A closed cycle for esterifying aromatic hydrocarbons with CO₂ and alcohol

Area of Science:

• Catalysis
• Organic Chemistry
• Materials Science

Background:

• Hydrocarbon functionalization with CO2 offers high-volume utilization opportunities.
• Current methods require stoichiometric, resource-intensive reagents due to low substrate reactivity.

Purpose of the Study:

• To develop a reagent-free method for converting aromatic hydrocarbons and CO2 into aromatic esters.
• To utilize solid bases with alkali carbonates dispersed on mesoporous supports.

Main Methods:

• A semi-continuous cycle involving C-H carboxylation and methylation.
• Utilizing alkali carbonates (K2CO3 or Cs2CO3) on mesoporous supports as solid bases.
• Employing nanoscale confinement to enhance base reactivity at intermediate temperatures.

Main Results:

• Successful conversion of aromatic hydrocarbons, CO2, and alcohol into aromatic esters without stoichiometric reagents.
• Demonstrated CO3(2-)-promoted C-H carboxylation forming supported carboxylates (RCO2M).
• Achieved ester formation and regeneration of the solid base via reaction with methanol and CO2.

Conclusions:

• The developed method provides a sustainable pathway for CO2 utilization in ester synthesis.
• Nanoscale confinement of alkali carbonates enhances reactivity for efficient hydrocarbon functionalization.
• The semi-continuous cycle offers a practical approach for producing aromatic esters from abundant feedstocks.