Green Synthesis Of Azotetrazole And Azofurazan Energetic Organic Compounds By Electrochemical Method

Azotetrazole and azofurazan energetic compounds are demonstrated to possess high enthalpy of formation,low sensitivity and good stability,and have important application value in the fields of high-energy tension-sensitive explosives and low-characteristic signal propellants and other fields.At present,chemical oxidation is the most commonly used method for synthesizing azotetrazole and azofurazan energetic compounds,but there are objective problems such as difficult control of reaction conditions,unsatisfactory reaction selectivity and safety.Organic electrosynthesis has the advantages of simple operation,high selectivity and green economy and has been used in large-scale synthesis of a variety of organic compounds.Based on the above background,this thesis systematically studied the feasibility of electrochemical green synthesis of 5,5'-azotetrazole and 4,4'-azofurazan energetic compounds and related synthesis mechanisms.The main research contents and conclusions of the thesis are as follows:(1)At room temperature,using noble metals(Au,Ag,Pt)and transition metals(Fe,Co,Ni,Cu,Mo,W)as oxidation electrodes,5-aminotetrazole could be electrochemically oxidized to synthesize disodium azotetrazole in 0.50 M Na₂CO₃-0.25 M 5-aminotetrazole aqueous phase electrolyte.Due to the parallel oxygen evolution reaction of water,the Faraday efficiency of the electrochemical synthesize of disodium azotetrazole by Pt anode was about40%under 1.89 V vs.RHE;Because the oxidative-coupling of 5-aminotetrazole on Ni anode occured before the water oxidation reaction,the Faraday efficiency of the electrosynthesis of disodium azotetrazole on Ni anode was higher than that on Pt anode.Mechanism studies had found that the oxidative-coupling of 5-aminotetrazole to disodium azotetrazole on Pt anode was mainly indirectly initiated by hydroxyl radical intermediate formed in the process of Pt electrolysis water;However,the oxidative-coupling of 5-aminotetrazole to synthesis of disodium azotetrazole driven by Ni anode was the direct electrochemical oxidation mechanism,without the involvement of hydroxyl radical.Based on the above findings,the electrochemical amplification synthesis of disodium azotetrazole and guanidinium azotetrazolate at the level of 10 g could be conveniently carried out using a Pt/Ti electrode with geometric area of 5×5×2cm²,with yields of about 72%and 70%,respectively.(2)The electrochemical synthesis of 3,3'-diamino-4,4'-azofurazan in aqueous electrolytes of 0.10 M Na HCO₃/0.020 M 3,4-diaminofurazan or 0.10 M NaOH/0.020 M 3,4-diaminofurazan and organic electrolytes was investigated at room temperature and pressure.Among them,3,4-diaminofurazan could be oxidize to form 3,3'-diamino-4,4'-azofurazan by Cu,Fe,Co and Ni electrodes in Na OH/3,4-diaminofurazan aqueous electrolyte,and the reaction yields were less than 30%;The yield of 3,3'-diamino-4,4'-azofurazan was about 63%in acetonitrile electrolyte system with graphite as anode and Pt as cathode under 5 m A constant current for 2.68 h.The Faraday efficiency of the electrochemical synthesis of 3,3'-diamino-4,4'-azofurazan by graphite anode was about 60%at 1.80 V vs.Ag/Ag Cl for 150 min in 0.020M ⁿBu₄NBF₄/0.025 M 3,4-diaminofurazan acetonitrile solution.Mechanism studies confirmed that the electrochemical oxidative-coupling of 3,4-diaminofurazan to synthesis of 3,3'-diamino-4,4'-azofurazan by graphite anode was the direct electrooxidation mechanism.The findings of this thesis on the electrochemical synthesis of azotetrazole and azofuroxan compounds could provide useful ideas and theoretical references for the green synthesis of azo energetic compounds.