| Aromatic nitration and amines nitrolysis are important unit reaction in the organic synthesis and explosives manufacturing field. Mixed acid、HNO3-(CH3COO)2O and HNO3-P2O5etc are usually used as nitrating agent, which are involved many sever problems, such as wasted acid disposal and less para-selectivity. In order to solve these problems above, new nitration processes were studied and mainly focused on green nitrating agent、catalysts, development and application of micro-chemical technique.In this dissertation, the research work mainly focused on aromatics nitration with green nitrating agent N2O5catalyzed by Lewis acid, Hβ zeolite and MoO3-SiO2; nitrolysis of TRAT to prepare RDX with N2O5/HNO3catalyzed by acidic ionic liquids; and the application of micro-chemical technique in the nitration area. The main work and results are listed as follows:(1) The aromatics nitration with N2O5catalyzed by Lewis acid Re(OTf)3was studied. Results showed N2O5/CH2Cl2was a relatively mild system, substrates conversion was enhanced remarkably under the Re(OTf)3catalyzed and the para-selectivity of products was improved than in the mixed system. Experiments studied the effects of reacting conditions, solvents, catalysts etc on the reaction. The conversion of toluene could be100%and o/p ratio is1.3under the best nitrating condition in the presence of Nd(OTf)3. The mechanism of N2O5nitration catalyzed by Lewis acid was also discussed in this dissertation.(2) The aromatics nitration with N2O5catalyzed by Hβ zeolite was studied. The results showed that follow the right order of addition of substrates, the substrates conversion were enhanced apparently, accompanied with a good para-selectivity of product isomer under the Hβ zeolite catalyzed. Take toluene nitration as an example, follow the best order of addition of substrates Hβ zeolite-N2O5/CH2Cl2-toluene, the mol ratio of toluene to N2O5is1:1, the catalyst amount is0.2g, reacting for30min at20℃, the reaction gave a conversion of toluene about97%and a o/p ratio0.59. The mechanism of N2O5nitration catalyzed by Hβ zeolite was discussed, and then o-xylene select nitration was catalyzed it.(3) The aromatics nitration with N2O5catalyzed by solid acid MoO3-SiO2, which was prepared by sol-gel method, was studied. The catalyst was characterized by XRD, BET, FTIR and SEM. Mo03-SiO2with15mol%Mo loading has the most acid amount of1.21mmol/g, the92%conversion of toluene and1.3ratio of o/p were obtained in the presence of20%catalyst (weight ratio to toluene). The positive correlation of its acid strength and catalytic activity was discovered, which validated the nitraton of arene by N2O5/CH2Cl2an acid-catalyzed reaction with NO2+. The catalytic activity would be decreased when the crystalline MoO3was formed on amorphous silica support.(4) The application of micro-reactor in the nitration with nitric acid and N2O5was studied, the suitable catalysts in the micro-reactor system were developed, which was a supplementary of micro-chemical technique in the nitration field. The conversion of arene nitrated in the micro-reactor was5%～15%higher than in the flask, and the reaction time was only1%to the normal process. In the presence of sulfonic ionic liquids(AIL) and lanthanide metal trifluoroacetates(Ln(TFA)3), nitration of alkylbenzenes gave a conversion of95%, and conversion of halobenzenes was10%higher than the result in the absence of catalysts. Nitration of alkylbenzenes with N2O5in the micro-reactor gave a conversion over80%, and conversion of halobenzenes was over60%, all the results were better than the nitric acid system.The mechanism of nitration with HNO3was illustrated.(5) RDX could be obtained by nitrolysis of TRAT with N2O5/HNO3in a yield of80.4%. This process, which was conducted in a mild condition and had a high yield, is a potential industrial method. The yield of RDX would decrease gradually along with the increasing content of N2O4from0to8.0%, fortunately, the yield only decreased slightly in a scope between0and3.9%. A high yield has been obtained when the nitrolysis catalyzed by AIL, and AIL could reuse5times without activity decrease. |
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