Comparative Study On Thermocatalytic And Photocatalytic Oxidative Coupling Of Alkyne Over CuFe₂O₄-based Catalyst

1,3-diyne compounds and their derivatives have a wide range of applications in medicine,organic synthesis,supramolecular chemistry and other fields.The synthesis of1,3-butadiyne is mainly an oxydimerization of the terminal alkyne,that is,the Glaser reaction.Copper catalysts have proven to be inexpensive and efficient catalysts for this reaction.They are widely studied and are mainly composed of Pd/Cu,Cu?I?,Cu?II?and CuNPs?copper nanoparticles?.CuNPs are widely used in the field of photocatalysis due to the plasmon resonance effect?SPR?,but its instability in the air,which limits the development of CuNPs,there has been no report on the use of CuNPs in the photocatalytic Glaser reaction.In this study,CuFe₂O₄ spinel catalysts were prepared by coprecipitation and low temperature combustion.Under visible light or under heat,it can effectively induce the phenylacetylene coupling to synthesize 1,4-diphenyl-1,3-diacetylene under room temperature,without alkali.Light-induced catalysis has a higher yield than the thermo-catalytic reaction.1.CuFe₂O₄ spinel materials were prepared by co-precipitation method and low-temperature combustion method respectively,and active catalysts were obtained under different reduction temperatures in hydrogen atmosphere.The composition and structure of the catalysts were characterized by means of XRD,H₂-TPR,AAS,UV-Vis,SEM,XPS and VSM.The similarities and differences of the composition,structure and properties of the two materials were compared.2.The catalyst is used for thermal catalytic coupling of phenylacetylene.The coupling of phenylacetylene can be carried out under alkali-free conditions,and the polar weakly basic DMSO facilitates the reaction.Compared with co-precipitation method,CuFe₂O₄spinel prepared by low-temperature combustion shows higher activity,and the catalytic activity of hydrogen reduced CuFe₂O₄ is as high as 93%at 300°C.However,the CuFe₂O₄catalyst reduced at 250°C showed better cycle stability,and the reaction conversion rate could reach 67%after 5 cycles.3.The catalyst was used for photocatalytic phenylacetylene coupling reaction.Under the irradiation of visible light,polar ethanol was used as the solvent,we obtain a room temperature,alkali-free and high-efficiency heterogeneous catalytic system,and the reaction yield was considerable and higher than that of thermal reaction.Similarly,CuFe₂O₄ spinel prepared by low-temperature combustion also shows higher activity.The300°C hydrogen reduced CuFe₂O₄ had the highest reactivity?100%?.However,the reduced CuFe₂O₄ at 250°C showed better cycle stability,and the reaction conversion rate was still up to 55%after 4 cycles.Moreover,the reaction was successfully converted under sunlight irradiation,and the conversion rate was 63%at 8 h.