3-Methyl-2-butyl-p-toluolsulfonat-1,1,1-d3

• 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: 3-Methyl-2-butyl-p-toluolsulfonat-1,1,1-d3
• 英文别名: (1,1,1-Trideuterio-3-methylbutan-2-yl) 4-methylbenzenesulfonate
• 化学式: C₁₂H₁₈O₃S
• 分子量: 245.315
• InChiKey: YFRJBSSHABTVOA-GKOSEXJESA-N

计算性质

• 辛醇/水分配系数(LogP)：
  3.3
• 重原子数：
  16
• 可旋转键数：
  4
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.5
• 拓扑面积：
  51.8
• 氢给体数：
  0
• 氢受体数：
  3

反应信息

• 作为产物：
  描述：

  3-Methyl-2-butanol-1,1,1-d3 、 对甲苯磺酰氯 在 吡啶 作用下， 生成 3-Methyl-2-butyl-p-toluolsulfonat-1,1,1-d3
  参考文献：
  名称：

  Secondary and tertiary 2-methylbutyl cations. 1. Trifluoroacetolysis of 3-methyl-2-butyl tosylate

  摘要：

  Trifluoroacetolysis rates for 3-methyl-2-butyl tosylate (4) and kinetic isotope effects st C(1) (k(H)/k(D) = 1.083 per H atom), C(2) (k(H)/k(D) = 1.10), and C(3) (k(H)/k(D) = 1.32) were determined. The products are 2-methyl-2-butyl trifluoroacetate (5, 98.5%) and 3-methyl-2-butyl trifluoroacetate (6, 1.5%). GC-MS analysis of products from labeled tosylates 4-1-d(3) and 4-2-d showed that 42% of the apparently unrearranged 6 had a methyl group shifted from the original C(3) to the original C(2), whereas 3.6% methyl shift occurred in 5. The results do not substantiate a k(s)-k(Delta) competition mechanism. Instead, two carbocations, the tertiary 2-methyl-2-butyl (1) and the nominally secondary 3-methyl-2-butyl (2) intervene. The intimate structure of 2 is not established, but a symmetrical, methyl-bridged ion (3) does not agree with the results. A high beta isotope effect does not require hydrogen assistance to ionization; ionization concerted with (assisted by) hydrogen migration is unimportant in formation of 1 (and 5) from 4. Instead, the reaction involves reversible formation of an intimate ion pair with subsequent rate-determining H shift (which for 2.OTs- is in competition with Me shift and ca. 25% elimination) followed by solvent capture. Methyl migration in 2 may occur in the solvent-separated ion pair; alternatively, methyl or hydrogen migration is conformationally determined. At least 9% of 1 is formed from 2 which has undergone methyl shift. Nucleophilic attack an 4 appears important only in strongly nucleophilic media like aqueous ethanol. The claim that nucleophilic solvent assistance is significant in solvolysis of other secondary alkyl substrates in TFA or 97% hexafluoro-2-propanol is evaluated. Such a conclusion cannot be accepted on the basis of rate correlations alone, (i.e without product studies to support it). The implications of our results for the trifluoroacetolysis of 2-butyl tosylate are briefly discussed.

  DOI：

  10.1021/jo00080a025

文献信息

• Secondary and tertiary 2-methylbutyl cations. 1. Trifluoroacetolysis of 3-methyl-2-butyl tosylate
  作者：Dan Farcasiu、Gaye Marino、J. Milton Harris、Bruce A. Hovanes、Chang S. Hsu

  DOI：10.1021/jo00080a025

  日期：1994.1

  Trifluoroacetolysis rates for 3-methyl-2-butyl tosylate (4) and kinetic isotope effects st C(1) (k(H)/k(D) = 1.083 per H atom), C(2) (k(H)/k(D) = 1.10), and C(3) (k(H)/k(D) = 1.32) were determined. The products are 2-methyl-2-butyl trifluoroacetate (5, 98.5%) and 3-methyl-2-butyl trifluoroacetate (6, 1.5%). GC-MS analysis of products from labeled tosylates 4-1-d(3) and 4-2-d showed that 42% of the apparently unrearranged 6 had a methyl group shifted from the original C(3) to the original C(2), whereas 3.6% methyl shift occurred in 5. The results do not substantiate a k(s)-k(Delta) competition mechanism. Instead, two carbocations, the tertiary 2-methyl-2-butyl (1) and the nominally secondary 3-methyl-2-butyl (2) intervene. The intimate structure of 2 is not established, but a symmetrical, methyl-bridged ion (3) does not agree with the results. A high beta isotope effect does not require hydrogen assistance to ionization; ionization concerted with (assisted by) hydrogen migration is unimportant in formation of 1 (and 5) from 4. Instead, the reaction involves reversible formation of an intimate ion pair with subsequent rate-determining H shift (which for 2.OTs- is in competition with Me shift and ca. 25% elimination) followed by solvent capture. Methyl migration in 2 may occur in the solvent-separated ion pair; alternatively, methyl or hydrogen migration is conformationally determined. At least 9% of 1 is formed from 2 which has undergone methyl shift. Nucleophilic attack an 4 appears important only in strongly nucleophilic media like aqueous ethanol. The claim that nucleophilic solvent assistance is significant in solvolysis of other secondary alkyl substrates in TFA or 97% hexafluoro-2-propanol is evaluated. Such a conclusion cannot be accepted on the basis of rate correlations alone, (i.e without product studies to support it). The implications of our results for the trifluoroacetolysis of 2-butyl tosylate are briefly discussed.