相关实验视频
Updated: Jun 28, 2025
06:19
Fractionation of Lignocellulosic Biomass using the OrganoCat Process
Published on: June 5, 2021
3.9K
半纤维素二氧化解:功能化西洛皮拉诺的机制和动力学
Leandro Ayarde-Henríquez1,2, Jacopo Lupi1,2, Stephen Dooley1,2
1School of Physics, Trinity College Dublin, Dublin 2, Ireland. leandro.ayarde@tcd.ie.
Physical chemistry chemical physics : PCCP
|April 16, 2024
概括
在β-D-xylopyranose上的功能组显著改变了其热解脱聚合. 环开放是最受欢迎的途径,功能化增加了反应速率并影响了分解动力学.
科学领域:
- 计算化学计算化学
- 热化学 热化学 热化学
- 化学动力学 化学动力学
- 生物质热解是生物质的热解.
背景情况:
- 了解像β-D-xylopyranose这样的生物质成分的 Pyrolytic 分解解聚合对于生物炼油厂的发展至关重要.
- 特定功能群对β-D-xylanopyranose分解途径的影响仍然不完全理解.
研究的目的:
- 研究关键功能化 (4-甲基,5-碳基,2-O-乙烯基) 对β-D-西洛皮拉诺斯脱聚合物的热化学动力效应.
- 确定首选的分解机制,并量化替代剂对反应速率的影响.
主要方法:
- 用M06-2X/6-311++G (d,p) 计算并用G4和CBS-QB3方法提炼的气相潜在能量表面.
- 速率常数是通过过渡状态理论计算的.
- 使用原子化方法确定形成的标准度.
主要成果:
- 与环收缩和消除相比,环开放表现出最低的激活度 (43.847.5 kcal mol-1).
- 功能组将基本反应障碍降低1.98.3 kcal mol-1,速度常数增加04个数量级.
- 环开放是占主导地位的途径,速度常数在101s-1左右,而其他途径则显著慢 (10−410−10s−1).
结论:
- 功能化显著影响β-D-xylopyranose分解动力学,有利于环开放.
- 该研究提供了准确的热化学数据和替代β-D-xylopyranose的运动见解.
- 这些发现有助于预测和优化各种半纤维素结构的热解途径.
相关概念视频
01:15Cellulose and Pectic Polysaccharides
3.6K
Every plant cell has a cell wall that protects the cell, provides structural support, and gives the cell shape. Cellulose, the main structural component of the plant cell wall, makes up over 30% of plant matter. It is the most abundant organic compound on earth. Cellulose is an unbranched polysaccharide composed of linear chains of glucose molecules linked by β (1→4) glycosidic bonds.
As a cell matures, its cell wall specializes according to its type. For example, the...
As a cell matures, its cell wall specializes according to its type. For example, the...
3.6K
01:23Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
2.6K
The addition of a hydrogen halide to 1,3-butadiene gives a mixture of 1,2- and 1,4-adducts. Since more substituted alkenes are more stable, the 1,4-adduct is expected to be the major product. However, the product distribution is strongly influenced by temperature; low temperature favors the 1,2-adduct, whereas the 1,4-adduct is predominant at high temperature.
2.6K
02:46E1 Reaction: Kinetics and Mechanism
15.4K
Here, in contrast to the E2 reaction mechanism, we delve into the aspects of the E1 reaction mechanism, which has two steps: rate-limiting loss of the leaving group and abstraction of the beta hydrogen by a weak base. Typically, the experimental proof for the E1 mechanism is via kinetic studies or isotope studies. While the former demonstrates the first-order kinetics—the dependence of the reaction solely on substrate concentration—the latter proves the abstraction of hydrogen only...
15.4K
02:45E2 Reaction: Kinetics and Mechanism
10.2K
SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...
10.2K
01:20Fates of Pyruvate
8.4K
Pyruvate is the end product of glycolysis, where glucose is oxidized to pyruvate, simultaneously reducing NAD+ to NADH. Two molecules of ATP are also produced by substrate-level phosphorylation.
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
8.4K