結合したH2の迅速かつ可逆的な異型解離性裂け方

Elliott B Hulley¹, Kevin D Welch, Aaron M Appel

¹Center for Molecular Electrocatalysis, Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, USA.

Journal of the American Chemical Society

|July 30, 2013

まとめ

研究者らは,マンガン複合体を用いて二水素 (H2) の可逆的異解分裂を達成した. この突破は,様々な化学反応に不可欠な,急速な陽子と水素イオン交換を容易にする.

科学分野:

有機金属化学有機金属化学
カタリシスカタリシスカタリシス
化学動力学化学動力学

背景:

二水素 (H2) を陽子 (H+) と水素イオン (H-) にヘテロリスティックに分解することは,酵素による水素酸化や有機水素化などの反応に不可欠である.
このプロセスを理解し制御することは,効率的な触媒システムの開発の鍵です.

研究の目的:

容易かつ可逆的な異解性H2分裂を行うことができる新しいマンガン複合体を報告する.
このシステムにおける陽子/ヒドリド交換の運動を調査する.

主な方法:

ペンダントアミンリガンドによるマンガン複合体の合成.
複合体とその反応性を特徴付けるために,スペクトロスコーピックと運動学的研究を行う.
H+/H-の為替レート定数の決定.

主要な成果:

マンガニウム複合体は,効率的かつ可逆的にH2を分割する.
マンガンの水化物と陽子化されたアミン種の形成.
H+/H-の例外的に高い交換レートは,25°Cで>10^7 s^-1であった.

結論:

このマンガンの複合体は,ヘテロリート分裂によるH2活性化を研究するための新しいプラットフォームを提供します.
急速な陽子/ヒドリド交換は,触媒応用におけるこのシステムの可能性を強調しています.
この発見は,有機金属化学におけるH2変換の基本的な理解に寄与する.

さらに関連する動画

12:31

Chemoselective Modification of Viral Surfaces via Bioorthogonal Click Chemistry

Published on: August 19, 2012

06:34

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Published on: June 20, 2014

関連する概念動画

00:54

Radical Formation: Homolysis

A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.

02:18

Ethers to Alkyl Halides: Acidic Cleavage

Ethers are generally unreactive and unsuitable for direct nucleophilic substitution reactions since the alkoxy groups are strong bases and, therefore, poor leaving groups. However, ethers readily undergo acidic-cleavage reactions. Ethers can be converted to alkyl halides when heated with strong acids such as HBr and HI in a sequence of two substitution reactions.

01:03

Radical Formation: Overview

A bond can be broken either by heterolytic bond cleavage to form ions or homolytic bond cleavage to yield radicals. A fishhook arrow is used to represent the motion of a single electron in homolytic bond cleavage. There are two main sources from which radicals can be formed:
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...

01:26

Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride

Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...

01:01

Acid Halides to Carboxylic Acids: Hydrolysis

Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...

01:17

Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene

The electrophilic addition of hydrogen halides such as HBr to alkenes and nonconjugated dienes gives a single product as per Markovnikov’s rule.

関連する実験動画