Study On The Preparation Of Nitrogen-containing Compounds From Organic Acids

Nitrogen-containing compounds are ubiquitous in natural substances and drug molecules,and have been widely used in materials,pesticides,medicine,dyes and other fields.Therefore,it is of great significance to study the synthesis of nitrogen-containing compounds.In recent years,with the gradual consumption of fossil energy,renewable biomass energy has received widespread attention.Organic acids can be hydrolyzed from biomass.The carboxyl group in its molecular structure can participate in many organic reactions and has been used to transform into a variety of valuable chemicals.At present,the use of organic acids as raw materials to synthesize nitrogen-containing compounds has become an emerging and rapidly developing topic,and a series of nitrogen-containing compounds have been obtained.Therefore,the systematic study of reductive amination reactions involving organic acids is of great significance.This thesis focuses on the reductive amination reaction of organic acids.The main contents are as follows:1.For the amidation reaction of fatty acids,an inorganic base/silane catalytic system was developed to realize the direct amination of fatty acids and primary amines to prepare amides.This reaction uses primary amine and n-valeric acid as a model,tetrabutylammonium fluoride as a catalyst and dioxane as a solvent,a series of amides compounds were prepared by reacting at 120 °C in the presence of triethoxysilane for 5 h,and the highest yield was 99%.When screening conditions,it was found that hydrosilane significantly affected the catalytic activity of the reaction.Hydrosilanes with too strong or poor reactivity are not suitable for the system,and triethoxysilane with medium reactivity is the best.On the other hand,when screening solvents,it was found that polar aprotic solvents are beneficial to the progress of the reaction.Research on the universality of substrates found that various fatty amines can be applied to this system.2.For the cyclic amination of levulinic acid,a fluorine-based ion catalytic system was developed,and the cyclic amination of levulinic acid was achieved for the first time to prepare N-substituted-5-methylene-2-pyrrolidone in the presence of hydrosilane.Different from the N-substituted-5-methyl-2-pyrrolidone reported in the literature,which is a pyrrolidone compound containing both an amide structure and an enamine structure.In this system,tetrabutylammonium fluoride is used as catalyst,dioxane is used as solvent.and levulinic acid is reacted with primary amine in the presence of diphenylsilane to synthesize N-substituted-5-Methylene-2-pyrrolidone.When screening the reaction conditions,it was found that fluorine-based catalysts are beneficial to the progress of the reaction.Among them,tetrabutylammonium fluoride with strong nucleophilic effect has the best reaction activity.Substrate universality studies have found that fatty amines react well with levulinic acid.3.For the selective reductive amination of biomass levulinic acid,an inorganic alkaline catalytic system was developed,and a series of arylpyrroles were synthesized using levulinic acid as a raw material for the first time.The reaction uses aromatic amine and levulinic acid as raw materials,cesium fluoride/18-crown ether-6 as catalyst,tetrahydrofuran as solvent,the pyrrole products with different functions were obtained at 120 °C in the presence of polymethylhydrosiloxane for 5 h,and the highest yield was 95%.Screening reaction conditions found that 18-crown ether-6 can cooperate with the cations of cesium fluoride to improve the nucleophilicity of fluoride anions and the solubility of the catalyst,thereby enhancing the catalytic effect.The investigation of the suitability of the substrate found that the reaction of various aromatic amines with levulinic acid has a good yield.Mechanism studies have shown that the strong interaction between the fluoride ion in the catalyst and the silane is the reason for the high activity of the reaction.