Research on catalytic synthesis of trioctyl citrate

The heterogeneous phase synthesis of trioctyl citrate (TOC) is carried out with citric acid and iso-octyl alcohol as raw materials and potassium bisulfate (KHSO₄) as catalyst. The effects of molar ratio of reactants, reaction temperature, reaction time and dosage of catalyst on the synthesis are investigated. The optimized reaction conditions are shown as follows: 5.0 of molar ratio of citric acid to iso-octanol, 150 °C of reaction temperature, 2 h of reaction time and 3% of catalyst mass fraction (based on all reaction materials).Under the optimal reaction condition, the esterification yield of citric acid can reach over 96%. It also finds that KHSO₄ has good reusability. The esterification yield is 90.85% after six times' consecutively reuse.Moreover, the catalyst has the characteristics of easy to separate from products, high recovery availability, lower corrosion and environmental pollution.