Applications Of Thermal Stabie Ruthenium Catalyst In Metathesis Of Methyl Oleate And Degradation Of Diene-based Rubber

In this thesis,four novel Grubbs III ruthenium based olefin metathesis catalysts were synthesized by ligand exchange reaction between pyridine-phosphinimine ligand and Grubbs III catalyst.The structure of the catalyst was determined by nuclear magnetic resonance spectroscopy(~1H NMR,¹³C NMR and ³¹P NMR)and high resolution mass spectrometry（HRMS）.The thermal stability of the catalysts was tested at 80℃.The results showed that the four catalysts could exist stably at 80℃for 2days without decomposition.Six Grubbs III ruthenium based catalysts were used to catalyze the cross metathesis of methyl oleate and terminal olefins.Six terminal olefins such as ethylene,eugenol,styrene,acrylonitrile,methyl acrylate and chloropropene were selected as reaction substrates.The results showed that 43%-58%conversion of methyl oleate and 18%-36%yield of CM Products could be obtained by using ethylene as reaction substrate and 200-1000 ppm catalyst at 60℃and 80℃;Using eugenol as the reaction substrate and 500-2000 ppm catalyst,68%-89%conversion of methyl oleate and 36%-62%yield of CM Products can be obtained.At high temperature,Ru6 showed the highest catalytic activity.Using ethylene,eugenol and methyl acrylate as olefin substrates,the yield of CM Products was 36%,62%and 57%in turn,the catalytic activity is higher than that of the commercially available Grubbs II and Grubbs III catalysts.The order of catalytic activity of the six catalysts was Ru6>Ru4>Ru3>Ru1>Ru5>Ru2.Six Grubbs III ruthenium based catalysts and two chain transfer agents（cis-1,4-diacetoxy-2-butene and cis-1,4-dichloro-2-butene）were used to degrade diene-based rubber cis-1,4-polyisoprene and cis-1,4-polybutadiene.The results show that Ru1,Ru3,Ru4 and Ru6 have high catalytic activity at 60℃and 80℃.Polyisoprene oligomers with molecular weight less than 3890 g/mol and molecular weight distribution less than 1.33 can be obtained by using 0.2 mol%catalyst,and polybutadiene oligomers with molecular weight less than 3340 g/mol and molecular weight distribution less than 1.42 can be obtained by using 0.1 mol%catalyst.Polyisoprene telechelic oligomer with molecular weight of 2000 g/mol and molecular weight distribution of 1.07 and polybutadiene telechelic oligomer with molecular weight of 1640 g/mol and molecular weight distribution of 1.03 were obtained by catalyst Ru6 at 80℃.Compared with the commercially available Grubbs II catalyst,under high temperature conditions,the molecular weight distribution of the product obtained from the catalysts ru1,Ru3,ru4 and ru6 is very narrow,and the control of the molecular weight distribution of the product is better.The order of catalytic activity of the six catalysts is:Ru6>Ru4>Ru3>Ru1>Ru5>Ru2.