Mechanism of the benzenediazonium tetrafluoroborate thermolysis in the solid state

The thermolysis of benzenediazonium tetrafluoroborate was studied by thermogravimetry in dynamic mode. The decomposition of [ArNtriple bond; length of mdashN]+BF4− in the solid state with the formation of C6H5F, BF3, C6H6, and N2 starts at T > 348 K. The speed of the thermolysis was estimated gravimetrically and by infrared spectroscopy, considering the change of the intensity of the absorption band at 1498 cm−1, which corresponds to fluorobenzene. The maximal rate of thermolysis observes at the 366.5 K. A kinetic scheme, which includes the formation of a neutral complex [C6H5δ+⋯BF4δ−], is proposed for the thermolysis of arenediazonium tetrafluoroborate. The decomposition of the complex with the formation of free-radical intermediates explains the chain character of the thermolysis.