在异形聚胺中对诺里什反应机制的理论分析
Jingcheng Sang1, Yuuichi Orimoto2, Yuriko Aoki2
1Department of Interdisciplinary Engineering Sciences, Chemistry and Materials Science, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga Park, Fukuoka 816-8580, Japan.
诺里什II型反应,具有较低的能量障碍,是聚胺的主要二次光降解路径. 这种机制,以及直接的C-N键裂变,起源于相同的单片激发状态,有助于设计光解学稳定的聚胺纤维.
科学领域:
- 计算化学的计算化学
- 材料科学 材料科学 材料科学
- 摄影化学的使用.
背景情况:
- 亚利法性聚胺,如尼龙,容易通过链分裂进行光降解.
- 了解诺里什反应机制对于提高聚胺耐用性至关重要.
- 之前的工作确定了直接的C-N键裂变作为主要的光降解途径.
研究的目的:
- 通过使用计算方法,研究形聚胺中诺里什反应机制.
- 阐明聚胺光降解中涉及的兴奋状态和过渡状态.
- 确定主导的二次光降解途径及其与主要机制的关系.
主要方法:
- 使用了时间依赖密度函数理论 (TD-DFT).
- 一个简化的模型,N-乙基胺 (NEA),用于表示聚胺.
- 对诺里什反应的低兴奋状态 (ESs) 和过渡状态的表征.
主要成果:
- 与诺里什型I (> 20 kcal mol-1) 相比,诺里什型II机制表现出较低的激活能量 (< 15 kcal mol-1),这表明它是一个重要的次要途径.
- 诺里什II型机制导致与碳基组相邻的N-C键断裂.
- 直接的C-N键光解离和诺里什反应机制都源于相同的单元激发状态.
结论:
- 诺里什II型机制是聚胺中二次光降解的主要贡献者.
- 对于初级和二级光降解途径的共享激发状态起源提供了新的见解.
- 这些发现对于设计具有增强光解降解耐受性的聚胺纤维具有价值.
更多相关视频
06:46Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
07:30A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones
Published on: January 21, 2020
相关概念视频
Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between...
Free-Radical Chain Reaction and Polymerization of Alkenes
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
Nitriles to Amines: LiAlH4 Reduction
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
Acid Halides to Amides: Aminolysis
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
