Separation,Characterization And Formation Mechanism Analysis Of By-Product In Hexanitrobibenzyl Manufacture

Hexanitrobibenzyl(HNBB)is an important intermediate in the synthesis of hexanitrostilbene(HNS)and its yield will directly affect the yield of HNS.This paper studies the formation mechanism of the main by-products in the synthesis of HNBB,which is of great significance for improving the synthesis process of HNBB and reducing its production cost.The by-products in the synthesis of HNBB were enriched,and 7 substances were separated by column chromatograp Hy.The structures were characterized by infrared spectroscopy,nuclear magnetic resonance and X-ray single crystal diffraction.It was confirmed that the substances contained 2,4-dinitro Toluene(DNT),trinitrobenzene(TNB),2,4-dinitrochlorobenzene(CDB),2,4,6-trinitrotoluene(TNT),HNS,3-methyl-2,6-dinitrop Henol and Sodium Picrate(SPA).The synthetic by-products of HNBB were analyzed by high performance liquid chromatograp Hy.Liquid chromatograp Hy conditions: the wavelength was 230 nm,the mobile p Hase composition was: acetonitrile/water=32.5/72.5(volume ratio),the flow rate was 0.5m L/min and the injection volume was 10 ?L.The results showed that there were no less than25 kinds of by-products,of which 6 kinds were more than 1%,accounting for 87.80% of the by-products.By comparing the structures of the raw materials and products of the reaction,combined with the basic theory of organic chemical reactions,the most probable generation mechanisms of the seven isolated by-products were analyzed.DNT is formed by electronic effect and steric hindrance effect causing a nitro group in the vicinal position of TNT to fall off in the oxidation reaction;TNB is formed by TNT first oxidized to TNBA and TNBA in the reaction system and then further decarboxylated;CDB is formed by TNT in the oxidation reaction Oxidation-denitrification in the system generates dinitrobenzoic acid,and dinitrobenzoic acid further undergoes nucleop Hilic substitution reaction with chloride ions in the system;TNT is the reaction raw material;HNS is the oxidation of TNT under alkaline conditions to generate trinitrobenzaldehyde,Trinitrobenzaldehyde and TNT are formed by Knoevenagel reaction dehydration condensation,and may also be further oxidized by HNBB;It is formed by the nucleop Hilic substitution reaction of aromatic hydrocarbons with chloride ions;SPA is the oxidation of TNT to TNBA in the reaction system,and the affinity substitution reaction of TNBA occurs under alkaline conditions to generate trinitrop Henol,which is further reacted with sodium hydroxide made.