アルミジヒドリドは,ヒドロブレーションと脱水結合における触媒として作用する
Zhi Yang1, Mingdong Zhong1, Xiaoli Ma1
1School of Chemical Engineering and Environment, Beijing Institute of Technology , 100081 Beijing, China.
Journal of the American Chemical Society
|February 11, 2016
まとめ
新しいアルミニウム二水素複合体 (1) は,移行金属のような触媒活性を示しています. それはアルキンの水酸化と,様々な化合物とのボランの脱水結合を効果的に触媒化し,B-E結合を形成する.
科学分野:
- 有機金属化学
- キャタリシス
- メイングループ 化学
背景:
- 移行金属複合体は,触媒で広く使用されています.
- アルミニウム複合体は触媒としてあまり研究されていない.
- アルミジヒドリド複合体の触媒的可能性はほとんど研究されていない.
研究 の 目的:
- アルミジヒドリド複合体LAlH2の触媒活性を調査する (1).
- 端末アルキンの水力採掘に応用する.
- アミン,チオール,フェノールとの脱水結合反応におけるその役割を調べる.
主な方法:
- アルミジヒドリド複合体のLAlH2の合成と特徴付け (1).
- 終端アルキンの触媒性水溶解の実験調査
- 様々なX-H化合物 (X = N,S,O) との脱水結合反応の実験研究.
- 反応メカニズムを解明するための量子力学的計算.
主要な成果:
- 複合体1は移行金属複合体と同等の触媒活性を示している.
- 終末アルキンの水酸化を成功させた.
- ボランとアミン,チオール,フェノールの脱水結合を効率的に開始し,H2除去でB-E結合 (E = N,S,O) を形成する.
- 量子力学的な計算により,連続した3つのサイクル加法反応とシグマ結合の活性化を含むメカニズムが明らかになった.
結論:
- アルミニウム二水素複合体1は,ヒドロブレーションおよび脱水結合反応の強力な触媒である.
- 触媒メカニズムは,連続的なサイクル添加とシグマ結合の活性化を含みます.
- この研究は,主要グループの有機金属化合物の触媒的応用を拡大する.
さらに関連する動画
05:50Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments
Published on: May 11, 2017
11.4K
08:40Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
Published on: December 6, 2021
4.4K
関連する概念動画
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
21.8K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
21.8K
03:08Hydroboration-Oxidation of Alkenes
12.1K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
12.1K
02:36Regioselectivity and Stereochemistry of Hydroboration
9.7K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
9.7K
01:19Acid Halides to Alcohols: LiAlH4 Reduction
4.3K
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
4.3K
02:23Alcohols from Carbonyl Compounds: Reduction
13.1K
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
13.1K
01:24Preparation of Aldehydes and Ketones from Nitriles and Carboxylic Acids
4.7K
Although it is possible to reduce a carboxylic acid to an aldehyde, strong reducing agents, like lithium aluminum hydride (LAH), prohibit a controlled reduction, instead causing the generated aldehyde to instantly over-reduce to a primary alcohol.
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H]...
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H]...
4.7K