Transition Metals Catalyzed Hydrodehalogenation Of Aromatic Halides

Aromatic halides are an important class of organic compounds and have important applications in agriculture,forestry,fireproofing materials,and chemical synthesis.However,it also causes serious pollution to the environment.Hydrodehalogenation of aromatic halides can effectively reduce the toxicity of pollutants and produce many useful industrial raw materials.Metal catalysts,possessing the characteristics of high catalytic activity,easy to recycling and convenient practical application,have been widely studied for the degradation of halogenated pollutants.But efficient and cost-effective catalysts remain a huge challenge.Based on the above,we developed three kinds of metallic catalysts and applied them to the hydrodehalogenation of aromatic halides in different systems.The main research contents are as follows:（1）Ni Ag bimetallic nanoparticles were prepared by using a surfactant-aided co-reduction process.The prepared Ni Ag bimetallic catalyst was thoroughly characterized and used to catalyze the hydrodehalogenation of aromatic halides.The optimized reaction conditions were screened by changing the reaction temperature,the solvent,and the reaction time.The high efficient dehalogenation of aromatic halides was achieved at mild temperature using pure water as solvent without adding other strong bases,showing good compatibility for different kinds of halogens and functional groups with different properties.Even fluoroaromatic compounds,which were extremely difficult to degrade,were readily converted.In addition,recycling experiments combined with characterization of the used catalysts showed that the catalytic efficiency decreased gradually due the oxidation of the metals and could restored by simple H₂reduction.（2）Highly crystalline silver-loaded mordenite（Ag@MOR）was prepared via the seed-directed growth by using the silver supported zeolite Beta as seeds.The obtained Ag@MOR catalyst was characterized by various methods such as XRD,BET,TEM,etc.It was proved that the silver was well dispersed in the support in size of about 2nm.The prepared catalysts were used for the selective hydrodehalogenation of aromatic halides with different types of halogens.It showed good selectivity for various substrates substituted with different functional groups.The prepared Ag@MOR catalyst could replace traditional catalysts for selective dehalogenation protection of specific reaction sites in organic synthesis.（3）Thiol-functionalized organic mesoporous phenolic resin materials were prepared in one pot by using p-dimercaptobenzene as the functionalizing reagent.The synthesized 2SH-MPs-x series materials possessed high content of S element,which could easily combine with metal Pd.2SH-MPs-x/Pd was then prepared by complexing the prepared 2SH-MPs-x series materials with metal Pd ions through-SH and then reducing with Na BH₄.A series of characterizations demonstrated the existence of ordered mesoporous structure and palladium nanoparticles in the material.The 2SH-MPs-x/Pd materials were used as catalysts for the degradation of 4-chlorobiphenyl by using use H₂as the hydrogen source,exhibiting efficient catalytic performance.