The Application Of Anderson Type Poly Acids With Inorganic Ligands In The Construction Of C-S Bond

The polyoxometalates have various structures,which are composed of cations and cations.The most basic structural unit is the oxygen polyhedron of MOX(x=5,6).M is generally expressed as the metal in the early transition state of high oxidation,such as W,Mo,V,Nb,etc.,and other metals can be partially replaced,including aluminum,titanium,chromium,manganese,iron,cobalt,nickel,copper,zinc,zirconium,ruthenium,palladium,silver and hafnium.Polyanions are large in volume and have high negative charges.The most flexible basic structural unit in polyacids is Anderson heteropoly acid.At present,the organic covalent modification of polyacid is a hot topic in the field of polyacidic chemistry.In this paper,Anderson heteropoly acid is used as the catalyst.A series of catalysts with various functions are obtained by changing the central metal atoms.The catalyst prepared does not change the original structure of polyacids,and the effect of the catalyst field is explored in depth.Then,the role of Anderson type polyacid catalyst in the construction of C-S bond was studied,and the reaction conditions were optimized continuously.It was hoped that the shortcomings of the original initial reactants in the synthesis could be solved,and the reaction conditions could be improved so as to meet the non stringent environmental requirements(such as temperature,humidity,etc.).This study provides a different path for the modification of polyacid and the choice of catalyst in organic reaction,and expands the application range of polyacid.It is applied to the synthesis of C-S bond,and provides a new,efficient and green way for the synthesis of C-S bond.Disulfides are widely found in nature.As a common structural motif,S-S bonds of biomolecules constitute the secondary and tertiary structures of proteins,regulate the production of hormones,and maintain the homeostasis of enzymes,growth factors and immunoglobulins in biochemical oxidation.Because disulfide bond plays a selective role in the cytoplasm of cancer cells,disulfide bond is also widely used as a linker in antibody drug binding(ADC),which can release molecules accurately in cytotoxic.The traditional synthesis method is mainly mercaptan oxidation,but the oxidant used is toxic,expensive,and difficult to control the oxidation degree of mercaptan to produce by-products.Therefore,it is urgent to find a green,efficient and non-toxic synthesis method.In this project,disulfide compounds are directly prepared by boric acid and sodium thiosulfate with the participation of Anderson heteropoly acid catalyst with low-cost metal as the center.The synthesis method has the advantages of easy raw materials,good atomic economy,mild reaction conditions,simple operation,catalyst recycling and so on,and has the prospect of industrial production.In recent years,polyoxometalates play an important role in the field of catalysis because of their high stability,clear active sites,and complex structure.In this paper,we mainly study catalytic oxidation and construct C-S bond with reference to many literature reports and research results of our team,The main contents of the work can be divided into the following parts:1)synthesis of Anderson type polyacid(Ni as the central metal atom),catalytic oxidation of reactants,construction of C-S bond,formation of symmetrical disulfide compounds.Through the experimental results,Ni Anderson type polyacid is used as catalyst,under the condition of oxygen in air,the mixed solvent is toluene and water,and the sulfur supply agent is sodium thiosulfate,The reaction time of 100 OC and 24 h was used to convert phenylboric acid into diphenyldisulfide.The yield was detected by GC-MS,and the yield was up to 99%.2)Disulfides were synthesized by one step with Cr Catalyst with inorganic ligands.The results show that the reaction of benzoborate and sodium thiosulfate is the starting reactant,the catalyst uses 1mol%Cr Anderson,oxygen in the air as oxidant,toluene/water mixed solvent,90 ~OC,reaction for 20 hours,diphenylsulfide is obtained,the yield is 95%.The products of aliphatic compounds and heterocyclic compounds were produced.3)The Anderson type polyacids with Cr as the central metal atoms were synthesized and the cross coupling of boric acid was carried out.When sodium sulfite was added as additive,the yield of the product was up to 61%after 24 hours reaction between benzoic acid and4-fluorobenzoic acid.The reaction conditions are mild,the operation process is simple,and no additional oxidant is needed,only the molecular oxygen in the air is required.The catalyst has good environmental protection,simple recovery and high stability.Besides,we also use control experiments and hydrogen spectrum tracking to predict the catalytic mechanism of the catalyst.