| 126526-50-9

• 分子结构分类: 有机化合物 - 有机酸及其衍生物 - 羧酸及其衍生物
• CAS: 126526-50-9
• 化学式: C₇H₁₁F₃O₂
• 分子量: 187.135
• InChiKey: IHMOIZUAENUCFQ-HPRDVNIFSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  2.14
• 重原子数：
  12.0
• 可旋转键数：
  3.0
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.86
• 拓扑面积：
  26.3
• 氢给体数：
  0.0
• 氢受体数：
  2.0

反应信息

• 作为产物：
  描述：

  3-Methyl-2-butanol-1,1,1-d3 、 三氟乙酸酐 在 吡啶 作用下， 生成
  参考文献：
  名称：

  Fragmentation processes of methylbutyl trifluoroacetates studied by tandem quadrupole mass spectrometry and isotope labeling

  摘要：

  AbstractThe fragmentation patterns of 3‐methyl‐2‐butyl trifluoroacetate and 2‐methyl‐2‐butyl trifluoroacetate were investigated by GC/MS/MS, with electron impact and collision‐induced dissociation, on regular and isotope‐labeled (deuterium and 18O) esters. The atoms found in various fragments could be traced back to specific positions in the parent molecules. In this way, molecular rearrangements potentially occurring during the formation of esters by trifluoroacetolysis of 3‐methyl‐2‐butyl p‐toluenesulfonate or trifluoroacetic acid addition to various 2‐methylbutenes could be shown. Rearrangements also occurred during the fragmentation, particularly during the expulsion of the small fragments CO, C2H4 and F2CO. For the decompositions of oxygen‐containing ions these rearrangements were highly specific. By contrast, alkyl cations lead to fragments that are fully scrambled (statistical label distribution). Alkene radical cations ([CnH2n]+ ˙) fragment to daughter ions that are extensively, but less than statistically scrambled. Hydrogen scrambling may also occur in fluoroalkyl cation fragments.

  DOI：

  10.1002/oms.1210240906

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.