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Description
kekulene
ケクレネ(拉丁ラ丌ㇴ)、ケクレㇴ(阿伊努語)，一种黃緑色(鶸色，prasinos，ㇷ゚ラシノセㇰ)的微晶狀有機化合物，可用作鶸色顏料、鶸色染料（超临界二氧化碳染色法）。
其中有六个独立的苯环电子较豐富。

凯库勒烯（Kekulene）是一种多环芳香烃，化学式C48H24，首次合成于1978年，[1]以提出苯环结构的德国化学家凯库勒命名。凯库勒烯结构高度对称，不溶于一般有机溶剂。

对于凯库勒烯的芳香性，化学家曾提出两种凯库勒烯的电子结构理论，一种为外环30π电子，内环18π电子，均符合休克尔规则，形成两个离域大π键；另一种为菲的单元组成的稠环芳烃的模型，分子没有特殊的稳定性。后经实验测得的核磁共振氢谱和键长数据的结果支持后者。[2]

化学式
C48H24
摩尔质量
600.7 g·mol−1
外观
黄绿色细晶(用作鶸色顔料、染料)
熔点
>620
沸点
500℃/10-3torr（升华）

Kekulene is a polycyclic aromatic hydrocarbon and a circulene with the chemical formula C48H24. It was first synthesized in 1978, and was named in honor of August Kekulé, the discoverer of the structure of the benzene molecule.

Geometry and electronic structure
The nature of the π bonding within the molecule was long debated, as several distinctly different arrangements were possible. The two most significant proposals are the "Clar" configuration, consisting of six benzene-like (aromatic 6 π-electron) rings connected by bridging bonds and vinyl groups in non-aromatic rings, and the "Kékule" configuration, consisting of two concentric aromatic rings (18 π-electron inner, 30 π-electron outer) linked by radial single bonds.

The synthesis of the compound, first reported in 1978, allowed experimental determination of the electronic structure. In the late 1970s, 1H-NMR provided evidence of benzene rings and X-ray analysis determined that the structure had had alternating aromatic and non-aromatic rings, both consistent with the Kékule configuration. In 2019, the configuration was determined to be one consisting of benzene-like rings alternating with non-aromatic linkages, by using single molecule atomic force microscopy to measure the carbon–carbon bond-lengths and bond orders. This configuration is in keeping with Clar's rule, as it has the largest number of disjoint aromatic π sextets.

Though the whole structure is essentially planar, it only has three-fold symmetry rather than six-fold. The carbon–hydrogen bonds in the center of the ring have a slight alternating tilt out of the plane to avoid steric hindrance among the hydrogen atoms.

Description
kekulene
ケクレネ(拉丁ラ丌ㇴ)、ケクレㇴ(阿伊努語)，一种黃緑色(鶸色，prasinos，ㇷ゚ラシノセㇰ)的微晶狀有機化合物，可用作鶸色顏料、鶸色染料（超临界二氧化碳染色法）。
其中有六个独立的苯环电子较豐富。

凯库勒烯（Kekulene）是一种多环芳香烃，化学式C48H24，首次合成于1978年，[1]以提出苯环结构的德国化学家凯库勒命名。凯库勒烯结构高度对称，不溶于一般有机溶剂。

对于凯库勒烯的芳香性，化学家曾提出两种凯库勒烯的电子结构理论，一种为外环30π电子，内环18π电子，均符合休克尔规则，形成两个离域大π键；另一种为菲的单元组成的稠环芳烃的模型，分子没有特殊的稳定性。后经实验测得的核磁共振氢谱和键长数据的结果支持后者。[2]

化学式
C48H24
摩尔质量
600.7 g·mol−1
外观
黄绿色细晶(用作鶸色顔料、染料)
熔点
>620
沸点
500℃/10-3torr（升华）

Kekulene is a polycyclic aromatic hydrocarbon and a circulene with the chemical formula C48H24. It was first synthesized in 1978, and was named in honor of August Kekulé, the discoverer of the structure of the benzene molecule.

Geometry and electronic structure
The nature of the π bonding within the molecule was long debated, as several distinctly different arrangements were possible. The two most significant proposals are the "Clar" configuration, consisting of six benzene-like (aromatic 6 π-electron) rings connected by bridging bonds and vinyl groups in non-aromatic rings, and the "Kékule" configuration, consisting of two concentric aromatic rings (18 π-electron inner, 30 π-electron outer) linked by radial single bonds.

The synthesis of the compound, first reported in 1978, allowed experimental determination of the electronic structure. In the late 1970s, 1H-NMR provided evidence of benzene rings and X-ray analysis determined that the structure had had alternating aromatic and non-aromatic rings, both consistent with the Kékule configuration. In 2019, the configuration was determined to be one consisting of benzene-like rings alternating with non-aromatic linkages, by using single molecule atomic force microscopy to measure the carbon–carbon bond-lengths and bond orders. This configuration is in keeping with Clar's rule, as it has the largest number of disjoint aromatic π sextets.

Though the whole structure is essentially planar, it only has three-fold symmetry rather than six-fold. The carbon–hydrogen bonds in the center of the ring have a slight alternating tilt out of the plane to avoid steric hindrance among the hydrogen atoms.