Study On Direct Acid Amination Catalyzed By Nickel And Titanium Cataly

As the key functional group of protein,amide bond is widely existed in many chemical structures such as polymer,medicine and food additive.The main methods of constructing amide bond include condensation,acyl halogen method and so on.These methods have many disadvantages such as producing lots of waste,poor atom economy,using expensive coupling reagent,etc.The catalytic direct amidation method to construct amide bond almost has no waste except water as by-product.Therefore,it is of great important to seek and develop catalysts for catalyzing direct amidation.In this paper,the feasibility of direct amidation catalyzed by nickel and titanium catalysts is explored.The main work of this paper includes the following two parts:Using phenylacetic acid and benzylamine as models,the catalytic properties of nickel chloride catalysts,such as NiCl₂?DPPE·NiCl₂?DPPP·NiCl₂?NiCl₂?PPh₃?₂?Ni?CH₃COO?₂ and Niacac.It was found that all of the catalysts have catalytic effect and nickel chloride is the best catalyst.The optimum reaction conditions were obtained by optimizing the reaction conditions with nickel chloride as catalyst,with toluene as the solvent,the 10%mole catalyst reacted at 110?for 20 hours,and the yield of the target amide was 99.2%.On the basis of this,the applicability of the catalytic method to different acid substrates was discussed.It was found that,except for benzoic acid substrates,other acid derivatives and benzyl amines could obtain the target amides in the yield of?58.1%-99.2%?.For phenylacetic acid substrates,the type and position of substituents on aromatic rings have great influence on the yield of target amides.In different positions,the yield order of the target amide is:para>meta>ortho.For long-chain fatty acid compounds,the method can obtain the target product in the yield of 68.4%-91.3%,and the yield increases with the increase of the carbon chain.For amino acid substrates,the target product was obtained in50.8%yield,but the amino acid reaction occurred racemization.In this method,the catalyst nickel chloride can be reused three times without losing activity.Using phenylacetic acid and benzylamine as models,the catalytic properties of titanium catalysts were discussed,such as TiCl₄?TiCp₂Cl₂?Ti?Oi Pr?_4?It was found that both TiCl₄ and TiCp₂Cl₂ had the catalytic effect and TiCp₂Cl₂ was the best.The reaction conditions with TiCp₂Cl₂ as catalyst were optimized.The optimum reaction conditions were obtained as follows:using dichloromethane as solvent,10%mol catalyst,the reaction was carried out at 70?for 36 hours.The yield of target amide was 95.2%.On this basis,the applicability of this catalytic method to different acid substrates was discussed.For phenyl acetic acid substrates,the type and position of substituents on aromatic rings have a great influence on the yield of target amide,the yield of phenylacetic acid substrates containing ortho-substituents was low?27.4%-44.0%?.For phenylacetic acid substrates containing meta and para substituents on the benzene ring,the yield of the substituent of an electron donor is higher than the yield of the electron sucking substituent.For the same substituents,the yield order of the target amides is:para>meta>ortho,and for long-chain fatty acids,this method can obtain the target product in the yield of?62.1%-82.0%?,and the yield increases with the increase of carbon chain.However,for the reaction of long chain aliphatic amine with phenyl acetic acid,the yield of target amide decreases with the increase of carbon chain.For amino acid substrates,the target product was obtained in?54.2%-60.2%?yield without racemization.