安定したウラン (((III)) アルキル複合体を用いて二酸化炭素と二酸化炭素の機能化
Ellen M Matson1, William P Forrest, Phillip E Fanwick
1Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Journal of the American Chemical Society
|March 10, 2011
まとめ
新しいウラン ((III) アルキル複合体が合成され,二酸化炭素と二酸化炭素と反応した. このウラン複合体は,二酸化炭素の機能化を可能にし,化学的変換のためのリサイクル可能な経路を提供します.
科学分野:
- 有機金属化学 有機金属化学
- ウラン化学 ウラン化学
- 協調化化学について
背景:
- ウラン複合体は,そのユニークな電子特性と潜在的応用により興味を惹きます.
- 低価ウランアルキルの合成と反応性は十分に研究されていない.
- 金属複合体を用いてCO2のような小分子を機能化することは,触媒の重要な分野である.
研究 の 目的:
- 希少なウラン (((III)) アルキル複合体を合成し,特徴づけること.
- 二酸化炭素や二硫化炭素のような小さな分子によるこの複合体の反応性を調査する.
- 発現した複合体の潜在能力を触媒応用,特にCO2機能化において探求する.
主な方法:
- ウランアルキル複合体の合成のための塩代謝反応.
- NMR,赤外線,電子吸収光譜,X線結晶学を用いた特徴付け.
- ウラン-炭素結合への挿入と,その後の変換を含む反応.
主要な成果:
- ウラン(III) アルキル複合体,Tp*(2)U(CH(2)Ph)(2) を合成し,U-C結合の長さは2.57(2) Åである.
- CO2とCS2を挿入することにより,新しい炭酸塩およびディチオ炭酸塩ウラン複合体の形成.
- シリルエステルの放出とCO2機能化サイクルのためのウランモノハリドの再生の実証.
結論:
- 合成されたウラン (III) アルキル複合体は,CO2とCS2に対する反応性を示し,新しい有機金属種を形成する.
- ウランの中心は,導出カルボキシラートおよびディチオカルボキシラート複合体で三価酸化状態を維持する.
- 開発された方法論は,ウランハリドを使用した二酸化炭素の機能化のためのリサイクル可能な経路を提供します.
関連する概念動画
02:10Carbocations
Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
03:08Hydroboration-Oxidation of Alkenes
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.
01:26Radical 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,...
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,...
02:26Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.