User:ItMarki/二乙炔基苯二阴离子

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ItMarki/二乙炔基苯二阴离子
识别
CAS号
SMILES
 
  • [C-]#Cc0ccccc0C#[C-]（邻）
    [C-]#Cc0cccc(c0)C#[C-]（偏）
    [C-]#Cc1ccc(cc1)C#[C-]（对）
性质
化学式 C10H4
摩尔质量 124.14 g·mol−1
若非注明，所有数据均出自标准状态（25 ℃，100 kPa）下。

在有机化学中，二乙炔基苯二阴离子是一种阴离子，其结构为与两个乙炔基链接的苯环。它的化学式为C
6H
4C2−
4，有三种结构异构：

  • 邻二乙炔基苯二阴离子
  • 偏二乙炔基苯二阴离子
  • 对二乙炔基苯二阴离子

这三种阴离子的气态有理论价值。他们都由苯二丙炔酸通过质谱法的脱羧反应制成。[1][2]它们是已知最强的三种超強鹽基，其中邻异构体嘴强，其质子亲和能为1,843.987 kJ/mol（440.723 kcal/mol）。[1]偏异构体次之，对异构体又次之。

观察结果[编辑]

这些二阴离子在线型四极离子阱质谱仪中生产。对二羧酸前体作电喷雾电离（英语：Electrospray ionization）（ESI）会使其失去两个电子，生成二羧酸根二阴离子[C
6H
4(C
3O
2)
2]2−，在质谱仪中的荷质比（m/z）为106。对这个二阴离子进行碰撞诱导解离（英语：collision-induced dissociation）（CID）后，它会失去两个二氧化碳分子，生成二乙炔基二阴离子[C
6H
4(C
2)
2]2−（m/z = 62）。邻异构体的反应如下所示，而其他异构体按照原本二羧酸的异构体遵循类似的过程：

由o-二丙炔酸前体制备o-二乙炔基苯二阴离子

Reactions[编辑]

Reactions of the gas-phase dianions were studied by reacting with a small quantity of various reagents added to the helium carrier gas in the spectrometer. For example, reaction with deuterium oxide (heavy water) produced the singly-deuterated monoanion C6H4(C2D)(C−
2) identified as m/z = 126. Reaction with benzene produced the phenyl anion (m/z = 77) highlighting the extreme basicity of the dianion. Attempted reaction with deuterium gas and deuterated methane was not successful despite the favourable thermodynamics; the authors attribute this to the high activation barrier for proton abstraction from those substrates.[1]

Basicity[编辑]

All three isomers are superbasic. According to calculations, ortho-diethynylbenzene dianion is the strongest superbase and has a proton affinity of 1,843.987 kJ/mol（440.723 kcal/mol）.[1] The meta isomer is the second-strongest, and the para isomer is the third. All three are readily able to accept any proton to its ethynyl tails, from almost any compound. All three isomers function as superbases better than helonium does as a superacid.

See also[编辑]

References[编辑]

  1. ^ 1.0 1.1 1.2 1.3 Poad, Berwyck L. J.; Reed, Nicholas D.; Hansen, Christopher S.; Trevitt, Adam J.; Blanksby, Stephen J.; Mackay, Emily G.; Sherburn, Michael S.; Chan, Bun; Radom, Leo. Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion. Chemical Science. 12 January 2018, 7 (9): 6245–6250. PMC 6024202 可免费查阅. PMID 30034765. doi:10.1039/C6SC01726F. 
  2. ^ Bergius, Will. Basically record breaking. Chemistry World. 19 July 2016. 
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