将氨放入化学开放的富勒烯中
Keith E Whitener1, Michael Frunzi, Sho-ichi Iwamatsu
1Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA.
Journal of the American Chemical Society
|September 27, 2008
概括
研究人员将氨 (NH3) 封装在一个开放的富勒中. 核磁共振和质谱学证实了NH3的含有,但它在六个月内慢慢脱离,表明稳定性有限.
科学领域:
- 超分子化学 超分子化学
- 纳米材料科学 科学 纳米材料科学
- 物理化学 物理化学
背景情况:
- 富勒伦是以碳为基础的纳米材料,具有独特的子状结构.
- 开放的富勒伦具有分子封装的潜力.
- 氨 (NH3) 是一种具有各种应用的基本化学物种.
研究的目的:
- 为了研究氨的封装在一个特定的开放的富勒烯.
- 描述由此产生的富勒-氨复合物的特性和稳定性.
- 为了确定氨的纳入分数和长期保留.
主要方法:
- 一种带有20个环孔的开放富勒烯的合成.
- 将氨 (NH3) 封装到富勒烯中.
- 使用核磁共振 (NMR) 谱学和MALDI-TOF质谱学进行了表征.
主要成果:
- 质子NMR证实了内分体NH3的存在,在delta H = -12.3 ppm时具有特征的共振.
- 马尔迪-托夫质谱验证了完整的富勒烯和富勒烯-氨复合体.
- 确定了35-50%的合并分数,在六个月内下降,表明氨泄漏.
结论:
- 氨可以成功地被封装在研究的开放的富勒烯中.
- 富勒-氨复合体表现出可测量的稳定性,但随着时间的推移,氨的扩散速度缓慢.
- 这项研究提供了对开放的富勒伦和客分子动态的宿主-客化学的见解.
相关概念视频
Preparation of 1° Amines: Gabriel Synthesis
Direct alkylation is not a suitable method for synthesizing amines because it produces polyalkylated products. Gabriel synthesis is the most preferred method to exclusively make primary amines. The method uses phthalimide, which contains a protected form of nitrogen that participates in alkylation only once to predominantly give primary amines.
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Preparation of Amines: Alkylation of Ammonia and Amines
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
2° Amines to N-Nitrosamines: Reaction with NaNO2
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia
Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone.
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
Free Energy Changes for Nonstandard States
The free energy change for a process taking place with reactants and products present under nonstandard conditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy change according to this equation:
Aldehydes and Ketones with Amines: Enamine Formation Mechanism
Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...


