Construction And Performance Of High-Efficient Catalytic System For Carbon Monoxide Carbonylation

Carbon monoxide(CO)is one of the cheap and abundant carbon resources.Its carbonylation with other chemicals is the most commonly used method to prepare carbonyl compounds.Among them,carbonylation reaction with transition metal as catalyst is one of the hot spots,which has been paid more and more attention.With the structural adjustment and technological upgrading of China's chemical manufacturing industry,carbonylation with higher atomic economy will play a more and more important role in this field.One of the most important research topics in carbonylation of CO under relatively mild conditions is how to construct an efficient catalytic system.This study will focus on the utilization of CO as carbonyl source.Firstly,the application of transition metal and carbene ligands in the carbonylation reaction and the transformation of lignin were reviewed.Then,some new catalytic systems based on iridium were designed and synthesized.Finally,the applications and the performances of these new catalytic systems in the preparation of methyl acetate,aryl acetates and aromatic amides were investigated.The main conclusions and progress are as follows:(1)Cyclic(alkyl)(amino)carbene iridium(CAAC-Ir)was synthesized for the first time under anhydrous and oxygen-free conditions.Potassium bis(trimethylsilys)amide was employed to remove the hydrogen from cyclic(alkyl)(amino)carbene ligand and chloro(1,5-cyclooctadiene)iridium(I)dimer was used to synthesis CAAC-Ir.Nuclear magnetic resonance,high resolution mass spectrometry,elemental analysis and single crystal diffraction were employed to characterize the CAAC-Ir catalyst.Then the experiment was carried out to investigate the catalytic performance of CAAC-Ir in the synthesis of methyl acetate from methanol carbonylation and the density functional theory(DFT)was employed to investigate the reaction mechanism of the methanol carbonylation process.Comparison of the previous methods in the preparation of methyl acetate with this catalytic method,it indicates that CAAC-Ir has a more efficient catalytic performance and can directly synthesize methyl acetate from methanol carbonylation under mild conditions.(2)A new catalytic system with iridium chloride as the main catalyst and methyl iodide as the cocatalyst was constructed for the preparation of phenylacetate from aromatic methyl ethers or phenols.Using anisole as the standard substrate,the optimized reaction conditions of carbonylation to phenylacetate were established by optimizing the experiments.The scope of substrates was tested and showed that aromatic methyl ethers and phenols with different substituents could achieve good results under the optimized reaction conditions.Based on the controlled experiments,a possible reaction mechanism was proposed for the preparation of aryl acetates from aryl methyl ethers and phenols.Comparison of this new catalytic system with the previous methods in the preparation of aryl acetates,it shows that CO can be used in directly synthesizing aryl acetates under much lower pressure of the reaction,which indicates that this new catalytic system has obvious technical advantages.(3)A new catalytic system with Ir Cl₃ as the main catalyst and Li I as the co-catalyst was established for the efficient synthesis of aromatic amides from amines.The reaction conditions were optimized using N-methylaniline as the standard substrate and anisole as source of methyl.The scope of substrates was also tested based on the optimized reaction conditions and excellent yields of aromatic amides were obtained when different kinds of amines were employed.On this basis of above studies,the transformation performances of N-methylaniline to N-methylacetanilide was investigated with different methyl ethers,kraft lignin and organosolv lignin as the source of methyl.The possible mechanism of the reaction was proposed based on the controlled experiments.Comparing with the previous preparation methods of aromatic amides,this new catalytic system of Ir Cl₃ as the main catalyst and Li I as the co-catalyst can effectively synthesize aromatic amides from amines without the additions of anhydride,acetyl chloride or other acylation reagents.This will provide a new potential route to the industrial utilization of lignin.