アルキネスのフォスフィン安定化モノゲルマニウムアナログの合成と反応性
Juliette Berthe1, Juan Manuel Garcia, Edgar Ocando
1Université de Toulouse, UPS and CNRS, LHFA UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9, France.
Journal of the American Chemical Society
|September 15, 2011
まとめ
研究者は,ユニークな結合を持つゲルマニウム化合物である新しいC-phosphino-Ge-aminogermyneを合成しました. このゲルミンはイソメリ化して安定したN-ヘテロサイクルのゲルミレンを形成し,リガンド移動化学を示した.
科学分野:
- 有機金属化学 有機金属化学
- メイングループ 化学
背景:
- ゲルマニウムは,高度に反応する低調整ゲルマニウム種である.
- 微生物の安定化は,それらのユニークな電子特性を研究するために非常に重要です.
研究 の 目的:
- 最初の分離可能なC-フォスフィノ-Ge-アミノゲルミンを合成し,特徴づけること.
- この新種のゲルミーン誘導体の反応性と構造的性質を調査する.
主な方法:
- C-フォスフィノ-ゲー-アミノゲルミンの合成は,フォスフィンリガンドの安定化を用いて行われます.
- 分子構造と結合長さを決定するX線 difraktion分析.
- イソメリゼーション反応により,N-ヘテロサイクルのゲルミレンが形成されます.
主要な成果:
- C-フォスフィノ-ゲー-アミノゲルミンの分離と特徴づけに成功した.
- X線 difraktionにより,単一結合と二重結合の間の中間である,かなり長いGe-C結合が明らかになった.
- イソメリゼーションにより,フォスフィーニリンガンドの移動を経由して安定したN-ヘテロサイクリックゲルミレンが形成された.
結論:
- この研究では,最初の分離可能なC-フォスフィノ-Ge-アミノゲルミネが報告され,フォスフィンのリガンドによって安定させられた.
- 観測されたGe-C結合の長さは,π-ドーナリングの置換素を持つ生殖細胞の理論的予測を裏付けている.
- 同性化経路は,安定したN-ヘテロサイクルのゲルミレンへの新しい経路を示しています.
関連する概念動画
02:34Preparation of Alkynes: Dehydrohalogenation
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.
01:19Aldehydes and Ketones to Alkenes: Wittig Reaction Overview
The Wittig reaction is the conversion of carbonyl compounds-aldehydes and ketones-to alkenes using phosphorus ylides, or the Wittig reagent. The reaction was pioneered by Prof. Georg Wittig, for which he was awarded the Nobel Prize in Chemistry.
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.