Synthesis Of Rosin Polyol Esters

Rosin,an important forest product,has been widely used in the areas of foods,inks,coatings,rubbers,and medical health products because of its excellent properties,such as moisture resistance,corrosion resistance,and isolation.A higher utilization value of rosin can be obtained through the modification process to overcome its low softening point and high acid value;the recycle of modified rosin has aroused much attention.Esterification is the conventional approach to modified rosin among the main modified methods?esterification,hydrogenation,disproportionation,and polymerization?,because the rosin polyol ester synthesized via esterification has several advantages comprising low acid value,high softening point,and the resistance of heat,acid,and alkali.Although the esterification has so many advantages,more eco-friendly and nontoxic catalysts are needed for the preparation of rosin polyol ester.In this paper,the synthesis of rosin polyol ester catalyzed by homogeneous catalysts and ionic liquid catalysts was investigated and the optimal reaction conditions were confirmed.?1?Homogeneous catalysts were used for the synthesis of rosin polyol esters.The optimal reaction conditions:m?zinc stearate?=0.20 g,m?rosin?=15.00 g,m?ethylene glycol?=3.15 g,atmospheric pressure,reaction temperature=270 ^oC,reaction time=10 h.Under this optimal reaction conditions,the acid value,softening point,and color of the obtained rosin ethylene glycol ester were 19.92 mgKOH/g,77.6 ^oC,and 9¹0?Fe-Co?,respectively.Under the optimal reaction conditions of m?rosin?=15.00 g,m?glycerol?=3.50 g,m?zinc stearate?=0.30 g,-0.01MPa of vacuum degree,reaction temperature=230 ^oC,reaction time=10 h,the rosin glyceride was achieved with acid value 9.84 mgKOH/g,softening point 96.5 ^oC,and color 9¹0?Fe-Co?.Under the optimal reaction conditions of atmospheric pressure,m?rosin?=30.00 g,0.20wt%?based on rosin?of zinc stearate,n?pentaerythritol?/n?rosin?=0.25,reaction temperature=250 ^oC,reaction time=7 h,the acid value,softening point,and color of the rosin pentaerythritol ester were 18.07 mgKOH/g,94.7 ^oC,and 9¹0?Fe-Co?,respectively.The analysis of the FT-IR characterization showed that the obtained products were rosin ethylene glycol ester,rosin glyceride,and rosin pentaerythritol ester,respectively.Compared with ZnO as a catalyst,this homogeneous catalyst has the advantages of higher catalytic activity,nontoxic,cheap,and easy to obtain.?2?Br?nsted acidic ionic liquid?[HO₃S-?CH₂?₃-NEt₃]Cl?and Br?nsted-Lewis diacid ionic liquids?[HO₃S-?CH₂?₃-NEt₃]Cl-FeCl₃?x=0.60?,[HO₃S-?CH₂?₃-NEt₃]Cl-CrCl₃?x=0.60?,[HO₃S-?CH₂?₃-NEt₃]Cl-CuCl?x=0.60?,[HO₃S-?CH₂?₃-NEt₃]Cl-CuCl₂?x=0.60?and[HO₃S-?CH₂?₃-NEt₃]Cl-ZnCl₂?x=0.60??were prepared and used for the synthesis of rosin polyol esters.The ionic liquids characterized by FT-IR,acetonitrile and pyridine infrared probes,¹H NMR and thermogravimetric analysis.The results showed that the Br?nsted-Lewis double acid ionic liquids have Br?nsted and Lewis acid sites.When they were applied in the synthesis of rosin polyol esters,it was found that[HO₃S-?CH₂?₃-NEt₃]Cl-ZnCl₂?x=0.60?had the best catalytic performance.Under the optimal reaction conditions:m?rosin?=15.00 g,m?ethylene glycol?=3.15 g,m?ionic liquid?=0.20 g,reaction temperature=270°C,normal pressure,reaction time=5 h,the acid value of the rosin ethylene glycol ester was 17.52 mgKOH/g,softening point was 96.9 ^oC,and color was 14¹5?Fe-Co?.The rosin glyceride had a softening point of 107.2 ^oC,an acid value of 9.66 mgKOH/g,a color number of 14¹5?Fe-Co?under the optimal reaction conditions of atmospheric pressure,15.00 g of rosin,3.50 g of glycerol,0.30 g of ionic liquid,230 ^oC of reaction temperature,and 5 h of reaction time.Under the optimal reaction conditions of 30.00 g of rosin,3.38 g of pentaerythritol,0.06 g of ionic liquid,250 ^oC of reaction temperature,and 5 h of reaction time,the rosin pentaerythritol ester acid value,softening point,and color were 14.42 mgKOH/g,119.4 ^oC,and 14¹5?Fe-Co?,respectively.In general,the rosin polyol esters had lower acid value and higher softening point,but the color was deeper.The FT-IR characterisation of the product confirms that the resulting products were rosin ethylene glycol ester,rosin glyceride,and rosin pentaerythritol ester.The results showed that the catalytic activity of ionic liquid was significantly reduced after reused for 4 cycles.In summary,the homogeneous catalysts had the properties of highly efficient,nontoxic,inexpensive,and not required separation.The process was simple and the product specifications was better,but the reaction time was longer.Further studing found that Br?nsted-Lewis double acid ionic liquids had good catalytic performance and effectively reduced the reaction time.