Nitriles and nitrogen

Little is known as yet of the chemistry of the monocyclic 1,2,3-triazines. The only reactions that have been reported are hydrolysis to substituted butane-1,3-diones, photolytic decomposition to acetylenes, nitriles, and nitrogen, and high temperature (250°) thermolysis, which leads to loss of nitrogen and formation of the corresponding diarylindenone imines. The structures of the latter compounds were confirmed on the basis of their physical properties and by hydrolysis to the corresponding known diarylindenones. ... 

All the well-characterized 1,2,3-triazine derivatives are stable, high-melting solids. The 4,5,6-triaryl derivatives show UV maxima in the range 259-286 nm (log e = 4.09-4.42), 4,5-diphenyl-1,2,3-triazine has Amai at 251 nm, while the 4,5,6-trimethyl derivative shows two maxima at 217 nm (log e — 3.63) and 278 nm (log e = 2.79). Mass spectral studies indicate that fragmentation takes place in an identical fasMon to that observed during photochemical decomposition, i.e., with production of acetylenes, nitriles, and nitrogen. ... 

Under flash vacuum thermolysis (FVT) the 1,2,3-triazine (32) was readily thermolyzed to an alkyne, a nitrile, and nitrogen in high yields. For unsymmetrically substituted 1,2,3-triazines as FVT substrates, fragmentation proceeded selectively a bulky substituent at C-4(6) made the adjacent C—N bond break more easily than the opposite C—N bond. The FVT method was applied to the synthesis of the fluorinated alkynes, perfluoro-3-methyl-l-butyne and difluoroethyne [(33), R = (CF3)2CF, F] (Equation (1)) (89CC1657, 91CC456). It has been claimed, however, that tris(dimethylamino)-1,2,3-triazine forms the monocyclic azete. 

Tetrazines (39) form nitriles and nitrogen on thermal degradation (59JA4342). Pyrolysis of Af-unsubstituted dihydro-1,2,4,5-tetrazines (41) is reported to lead to the tetrazines (39) but this reaction was probably an oxidation since oxygen was not excluded. 

In general, pyrolysis of monocyclic 1,2,3-triazines 1 leads to acetylenes, nitriles and nitrogen.46, 295 297 300 Heating simple 1,2,3-triazines in a sealed tube led to the isolation of pyridines, pyrimidines, pyrazoles, pyrroles, pyridazine, and indeno[3,2-/>]pyridine, depending on the substituents bound to the 1,2,3-triazine ring and the reaction conditions.46 A mechanism formulated for the formation of these products involves an azete as an intermediate. 

Photochemistry of monocyclic 1,2,3-triazines has not been studied very intensively. The main route on photolysis is the fragmentation into acetylenes, nitriles and nitrogen. 

Tables 9.1-9.4 list some important chemical, physical, and chromatographic properties as well as general manufacturing and safety parameters for the nitriles and nitrogenous solvents [84-92]. Figure 9.1 shows the structure of the solvents listed in Tables 9.1-9.4.

TABLE 9.2 Chromatographic Parameters of Nitriles and Nitrogeneous Solvents"... 

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