Thermal analytical and infrared spectroscopic investigations on polymorphic organic compounds—V

All the polymorphic compounds described are enantiotropic, so that in four cases, order-disorder or rotational transformation can be deduced on the basis of the relationships between enthalpy of transformation and enthalpy of fusion. The following compounds are of this type: (±)-1-azabicyclo- [2.2.2]-octan-3-ol (4 modifications), 5-norbornene-2,3-dicarboxylic anhydride (3 modifications), (l.R)-(–)-camphorquinone (3 modifications) and 2-bromoethylamine hydrobromide (3 modifications). For tris(acetylacetonato)aluminium(III) (3 modifications) and 2-(4-aminophenyl)-6-methylbenzothiazole (5 modifications), another type of transformation must be assumed.