Study On Synthesis And Mechanism Of Cyclododecatriene

The field of new energy vehicles is on the highway of development,and the demand for lightweight vehicles is also increasing.Nylon 12 is one of the important materials for lightweight applications,and 1,5,9-cyclododecaectriene is the key intermediate in the synthesis of nylon 12,and can also be used in the synthesis of many organic compounds.However,there are some problems in the synthesis of 1,5,9-cyclododecatriene,such as low catalyst activity,low monomer conversion and low structural selectivity.In addition,there are few researches on the mechanism of the synthesis of macrocyclic structure,and there is a lack of effective calculation and analysis.Therefore,it is very important to develop a simple and efficient catalyst for the synthesis of 1,5,9-cyclododecatriene and to study the synthesis mechanism.Based on this,four supported metal catalysts were designed and synthesized in this paper,and 1,5,9-cyclododecatriene was synthesized with 1,3-butadiene as the oligomer.The influence of oligomerization experimental conditions on the catalytic effect was explored,and the structural selectivity of the synthesized products was studied theoretically.Firstly,a new supported metal catalyst Cat.1-Cat.4 with four kinds of cationic surfactants containing nitrogen elements as raw materials was synthesized.¹H-NMR spectra showed that the ligands in the catalyst structure were successfully complexed with Ti atoms.Scanning electron microscopy showed that the surface morphology of the catalyst was rough and there were many voids.The half-peak width of Ti2p₃ of Cat.2 was significantly reduced by XPS characterization,which indicated that the type of catalytic active center of the synthesis catalyst was relatively single.The results of oligomerization of 1,3-butadiene with the synthesized catalyst show that Cat.2 has the best catalytic effect.Under the optimal reaction conditions,toluene was used as the solvent,catalyst amount was0.2 g/L,cocatalyst was selected as thelixyethyl aluminum chloride,n（Al）/n（Ti）=50,oligomeric reaction temperature was 50℃,butadiene amount was 1.0 g,the monomer conversion of cyclododecatriene was as high as 93%.The results of NMR,FT-IR and GC-MS of the oligomers showed that ctt-1,5,9-cyclododecatriene was synthesized without isomers,and the structural selectivity of 1,5,9-CDT was 100%.The synthesis process is green and has potential industrial application value.DFT calculation was used to study the oligomerization pathways and analyze the reasons for the structural selectivity.The results showed that the structure obtained from the optimal path was consistent with the structure of the experimental product,which was ctt-1,5,9-cyclododecatriene.The structural selectivity was the result of thermodynamic selection.This conclusion enriches the theoretical system of the synthesis mechanism of macrocyclic organic matter.