Perfluoro-3-methyl-l-butyne

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. 

The FVT method can be applied for the synthesis of the fluorinated alkynes, perfluoro-3-methyl-l-butyne and difluoroethyne 40 (R = (CF3)2CF, F) (Scheme 3) <1989CC1657, 1991CC456>. It has been claimed, however, that tris (dimethylamino)-l,2,3-triazine forms the monocyclic azete. 

A remarkable example has recently been described in the flash vacuum pyrolysis of the perfluorodialkyl-l,2,3-triazine 138 which leads to perfluoro-3-methyl-l-butyne, 139 [Eq. (24)]. The 1-fluoroacetylene which was obtained in quantitative yield is a stable compound which does not undergo thermal oligomerization on heating up to 200 °C — in striking contrast to the explosive 1-fluoroacetylene (92) [84] ... 

Diphenyl-5-(4-methoxyphenyl)-l,2,3-triazine has been converted to (4-methoxyphenyl)phenylethyne at 625°C/10 Torr <1981JCM162>. Beyond the preparation of two perfluoroalkynes, namely perfluoro-3-methyl-l-butyne from perfluoro-4,6-diisopropyl-l,2,3-triazine (600 °C, 10 Torr) <1989CC1657> and difluoroethyne from... 

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