The Iron-based Catalyst Aromatic Heterocyclic Ketone Asymmetric Hydrogenation Catalysis Research

Chiral alcohols as a structural unit having a specific spatial configuration,play a very important role in terms of synthetic drugs,agricultural chemicals or functional materials.Metal catalysts for asymmetric reduction of prochiral ketones is an efficient method to obtain chiral alcohols,however,there is defect that the central atoms are precious metal,the ligands structure are complex,and its preparation process are complicated.Iron-based catalyst attracted more and more attention of researchers with inexpensive price,simple preparation,environmental friendliness.This paper takes Triphenylphosphine as the first ligand,?1R,2R?-DPEN as chiral reagent,Al₂O₃ as a carrier,for prepare a supported iron-based catalyst?1R,2R?-DPEN-Fe?TPP?_nCl₂-?-Al₂O₃.By SEM analysis,the catalysts is arranged by a number of needle-like structures,and uniformly distributed on the carrier;through DSC-TGA prove the longer the reaction time,Fe?TPP?_n Cl₂ catalyst relative to the decomposition temperature is higher;XPS prove the surface of the catalyst of Fe to Fe²⁺,Fe³⁺forms coexist.In the essay,we probe the iron content in catalyst,the ratio between iron atom and two ligands to effects on catalytic activity and enantioselectivity,and recycle times.The optimum ratio of catalyst is n?Fe?:n?TPP?:n?DPEN?=1:3:2,supported catalystironcontentFe%_wt=1.5.Underthesecondition,3-chloro-1-?2-thienyl?acetone conversion is 87.56%,e.e.Value is 91.8%.When the number of catalyst use four times,the conversion rate is 73.2%,e.e.Value is 90.2%.To sum up,the catalyst have a good potential value.In the essay,we select two prochiral ketone,2-acetyl thiophene and2-acetyl pyridine to make research on catalytic hydrogenation.We investigated various factors'influence on them,the study found that the processes of catalytic hydrogenation in hetero atom aromatic ketones effected by temperature,time,pressure and alkali varying degrees.The optimum conditions were:2-acetyl thiophene,T=110?,t=6h,P_H2=0.8MPa,C_KOH=0.4mol.L^-1;2-acetylpyridine,T=110?,t=7h,P_H2=1.0Mpa,C_KOH=0.3mol.L^-1.