Synthesis of pyrogallol derivative as antioxidant additive for biodiesel using methyl linoleate from sunflower oil

Biodiesel is a renewable plant-based fuel as an alternative to fossil fuels containing fatty acid methyl esters. However, biodiesel has the disadvantage of oxidation instability because of the double bonds in the constituent fatty acid structures. One of the most effective antioxidant for biodiesel is pyrogallol. Unfortunately, pyrogallol has a low solubility in biodiesel. Subsequent research was developed by synthesizing pyrogallol derivative through the reaction between pyrogallol and a pure methyl linoleate using 2,2-diphenyl-1-picrylhydrazyl or DPPH as a catalyst. The results showed that the pyrogallol derivative formed was more soluble in biodiesel. However, the use of pure methyl linoleate is not economical because it has a high selling price. In this research, sunflower oil biodiesel with 54.13 % methyl linoleate which has been tested by GCMS will be used to synthesize pyrogallol derivative with a ratio of 10 mL biodiesel, 5 ml DPPH, and 5 mL pyrogallol. FTIR shows a shifting peak at 1240 cm-1 which shows the formation of pyrogallol derivative. LCMS-MS indicates a possible molecular weight at 634 m/z consisting of methyl linoleate and dimer pyrogallol. UV-Vis of the derivatives in biodiesel shows that the derivative is more soluble in biodiesel in comparison with the solubility of pure pyrogallol.