Synthesis Of Paraben And Cinnamate Catalyzed By Ionic Liquids

Parabens and cinnamates compounds have high practical value,and they are non-toxic in green.Among them,the paraben compound has a hydroxyl structure,and its antibacterial activity and broad-spectrum is significantly higher than other conventional additives such as sorbic acid.Because of its non-toxic and easily degradable characteristics,it is an indispensable member of the food industry.The cinnamic acid compound has an irreplaceable role in the flavor additive because of its unique aromaticity.However,many reports about the esterification reaction with the strong acid as the catalyst.This process not only has high time cost,but also has strong corrosiveness and cannot be recycled.Therefore,the development of a green and efficient new esterification process still has high research value.Ionic liquids are stable in physical and chemical properties,have high catalytic activity and can be adjusted by changing anions and cations.The most important thing is that they are easy to recycle and have recycling characteristics.They are currently green and efficient in the field of catalysis.One of the important members.In this paper,nine benzothiazole ionic liquids were synthesized by reacting benzothiazole with five inorganic acids and two organic acids,and two new heteropoly acid-benzothiazole ionic liquids were designed and characterized by FT-IR,scanning electron microscopy(SEM),powder XRD,and thermogravimetry(TGA).their structure and associated physical properties were characterized.Using the prepared benzothiazole ionic liquids,a total of 20 parabens and cinnamates compounds were synthesized,and divided them into 3 categories according to the physical properties alcohol raw materials and the post-treatment methods.The best synthesis process was discussed,and the effects of molar ratio of alcohol and acid,reaction temperature,reaction time,beating(recrystallization)temperature,ionic liquids dosage and recycling times on the process were investigated.A completely environmentally friendly esterification process for p-hydroxybenzoic acid and cinnamic acid was established.The results show that when the amount of catalyst is 12% mol,the catalytic effect of benzothiazole ionic liquids is particularly significant,and the average yield is higher than 80%.By comparing the catalytic effects of the nine ionic liquids on the esterification reaction,it was found that the heteropoly acid-benzothiazole ionic liquid had the best catalytic effect.The benzothiazole ionic liquid is a typical heterogeneous solid catalyst,which is easy to recover and has good stability.When it is repeatedly used for 5 times by vacuum drying,the catalytic activity is still not significantly reduced,and it is a high-efficiency,green new catalyst.