Selective and Efficient Synthesis of Pine Sterol Esters Catalyzed by Deep Eutectic Solvent.

Area of Science:

• Green Chemistry
• Organic Synthesis
• Biocatalysis

Background:

• Phytosterol esters offer health benefits like cholesterol reduction and antioxidant properties.
• Current synthesis methods generate by-products, limiting food industry applications.
• Deep eutectic solvents (DESs) present a sustainable alternative due to their eco-friendly nature.

Purpose of the Study:

• To develop an efficient and eco-friendly method for synthesizing pine sterol esters.
• To optimize reaction conditions using a specific DES catalyst.
• To investigate the minimization of by-products and catalyst reusability.

Main Methods:

• Screening and optimization of an acidic DES catalyst (choline chloride:p-toluene sulfonic acid monohydrate).
• Optimization of substrate ratio, catalyst loading, temperature, and reaction time.
• Synthesis of pine sterol esters using various fatty acids.
• Analysis of by-product formation and catalyst recyclability.
• Density Functional Theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• An acidic DES (ChCl:PTSA, 1:3 molar ratio) demonstrated optimal catalytic performance.
• Optimized conditions yielded up to 94.1% pine sterol ester.
• By-product formation from sterol dehydration was significantly inhibited.
• High yields (>92.0%) were achieved with different fatty acids.
• The DES catalyst maintained efficiency over five recycling uses.
• DFT calculations confirmed the role of DES in reducing by-products.

Conclusions:

• A reliable and eco-friendly strategy for high-quality phytosterol ester preparation was established.
• The developed method offers high selectivity and low catalyst dosage.
• DES-catalyzed synthesis is a promising approach for industrial applications in the food sector.