Preparation Of Nanometer Iron Oxide And Its Catalytic Performance For C-N Bone Formation

In recent years,with the increasing demand for steel,in the process of steel processing will produce a lot of pickling waste,if not properly handled,it will cause devastating damage to the ecological environment.In this paper,nano-iron oxide was prepared by sol-gel method,pickling waste liquid or ferric chloride as raw material,polyethylene glycol 400 as dispersant and ammonia as precipitant.The samples were characterized by XRD,TEM,SEM,FT-IR,UV-Vis and ICP-MS.The results show that the iron oxide is a spherical nano-?-Fe₂O₃ with good crystallinity,dispersibility and purity,and the grain size is about 30 nm.The?-Fe₂O₃ was demonstrated to be an efficient catalyst for N-benzylation of aliphatic and aromatic amines with benzyl chloride and benzyl bromide in 8%Na₂CO₃aqueous solution,he?-Fe₂O₃ was demonstrated to be an efficient catalyst for N-benzylation of aliphatic and aromatic amines with benzyl chloride and benzyl bromide in 8%Na₂CO₃ aqueous solution,achieving ca.100%conversions and>82%selectivity to monosubstituted products for aromatic amines and higher selectivity to disubstituted products for aliphatic amines at 50-80°C and reaction time 1-3 h.In order to determine the effect of reaction temperature,reaction time,catalyst dosage and molar ratio of reactants on the benzylation of amines,the benzylation reaction of diethylamine with?-Fe₂O₃ as catalyst was studied.The optimal operating conditions were obtained:reaction temperature 50 ^oC,reaction time 3 h,molar ratio of Diethylamine to benzyl chloride 3:1,amount of nano-iron oxide 0.1 g.Under these conditions,the conversion of benzyl chloride was 99%,the selectivity to N-benzyl aniline was 97%.The benzylation reaction of 4-methylaniline with spherical?-Fe₂O₃ as catalyst was studied.The optimum conditions were as follows:reaction temperature 60?,reaction time 1 h,catalyst dosage 0.1 g,4-methyl aniline/Benzyl chloride molar ratio of 3:1.Under this condition,the conversion of benzyl chloride can reach 99%,and the selectivity of N-monosubstituted product can reach 87%.In the experiment,we also investigated the properties of benzyl chloride,benzyl bromide and benzyl alcohol as benzylation reagents.The conversion of benzyl bromide is the same as that of benzyl chloride,but the selectivity of the substituted product is slightly lower.When benzyl alcohol is used as the benzylating agent,N-benzylation is not carried out at all.We also investigated the effect of different solvents on the reaction.When acetonitrile was used as the solvent,N-benzylation of diethylamine and aniline with benzyl chloride also exhibited the same activity as the system using 8%Na₂CO₃aqueous solution.However,due to the solubility of acetonitrile in the organic compound,the separation of the product from the reaction mixture becomes difficult.Thus,the use of an alkaline aqueous solution as a solvent is the best choice for N-benzylation of amines with benzyl chloride or bromine.This paper also studies the performance of the catalyst after repeated use.After the re-use of the catalyst although the morphological changes,but still belong to the?-Fe₂O₃,and the catalyst can be effectively recovered and reused more than 3 times,and can maintain good catalytic activity,has a good application prospects.In addition,the oxidation-reduction mechanism of benzylation reaction under the catalysis of?-Fe₂O₃ was proposed according to the reported reports and the results of this experiment.