Synthesis And Characterization Of Fluoroalkylation Reagents And Polymers Based On Chlorotrifluoroethene

Since the first artificial fluorinated compound ethyl fluoroacetate being synthesized in 1896,fluoroorganic chemistry(including fluoropolymer chemistry)has been developed tremendoously as an important branch of organic chemistry in the last one hundred year.Due to the high electronegativity,smaller atomic radius and low polarizability of fluorine atom,the incorporation of fluorine atom into organic compounds can lead to unique physical,chemical and physiological characteristics,fluorinated compounds have been widely explored and used in many applications,including high-technology(nuclear,aerospace,semiconductor,etc.),major industrial(chlor-alkali industry and new energy projects),medicine and pesticide.Owing to the fact that there are only a handful of natural biosynthesized organic compounds containing fluorine atoms,the main method to obtain fluoroorganic compounds is through chemical synthesis.In the past twenty years,tremendous investigations of fluorination and fluoroalkylation methods have been developed for the preparation of new fluoroorganic compounds and many of these compounds have been successfully applied in the field of pharmaceutical compounds and engineering materials.With the development of biomedical research and advanced high-tech materials,the exploration of new fluoroorganic compounds and polymer materials is becoming more and more important in the field of fluoroorganic chemistry.In this thesis,we systematically investigated the difunctionalization reaction and radical copolymerization of chlorotrifluoroethene(CTFE).Based on these reactions,we have prepared several novel fluorinated compounds and polymer materials,including fluoroalkylation reagent,thiofluoroalkylation reagent,fluorinated sulfonic acid polymer membrane and degradable polymers.The main results obtained in this thesis are listed as follows:1.The three component reaction of sodium azide,CTFE and iodine chloride has been investigated systematically.The experimental results showed that a new fluorooganic compound,1-azido-2-chloro-1,1,2-trifluoro-2-iodoethane(ACTI),could been obtained in high yield by this facile method.As a heterobifunctional fluoroalkylation reagent,the reactivity of ACTI was investigated for the first time.The results indicated that the azide group could react with different alkynes with aromatic and aliphatic structures to give the products in high yields using CuI/TBAA as a catalyst.It was found that TBAA not only played as a base and ligand,but also provided the acetate ion(CH3COO-)to promote the click reaction.Moreover,the iodine atom can also chemically or photochemically react with different reagents.To the best of our knownledge,ACTI is the first highly stable and versatile heterobifunctinal fluoroalkylation agent.Therefore,it will be very useful for preparation of new functional fluorinated organic compounds,or functional fluorinated polymers,such as medicines and pharmaceutics.2.we have developed a diheteroatom fluoroalkylation reagent,2-((2-azido-l-chloro-1,2,2-trifluoroethyl)-thio)pyrimidine(ACTP),by the three components reaction of NaN3,CTFE and 2-thiocyanatopyrimidine.As the first diheteroatom bifunctional fluoroalkylation reagent,ACTP contains fluoroalkyl azide group and pyrimidine thioether group.The reactivity of the two functional groups for reactions was examined carefully.A variety of organic fluorinated thioethers and sulfones with trizole groups were successfully prepared by the CuI/TBAA catalytic click reaction and oxidation reaction respectively.On the other hand,the fluorinated sulfones were successfully converted to the fluoroalkyl sulfinates and sulfonates with high yield by the dearylation and oxidation reactions.Based on this approach,fluorinated sulfonic acid proton-exhange membrane was prepared by using ACTP.Therefore,ACTP is a very useful reagent not only for synthesis of various organic fluorinated compounds,but also for the preparation of new fluorinated sulfonic acid polymers.3.Based on the relationship between chain transfer agent and monomer property,we designed and synthesized several RAFT agents,including dithiobenzoates,trithiocarbonates,xanthates and dithiocarbamates,for the radical copolymerization of CTFE and butyl vinyl ether(BVE)under thermal initiation at 70?.We found that O-ethyl S-(4-(trifluoromethyl)benzyl)carbonodithioate had the best control effect for the copolymerization with a moderate polymerization rate.The results of polydispersity index(PDI)and kinetics indicated that the copolymerization process had the features of living/controlled free radical polymerization.The alternating structures of the obtained copolymers were confirmed by 1H,19F and 13C NMR spectroscopy.However,the measurement of MALDI-TOF-MS and absolute molecular weight calculations showed that that the dyad of CTFE in the copolymer indicating the alternating copolymerization of CTFE and BVE was dominated by the addition of free radicals to single monomer rather than to the charge transfer complex of monomer pair.The results from the analysis of 1H NMR under different conversions and the model reaction of small molecules suggested that the fluoroalkyl radicals in the polymerization were difficult to undergo the reversible addition fragmentation reaction with the dithioester compound,and prefered to add to BVE monomer,and then the resulting free radicals of the ethyl butyl ether dominated the reversible addition fragmentation reaction with the dithioester compounds,leading to the living/controlled free radical polymerization.Finally,a fluorinated branched copolymer based on CTFE and BVE was successfully prepared by the method of vinyl self-condensation polymerization(SCVP).4.5,6-benzo-2-methylene-1,3-dioxepane(BMDO)can be used to prapare polyesters via free ring-opening polymerization.Herein,we investigated the conventional radical terpolymerization of BMDO as comonomer with CTFE and BVE initiation.The obtained coplymer with alternating structures were confirmed by 'H,19F,13C NMR and FT-IR spectroscopy.The contents of each monomer in copolymer were calculated from the results of elemental analysis.The results suggested that either BVE or BMDO tend to be alternately copolymerized with CTFE,and the content of CTFE units in the copolymer remained almost unchanged at 50%.The ratio of BMDO and BVE in copolymer was higher than the initial feed ratio of BMDO and BVE.The thermal properties of the copolymer were examined by TGA.The results showed that the higher the content of BMDO in the copolymer,the lower the thermal stability would be.Finally,the hydrolysis of the fluorinated copolymer were studied in alkaline mixed solvent and the results showed that the copolymer had good chemical degradability.