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Updated: May 26, 2025

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes

Published on: December 16, 2019

三重基底状態のベンゼンダイアニオンの合成と安定化

Yi Wang¹, Rong Sun¹, Jiefeng Liang¹

¹Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.

Journal of the American Chemical Society

|February 22, 2025

まとめ

研究者たちは難解な三重ベンゼンダイアニオンを分離しその予測された芳香性を確認しましたこの突破は,エウロピウム複合体を用いて達成され,磁気結合によってトリプレット状態を安定させ,スピン化学の新たな道を開きます.

科学分野:

有機金属化学
アロマティック性研究
スピン化学

背景:

ベアードの法則は三重ベンゼンダイアニオンの芳香性を予測する.
Jahn-Tellerの歪みは歴史的にその孤立を防ぐことができました.
異常な電子状態を安定化することは,依然として重要な課題です.

研究の目的:

トリプルベンゼンダイアニオンを分離し,特徴づけること.
三重の基本状態を安定させる要因を明らかにする.
スピンの調節におけるランタニドイオンの役割を調査する.

主な方法:

逆サンドイッチエウロピウムベンゼン複合体の合成
磁気結合の研究を含む実験的特徴づけ
電子構造とスピン状態を理解するための理論的計算.

主要な成果:

エウロピウム複合体における三重ベンゼンダイアニオンの成功分離
トリプル状態を安定させる強力な反鉄磁気結合の実証
スピンの状態に影響を与える重要な要因として,スピン-スピンの相互作用と局所的対称性を特定する.

結論:

長い間探していた三重ベンゼンダイアニオンが分離され,バード芳香性を確認しました.
ランタニドイオン,特にユーロピウムは,異常なスピン状態を安定させるのに有効です.
この研究は,分子特性を制御するためのスピン調節の洞察を提供します.

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Frost Circles for Different Conjugated Systems

Frost Circles for Different Conjugated Systems

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Electrophilic Aromatic Substitution: Sulfonation of Benzene

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According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).

Structure of Benzene: Kekulé Model

Structure of Benzene: Kekulé Model

In 1865, August Kekule suggested the structure of benzene according to the structural theory of organic chemistry based on the three assertions—formula of benzene is C6H6, all the hydrogens of benzene are equivalent, and each carbon must have four bonds due to its tetravalency.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.

Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

Chlorination and bromination are important classes of electrophilic aromatic substitutions, where benzene reacts with chlorine or bromine in the presence of a Lewis acid catalyst to give halogenated substitution products. A Lewis acid such as aluminium chloride or ferric chloride catalyzes the chlorination, and ferric bromide catalyzes the bromination reactions. During the bromination of alkenes, bromine polarizes and becomes electrophilic. However, in the bromination of benzene, the bromine...

NMR Spectroscopy of Benzene Derivatives

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Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm in the 1H NMR spectrum. The observed shift is far downfield because the aromatic ring current strongly deshields the protons. Any substitution on the benzene ring makes the aromatic protons nonequivalent, and the protons split each other. The peak is, therefore, no longer a singlet and the splitting pattern and their associated coupling...