New silica supported HClO4 as an efficient catalysts for the estolide synthesis from oleic acid

Abstract

The synthesis of estolides via condensation reaction of oleic acid were investigated using heterogenous and homogenous catalysts. The condensation reaction usually carried out by using of various acids catalysts, such as H2SO4, H3PO4 and HClO4. HClO4 is highly toxic, give a major problem to cleaner technology and cause severe corrosion problem. In this studies HClO4 could be made environment friendly catalyst by supporting onto suitable supports. A series of the solid acid catalyst containing 5-45 % of perchloric acid supported onto silica was synthesized. All amorphous material catalysts were characterized using XRD, BET surface area measurement, TEM and XPS surface analysis. Silica modified with perchloric acid has been found to be efficient and environmentally benign solid acid catalyst for estolide synthesis. The reaction has been performed for 10 hours at 70 0C to give oleic-oleic monoestolide acid, m/z 563.51 as (M - H) -. The solid acid catalyst is easily separated from the reaction mixture. Based on the experimental findings above, catalytic performance was optimized with loading 15 % HClO4 onto SiO2. These catalyst was HClO4 on silica gave 98.98 % conversion with 63.98 % oleic-oleic monoestolide acid, m/z 563.51 (M-H) - selectivity. The similarities between homogenous and heterogenous acid-catalyzed are also discussed.