Synthesis of Maleic-Modified Rosin Ester from Pine Rosin

Abstract

Rosin is the major component of Pine sap that has a composition of up to 90%. Rosin is an organic compound that consists of diterpene tricyclic compounds with carboxyl functional group. The presence of this functional group makes rosin becoming acidic and corrosive. Furthermore, rosin also has double bonds that are prone to oxidation when exposed to air. To improve the weaknesses, modifications shall be done. Esterification reaction can be done through transforming into a more stable functional group, ie. ester, while Diels-Alder reaction will saturate the double bonds into more stable cyclic compounds. The results indicate that synthesizing maleic modified rosin ester could improve the properties of pine rosin. Esterification was done using a ratio of glycerol to rosin of 1:3 mol. Esterification was done for 6 hours at 250°C at room and vacuum pressure. The Diels-Alder reaction was done using maleic anhydride at 1:1 stoichiometric ratio to rosin, reacted at 150°C for 1 hour at vacuum condition.