Design Of Novel Catalysts For Olefin Oligomerization And The Study On The Nitrilation Of Conjugated Dienes

Polyethylene and alpha-olefin are the two main products in the petrochemical industry.Polyethylene is mainly used as the raw material for polyolefin plastics,while alpha-olefin is utilized in the production of various items such as lubricants,detergents,cosmetics,adhesives,and coatings.Ethylene polymerization is the primary method for producing these two products,and the catalyst used in this process plays a significant role.Currently,extensive research has been conducted on these catalysts.The diimine pyridine based-cobalt complexes are a group of widely used catalyst in ethylene polymerization,and the distribution of oligomerization can be controlled by regulating the steric hindrance of the arenes in the cobalt-diimine catalysts.In the 2-aryliminophenanthroline based cobalt catalysts,the increase of steric hindrance of arenes can increase the proportion of long chain products,but the oligomer products are still mainly butene with only a few long chain products.This project comes from the cooperation of petrochemical enterprises.According to the current studies that only focused on the increase of the steric hindrance on the arenes,we designed a series of2-aryliminophenanthrolines with large steric hindrance（tert-butyl）on side-chain and long alkyl side chain to explore their influence on ethylene oligomerization.Herein,a series of long chain and high steric hindrance cobalt complexes were synthesized from acyl chloride and vinyl ether through a five-step reaction.The catalyst with high steric hindrance has higher activity which can promote the formation ofα-olefins with longer chain,but the activity of catalyst decreases with the extension of chain.Based on Co-catalyst,the functionalization of olefin and dienes was designed.Preliminary results were obtained in the silylation and nitrile reaction of olefin.Under the condition of a series of co-catalysts synthesized in this project,the reduction and hydrosilylation of bridged norbornene were successfully realized.Though the regioselective conversion of conjugated dienes to cinnamaldehydes has been fully studied in past few decades,the direct conversion of conjugated dienes toα,β-unsaturated nitriles has still been uncovered.For the further development of the functionalization of olefins and dienes,we designed the directly regioselective oxidative cleavage of conjugated dienes intoα,β-unsaturated nitriles through an aziridine intermediates,a ring-opening with ammonium carbamate followed by the further oxidative.The current protocol has high regioselectivity,where only terminal alkene was cleaved in the conjugated dienes.As a cyanation process,none of toxic cyanide was used as a cyanide source.A large variety of conjugate dienes were tolerated,including mono-substituted butadienes,1,1-disubstituted butadienes and1,2-disubstituted butadienes.Comparing with the electron-rich dienes,electron-deficient conjugated dienes are more compatible for the current transformation.Beside the aromatic conjugated butadienes,the alkyl butadienes are also tolerated in current condition.Furthermore,the internal alkenes are also suitable,where two nitriles were obtained.Finally,this method is also applied to the synthesis of ¹⁵N labeledα,β-unsaturated nitriles,especially used for the synthesis of ¹⁵N labeled Ripiverine precursors.