基对苯醌 、 3-tert-Butyl-4-hydroxy-phenol anion
  参考文献：
  名称：

  Equilibria and Rates of Redox Reactions Involving the 2-tert-Butyl-1,4-benzosemiquinone Radical in Aqueous Solution: An Investigation by Potentiometry, ESR, and Pulse Radiolysis

  摘要：

  Midpoint potentials, E(m) for two-electron reduction of 2-tert-butyl-1,4-benzoquinone (TBQ) were measured in aqueous solution as a function of pH at 22 degrees C and given ionic strength I. From E(m)(pH), the practical pK values, pK'(I), of the corresponding hydroquinone (TBQH(2)) were obtained at given values of I. By use of an empirical Debye-Huckel (D-H) type approximation, the values of pK' were extrapolated to I = 0 for estimating the thermodynamical pK(a) values for acid dissociation of TBQH(2) (pK(a,1) = 10.7 +/- 0.1; pK(a,2) ca. 13.6 +/- 0.2). Optical absorption spectra and molar extinction coefficients of the transient semiquinone radical (TBQH(.) and TBQ(.-)) were obtained by pulse-radiolytic one-electron reduction of TBQ in aqueous solution. The pK(a) of TBQH(.) is 4.3 +/- 0.1 at 22 degrees C in the presence of 2-propanol (2 M) and acetone (0.1 M). Oxidation of TBQH(2) by OH. to eventually give TBQ(.-) has been studied (k(15) = 8 x 10(9) M(-1) s(-1) for formation of the intermediate [(HO)TBQH(2)](.) in aqueous solution at 22 degrees C). The equilibrium for formation of TBQ(.-) from TBQ and TBQH(2) was investigated by ESR (aqueous solution, pH 6.8-9.4, I = 0.12 M). Hyperfine couplings and the g value of TBQ(.-) are given. The apparent semiquinone formation constant at pH i, K'(f,i)(I), was determined as a function of pH (log K'(f,7) = -8.8 +/- 0 1, pH 7) at I = 0.12 M. The pH-independent thermodynamical formation constants, at I = 0, of TBQH(.) from TBQ and TBQH(2) (log K-17 = -14.4 +/- 0.3) and of TBQ(.-) from TBQ and TBQ(2-) (log K-18 = 1.3 +/- 0.4) were determined by use of the above pK(a) values and D-H type approximations. Various other one-electron-transfer reactions involving TBQH(.) or TBQ(.-) have been investigated in detail. The standard potentials, E degrees (at I = 0), for one-electron reduction of TBQ and of TBQH(.) (or TBQ(.-)) have been obtained by combining the two-electron reduction potentials of TBQ and the semiquinone formation constants. Pulse-radiolytic equilibration studies of TBQ with O-2(.-) and of TBQ(2-) with DMAP(.) (DMAP(.) = 4-(dimethylamino)phenoxyl) afforded the redetermination of the thermodynamical standard potential for one-electron reduction of O-2 (E degrees = -0.140 +/- 0.012 V vs NHE for 1 M O-2 in aqueous solution at 22 degrees C and I = 0) and of the midpoint potential of the couple DMAP(.)/DMAP(-), respectively, at pH 13.5 (E(m,13.5) = 0.10 +/- 0.02 V vs NHE at 22 degrees C and I = 0.5 M). The respective rate and equilibrium constants are given. All these results are discussed in terms of substituent and solvent effects as well as in view of the Marcus theory of electron transfer. Another objective of the present study is to contribute to a better understanding of the properties of the synthetic antioxidant 2- or 3-tert-butyl-4-hydroxyanisole (BHA).

