Predicting gold-mediated catalytic oxidative-coupling reactions from single crystal studies

Area of Science:

• Surface Chemistry
• Catalysis
• Materials Science

Background:

• Metallic gold is typically inert but becomes reactive when activated by atomic oxygen.
• Understanding gold's surface reactivity is key to developing efficient catalytic processes.
• Oxidative chemical transformations are crucial in various chemical syntheses.

Purpose of the Study:

• To establish a molecular-level mechanistic framework for oxidative-coupling reactions on gold surfaces.
• To apply these principles to steady-state catalytic conditions and predict new reactions.
• To understand the role of atomic oxygen in gold-mediated chemistry.

Main Methods:

• Fundamental studies on oxygen-activated Au(111) single crystals.
• Mechanistic investigations of substrate activation and reaction pathways.
• Application of established principles to nanoporous gold catalysis.

Main Results:

• Adsorbed atomic oxygen facilitates substrate activation via nucleophilic attack and β-H elimination.
• Self-coupling of primary alcohols yields esters, with β-H elimination as the rate-limiting step.
• The framework predicts new oxidative-coupling reactions involving amines, aldehydes, and alcohols, including carbonylation.

Conclusions:

• The mechanistic framework provides insights into gold-catalyzed oxidative coupling reactions.
• This understanding can predict new reactions and explain existing gold-mediated chemistry.
• The principles are applicable to both model systems and practical nanoporous gold catalysts.