Nitration Mechanism Research Of Nitrogen Pentoxide

The new technology of using nitrogen pentoxide as nitrating agent is a representative new nitration technology.The nitrogen pentoxide/nitric acid system,which is on the basis of the nitrogen pentoxide,is widely used in energetic materials,for example,nitrolysis of 3,7-dinitro-1,3,5,7-tetrazabicyelo[3,3,1]nonan(DPT)to 1,3,5,7– tetranitro-1,3,5,7-tetraazacyclooctane(HMX).With the electrolytic preparation of nitrogen pentoxide is matured gradually,nitrogen pentoxide/nitric acid system is expected to get large-scale application in industry in the future,so the related nitration mechanism research is more and more important.In this dissertation,a research has been made on the mechanism of nitrolysis of DPT to HMX by nitrogen pentoxide/nitric acid system,which is in two aspects: the broken bonds form of DPT and the nitrogen pentoxide is in what form to attack DPT.Through the liquid chromatography-mass spectrometry to monitor the intermediate of the reaction process,the possible broken bonds form of DPT has been deduced,at the same time,the conditions of low temperature and low acidity and not too strong nitrification ability are conducive to the formation of HMX.The result of several experiments directly and indirectly makes sure that dinitrogen pentoxide is in the form of nitronium cation to attack DPT in nitric acid.The reaction of nitrogen pentoxide/nitric acid system nitrates parachloronitrobenzene is one order reaction,and the reaction rate has nothing to do with nitrogen pentoxide molecule,which excludes the dinitrogen pentoxide molecular mechanism.The reaction of nitrogen pentoxide/nitric acid system nitrates naphthalene doesn't generate 1,3-dinitronaphthalene and 2,3-dinitronaphthalene,and it excludes the free radical mechanism.The roman spectra of nitrogen pentoxide/nitric acid system has the characteristic absorption of nitronium cation and the area of the peak increases with the increase of dinitrogen pentoxide concentration.The amount of the production of nitrogen pentoxide/nitric acid system nitrates chlorobenzene decrease with the addition of ammonium nitrate.The nitrogen pentoxide/nitric acid system will nitrate paranitrotoluene first then parachloronitrobenzene,when the two reagents add to the system at the same time.These experiments prove the nitronium cation mechanism.According to the result of the research on the mechanism of nitrolysis of DPT to prepare HMX by nitrogen pentoxide/nitric acid system,The nitrogen pentoxide/nitric acid/organic solvent systems have been put forward.In the study of four different solvents,under the condition of the same proportion,the nitrogen pentoxide/nitric acid /acetic anhydride system is in line with the condition of nitrification capacity is moderate and the acidity is low.When nitric acid and acetic anhydride volume ratio is 3:2,the yield of HMX of the nitrogen pentoxide/nitric acid/acetic anhydride system was 87.9%,which provides a new idea for the preparation of HMX.