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Interface-tuned selective reductive coupling of nitroarenes to aromatic azo and azoxy: a first-principles-based
Lidong Zhang1, Zheng-Jiang Shao1, Xiao-Ming Cao1
1Key Laboratory for Advanced Materials, Center for Computational Chemistry and Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237, P. R. China. xmcao@ecust.edu.cn.
Physical Chemistry Chemical Physics : PCCP
|June 1, 2019
Summary
Adding KOH to platinum-catalyzed nitrobenzene hydrogenation shifts selectivity from aniline to valuable N-N coupling products. This occurs because KOH alters nitrobenzene
Area of Science:
- Heterogeneous Catalysis
- Surface Chemistry
- Reaction Mechanism
Background:
- Platinum (Pt) catalysts are widely used for hydrogenation reactions.
- Nitrobenzene hydrogenation typically yields aniline.
- Controlling catalyst selectivity is crucial for producing desired chemical products.
Purpose of the Study:
- To investigate the key factors influencing selectivity in nitrobenzene hydrogenation.
- To understand the role of potassium hydroxide (KOH) in altering reaction pathways.
- To elucidate the mechanisms favoring N-N coupling products (aromatic azoxy and azo).
Main Methods:
- Microkinetic simulations were employed to study reaction mechanisms.
- Calculations were based on Density Functional Theory (DFT) with PBE-D3 functional.
- The study focused on the Pt(111) surface and the KOH/Pt(111) interface.
Main Results:
- Nitrobenzene adsorption configuration significantly impacts selectivity, more than hydrogen coverage.
- In neutral environments, flat adsorption of nitrobenzene on Pt(111) favors aniline production.
- KOH addition promotes nitro group adsorption at the interface, favoring N-N coupling products.
Conclusions:
- KOH induces a tilted adsorption of nitrobenzene, stabilizing key intermediates for N-N coupling.
- The altered adsorption configuration and stabilization by KOH promote the formation of PhN*, a crucial intermediate.
- This study provides insights into catalyst regulation for selective synthesis of valuable aromatic azoxy and azo compounds.
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