在动力控制的固态转化反应中绕过扩散
Andrew J Martinolich1, Joshua A Kurzman1, James R Neilson1
1Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States.
Journal of the American Chemical Society
|August 5, 2016
概括
研究人员探索了固态转化反应以合成无机材料. 在空气中研磨反应物,而不是在无空气环境中,可以绕过扩散限制和中间阶段,从而直接形成所需的金属硫化物 (MS2).
科学领域:
- 材料科学
- 固态化学
- 无机合成
背景情况:
- 固态扩散往往限制了新型晶体无机材料的合成.
- 开发绕过扩散的合成路径对于获取转移稳定的化合物至关重要.
研究的目的:
- 为了研究M = Fe,Co,Ni的固态转化反应 (MCl2 + Na2S2 → MS2 + 2 NaCl).
- 探索不同的反应剂制备方法如何影响反应途径和产品的形成.
主要方法:
- 在现场同步光粉X射线衍射.
- 不同扫描热量计.
- 对分布函数的分析.
主要成果:
- 无空气反应显示扩散有限的产物形成与中间阶段.
- 在空气中研磨反应物导致直接NaCl的形成,将离子移到无形矩阵中.
- 加热空气和土壤混合物导致MS2的直接核化,避免二进制中间体.
结论:
- 在空气中研磨改变了反应路径,形成NaCl,从而分散了晶格能量,并促进了直接的MS2核化.
- 这种方法提供了各种化合物的批量合成的途径,规避了扩散有限的二进制中间体.
相关概念视频
Olefin Metathesis Polymerization: Overview
2.7K
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
2.7K
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
2.3K
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
2.3K
Cycloaddition Reactions: MO Requirements for Thermal Activation
5.0K
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
5.0K
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
3.3K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
3.3K
Reaction Mechanisms: Rate-limiting Step Approximation
50
The rate-determining step, or RDS, in a chemical reaction is the slowest step that determines the overall reaction rate. It is identified by using the observed rate law and typically involves approximation methods like the RDS approximation or the steady-state approximation.In the RDS approximation, also known as the rate-limiting-step or equilibrium approximation, the reaction mechanism consists of one or more reversible reactions near equilibrium, followed by a slower RDS, and then one or...
50
Radical Reactivity: Intramolecular vs Intermolecular
2.3K
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...
2.3K

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
