使用者:ItMarki/二乙炔基苯二陰離子

ItMarki/二乙炔基苯二陰離子
識別
CAS號
SMILES	[C-]#Cc0ccccc0C#[C-]（鄰） [C-]#Cc0cccc(c0)C#[C-]（偏） [C-]#Cc1ccc(cc1)C#[C-]（對）
性質
化學式	C10H4
摩爾質量	124.14 g·mol−1
若非註明，所有數據均出自標準狀態（25 ℃，100 kPa）下。

在有機化學中，二乙炔基苯二陰離子是一種陰離子，其結構為與兩個乙炔基鏈接的苯環。它的化學式為C
6H
4C2−
4，有三種結構異構：

• 鄰二乙炔基苯二陰離子
• 偏二乙炔基苯二陰離子
• 對二乙炔基苯二陰離子

這三種陰離子的氣態有理論價值。他們都由苯二丙炔酸通過質譜法的脫羧反應製成。它們是已知最強的三種超強鹽基，其中鄰異構體嘴強，其質子親和能為1,843.987 kJ/mol（440.723 kcal/mol）。偏異構體次之，對異構體又次之。

觀察結果

這些二陰離子在線型四極離子阱質譜儀中生產。對二羧酸前體作電噴霧電離（ESI）會使其失去兩個電子，生成二羧酸根二陰離子[C
6H
4(C
3O
2)
2]²⁻，在質譜儀中的荷質比（m/z）為106。對這個二陰離子進行碰撞誘導解離（CID）後，它會失去兩個二氧化碳分子，生成二乙炔基二陰離子[C
6H
4(C
2)
2]²⁻（m/z = 62）。鄰異構體的反應如下所示，而其他異構體按照原本二羧酸的異構體遵循類似的過程：

由o-二丙炔酸前體製備o-二乙炔基苯二陰離子

Reactions

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.

Basicity

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）. 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

• Lithium monoxide anion