Studies On Synthesis, Characterization And Antibacterial Activities Of Derivatives Of Dehydroabietic Acid

Dehydroabietic acid (DAA) is one of the rosinolic acid isomers in rosin, and is the main component of disproportionated rosin. It is a chiral compound with three chiral carbon atoms. Because of the special properties from its aromatic diterpene structure with carboxyl group, it has been widely used in different fields e.g. paint, printing ink, adhesives, papermaking, biological product, etc. In this dissertation, two new rosin derivatives based on alteration of the carboxyl group have been synthesized.Glucose dehydroabietate has been synthesized from dehydroabietic acid and glucose in propanediol. The effects of reaction temperature, time, the amount of catalyst, the amount of solvent and the mixing mole ratio of reactants have been investigated. The structure of product has been characterized with several analytical methods e.g. UV, FT-IR, TLC etc. The results indicate that the optimum reaction conditions were: the reaction temperature 190℃, reaction time 6h, the mixing mole ratio for glucose to dehydroabietic acid is 5:1, the catalyst amount is 4%( based on the mass of dehydroabietic acid), the solvent amount is 5mL. The yield of product could reach 50.95%. Furthermore, the general characters of the product e.g. surface tension, critical micelle concentration and emulsified ability, etc. were measured respectively. It can be also concluded from CMC that GDA have satisfactory surface activity.Under normal atmosphere, Dehydroabietic acid, which was purified from disproportionated rosin, reacted with dimethyl sulfoxide to form a new rosin derivative—methylthiomethyl dehydroabietate. The effects of reaction temperature, time, the amount of catalyst and mixing mole ratio of reactants on the yield have been investigated. The optimum reaction conditions were as follows: the reaction was kept at 215℃for 3h with dimethyl sulfoxide/ dehydroabietic acid mixing mole ratio of 22: 1 and 0.4% catalyst ( based on the mass of dehydroabietic acid). The yield of product could reach 94%. The precise structure of the product was characterized as methylthiomethyl dehydroabietate by TG-DTA, GC-MS, UV, FT-IR, FT-IR, High-Resolution Mass Spectrometry ¹³CNMR and ¹HNMR.From methylthiomethyl dehydroabietate, another derivative—methylsulfinylmethyl dehydroabietate has been synthesized by oxidation of hydrogen peroxide. The effects of reaction temperature, time, the amount of hydrogen peroxide and solvent on the yield have been discusstioned. The optimum reaction conditions were found as: the reaction was kept at 60℃for 5h with the mole ratio for methylthiomethyl dehydroabietate/hydrogen peroxide 1:21 and 15 mL solvent. The purity of product was above 95% and the yield of product was up to 97.91%. The precise structure of this product was characterized as methylthiomethyl dehydroabietate based on UV, HPLC, TG, LC-MS, FT-IR and 1H NMR results.Besides, the antibacterial activity of the two products has also been investigated. The biological tests showed that methylsulfinylmethyl dehydroabietate possessed obvious antibacterial activities against staphylococcus aureus(SA) with the minimal inhibitory concentration (MIC) of 6.25ug/mL.