Study On N-alkylation Of Alcohols And Amines Catalyzed By Polyoxometalates

Imines,secondary amines and tertiary amines are widely found in various natural substances with biological activities.Therefore,the synthesis of this substance has become a hot spot in chemical research in recent years.The N-alkylation reaction of alcohol and amine has high atomic economy,and water is the only by-product.At present,noble metals and metals containing organic ligands are usually used as catalysts for the N-alkylation of alcohol and amine,and good results have been obtained.However,due to the complex preparation of catalysts and the difficulties in catalyst recycling,it is difficult to carry out industrialization.Therefore,developing a cheap and recyclable catalyst for the N-alkylation of alcohols and amines is a subject of practical significance.Polyoxometalates have adjustable acidity,oxidation-reduction and other characteristics.At present,polyoxometalates have been used as catalysts in industrial production.Based on our research on polyoxometalates,we try to use polyoxometalates as catalysts to promote N-alkylation of alcohols and amines,which is divided into the following three parts:1)Lindqvist polyoxometalate-[N（C₄H₉）₄]₂[Mo₆O₁₉]was selected as a catalyst to selectively catalyze alcohols and amines to produce imines.With aniline and benzyl alcohol as raw materials,better synthesis conditions were obtained.At the same time,the universality of the reaction was studied,and the possible reaction mechanism was deduced through controlled experiments.2)On the basis of the experiment in Chapter 2,we continue to use homomolybdate as catalyst and aniline and benzyl alcohol as template substrates to obtain the optimal reaction conditions.The research shows that this method has good substrate universality.The catalyst has been recycled for at least 6 times,which has strong industrial value.In order to verify the hydrogen borrowing reaction mechanism of alcohol and amine,control experiments and hydrogen spectrum tracing were carried out.3)Anderson-type polyoxometalate-heteropolysic acid（NH₄）₃[Co Mo₆O₁₈（OH）₆]·7H₂O was selected as a catalyst to selectively catalyze the N-alkylation of alcohols and amines to form tertiary amines,and better synthesis conditions were obtained.