Modification of Tert-butylhydroquinone with Palmitic Acid as a Soluble Antioxidant for Biodiesel Additive

Biodiesel is a product resulted from the process of transesterification of vegetable oil or animal fat. Biodiesel is a renewable fuel and uses as alternative to fossil fuel diesel. However, one of the biodiesel drawbacks which is oxidation can affect the storage stability of the biodiesel. One way to solve this issue is by using antioxidant additives to improve the storage stability of biodiesel. Tert-Butylhydroquinone is a common synthetic phenolic antioxidant and has a proven superior antioxidant activity due to its polar characteristic. The difference in polarity between non-polar biodiesel and phenolic antioxidant makes their solubility becomes very low. In this study, modification of TBHQ with palmitic acid was done by using Friedel-Crafts acylation to increase its solubility in biodiesel. The resulting proposed product 1-(2-(tert-butyl)-3,6-dihydroxyphenyl)hexadecane-1-one, was confirmed using TLC, LC-MS/MS and ¹H-NMR. The product showed solubility limit at concentration 2500 ppm and antioxidant activity with the IC50 value of 675.38 ppm, which both results are lower compared to TBHQ.