氨三:一种新的合成方法,结构的确定,以及水溶性释放的特性
Chang Won Yoon1, Patrick J Carroll, Larry G Sneddon
1Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
Journal of the American Chemical Society
|December 17, 2008
概括
氨三 (NH 3 B 3 H 7) 可以安全地制备,并且由于二结合,具有不对称的固态结构. 它的水溶液通过过渡金属催化剂迅速释放.
科学领域:
- 无机化学 无机化学
- 材料科学 材料科学 材料科学
- 计算化学的计算化学
背景情况:
- 子是一种-化合物的类,在储存中具有潜在的应用.
- 氨三 (NH 3 B 3 H 7) 的合成和表征对于探索其特性至关重要.
- 了解三氨的结构和反应性方面是其实际利用的关键.
研究的目的:
- 开发一种安全和方便的方法来制备氨三博 (NH 3 B 3 H 7)).
- 通过X射线晶体学和DFT计算,研究氨三及其添加物的固态结构.
- 为了研究水性氨三溶液的释放的特性.
主要方法:
- 通过氧化B ((3) H ((8) ((-) 合成氨三,然后通过氨排位.
- 用X射线结晶学测定NH(3) B(3) H(7) 的固态结构及其18-crown-6 adduct.
- 密度函数理论 (DFT) 计算分析分子结构和结合.
- 使用酸性或过渡金属催化剂 (Rh/Al(2) O(3) 的水解反应研究,以测量释放的.
主要成果:
- 建立了一种安全且方便的氨三 (NH 3 B 3 H 7) 制剂.
- X射线结晶学和DFT研究揭示了NH(3) B(3) H(7) 的高度不对称的固态结构,由分子间N-H(+)...H(-) -B二键驱动,与对称性的计算预测相反.
- 在添加酸或Rh/Al2O3催化剂后,氨三的水溶液迅速释放,在特定条件下达到6.1%重量%的H2释放.
结论:
- 氨三 (NH 3 B 3 H 7) 可以通过一种新的方法有效合成.
- 氨三的固态结构受到分子间二键的显著影响,导致不对称.
- 氨三是一种有前途的储物材料,具有可控制的释放率,由催化剂促进.
相关概念视频
Hydroboration-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.
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,...
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,...
Regioselectivity 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.
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...
Alkynes 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.


