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A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments
Published on: October 2, 2012
稳定的基含有非常长的碳-碳键
Andrey A Fokin1, Lesya V Chernish, Pavel A Gunchenko
1Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev, Ukraine. aaf@xtf.kpi.ua
Journal of the American Chemical Society
|July 28, 2012
概括
合成了具有非常长碳-碳键的高度稳定的碳化合物二聚体. 内分子范德瓦尔斯力稳定了这些不寻常的键,挑战了传统的化学理论.
科学领域:
- 有机化学 有机化学
- 计算化学计算化学
- 材料科学 材料科学 材料科学
背景情况:
- 金属诱导的三级钻石状化物合产生了固态阻碍的碳化合物二极体.
- 这些二极体具有异常长的中央碳-碳 (C-C) 键 (高达1.71 Å) 和高热稳定性 (>200 °C).
- 这种稳定性与典型的C-C键长度-强度相关性相矛盾.
研究的目的:
- 研究高度拥挤的碳化合物二次体的结构和动态特性.
- 了解导致钻石状系统中长C-C键异常稳定的因素.
- 评估各种密度函数理论 (DFT) 方法在描述这些独特的结合场景中的性能.
主要方法:
- 通过金属诱导的合三级钻石化物合成碳化合物二极体.
- 可变温度核磁共振 (NMR) 光谱学 ((1) H和 (13) C) 用于研究C-C键旋转动力学.
- 使用多个DFT函数和基础集进行计算分析,以建模几何和旋转障碍.
主要成果:
- 合成的二极体,如2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 的四极长的C-C键,其稳定通过分子内范德瓦尔斯的吸引力.
- 基于钻形表面的形状,C-C键旋转障碍物有很大的差异 (733 kcal mol(-1)) .
- 分散校正的DFT函数准确预测实验几何形状;大多数DFT函数捕获由于错误取消的旋转障碍.
- 计算研究表明,有可能创建仅由分散力稳定的激素二元和聚合物.
结论:
- 内部分子范德瓦尔斯力对于稳定异常长的C-C键在固态拥挤的金刚形二次体中至关重要.
- 钻形CH表面几何学决定了C-C键的旋转动力学和相关的能量障碍.
- DFT方法,特别是包括分散校正的方法,对于准确建模这些复杂的结合情况至关重要.
- 观察到的原则可能使基于分散力的新材料,包括基聚物质的设计成为可能.
相关概念视频
Constitutional Isomers of Alkanes
Organic compounds of the same molecular formula can have different structural formulas called constitutional isomers, and the phenomenon is known as constitutional isomerism. Alkanes with four or more carbons showing multiple structures with the same molecular formula thereby exhibit constitutional isomerism.
The linear isomer of an alkane is prefixed by the term “n”; hence a linear isomer of pentane is known as n-pentane. Based on the type of branching, some of the branched isomers are given...
The linear isomer of an alkane is prefixed by the term “n”; hence a linear isomer of pentane is known as n-pentane. Based on the type of branching, some of the branched isomers are given...
Structure of Alkanes
The formation of carbon-carbon bonds leading to the creation of the carbon chain is the basis of organic chemistry. August Kekulé and Archibald Scott Couper independently developed this idea of carbon chain formation.
Hydrocarbons are the simplest organic compounds composed of carbons and hydrogens. Based on the bond order between carbons, the hydrocarbons are further classified into alkanes, alkenes, and alkynes.
Alkanes are the simplest hydrocarbons with sp3 hybrid carbon atoms. These sp3...
Hydrocarbons are the simplest organic compounds composed of carbons and hydrogens. Based on the bond order between carbons, the hydrocarbons are further classified into alkanes, alkenes, and alkynes.
Alkanes are the simplest hydrocarbons with sp3 hybrid carbon atoms. These sp3...
Structure and Bonding of Alkenes
Olefins, which are unsaturated hydrocarbons containing one or more carbon–carbon double bonds, are broadly divided into alkenes and cycloalkenes. The general chemical formula of an alkene is CnH2n.
Doubly bonded carbons are sp2 hybridized and have a trigonal planar geometry. The double bond is composed of a σ bond formed by the overlap of hybrid orbitals and a π bond produced by the lateral overlap of unhybridized 2p orbitals on both the carbons. Each carbon atom is bonded to two hydrogen atoms...
Doubly bonded carbons are sp2 hybridized and have a trigonal planar geometry. The double bond is composed of a σ bond formed by the overlap of hybrid orbitals and a π bond produced by the lateral overlap of unhybridized 2p orbitals on both the carbons. Each carbon atom is bonded to two hydrogen atoms...
Combustion Energy: A Measure of Stability in Alkanes and Cycloalkanes
The low reactivity in alkanes can be attributed to the non-polar nature of C–C and C–H σ bonds. Alkanes, therefore, were initially termed as “paraffins,” derived from the Latin words: parum, meaning “too little,” and affinis, meaning “affinity.”
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
Nomenclature of Alkanes
In the late 19th-century, the number of new chemical compounds discovered increased tremendously. Hence, the necessity arose to develop a naming system for the systematic nomenclature of these newly discovered compounds. IUPAC (International Union for Pure and Applied Chemistry), established in 1919, sets rules for the nomenclature.
The alkane nomenclature considers the length of the carbon chain, the number, and the location of the substituent to arrive at its systematic name. The IUPAC...
The alkane nomenclature considers the length of the carbon chain, the number, and the location of the substituent to arrive at its systematic name. The IUPAC...
Physical Properties of Alkanes
Alkanes are nonpolar molecules due to the presence of only carbon and hydrogen atoms. The electronegativity difference between carbon and hydrogen is minimal, and hence alkanes have a zero dipole moment. This leads to the presence of only dispersion forces between the molecules. The strength of dispersion forces is dependent on the surface area of the molecules on which they act. Since the surface area increases with the molecular length for straight-chain alkanes, the dispersion forces also...

