Process for the preparation of highly pure 5,5'-bi-1H tetrazolediammonium salts

摘要

A process for the preparation of a highly pure 5,5'-bi-1H-tetrazolediammonium salt (BHT.2NH3) in a high yield by efficiently synthesizing the 5,5'-bi-1H-tetrazolediammonium salt (BHT.2NH3) from cheap and easy-to-handle starting materials based on a one-pot reaction, and removing copper components which are impurities in the form of a copper.ammonia.5,5'-bi-1H-tetrazole complex from the reaction solution or from the coarse crystals isolated from the reaction solution. By further conducting the treatment with a chelating resin, the copper content can be further decreased. The refining process is conducted by either: (A) adding small amounts of aqueous hydrogen peroxide and ammonia water to the reaction solution containing the 5,5'-bi-1H-tetrazoledisodium salt that is obtained by synthesizing a dicyan by adding, as an oxidizing agent, a aqueous hydrogen peroxide to an aqueous solution of the starting materials of which the pH has been adjusted to be 5 to 7 by the addition of a small amount of acidic substance in the presence of hydrogen cyanide or sodium cyanide, sodium azide and a catalytic amount of a copper salt, followed by the heat-cyclization reaction, and removing by filtration the insoluble component of the precipitated copper.ammonia.5,5'-bi-1H-tetrazole complex, and reacting the reaction solution with an aqueous solution of ammonium chloride, or (B) adding the aqueous solution of ammonium chloride to the reaction solution, transforming the separated 5,5'-bi-1H-tetrazolediammonium salt (BHT.2NH3) into a 5,5'-bi-1H-tetrazoledisodium salt (BHT.2Na), dissolving the disodium salt again, and reacting the aqueous solution of the obtained 5,5'-bi-1H-tetrazoledisodium salt from which the insoluble component of the formed copper.ammonia.5,5'-bi-1H-tetrazole complex has been removed by filtration with the aqueous solution of ammonium chloride. The process of preparing the highly pure 5,5'-bi-1H-tetrazolediammonium salt (BHT.2NH3) combines the refining process (A) or (B) with a step of treatment with a chelating resin to react the treated solution with ammonium chloride or an aqueous solution thereof to recover the formed highly pure ammonium salt in the form of crystals.