THE THERMAL-DECOMPOSITION OF AMINOTETRAZOLES .2. 1-METHYL-5-AMINOTETRAZOLE AND 1,5-DIAMINOTETRAZOLE

The thermal decompositions of 1-methyl-5-aminotetrazole and of 1,5-dia minotetrazole have been studied using thermogravimetry, differential s canning calorimetry and thermal volumetric analysis. The solid residue s, and the high boiling point and gaseous products of the decompositio ns have been collected and identified using IR spectroscopy and mass s pectrometry. Both aminotetrazoles start to decompose just after meltin g: 1-methyl-5-aminotetrazole at 495 K and 1,5-diaminotetrazole at 460 K. The decomposition is accompanied by elimination of gaseous and high boiling point products, partial evaporation of the original substance s and formation of thermally stable residues.Both 1-methyl-5-aminotetr azole and 1,5-diaminotetrazole, in the solid state and probably in the melt, coexist in amino and imino tautomeric forms. Therefore, two com peting mechanisms of tetrazole ring-breaking, with elimination of resp ectively nitrogen or hydrogen azide molecule, are proposed.