1.2.3- Triazine thermal fragmentation

Pyrolysis of tris(heptafluoroisopropyl)-1,2,4-triazine (329) affords bis(heptafluoroiso-propyl)acetylene and perfluorobutyronitrile, besides nitrogen (79JCS(P1)1978, 80JCS(P1)2254). The thermal fragmentation of this compound is analogous to the mass spectral fragmentation of many other 1,2,4-triazines. 

The authors claim that the thermal stability of polymers with aroxy-triazine groupments is much better than that with alkoxy-triazine fragments. It can be assumed that the proper way to increase the thermal stability is to enhance oxazoline ring formation. 

Successive introduction of nitrogen atoms into benzene causes a gradual reduction in aromatic stabilization. The diazines still show typical aromatic behavior in that in most of their reactions they revert to type. However, with the triazines and tetrazines, decreasing aromaticity increases the ease of both thermal and photochemical fragmentations and rearrangements, and of cyclic transition state reactions with other reagents. 

Triazines (XXXII) are a class of symmetrical initiators where multiple fragmentations are brought about by a scission, which on excitation dissociate into three substituted nitriles (XXXIII) (Scheme 631) Specifically, the primary photoproducts are not radicals, but they dissociate into radicals in a secondary thermal step (Scheme 6.38). ... 

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