一个通往器官密码化学的门户:HKrCCHH
Leonid Khriachtchev1, Hanna Tanskanen, Arik Cohen
1Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Finland. Leonid.Khriachtchev@Helsinki.Fi
Journal of the American Chemical Society
|June 5, 2003
概括
研究人员利用光解和热调动合成了一种新的含有的有机分子HKrCCH. 这一突破为新的基于的催化和有机化合物开发开辟了道路.
科学领域:
- 无机化学 无机化学 有机化学
- 有机化学 有机化学
- 计算化学的计算化学
背景情况:
- 贵族气体,特别是,历史上一直被认为是惰性的.
- 最近的进展使得高贵气体化合物的合成和表征成为可能.
- 了解这些化合物的结合和反应性对于探索新的化学前沿至关重要.
研究的目的:
- 报告成功合成和识别含有的新型有机分子,特别是HKrCCH.
- 用光谱和计算方法研究这个有机密子分子的结合特性.
- 探索准备一系列类似的有机密化合物及其在催化中的应用的潜力.
主要方法:
- 通过193nm光解合成乙烯 (H2C2) 和 (Kr) 固体混合物,在低温 (8K) 处进行合成.
- 随后的热调动原子在高于或等于30K的温度.
- 使用红外吸收光谱法进行识别.
- 通过ab initio计算计算进行支持性分析.
主要成果:
- 成功制备和光谱识别了有机密分子HKrCCH.
- 最初的计算显示了对Kr-C债券的显著离子和共价贡献.
- 计算证据表明,合成相关的有机密码子分子,如HKrC4H和HKrC3H3.3,是可行的.
- 展示了一种用于化学激活H-CC-组的新方法.
结论:
- 合成HKrCCH证实了将融入有机框架中的可能性.
- 在HKrCCH中的结合是离子和共价相互作用的混合体,挑战了贵重气体惰性的传统观点.
- 演示的合成策略为开发各种有机密化合物提供了一个新的平台.
- 这些发现为在有机合成中对子催化物的实际应用铺平了道路.
相关概念视频
02:54Noble Gases
The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name “noble” because they were assumed to be nonreactive since they have filled valence shells. In 1962, Dr. Neil Bartlett at the University of British Columbia proved this assumption to be false.
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.
02:47Alkynes 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.
01:32Aldehydes and Ketones with HCN: Cyanohydrin Formation Overview
Cyanohydrins are compounds that contain –CN and –OH groups on the same carbon atom. They are formed by the nucleophilic addition of the cyanide ions to the carbonyl group. Cyanide ions are highly basic and nucleophilic and can be generated from HCN under aqueous conditions. However, since HCN is a weak acid, the number of cyanide ions generated is very small. Hence, a small amount of base or KCN/NaCN is added to HCN to increase the concentration of the cyanide ions in the reaction mixture.
01:24ortho–para-Directing Deactivators: Halogens
Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through the inductive effect and deactivate the aromatic ring towards electrophilic substitution. Halogens also have an electron-donating resonance effect on the ring, which influences the orientation of the incoming electrophile. If an electrophile attacks at the ortho or the para position, the halogen donates electrons and stabilizes the intermediate...
01:29Chain Reactions
Chain reactions involve highly reactive transient species, such as atoms or free radicals, as intermediates. These intermediates facilitate rapid reactions over an extended period. The process includes a series of steps: a reactive intermediate is consumed, reactants are converted to products, and the intermediate is regenerated. This cycle enables continuous repetition, amplifying the production of products with a small amount of intermediate. Chain reactions often utilize free radicals as...