Synthesis Of HMX By Nitrolysis With Dinitrogen Pentoxide Catalyzed By Acidic Ionic Liquid And Study On The Nitrolysis Mechanism

HMX is an excellent high explosive and used widely nowadays. It is prepared in industrial scale by nitrolysis of urotropine in ammonium nitrate-nitric acid-acetic anhydrate or nitrate salts-nitric acid. These traditional methods have some drawbacks such as producing large quantity of weaste acid and hard to deposit. Dinitrogen pentoxide (N2O5) is a green nitrating agent with some merits, e.g., high nitrating ability, easy to control the reaction temperature, convenience of product speration, high purity, much lower weaste acid. Ionic liquid is a eco-friendly reaction media and catalyst and the correlative research has becoming a hot area. Application of N2O5and ionic liquid in the nitrolysis to prepare azo-cyclic nitroamine energetic materials is beoming a new research area. In this dissertation, a research has been made on nitrolysis of DPT, DADN and TAT to prepare HMX by N2O5and catalyzed by ionic liquids. The main work and results are listed as follows:18acidic ionic liquids (AILs) were used to nitrolyze DPT and afford HMX in a yield up to61.0%against45.0%without any AIL. Nitrolysis of DPT in N2O5/molecular solvent could not afford any target product, while N2O5/HNO3could give HMX in a high yield up to58.0%with a purity of99.0%at optimized conditions. Then study on the nitrolysis of DPT, DADN and TAT was carried out in N2O5/HNO3/AIL system to find that all the28AILs showen high catalytic acitivties and HMX could be achieved in high to excellent yields of up to69.0%,95.6%and94.0%. The AILs could be efficiently recovered by simple extraction without any apparent loss of catalytic activity even after five runs.The yield of HMX would decrease gradually along with the increasing content of N2O4from0to8.0%when DPT, DADN and TAT were nitrolyzed by N2O5/HNO3. Fortunately, the yield only decreased slightly in a scope between3.2%and4.6%. When N2O4/HNO3system was used to nitrolyze DPT, a yield of40.0%could still be gotten, which is comparable to N2O5/HNO3system. So it is safe to say that N2O4has little affect on the nitrolysis reaction. On the contrary, when N2O4/HNO3system was used to nitrolyze DADN and TAT, no HMX could be obtained.Study on the reaction kinetics about nitrolysis of DADN was carried out in N2O5/HNO3system. As a result, the activation energies of DADN to SEX and SEX to HMX were3.3774×104J·mol-1andl.6598×104J·mol-1respectively, and their pre-exponential factors were2.2000×104h-1and6.5178×102h-1. The free energy, free enthalpy and free entropy of DADN were2.1310×104J·mol-1,-170.7680J-mol-1·K-1and7.6468×104kJ·mol-1; The free energy, free enthalpy and free entropy of SEX were1.3912×1O4J·mol-1,-200.0280J·mol-1.K-1and7.8521×1O4J·mol-1. The half life of DADN at different temperature was0.5728h (303K),0.4599h (313K),0.3210h (323K),0.2330h (333K); The conversions of99%of DADN would require3.8052h (303K),3.0554h(313K),2.1326h (323K),1.5477h (333K).When N2O5/HNO3system was used to nitrolyze DPT, two by-products N,N-bis-(hydroxymethyl) nitramide and1,9-dinitroxy-2,4,6,8-tetranitro-2,4,6,8-tetrazanonane were separated by flash column chromatography. As for TAT, still two byproducts1,5-diacetyl-3,7-dinitro-1,3,5,7-tetrazacyclooctane (DADN) and1-acetyl-3,5,7-trinitro-1,3,5,7-tetrazacyclooctane (SEX) were obtained by flash column chromatography. Unfortunately, no mono-nitrolysis intermediate was obtained at all kinds of reaction and separation conditions. These experimental results revealed the possible fact that the nitrolysis of TAT to produce HMX via a consecutive four steps and the order of the reaction rate is k2>>k1,k2>k3>k4.