Investigation On Conversion Of Aryl Halides To Phenols And Biphenyls

Phenols and biphenyls are important building blocks for constructing pharmaceuti -cals, polymers, and natural compounds, and they are widely used in the production of pharmaceuticals, pesticides and dyes, so methods of the investigation on conversion of aryl halides to phenols and biphenyls would be of great significance.The conversion of aryl halides to phenols and biphenyls are part of Ullmann reactions. Copper and palladium catalysts are often used in the process of the conversion of aryl halides to phenols and biphenyls. Compared with these two metals, iron compounds have such two potential advantages as relative low price, no heavy metal pollution and meet the requirement of greenization of the chemical process, so here we make an attempt to develop a highly effective iron catalyst in the reaction of conversion of aryl halides to phenols.On the other hand, in the transition-metal catalyzed reaction of conversion of aryl halides to biphenyls,palladium compounds often serve as a kind of effective catalyst. However, it will not only raise economic costs due to uneffective recycling in palladium-catalyzed homogeneous reactions but also pollute environment due to loss of palladium catalysts, so here we make an investigation on the immobilization of palladium catalysts in the reaction of conversion of aryl halides to biphenyls.The main research contents and results in the presented thesis are as follows:1. It was investigated that reaction conditions of the iron-catalyzed conversion of aryl halides to phenols in water. The experimental results revealed that aryl halides can be smoothly converted to phenols in the case of using FeCl3 as the iron salt, DMEDA as the ligand and K3PO4·3H2O as the base at 180℃for 20 hours in high-pressure autoclave. The reactions of some unactivated aryl halides also gave moderate to high yield and selectivity.2. An immobilized CMPS-NHC-Pd catalyst was prepared, then the immobilized catalyst was applied into conversion of iodobenzene to biphenyl. Some influence factors of the reaction were investigated, and the reaction conditions were optimized. On the mild condition, iodobenzene can be smoothly converted to biphenyl.