Construction Of Organic Phosphonate Hafnium Diacid Materials And Their Catalytic Synthesis Of Biomass-based Anethole

With the rapid development of human society,the demand for resources is increasing rapidly.Due to the limit of the non-renewable fossil resouce,it is urgent to seek renewable resource to replace it.Biomass possesses broad application prospect because of its abundant reserves,low cost and easy to obtain.It is one of the focuses in the field of sustainable chemistry by conversion of biomass into fuel and value-added chemicals.Biomass-based anethole possesses special smell and pharmacological properties,which can be used in food and pharmaceutical industry widely.In this thesis,we design a green sustainable route via preparation of organic phosphonic-hafnium daul acid material as catalyst,and using biomass-based 4-methoxyphenylacetone as substrate that proceeds through Meerwein-Pondorf-Verley(MPV)reduction and dehydration/dealcoholize to produce anethole.The details are listed as follows:(1)The catalyst PhP-Hf was prepared with phenylphosphonic acid(PHP)as an organic ligand and Hf Cl₄ by a simple thermal solvent method.The optimal catalyst PhP-Hf(1:1.5)was obtained by adjusting the ratio of organic phosphonic acid and metal.The catalyst was used to convert cheap biomass based 4-methoxyphenylacetone(4-MOPP)into high value-added anethole.Through the selection of reaction time,temperature,catalyst dosage,catalyst ratio and hydrogen source,obtained the 4-MOPP conversion is 99.8%and 98.1%yield of AN with is 0.1g PhP-Hf(1:1.5)as catalyst and 2-pentanol as hydrogen source under 220oC for 2 h.in addition,the catalyst possess high stability,which can be reused for at least 5 times and the catalytic activity without decreased significantly.(2)Biomass possesses abundant and renewable features,which conforms to the current theme of sustainable development.It is significant to use biomass as raw material to prepare functional materials.Phytic acid(PA)obtained from seeds and grains are a major phosphorus resource in plants.Due to the existence of six phosphate groups in its structure,it can coordinate with metal ions to prepared functional materials.Based on this,this chapter designed and prepared phytate hafnium catalyst(PA-Hf)with PA as organic phosphonic acid ligand and coordinate with Hf Cl₄ without template.The preparation conditions of the catalyst and the ratio of PA/Hf were optimized to get the best catalyst PA-Hf(1:2.5).In order to study catalyst structure and properties of PA-Hf(1:2.5),FT-IR,XRD,SEM,TEM,TG,BET and CO₂/NH₃-TPD were used,which can further be the evidence of the successful preparation of PA-Hf(1:2.5).The catalyst was used for catalytic conversion of biomass-based 4-MOPP into AN.By optimizing the reaction conditions,the yield of AN could be up to 98.8%.(3)Organic polymers have good hydrophobicity and thermal stability,which can provide a broad prospect for their new applications in heterogeneous catalysis.In this chapter,a“one-pot”method was used to prepare the organic polymerized phosphonic acid hafnium dual acid functional material(PDVP-Hf).PDVP-Hf was used to convert biomass based 4-MOPP into AN,and the yield of AN could be up to 98.9%.At the same time,the thermal stability(TG)and contact angle(CA)characterization of the catalyst confirmed that the catalyst had good thermal stability and hydrophobicity.The PDVP-Hf catalyst can be widely used in the MPV reduction of various aldehydes and ketones.In addition,the catalyst can be used in the cascade MPV reduction and dehydration of aldehyde and ketone reduction.A series of control experiments and density functional theory calculation(DFT)were designed to infer the reaction mechanism.