Research On Synthesis Of Glutaric Acid Using γ-Butyrolactone As A Raw Material

Glutaric acid and its derivatives are important chemical raw materials and organic intermediates,which are widely used in chemistry,agriculture,medicine,construction and so on.With the continuous promotion of glutaric acid in the synthesis of glutaric anhydride,sterilization and disinfection lotion,organic synthesis,and other fields,the demand for glutaric acid has grown steadily.In this paper,the method of synthesizing glutaric acid usingγ-butyrolactone as a raw material is selected,which is different from the traditional process of reactingγ-butyrolactone with potassium cyanide at high temperature,adding hydrochloric acid for acidification to obtain glutaric acid monoamide,and then heating and hydrolyzing to obtain the product.Potassium cyanide used in the traditional method is a highly toxic drug,which is dangerous for industrial large-scale production and has serious environmental pollution risks.Several directions studied in this paper are all progressing towards the goal of low toxicity and pollution-free.In the halide intermediate route,the idea of this paper is to open the ring ofγ-butyrolactone to generate the halide intermediate,and then carry out carbonylation to synthesize glutaric acid.Theγ-butyrolactone halogenated ring-opening reaction can be successfully completed,the yield and purity of ethyl bromobutyrate are high,and the yield of ethyl chlorobutyrate can also reach 90%.However,in the carbonylation reaction,both the photocatalytic carbonylation of ethyl bromobutyrate and the carbonylation of ethyl chlorobutyrate by potassium ferrocyanide were unsuccessful.Both have low reactant concentrations and are not suitable for industrial applications.Moreover,both photocatalytic carbonylation and potassium ferrocyanide carbonylation are more suitable for unsaturated halides,and saturated linear halides are difficult to use the above two milder reactions.In addition,these two routes need to consume a lot of other raw materials exceptγ-butyrolactone,and the production cost is too high,and it is not suitable for industrial application,so it is necessary to find a solution with few synthesis steps and high yield of glutaric acid.In the route of catalyzingγ-butyrolactone carbonylation to synthesize glutaric acid by rhodium catalyst,the optimal conditions for obtaining the reaction under laboratory conditions are as follows:the amount of catalyst Rh₂（CO）₄Cl₂ is 0.1g;the amount of co-catalyst methyl iodide is 10g;the amount of added stabilizer HI is 5g;the temperature is 180°C.In the follow-up experiments,the effect of pressure on the reaction should be supplemented,and the purification and separation process of glutaric acid should be further explored.In this paper,a new route to synthesize glutaric acid fromγ-butyrolactone was reported based on the principles of green environmental protection and lower cost of raw materials.The conditional screening and optimization of the synthetic route were carried out,and the technological route suitable for industrial production was explored.It provides a new idea in the production of glutaric acid for researchers.