Rich polymorphism in triacetone-triperoxide

The improvised explosive triacetone-triperoxide (TATP) (1), previously considered to have a single solid-state structure, was found to form at least six different polymorphic crystals (1a-f), depending on the acid catalyst used for its synthesis and on the solvent used for its recrystallization. The structure of each polymorph was solved by single-crystal X-ray crystallography, showing that there is no solvent inclusion in any of the polymorphs, and all exhibit the same molecular conformation of D₃ point symmetry. There is no molecular disorder in polymorphs 1a, 1d, and 1f, but the other polymorphs (1b, 1c, and 1e) contain disordered molecules in the unit cell that lead to domains of enantiomeric excess. The relation among the polymorphs was studied by differential scanning calorimetry.