一个协调的oxoborane的合成和表征:易斯酸稳定氧双键的氧双键
Dragoslav Vidovic1, Jennifer A Moore, Jamie N Jones
1Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165, USA.
Journal of the American Chemical Society
|March 31, 2005
概括
研究人员使用化 (AlCl3) 复合合成了第一个稳定的氧波单体 (LB=O). 这一突破保留了重要的-氧双键特性,推动了无机化学的发展.
科学领域:
- 无机化学 无机化学 有机化学
- 有机金属化学 有机金属化学
- 计算化学的计算化学
背景情况:
- 氧波是反应性物种,通常以聚合物形式存在.
- 由于它们的高反应性,单质氧玻的稳定具有挑战性.
- 之前的研究集中在过渡性或不太稳定的形式上.
研究的目的:
- 为了合成和表征第一个稳定的单体氧波.
- 为了研究稳定氧波的电子结构和结合.
- 探索易斯酸复合的实用性,以稳定反应性主要群体物种.
主要方法:
- 合成一种新型的配体L ([HC(CMe) 2 ((NC6F5) 2)).
- LAlCl2与三化物 (BCl3) 的反应,然后进行水解.
- 密度函数理论 (DFT) 计算来分析电子结构.
主要成果:
- 成功制备了与化 (AlCl3) 复合的稳定氧波单体 (LB=O).
- 描述证实了该化合物的单体性质和稳定性.
- DFT计算显示了重要的氧双键性质.
结论:
- 与AlCl3的复合有效地稳定了oxoborane单体.
- 该研究表明,对于分离和研究活性主要组化合物的可行策略.
- 这项工作为氧化合物的化学开辟了新的途径.
相关概念视频
02:54Lewis Structures of Molecular Compounds and Polyatomic Ions
To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:
02:52Resonance
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O bonds.
02:16Resonance and Hybrid Structures
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
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.
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.
02:47Alkynes 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.