Study On Synthesis And Properties Of Several Pentazol Anion （cyclo-N₅^-） Non-metallic Salts

Polynitrogen compounds（containing only nitrogen atoms）contain a large amount of N-N and N=N,and the decomposition products are mainly nitrogen,and have the advantages of high density,high heat,high energy,and detonation products clean and pollution-free.These compounds have potential application prospects and are candidates for a new generation of energetic materials.Their research has important strategic and scientific significance for national security.Polynitrogen compounds can be divided into three categories:ionic,covalent,and polymeric nitrogen.The ionic total nitrogen has been reported as N₃^-,cyclo-N₅^- and N₅⁺.Cyclo-N₅^-,as an anion for the preparation of ionic pernitrogen compounds,has slightly lower stability than N₃^-,and cyclo-N₅^-has received increasing attention.Cyclo-N₅^- is obtained by oxidative cleavage of arylpentazoles.In this paper,the reaction condition for oxidative cleavage of the arylpentazole C-N bond were optimized.Based on this,the synthesis process of sodium pentazole was scaled up.Three pentazolate non-metal energetic salts were synthesized by metathesis displacement reaction.The single crystal structure,thermal stability and sensitivity were characterized and analyzed.The detonation performance was theoretically estimated.First,the reaction conditions for the cleavage of the C-N bond of arylpentazol to prepare sodium pentazole were optimized.Surfactants and amino acids were added separately,and substitutes for ferrous glycine were replaced.The amount of m-chloroperoxybenzoic acid was reduced.Also study on the influence of temperature,reaction time and amount of reaction solvent on the reaction.Surfactants and amino acids were added in the process of cutting the C-N bond of arylpentazol.As a result,it was found that the addition of cysteine helps to improve the yield of sodium pentazole.The average yield of sodium pentazole was 4% to 5%increased to about 6%,indicating that the cysteine and glycine ferrous complexes have a certain synergistic effect on the reaction.Experiments with ferrous cysteine instead of ferrous glycine have shown that other amino acid anions can be used instead of ferrous glycine anions.Without reducing the yield of sodium pentazolium,the feeding amount of m-CPBA was reduced by 15%,which not only reduced the amount of reactants with a certain risk,improved the safety of the experiment,but also facilitated the further experimental reaction expand.Through orthogonal experiments,the effects of reaction temperature,reaction time and the amount of reaction solvent on the reaction were studied.The feed amount was 8g of arylpentazole,13g of ferrous glycine,28g of m-chloroperoxybenzoic acid,and 0.4% of cysteamine,the preferred process conditions to obtain the cut-off reaction are:the reaction temperature is-40℃,the reaction time is 24 h,and the mixed solvent（methanol:acetonitrile=1:1）is 150 mL.Secondly,the synthesis process of sodium pentazole was enlarged,and the output of sodium pentazole was increased from 0.2g to 1.0g.The experiments show that the reaction yield has a certain downward trend after reaction amplification,which indicates that the reaction amplification effect is obvious.In the post-treatment part of the reaction,there is a multi-step rotary steaming process.Due to the effects of vacuum and heating,the sodium pentazolium product is decomposed to some extentFinally,using the low solubility of BaSO₄,three energetic non-metal salts of pentazolium anions were synthesized through the metathesis reaction of barium pentazolium and corresponding sulfates:O-（carboxymethyl）hydroxylammonium,O-（4-nitrobenzyl）hydroxylammonium,and ethane-1,2-diaminium pentazolates.Using traditional single crystal culture methods,three single crystals of non-metal salts were obtained.Characterized by single crystal X-ray diffraction,infrared（IR）,¹H and ¹³CNMR spectra,thermal analysis（TGA and DSC）,and elemental analysis.These three salts show good detonation performance,low sensitivity and good thermal stability.This new method provides more options for the cost-effective preparation of pentazole anionic energetic compounds.