通过低分子量有机酸在冷溶液中的Cr(VI) 的功能组特异性减少:动力学,机制和DFT计算
Jialiang Liang1, Peng Zhen1, Liping Liu1
1Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, P. R. China.
Water research
|August 11, 2024
概括
低分子量有机酸 (LMWOA) 加快降解在冷水中. 特定的功能组和结效应增强了电子转移,影响了反应速率和土壤溶液的抑制.
科学领域:
- 环境化学环境化学
- 地质化学 地质化学
- 物理化学 物理化学
背景情况:
- 低分子量有机酸 (LMWOA) 在自然水中无处不在.
- 众所周知,LMWOA有助于减少六价 (Cr(VI)).
- 水溶液中的结度效应可以显著改变反应动力学.
研究的目的:
- 调查LMWOA功能组在冷条件下的Cr(VI) 减少中的作用.
- 阐明增强电子转移和反应动力学的机制.
- 评估结和土壤溶液对LMWOA介导的Cr (VI) 减少的影响.
主要方法:
- 在冷溶液中通过各种LMWOA进行Cr(VI) 减少的实验研究.
- 密度函数理论 (DFT) 计算以建模复杂的形成和电子转移.
- 分析反应固体测量和土壤溶液的抑制.
主要成果:
- LMWOA促进了Cr(VI) 的减少,由于度效应,冷提高了效率.
- 在LMWOA和CrVI之间形成五个环复合体,通过合物到金属电荷转移 (LMCT) 增强电子转移.
- 在阿尔法位置的含氧组对复杂的形成和反应动力学至关重要;结改变了LMWOA的物种化和反应机制.
- 由于Cr (III) 复杂化,软体测量比率超过理论值.
- 土壤溶液抑制LMWOA介导的Cr(VI) 减少,根据LMWOA类型不同程度.
结论:
- 在冷溶液中,LMWOA的功能组,特别是α-氧化组,对于有效的Cr (VI) 减少至关重要.
- 结将反应物缩并改变LMWOA的物种化,显著影响反应动力学和机制.
- 土壤溶液可以抑制这种减少过程,突出显示自然水系统的复杂性.
相关概念视频
01:23Protecting Groups for Aldehydes and Ketones: Introduction
6.8K
Protecting groups are compounds that can bind to a specific functional group in the presence of other functional groups to protect them from undesired chemical reactions. These compounds can selectively bind to particular functional groups and advance chemoselective reactions in polyfunctional systems (Figure 1). After the functional group has served its purpose, it is removed by reacting it with specific compounds.
6.8K
01:17Carboxylic Acids to Primary Alcohols: Hydride Reduction
2.8K
Carboxylic acids, upon reaction with strong reducing agents such as lithium aluminum hydride followed by hydrolysis, undergo reduction to form primary alcohols.
2.8K
02:23Alcohols from Carbonyl Compounds: Reduction
10.2K
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
10.2K
01:24Acetals and Thioacetals as Protecting Groups for Aldehydes and Ketones
4.1K
Acetals are formed by reacting two equivalents of alcohol with carbonyl compounds like aldehydes or ketones. Acetals are unaffected by bases, nucleophiles, oxidizing agents, and reducing agents. They serve as protecting groups for aldehydes and ketones. Acetals can be easily formed and also easily removed via mild acid hydrolysis.
In the presence of multiple functional groups, when selective reduction of one group over the other is desired, groups like aldehydes and ketones that form acetals...
In the presence of multiple functional groups, when selective reduction of one group over the other is desired, groups like aldehydes and ketones that form acetals...
4.1K
01:19Acid Halides to Alcohols: LiAlH4 Reduction
2.7K
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
2.7K
01:24Preparation of Aldehydes and Ketones from Nitriles and Carboxylic Acids
3.4K
Although it is possible to reduce a carboxylic acid to an aldehyde, strong reducing agents, like lithium aluminum hydride (LAH), prohibit a controlled reduction, instead causing the generated aldehyde to instantly over-reduce to a primary alcohol.
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H]...
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H]...
3.4K