六角性ボルンニトリドとブロンステッド酸の可逆インターキャレーション
Nina I Kovtyukhova1, Yuanxi Wang, Ruitao Lv
1Department of Chemistry and ‡Department of Physics, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Journal of the American Chemical Society
|May 14, 2013
まとめ
研究者らは,ブロンステッド酸を用いて,半角性ボロン窒化物 (h-BN) の絶縁剤を間隔した. この新しい方法は,先端の電子機器に不可欠なh-BNの化学剥離を可能にします.
科学分野:
- マテリアルサイエンス 材料科学
- 固体化学 固体化学
- ナノテクノロジー ナノテクノロジー
背景:
- 六角性ボン・ニトリド (h-BN) は,2D素材で,構造的にはグラフェンに類似しています.
- その絶縁性により,トランジスタやコンデンサなどのハイブリッド電子機器に価値があります.
- グラファイトとは異なり,h-BNは一般的なリドックス法によるインターキャレーションに耐性があります.
研究 の 目的:
- 絶縁性六角性ボン・ニトリドを間隔する方法を開発する.
- h-BNを単一層に化学的に剥がすことができるように.
- h-BN.のインターキャレーションを駆動するメカニズムを理解する.
主な方法:
- h-BNを強いブロンステッド酸 (H2SO4,H3PO4,HClO4) で熱乾燥する.
- X線光電子スペクトロスコーピー (XPS) と振動スペクトロスコーピーを用いた特徴付け.
- 電子構造と分子動力学シミュレーションを含む計算分析.
主要な成果:
- h-BNとブロンステッド酸による第1段階のインターキャレーション化合物の形成.
- 酸化酸と窒素原子の間の非共性相互作用の実証.
- 強い酸化剤を必要とせずに,成功裏にインターカレーションが行われた証拠.
結論:
- 特定のブロンステッド酸で単純な熱乾燥は,h-BN.をインターカレートするための効果的な方法です.
- ノンコヴァレンスの相互作用は,h-BNの惰性を克服し,インターキャレーションに向かうための鍵です.
- この研究は,高度な材料とデバイスのための脱皮されたh-BNを生産するための経路を開きます.
関連する概念動画
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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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
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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.
02:36Regioselectivity and Stereochemistry of Hydroboration
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.
02:46Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
02:16Lewis Acids and Bases
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02:33Lewis Acids and Bases
In 1923, G. N. Lewis proposed a generalized definition of acid-base behavior in which acids and bases are identified by their ability to accept or to donate a pair of electrons and form a coordinate covalent bond.
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A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...