ダイアゾアルカンにおけるN-N結合の割れは,ビス・イミノ・ピリジン・鉄複合体によるものです
Sarah K Russell1, Emil Lobkovsky, Paul J Chirik
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|January 9, 2009
まとめ
鉄二酸化窒素複合体は,ダイアゾアルカンと反応してN-N結合を裂き,鉄ニトリルおよびイミン複合体を形成する. この反応は,鉄アルキリデン中間体と [4pi + 2pi] サイクル添加経路を経由して進行します.
科学分野:
- 有機金属化学 有機金属化学
- 協調化化学について
- 窒素固定に関する研究
背景:
- ビスミノピリジンリガンドは,反応性鉄複合体の安定化に不可欠です.
- 鉄複合体は,貴金属の代替品として,触媒処理で研究されています.
- 調整された二酸化窒素 (N2) の反応性は,窒素固定の鍵です.
研究 の 目的:
- ビス・イミノ・ピリジンの鉄二酸化窒素複合体と単位置換ダイアゾアルカンとの反応を研究する.
- 鉄二酸化窒素複合体におけるN-N結合分裂のメカニズムを解明する.
- 新しい鉄複合体を生成するためのこの反応の合成的有用性を探求する.
主な方法:
- ((iPr) PDI) Fe (((N2) 2が様々な単位置換ダイアゾアルカン (N2CHR) と反応する.
- ベンゼン-d6で23°Cで光譜分析 (NMR) を行う.
- 運動分析と中間捕獲 (暗示) を含むメカニズム研究.
主要な成果:
- N-N結合の急速な割れは,ダイアゾアルカネを添加すると発生した.
- 鉄ニトリル (((iPr) PDI) FeNCR) とイミン (((iPr) PDI) FeHNCHR) 複合体の形成.
- アリルアジンも割れ,同じ製品が得られました.
- 機械学的研究は,鉄アルキリデンと [4pi + 2pi] サイクル添加を含む経路を示した.
結論:
- モノ置換ダイアゾアルケンは,鉄二酸化窒素複合体のN-N結合を効果的に裂く.
- 反応は,サイクル添加と水素移動を含む複雑なメカニズムを通過します.
- これは,二酸化窒素前駆体から鉄ニトリルおよびイミン複合体への合成経路を提供します.
関連する概念動画
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
Oxidation of Phenols to Quinones
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...


