Synthesis Of Zinc Citrate By Conventional And Microwave Heating Methods

Microwave technology has been widely used in organic chemistry, material sciences, medicinal chemistry, biochemical processes, nanotechnology, green chemistry and food chemistry, as a way to provide microwave energy. The most important characteristic is that it can accelerate the reaction rate, and reduce the reaction time. This method makes chemical reactions become more and more high-speed, low-energy-costing, high-efficiency, green and environmentally friendly.With the water as the solvent, Water soluble zinc citrate(Zn3(C6H7O2)2·3H2O)was successfully synthesized from citric acid and zinc oxide as the raw material by microwave heating method and conventional heating methods. The obtained products was characterized by means of EDTA complexometric method, EA, FT-IR and TG.The effects of reaction temperature, time, molar ratio of citric acid/zinc oxide and dosage of deionized water in the two synthesis process on the yield of Zn3(C6H7O2)2·3H2O were studied, and the optimal combination of the yield of Zn3(C6H7O2)2·3H2O was obtained. Response surface analysis was conducted for optimizing the main technical parameters with the content of the yield of Zn3(C6H7O2)2·3H2O as index, and received the regression model. And the effect of microwave irradiation on the reaction conditions was investigated through parallel experiments.The yield of Zn3(C6H7O2)2·3H2O was 97.81% under the optimal conditions(Temperature 75℃, Moral ratio of citric acid/zinc oxide 2.4:3, Reaction time 120 min, Dosage of deionized water 35 mL) in the conventional heating method.And on the basis of single factor experiment, response surface experiments were conducted on the four significant effects factors synthesis zinc citrate, the results showed that temperature was 75℃, moral ratio of citric acid/zinc oxide 2.4:3, reaction time 115 min, dosage of deionized water 35 mL, the average yield of zinc citrate was98.32%.Compared with conventional heating method, the yield of Zn3(C6H7O2)2·3H2O was 98.56% under microwave power 300 W, temperature 55℃, moral ratio of citric acid/zinc oxide 2.1:3, reaction time 40 min and dosage of deionized water 40 mL.After response surface experiments, the average yield of zinc citrate increased to 99%.Microwave synthesis is a kind of new method, which is better than conventionalheating method. Not only is direct microwave heating able to reduce chemical reaction times from hours to minutes, but it is also known to increase yields, save the raw material and energy.