Optimization and kinetic study of methyl laurate synthesis using ionic liquid [Hnmp]HSO₄ as a catalyst

Area of Science:

• Green Chemistry
• Catalysis
• Organic Synthesis

Background:

• Esterification is a key reaction in organic synthesis.
• Traditional acid catalysts pose environmental challenges.
• Ionic liquids offer a promising alternative for cleaner chemical processes.

Purpose of the Study:

• To synthesize methyl laurate from lauric acid and methanol using ionic liquids as catalysts.
• To compare the catalytic efficiency of different ionic liquids and sulfuric acid.
• To optimize the esterification reaction conditions for maximum yield.

Main Methods:

• Esterification reaction using three catalysts: [Hmim]HSO4, [Hnmp]HSO4, and H2SO4.
• Single-factor experiments to investigate reaction parameters (molar ratio, temperature, time, catalyst dosage).
• Response surface methodology for optimizing reaction conditions.
• Kinetic study to determine reaction order and activation energy.
• Catalyst recyclability assessment over five cycles.

Main Results:

• The ionic liquid [Hnmp]HSO4 demonstrated superior catalytic activity compared to [Hmim]HSO4 and H2SO4.
• Optimal reaction conditions were identified as 5.23% [Hnmp]HSO4 dosage, a 7.68:1 methanol/LA molar ratio, 2.27 h reaction time, and 70°C reaction temperature.
• Under optimal conditions, lauric acid conversion reached 98.58%.
• The esterification followed second-order kinetics with an activation energy of 68.45 kJ mol⁻¹.
• [Hnmp]HSO4 maintained high catalytic activity after five reaction cycles.

Conclusions:

• Ionic liquid [Hnmp]HSO4 is an effective and recyclable catalyst for methyl laurate synthesis.
• Optimized reaction conditions significantly enhance lauric acid conversion.
• This study presents a greener and more efficient method for ester production.