アニリンとニトロアロマティックからアロマティックアゾ化合物の金触媒合成
Abdessamad Grirrane1, Avelino Corma, Hermenegildo García
1Instituto de Tecnología Química, Consejo Superior de Investigaciones (CSIC), Universidad Politécnica de Valencia, 46022-Valencia, Spain.
Science (New York, N.Y.)
|December 17, 2008
まとめ
金ナノ粒子は,アニリンとニトロアロマティックからアロマティックアゾ化合物の効率的な合成を触媒化する. この緑色化学のアプローチは,苛酷な反応剤を避け,穏やかな条件下でも高い収量を提供します.
科学分野:
- カタリシス カタリシス カタリシス
- グリーン・ケミストリー (Green Chemistry)
- マテリアルサイエンス 材料科学
背景:
- 芳香性アゾ化合物の伝統的な合成は,しばしば,移行金属や窒素酸塩のようなステキオメトリック,環境有害な反応剤に依存しています.
- アゾ化合物の合成のための持続可能で効率的な触媒方法の開発は,産業用アプリケーションにとって極めて重要です.
研究 の 目的:
- アロマティックアゾ化合物の選択的形成のための新しい触媒システムを開発する.
- 金のナノ粒子の金属酸化物への使用は,エアロビック酸化と還元結合反応のための金属酸化物サポートを探求する.
主な方法:
- タイタン酸化物 (TiO2) とナノ粒子化されたセリウム酸化物 (CeO2) をサポートした金のナノ粒子を使用しています.
- アロマティックアニリンのアゾ化合物へのエアロビック酸化を調査.
- TiO2に黄金を用いて,アゾ化合物に対するニトロアロマティックを二段階,一鍋の還元結合で試験する.
主要な成果:
- アニリンのエアロビック酸化による芳香性アゾ化合物の98%を超える収量を達成しました.
- 軽度な反応条件下で高い触媒効率を証明した.
- シンメトリックなアロマティックアゾ化合物と非シンメトリックなアロマティックアゾ化合物を合成し,その方法の汎用性を示しました.
結論:
- TiO2とCeO2の金ナノ粒子は,芳香アゾ化合物の合成のための非常に効率的で環境に優しい触媒経路を提供します.
- 開発された触媒システムは,伝統的な方法に対する持続可能な代替手段を提供し,産業規模拡大の可能性があります.
- このアプローチは,アニリンやニトロアロマティックなどの容易に入手可能な前駆体からアゾ化合物の直接合成を可能にします.
関連する概念動画
01:22Preparation of 1° Amines: Azide Synthesis
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
01:29Preparation of Amines: Reduction of Oximes and Nitro Compounds
Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
01:28Preparation of 1° Amines: Gabriel Synthesis
Direct alkylation is not a suitable method for synthesizing amines because it produces polyalkylated products. Gabriel synthesis is the most preferred method to exclusively make primary amines. The method uses phthalimide, which contains a protected form of nitrogen that participates in alkylation only once to predominantly give primary amines.
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
01:14Nucleophilic 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...
01:20Diazonium 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...
01:11Aryldiazonium 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.