Ionic And Neutral Phosphines:Synthesis, Characterization And Application To Carbonylations

Carbonylations are the transformations of organic substrates?aryl halides or unsaturated hydrocarbons?,CO and the nucleophiles?such as primary alcohols,primary/secondary amines,water,hydrogen etc.?towades the high value-added carbonyl compounds?esters,amines,acids,aldehydes etc.?.When the nucleophiles are primary alcohols,primary/secondary amines,water or hydrogen,the corresponding carbonylation are called alkoxycarbonylation,aminocarbonylation,hydrocarboxylation or hydroformylation.In this thesis,the invenstigations on alkoxycarbonylation of aryl halides and hydroformylation of alkenes were carried out and the obtained results were summarized as follows.?1?Neutral/ionic phosphines based Ru-catalysts for alkoxycarbonylation of aryl halides.Alkoxycarbonylation of aryl halides with alcohols has become an attractive route for synthesis of aromatic esters.Palladium complexes modified by phosphine ligands play an important role in the reaction of alkoxycarbonylation,while Ru complexes have been rarely used to catalyze this reaction.In this part,the Ru³⁺-complex?RuCl₃·3H₂O as the precursor?was used as an efficient catalyst for alkoxycarbonylation of aryl halides.A series of neutral phosphines?L1,L3 and L5?and ionic phosphines?L2,L4 and L6?were prepared and applied to modulate the catalytic performance of RuCl₃·3H₂O.The ionic phosphine L4 which has strong?-acceptor ability based RuCl₃·3H₂O system shows the best catalytic performance for alkoxycarbonylation.The single crystal structure of Ru^III-L4 indicated that a quadrilateral ring dimer was formed and due to the electron-deficient nature of L4,the redox between L4 and the high valence state Ru³⁺was avoided.It was found in Ru^III-L4 that the distance of the four Ru-Cl bonds inside the quadrilateral ring were dramatically lengthened due to the additional developed hydrogen bond between Cl^-and H-butylenyl group.The weakened Ru-Cl bonds inside the quadrilateral ring were able to be cleaved preferentially to provide unsaturation site for oxidative addition of aryl halids and coordination of CO for the formation of Ru-acyl intermediate?Scheme1?.In addition,as an ionic phosphine,L4-based RuCl₃·3H₂O system could be recycled successfully for at least eight runs in the room temperature ionic liquid which solved the problem of catalysts recovery and recycling in homogeneous catalytic process.?2?Neutral/ionic phosphines based Rh-catalysts for hydroformylation of mixed long-chain?-olefinsHydroformylation of olefins and syngas?CO/H₂?is a 100%atom-economic route for the production of aldehydes.The phosphine-modified rhodium complexes are the most efficient catalytic systems in this reaction.Coal based Fischer-Tropsch synthesis can produce a large amount of long-chain?-alkenes.They can be converted into aldehydes via hydroformylation and then be transformed into high carbon alcohols which are the main raw materials of detergent and plasticizer.Hence,hydroformylation of mixed long-chain?-olefins not only improves the economic benefit of coal-based Fischer-Tropsch synthetic oil industry,but also expands the synthesis route of high-carbon alcohols.In order to explore the influence of phosphines on the catalytic performance of Rh?acac??CO?₂ for hydroformylation of long-chain mixed olefins?1-octene,1-decene,1-dodecene,1:1:1 molar ratio?,a series of neutral/ionic phosphines?L1-L8?were synthetized and applied in this reaction.The result demonstrated that diphosphines showed better catalytic activity than monophosphines.In addition,L7-based Rh?acac??CO?₂ catalyst exhibited the best catalytic activity?Scheme 1?.L7 have strong?-acceptor ability and the two PPh₂-located in cis-position,both were favorable for chelating to Rh enter.The stable Rh-P complex promotes the reaction of hydroformylation smoothly.Scheme 1 The as-synthesized phosphine ligands and Ru^? complex(Ru^?-L4)...