Double Dehydrogenation Of Primary Amines To Nitriles Catalyzed By Transition Metal Complexes

Nitrile compounds are important intermediates in organic chemistry.They are widely used in the production of chemical products such as pharmaceuticals,pesticides,dye,and textile additives.Traditional methods for obtaining nitrile compounds include: the reaction of halogenated hydrocarbons with inorganic cyanide,the Sandmeyer reaction of aryl diazonium salt and the ammoxidation method.These traditional methods to get nitriles need complicated steps and harsh reaction conditions with low atom utilization rate and poor reaction selectivity.The use of highly toxic reagents such as cyanide causes serious environmental pollution.In recent years,it has been found that in the presence of oxidants,amines can be catalyzed by transition metal complexes to produce nitriles,but this process often requires strong oxidants,which can lead to harmful by-products.The method of directly releasing two molecules of hydrogen to convert amines to nitriles has the advantages of high atomic economy and environmental friendliness.However,it is difficult to accomplish the catalytic conversion process in dehydrogenation of amine to nitrile due to the strong nucleophilicity of amines.Therefore,it has become a big challenge for chemists to design and synthesize highly efficient and environmentally friendly catalysts to obtain nitrile compounds in a green method.In this thesis,a series of ruthenium metal complex catalysts containing pyridyl amido ligands were successfully designed and synthesized.These catalysts showed good catalytic effect in double dehydrogenation of primary amine to obtain nitrile compounds.It provided a green and environmentally friendly method for the synthesis of nitrile compounds.The preparation of the ruthenium metal complex is simple.And the ruthenium complex has good stability,and it can achieve the selective hydrogenation of primary amine compounds to produce nitrile with high selectivity.The catalytic reaction can proceed smoothly under the condition of lower reaction temperature(80 ?)with Cs2CO3 as the base additives.Taking dehydrogenation of benzylamine as an example,the yield of benzonitrile can reach 95%.Moreover,we investigated the primary amine substrates with different substituent groups and found that these catalysts showed good substrate applicability.Finally,this article has made a preliminary exploration in the mechanism of the catalytic reaction,using in-situ infrared technology to monitor the progress of the reaction,and proposed a possible reaction mechanism.It is worth noting that this reaction does not use highly toxic reagents and oxidants such as potassium cyanide,which avoids environmental pollution and provides a green and efficient method to produce nitrile compounds.In addition,the only by-product of the catalytic reaction is hydrogen,which can be used as green energy source or hydrogen source for other reactions.The realization of this catalytic reaction also provides ideas for amines as liquid hydrogen storage materials.