  DOI：

  10.1021/j100004a023
• 作为产物：
  描述：

  叔丁基对苯醌 在 特丁基对苯二酚 作用下， 以 水 为溶剂， 生成 2-tert-butylsemiquinone radical
  参考文献：
  名称：

  Equilibria and Rates of Redox Reactions Involving the 2-tert-Butyl-1,4-benzosemiquinone Radical in Aqueous Solution: An Investigation by Potentiometry, ESR, and Pulse Radiolysis

  摘要：

  Midpoint potentials, E(m) for two-electron reduction of 2-tert-butyl-1,4-benzoquinone (TBQ) were measured in aqueous solution as a function of pH at 22 degrees C and given ionic strength I. From E(m)(pH), the practical pK values, pK'(I), of the corresponding hydroquinone (TBQH(2)) were obtained at given values of I. By use of an empirical Debye-Huckel (D-H) type approximation, the values of pK' were extrapolated to I = 0 for estimating the thermodynamical pK(a) values for acid dissociation of TBQH(2) (pK(a,1) = 10.7 +/- 0.1; pK(a,2) ca. 13.6 +/- 0.2). Optical absorption spectra and molar extinction coefficients of the transient semiquinone radical (TBQH(.) and TBQ(.-)) were obtained by pulse-radiolytic one-electron reduction of TBQ in aqueous solution. The pK(a) of TBQH(.) is 4.3 +/- 0.1 at 22 degrees C in the presence of 2-propanol (2 M) and acetone (0.1 M). Oxidation of TBQH(2) by OH. to eventually give TBQ(.-) has been studied (k(15) = 8 x 10(9) M(-1) s(-1) for formation of the intermediate [(HO)TBQH(2)](.) in aqueous solution at 22 degrees C). The equilibrium for formation of TBQ(.-) from TBQ and TBQH(2) was investigated by ESR (aqueous solution, pH 6.8-9.4, I = 0.12 M). Hyperfine couplings and the g value of TBQ(.-) are given. The apparent semiquinone formation constant at pH i, K'(f,i)(I), was determined as a function of pH (log K'(f,7) = -8.8 +/- 0 1, pH 7) at I = 0.12 M. The pH-independent thermodynamical formation constants, at I = 0, of TBQH(.) from TBQ and TBQH(2) (log K-17 = -14.4 +/- 0.3) and of TBQ(.-) from TBQ and TBQ(2-) (log K-18 = 1.3 +/- 0.4) were determined by use of the above pK(a) values and D-H type approximations. Various other one-electron-transfer reactions involving TBQH(.) or TBQ(.-) have been investigated in detail. The standard potentials, E degrees (at I = 0), for one-electron reduction of TBQ and of TBQH(.) (or TBQ(.-)) have been obtained by combining the two-electron reduction potentials of TBQ and the semiquinone formation constants. Pulse-radiolytic equilibration studies of TBQ with O-2(.-) and of TBQ(2-) with DMAP(.) (DMAP(.) = 4-(dimethylamino)phenoxyl) afforded the redetermination of the thermodynamical standard potential for one-electron reduction of O-2 (E degrees = -0.140 +/- 0.012 V vs NHE for 1 M O-2 in aqueous solution at 22 degrees C and I = 0) and of the midpoint potential of the couple DMAP(.)/DMAP(-), respectively, at pH 13.5 (E(m,13.5) = 0.10 +/- 0.02 V vs NHE at 22 degrees C and I = 0.5 M). The respective rate and equilibrium constants are given. All these results are discussed in terms of substituent and solvent effects as well as in view of the Marcus theory of electron transfer. Another objective of the present study is to contribute to a better understanding of the properties of the synthetic antioxidant 2- or 3-tert-butyl-4-hydroxyanisole (BHA).

  DOI：

  10.1021/j100004a023

文献信息

• Myricetin, rosmarinic and carnosic acids as superior natural antioxidant alternatives to α-tocopherol for the preservation of omega-3 oils
  作者：Romain Guitard、Jean-François Paul、Véronique Nardello-Rataj、Jean-Marie Aubry

  DOI：10.1016/j.foodchem.2016.06.038

  日期：2016.12

  transfer, number of radicals scavenged per antioxidant molecule, BDE and formation of antioxidant dimers from the primary radicals play an important role regarding the antioxidant activity of phenols. Based on this, it is finally shown that myricetin, rosmarinic and carnosic acids are more efficient than α-tocopherol and synthetic antioxidants for the preservation of omega-3 oils.

