Abstract: [Objective] A novel monomer, tri-allyl maleopimarate with three functional C=C bonds, was synthesized by introduction of maleic anhydride in rosin structure under microwave irradiation through Diels-Alder reaction. The newly synthesized monomer, consisting of three functional C=C bonds, is proposed to have plenty of reactive functionalities during free radical polymerization. Then the rosin structure can be directly introduced into polymers. The successful synthesis of the new multi-functional polymerization monomer provides a new path for the deep processing in China.[Method] Sodium maleopimarate was prepared from maleopimaric acid and sodium hydroxide through neutralization reaction using ethanol or water as solvent respectively. Then tri-allyl maleopimarate was synthesized from sodium maleopimarate followed by phase transfer reaction with allyl choloride under microwave-assisted conditions. The structure of the product was characterized by FT-IR, GC and MS.[Result] The optimized reaction conditions were as follows:microwave power 400 W, reaction temperature 55℃, reaction time 4 h, n(allyl chloride):n(sodium malaypimarate)=3:1, and the amount of catalyst 5%. Under the above conditions the yield of the product was 93.2%, and the purity of tri-allyl maleopimarate was 96.1%. FT-IR analysis showed that three carboxyl groups were successfully introduced in the rosin structure through esterification reaction. The byproducts identified in this reaction are allyl maleopimarate and di-allyl maleopimarate using ethanol as solvent. Only single byproduct can be observed using water as solvent. The physical and chemical properties of the synthesized products were tested. The products appeared as a viscous liquid at room temperature, with a viscosity of 8.5×10³ mPa·s at 25℃. The density and the acid value of the product were determined as 1.109 7×10³ kg·cm^-3 and 2.5 mg KOH·g^-1 sample, respectively.[Conclusion] Tri-allyl maleopimarate is proposed as a new type of natural rosin-derived reactive monomer. The purity of tri-allyl maleopimarate using water as solvent was higher than that of using ethanol as solvent.

Key words: maleopimaric acid anhydride(MPA), microwave-assisted, synthesis, tri-allyl maleopimarate, characteristic