5-Methyl-dihydro-furan-2-ylidene-oxonium | 140843-82-9

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 氧唑烯
• 英文名称: 5-Methyl-dihydro-furan-2-ylidene-oxonium
• 英文别名: (5-methyloxolan-2-ylidene)oxidanium
• CAS: 140843-82-9
• 化学式: C₅H₉O₂
• 分子量: 101.125
• InChiKey: GAEKPEKOJKCEMS-UHFFFAOYSA-O

计算性质

• 辛醇/水分配系数(LogP)：
  0.6
• 重原子数：
  7
• 可旋转键数：
  0
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.8
• 拓扑面积：
  10.2
• 氢给体数：
  1
• 氢受体数：
  1

反应信息

• 作为产物：
  描述：

  4-戊烯酸 在 三氟甲磺酸 作用下， 生成 5-Methyl-dihydro-furan-2-ylidene-oxonium
  参考文献：
  名称：

  C5H9O2+ ions: the correlation between their thermochemistry in acidic solution and their chemistry in the gas phase

  摘要：

  Each of a series of C5H8O2 isomeric carboxylic acids and lactones (1-9) was protonated in both concentrated sulfuric acid and trifluoromethanesulfonic acid. The thermally induced transformations of the protonated species were then studied over the temperature range -40 to +160-degrees-C. As a general rule, all the initially generated cations were eventually converted to protonated gamma-valerolactone (1H(O)+) and, finally, to protonated cyclopentenone (10H(O)+). The cations derived from the cyclopropanecarboxylic acids 7 and 8 both underwent ring opening to the unsaturated cation 6H(O)+, which then rearranged to a protonated alpha-lactone. In concentrated sulfuric acid the latter species loses carbon monoxide to afford protonated 2-butanone 11H(O)+. The CIMS spectra of compounds 1-9 were recorded, allowing a correlation between the fragmentation routes in the gas phase and the transformations observed in solution. In this way, the data obtained in strong acids are used to assign reasonable structures to the gas-phase ions.

  DOI：

  10.1021/jo00049a029

文献信息

• Charge inversion under plasma-nanodroplet reaction conditions excludes Fischer esterification for unsaturated fatty acids: a chemical approach for type II isobaric overlap
  作者：Dmytro S. Kulyk、Glib V. Baryshnikov、Purva S. Damale、Simon Maher、Abraham K. Badu-Tawiah

  DOI：10.1039/d3sc05369e

  日期：——

  stabilized cyclic carbonium ion), whose mass is the same as the original protonated unsaturated FA. Therefore, the monoisotopic signal from any saturated FA can be selectively shifted away from the mass-to-charge position where the isobaric interference occurs to enable effective characterization by MS. The mechanism governing the spontaneous intramolecular reactions for unsaturated FAs was validated

  直接输注电离方法为低容量样品的质谱 (MS) 分析提供了最高通量的策略。但这种权衡包括基质效应，这会显着降低分析性能。在此，我们提出了一种新的化学方法来解决特殊类型的基质效应，即 II 型同量异位重叠。我们专注于对基于纳米液滴的酯化化学的详细研究，以区分不饱和脂肪酸 (FA) 引起的同位素异体 [M + 2] 信号与饱和 FA 的单同位素信号。开发的方法涉及非热等离子体与带电纳米液滴的在线融合，从而实现饱和脂肪酸的选择性酯化。我们发现不饱和 FA通过基于碳阳离子中间体的新机制进行自发分子内反应，提供质子化内酯部分（共振稳定的环状碳鎓离子），其质量与原始质子化不饱和 FA 相同。因此，来自任何饱和 FA 的单同位素信号都可以选择性地远离发生同量异位素干扰的质荷位置，从而能够通过 MS 进行有效表征。通过 DFT 计算、标准实验和同位素标记验证了控制不饱和 FA 自发分子内反应的机制。通过超快