  22种天然多酚与7种合成抗氧化剂（包括BHT，BHA，TBHQ和PG）在保护omega-3油免于自氧化方面的能力进行了比较。使用DPPH评估酚类的抗氧化效率富含omega-3脂肪酸的油的自氧化过程中的测试和耗氧量的测量。同样，计算了Ar-OH键的键解离焓（BDE），并获得了热力学，动力学和氧化数据之间的极佳相关性。结果表明，氢转移的动力学速率，每个抗氧化剂分子清除的自由基数量，BDE以及由初级自由基形成的抗氧化剂二聚体在酚类抗氧化剂活性方面起着重要作用。基于此，最终表明，在保存omega-3油方面，杨梅素，迷迭香酸和肌酸比α-生育酚和合成抗氧化剂更有效。
• Equilibria and Rates of Redox Reactions Involving the 2-tert-Butyl-1,4-benzosemiquinone Radical in Aqueous Solution: An Investigation by Potentiometry, ESR, and Pulse Radiolysis
  作者：Juergen K. Dohrmann、Barbara Bergmann

  DOI：10.1021/j100004a023

  日期：1995.1

  Midpoint potentials, E(m) for two-electron reduction of 2-tert-butyl-1,4-benzoquinone (TBQ) were measured in aqueous solution as a function of pH at 22 degrees C and given ionic strength I. From E(m)(pH), the practical pK values, pK'(I), of the corresponding hydroquinone (TBQH(2)) were obtained at given values of I. By use of an empirical Debye-Huckel (D-H) type approximation, the values of pK' were extrapolated to I = 0 for estimating the thermodynamical pK(a) values for acid dissociation of TBQH(2) (pK(a,1) = 10.7 +/- 0.1; pK(a,2) ca. 13.6 +/- 0.2). Optical absorption spectra and molar extinction coefficients of the transient semiquinone radical (TBQH(.) and TBQ(.-)) were obtained by pulse-radiolytic one-electron reduction of TBQ in aqueous solution. The pK(a) of TBQH(.) is 4.3 +/- 0.1 at 22 degrees C in the presence of 2-propanol (2 M) and acetone (0.1 M). Oxidation of TBQH(2) by OH. to eventually give TBQ(.-) has been studied (k(15) = 8 x 10(9) M(-1) s(-1) for formation of the intermediate [(HO)TBQH(2)](.) in aqueous solution at 22 degrees C). The equilibrium for formation of TBQ(.-) from TBQ and TBQH(2) was investigated by ESR (aqueous solution, pH 6.8-9.4, I = 0.12 M). Hyperfine couplings and the g value of TBQ(.-) are given. The apparent semiquinone formation constant at pH i, K'(f,i)(I), was determined as a function of pH (log K'(f,7) = -8.8 +/- 0 1, pH 7) at I = 0.12 M. The pH-independent thermodynamical formation constants, at I = 0, of TBQH(.) from TBQ and TBQH(2) (log K-17 = -14.4 +/- 0.3) and of TBQ(.-) from TBQ and TBQ(2-) (log K-18 = 1.3 +/- 0.4) were determined by use of the above pK(a) values and D-H type approximations. Various other one-electron-transfer reactions involving TBQH(.) or TBQ(.-) have been investigated in detail. The standard potentials, E degrees (at I = 0), for one-electron reduction of TBQ and of TBQH(.) (or TBQ(.-)) have been obtained by combining the two-electron reduction potentials of TBQ and the semiquinone formation constants. Pulse-radiolytic equilibration studies of TBQ with O-2(.-) and of TBQ(2-) with DMAP(.) (DMAP(.) = 4-(dimethylamino)phenoxyl) afforded the redetermination of the thermodynamical standard potential for one-electron reduction of O-2 (E degrees = -0.140 +/- 0.012 V vs NHE for 1 M O-2 in aqueous solution at 22 degrees C and I = 0) and of the midpoint potential of the couple DMAP(.)/DMAP(-), respectively, at pH 13.5 (E(m,13.5) = 0.10 +/- 0.02 V vs NHE at 22 degrees C and I = 0.5 M). The respective rate and equilibrium constants are given. All these results are discussed in terms of substituent and solvent effects as well as in view of the Marcus theory of electron transfer. Another objective of the present study is to contribute to a better understanding of the properties of the synthetic antioxidant 2- or 3-tert-butyl-4-hydroxyanisole (BHA).