Synthesis and Characterization of Pentazole Anion in Methanol

3,5-Dimethyl-4-hydroxy aniline hydrochloride was synthesized with a total yield of 75％ from p-aminobenzene sulfonic acid via diazotization,condensation and hydrolysis reaction.3,5-Dimethyl-4-hydroxy phenyl-pentazole,which is stable at-50 ℃was synthesized from 3,5-dimethyl-4-aniline hydrochloride,and the yield was 66.7％.A small amount of pentazole anion was synthesized from 3,5-dimethyl-4-hydroxy phenyl-pentazole by using methanol as solvent,ferrous salts as reductant,and m-chloroperoxybenzoicacid as oxidant to break the C-N bond.Pentazole anion was characterized by MS and NMR.According to the isotope labeling experiments,nitrogen atoms in pentazole anion are in the same chemical environment,which means pentazole anion may possess aromaticity.