Study On Synthesis And Properties Of Novel Functional Derivatives From Modified Rosin And Condensed Tannins

Rosin and condensed tannins are extremely abundant in China, and both ofthem are natural and renewable resources. However, most of rosin is nowexported as raw material, and condensed tannins are mainly used as leathertanning. Therefore, the exploitation of deep processing products of them toincrease their commodity additional value is a significant research projectworthy of carrying out deeply. The three-ring phenanthrene skeleton inmolecules of rosin is hydrophobic as the long-chain alkyl group in higher fattyacids, and hydrophilic groups can be introduced through the carboxyl groups inthe resin acids of rosin, so rosin can be used as raw material to synthesizesurfactants. Condensed tannins have excellent antioxidative property andhydrophilic ability, because they contain a large amount of phenolic hydroxylgroups. Based on the structural characteristics and chemical properties of rosinand condensed tannins, esterification reaction can take place between resin acidsin rosin and condensed tannins under some conditions. Modifiedrosin-condensed tannins esters were synthesized by O-acylation reaction ofcondensed tannins with modified rosin chloride. The properties of the products,such as antioxidation and surface activities were also determined. This researchaims at the investigation of a new path for the deep processing of condensedtannins and rosin which are both natural and renewable resources in China.Firstly, dehydroabitetic acid chloride was prepared at first by the reaction ofdehydroabitetic acid with SOCl₂. Then, dehydroabitetic acid phenol ester(DHA-PE) and dehydroabitetic acidβ-naphthol ester (DHA-NE) weresynthesized by O-acylation reaction of the dehydroabitetic acid chloride withphenol andβ-naphthol, respectively. The main influence factors for the synthesis of DHA-NE were studied and the optimal conditions were found by orthogonalexperimental design to be as follows: reaction temperature 100℃, reaction time3.0 h, molar ratio of dehydroabitetic acid chloride to pyridine 1:1.4, molar ratioof dehydroabitetic acid chloride toβ-naphthol 1:1.2. As a consequence, the yieldof DHA-NE was 78.5%. The target product was analyzed and characterized byTLC, IR, UV, GC-MS,¹³C-NMR and ¹H-NMR methods.Secondly, microwave irradiation method, ultrasonic method and highpressure steaming method were applied to extract condensed tannins fromAcacia mearnsii bark. The optimum extraction conditions were studied and allthe extraction methods were compared. The optimum extraction conditions bymicrowave irradiation method were found to be as follows: temperature 85℃,ratio of solid to liquid 1:55 (w/v), radiation time 25min, and under the optimumconditions the content of condensed tannins in Acacia mearnsii bark amountedto 49.45% which was the maximal value among the three methods. Theoptimum extraction conditions by ultrasonic method were found to be as follows:supersound power 90%, ratio of solid to liquid 1:75 (w/v), supersound time20min, and under optimum conditions the content of condensed tannins inAcacia mearnsii bark amounted to 43.71%. The optimum extraction conditionsby high pressure steaming method were found to be as follows: steamingtemperature 160℃, ratio of solid to liquid 1:75(w/v), steaming time 30min, andunder the optimum condition the content of condensed tannins in Acaciamearnsii bark amounted to 48.25%. The results showed that microwave methodwas the best method in the extraction of condensed tannins. The condensedtannins extracted by microwave irradiation method under the optimumconditions were analyzed and characterized by means of IR, UV, TG-DTA andXRD.Finally, under microwave irradiation and in the presence of pyridine ascatalyst, a series of modified rosin-condensed tannins esters were synthesized byO-acylation reaction of condensed tannins and modified rosin chloride, and thesynthetic conditions were studied. The target products were analyzed andcharacterized by means of UV, IR, TG-DTA, XRD and elemental analysis. Thetest of antioxidative property showed that modified rosin-condensed tanninsesters had better oil-solubility in peanut oil than condensed tannins, and theantioxidative effect of modified rosin-condensed tannins esters were also better than that of condensed tannins. The surface activity such as surface tension,emulsifying power and foaming ability were tested. It indicated that sodium saltsof the modified rosin-condensed tannins esters, especially sodium salts of thehydrogenated rosin-condensed tannins esters had satisfying surface activity.