在金纳米颗粒上发生基醇的交换位反应
Adil Kassam1, Glen Bremner, Brad Clark
1Department of Chemistry and Centre for Self-Assembled Chemical Structures, McGill University, 801 Sherbrooke Street W, Montreal, QC H3A 2K6, Canada.
Journal of the American Chemical Society
|March 16, 2006
概括
黄金纳米粒子的位置交换反应达到平衡,其Keq大约为1. 这些反应遵循兰格穆尔扩散动力学,通过气色谱分析基醇进行监测.
科学领域:
- 纳米粒子化学 纳米粒子化学
- 表面科学是一门科学.
- 化学动力学 化学动力学
背景情况:
- 金纳米粒子广泛用于催化和电子.
- 了解表面连接体交换对于控制纳米粒子特性至关重要.
- 之前的研究已经探索了连接体交换,但缺乏详细的动力学分析.
研究的目的:
- 为了研究金纳米颗粒上的位置交换反应的动力学和平衡.
- 为了确定基醇与基醇交换的平衡常数 (Keq).
- 为了阐明控制这些表面反应的动力模型.
主要方法:
- 使用气相色谱监测场所交换反应.
- 随着时间的推移,分析结构上相似的进出基醇.
- 将运动模型应用于产品时间数据.
主要成果:
- 在金纳米颗粒上的位置交换反应会进入一个定义的平衡.
- 发现平衡常数 (Keq) 大约为1.
- 反应动力学被Langmuir扩散模型准确地描述.
结论:
- 金纳米颗粒上的基醇与基醇交换是一个可逆的过程,达到平衡.
- 兰木尔扩散动力学决定了这些位置交换反应的速率.
- 这项工作为纳米粒子表面动力学提供了基本的见解.
相关概念视频
02:26SN2 Reaction: Transition State
An SN2 reaction of an alkyl halide is a single-step process in which bond formation between the nucleophile and the substrate and bond breaking between the substrate and the halide occurs simultaneously through a transition state without forming an intermediate.
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
01:38Preparation of Alcohols via Substitution Reactions
Overview
Alcohols can be synthesized from alkyl halides via nucleophilic substitution reactions. The highly polar carbon-halogen bond in the substrate makes halide a good leaving group. The hydroxide ion or water can act as a nucleophile to take the place of halide and form an alcohol. The substitution reactions occur via two different reaction pathways, SN1 or SN2, depending on the nature of carbon attached to the halide.
Primary alcohols are synthesized from primary alkyl halides, and the...
Alcohols can be synthesized from alkyl halides via nucleophilic substitution reactions. The highly polar carbon-halogen bond in the substrate makes halide a good leaving group. The hydroxide ion or water can act as a nucleophile to take the place of halide and form an alcohol. The substitution reactions occur via two different reaction pathways, SN1 or SN2, depending on the nature of carbon attached to the halide.
Primary alcohols are synthesized from primary alkyl halides, and the...
02:48Conversion of Alcohols to Alkyl Halides
This lesson delves into the conversion of alcohols to corresponding alkyl halides and the mechanism of action for different reagents. Typically, the hydroxyl group is first protonated to convert it to a stable leaving group. Consequently, based on the starting alcohol, the mechanism undergoes either of the nucleophilic substitution routes, SN1 or SN2. Tertiary alkyl halides are made using the two-step SN1 mechanism that occurs via a carbocation intermediate, which is stabilized by...
02:33Preparation and Reactions of Thiols
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
02:26Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.