Theoretical Studies And Synthesis Of Some Furazan And Tetrazine Energetic Compounds

Energetic nitrogen-rich heterocyclic compounds are attracting considerable attention at present in order to satisfy the increasing of modern civil and military applications recently.Furazan-based and tetrazine-base high-energy-density materials(HEDMs)have been investigated extensively due to their high formation enthalpy,good thermal stability and active-oxygen bearing cycle.In this thesis,a series of furazan-based,tetrazine-base or pyrazine-base high-energy-density materials were designed,and theoretical and computational chemistry methods were employed to study the compounds.The structures and properties of new targets were predicted and among which,potential candidates of HEDC were selected.The main arches are as follows:3,3'-dinitramino-4,4'-azofurazan(DNAAz F)was synthesized from DAF via oxidation and nitrification.Five salt compounds of DNAAz F were prepared from aqueous ammonia,hydrazine,hydroxylamine,guanidine nitrate,diaminoguanidine monohydrochloride by using DNAAz F as the starting material.The influence factors and the optimal reaction conditions for the synthetic compounds were investigated.The detonation performances of the target compounds were studied.The results showed that DNAAz F and its salt compounds all have good detonation performances,and equal as RDX.In this thesis a series of double furazan-based and furoxan-based compounds have designed.Density functional theory(DFT)based on B3LYP/6-311++G**level was employed to study the optimized structures,energetic properties,heat of formation(HOF),detonation properties and bond dissociation energies.The results show that the N-O bond,which close to the adjacent coordinated oxygen atom in furoxan ring,is more fragile than the other N-O bond in the ring.The double furazan-based derivatives are more stable than the double furoxan-based derivatives.The different substituent groups offer the HOFs obey the order as1,2,3,4-tetrazine(4 group)?1,2,4,5-tetrazine(5 group)>tetrazole(3 group)?1,2,3-triazole(1 group)>1,2,4-triazole(2 group).The linkages supply the HOFs obey the order-N=N->-N=N(O)->-NH-NH-,and there is no obvious difference between furazan ring and furoxan ring in providing the HOFs.The tetrazole ring plays an important role in improving detonation velocities and pressure.Bis[4-nitraminofurazanyl-3-azoxy]azofurazan(ADNAAF)and its salt compounds synthesized by our group.Another five new compounds were designed by drawing into some energetic groups.Their densities,enthalpies of formation,and detonation properties were estimated by DFT method.The results show that all the compounds above have good detonation performances,but the stabilities lower than RDX and HMX.9 structures were designed base on bis-1,2,3,4-tetrazine annulated with pyrazine orpiperazine and their densities,enthalpies of formation,and detonation properties were studied by density functional theory(DFT)method.It shows that 9 structures have good detonation performances which can equal with RDX.Among them,P9 is the best one.((35)H_f=1714.71k J·mol^-1,?=1.91 g·cm^-3,D=9.92 km·s^-1,Q=2343 cal·g^-1,P=45.19 Gpa)DFT method was employed to study the 12 compounds designed based on azolo-1,2,3,4-tetrazine,among which,promising candidates for high energy low sensitivity explosives were selected by predicting their detonation properties,thermal stabilities and sensitivities;their structure-properties relationships were summarized:the position of the electron-withdrawing group such as nitro group or adjecture oxygen has considerable influences on structures'stabilities,the negative effect will be minimized when the nitro group is substituted on the carbon atom of position 6.In this article,3,5-dinitro-2-tertbutylamino-6-aminopyrazin(5)was investigated by2,6-dichloropyrazine(1).The optimum synthesis methods of 2-chloro-6-methoxypyrazine(2)and 3,5-dinitro-2-chloro-6-methoxypyrazine(3)were obtained.1)Compound 1 was added in sodium methoxide-methanol solution,the reaction temperature was 50?,the reaction time was 3 hours.Sodium and Compound 1 ratio of 1.2:1,Sodium methoxide-methanol solution was 20%mass fraction,the yield of the Compound 2 was80.5%.2)Synthesis of Compound 3:1.45g Compound 2,2m L of nitric acid and 9m L of 98%sulfuric acid,reacted for 4h at 70?,yield 51%.