热化学洞察 CO 通过 [Re(CO) ](+) 和 [Mn(CO) ](+) 复合物降解为 CH3OH 的过程
Eric S Wiedner1, Aaron M Appel
1Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, K2-57, Richland, Washington 99352, United States.
Journal of the American Chemical Society
|May 24, 2014
概括
了解一氧化碳 (CO) 降解为甲醇 (CH3OH) 的热力学障碍至关重要. 该研究确定H2添加到[CpRe(PPh3) ((NO) ((CO) ((+) 作为主要障碍,有潜力通过连接体和金属变化进行优化.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 热力学是一种热力学.
背景情况:
- 将一氧化碳 (CO) 减少为甲醇 (CH3OH) 是化学合成和能量转化中的一个关键过程.
- 了解热力学限制对于设计高效的催化剂至关重要.
研究的目的:
- 确定与将[CpRe(PPh3) ((NO) ((CO))) ((+)) 减少为CpRe(PPh3) ((NO) ((CH2OH)) 的自由能量.
- 确定阻碍二氧化碳减少的主要热力学障碍.
- 探索使用有机金属复合体克服这些障碍的战略.
主要方法:
- 使用模型复合体,实验确定质子 (H+),化物 (H-) 和电子 (e-) 转移的自由能量.
- 热量测量测量以确定化物供体能力 (ΔG°H(-)).
- 循环电压测量用于估计氧化和还原潜力.
- 密度函数理论 (DFT) 计算用于分析热力学障碍的变化.
主要成果:
- 对于[CpRe(PPh3) ((NO) ((CHOH))) 的pKa估计为10.6.
- 发现CpRe(PPh3)(NO)(CH2OH) 的化物捐赠能力 (ΔG°H(-)) 是58.0千卡的mol(-1).
- 为[CpRe(PPh3) ((NO) ((CO))) 添加H2的自由能量 (ΔG°H2) 确定为+15 kcal mol ((-1),被确定为最重要的热力学障碍.
- DFT的计算表明,ΔG°H2可以通过连接物和金属修饰来调节多达11kcalmol.
结论:
- 将H2添加到碳复合体是减少CO2的主要热力学障碍.
- 修改辅助连接物和相关复合体中的金属中心提供了一个可行的途径来降低这一障碍.
- 这些发现为开发改进的碳减排催化剂提供了关键的见解.
相关概念视频
Redox Reactions
50.9K
Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...
50.9K
Redox Reactions
1.2K
Redox reactions are vital biochemical processes that underpin energy metabolism in cells. These reactions involve the transfer of electrons between molecules, occurring in tandem as oxidation and reduction. Oxidation refers to the loss of electrons, while reduction denotes their gain. This coupling ensures the seamless flow of electrons through metabolic pathways. For example, in bacterial metabolism, glucose undergoes oxidation to carbon dioxide, while oxygen is simultaneously reduced to...
1.2K
Alcohols from Carbonyl Compounds: Reduction
9.3K
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...
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...
9.3K
Aldehydes and Ketones to Alkanes: Wolff–Kishner Reduction
4.0K
Wolff–Kishner reduction involves converting aldehydes and ketones to alkanes using hydrazine and a base. The reaction converts a carbonyl group to a methylene group. The method was independently discovered by N. Kishner in 1911 and L. Wolff in 1912. The reduction is carried out in high-boiling solvents such as ethylene glycol and diethylene glycol because heat is required to deprotonate the N–H proton in one of the reaction steps.
4.0K
Phase I Reactions: Reductive Reactions
797
Phase I biotransformation reductive reactions are chemical processes that modify drugs by introducing or revealing polar functional groups via reduction. Enzymes called reductases catalyze these reactions, playing a pivotal role in drug metabolism by transforming lipophilic drugs into more polar, water-soluble metabolites for easy excretion. An essential type of reductive reaction is the carbonyl group reduction, where aldehydes and ketones are reduced to alcohols. An example is the...
797
Acid Halides to Alcohols: LiAlH4 Reduction
3.3K
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...
3.3K


