Heterocyclic polyfluoro-compounds. Part 30. Perfluoroalkylation of trifluoro-1,2,4-triazine

Abstract

Reaction of trifluoro-l,2,4-triazine with hexafluoropropene and caesium fluoride in the absence of solvent leads to successive replacement of fluorine by perfluoroisopropyl groups to give 5-mmo-, 35and possibly 3,6-di-, and tri-substituted derivatives. Similarly, perfluoro-2-azapropene yields 5and some 6-, 3,6-bis-, and tris-perfluorodimethylamino-derivatives. Pyrolysis of trifluoro-l,2,4-triazine at 500 "C/42 h yields trifluoro-l,3,5-triazine (32%) ; of perfluoro(tri-isopropyl-l,2,4-triazine) at 560 OC/O.26 s yields perfluoroisobutyronitrile and perfluoro-2,5-dimethylhex-3-yne ; and of perfluoro(trisdimathylamino-l,2,4-triazine) at 620 "C/2.4 s yields N,N-bis(trifluoromethy1)cyanamide and perfluorobis(dim3thylamino)acetylene.TRIFLUORO-1,2,4-TRIAZINE, readily prepared by the fluorobut-2-yne and fluoride ion,6 were less successful. vapour-phase fluorination of trichloro-l,2,4-triazine with Hexafluorocyclobutene and caesium fluoride with tripotassium fluoride,2 is a versatile and reactive com-fluoro-l,2,4-triazine yielded small amounts of a mixture pound, undergoing Diels-Alder addition with ole fin^,^ which contained by mass spectrometry, mono-, di-, and nucleophilic displacement of fluorine. Here we and tri-substituted compounds. Hexafluorobut-2-ync describe its successful perfluoroalkylation, and the and caesium fluoride yielded trace amounts of a. pyrolysis of its trisheptafluoroisopropyl and bistri-compound which may have been the trisubstituted

Fluorinated Triazines

“…The data of 19 F NMR spectroscopy show that chemical shifts of fl uorine atoms attached to the ring in 1,2,3-triazines are varied greatly and lay in range from −79.5 to −166.0 ppm [ 11 ]. The data on 19 F NMR spectra of fl uorinated 1,2,4-triazines have recently been presented and discussed [ 12 ]. Coupling constants 5 J F(3),F(6) lay in range from 35 to 37 Hz, constant 3 J F(5),F (6) proved to be 24 Hz, whereas the 4 J F(3),F(5) has smallest value (<4 Hz) (Scheme 5 ).…”

“…Being UV-irradiated 4,5,6-trifl uoro-1,2,3-triazine 2 is transformed into trifl uoroazet 88 (Scheme 39 ) [ 78 ]. It is worth to note that the replacement of fl uorine atoms in 3,5,6-trifl uoro-1,2,4-triazine 18 by action of bis(trifl uoromethyl)amino anion (the latter can be obtained from perfl uoro-2-azapropene and cesium fl uoride) provides a mixture of mono-, diand trisubstituted perfl uorodimethylamino-1,2,4-triazines 96-98 (Scheme 41 ) [ 12 ]. Incorporation of perfl uoroisopropyl groups into trifl uoro-1,2,4-triazine takes place smoothly in the reaction of 18 with hexafl uoropropene and cesium fl uoride without of any solvent [ 12 ].…”

“…Heating of 3,5,6-trifl uoro-1,2,4-triazine 18 at a high temperature (approximately 500 °C) for many hours gave 2,4,6-trifl uoro-1,3,5-triazine 55 , as the ring transformation product, and perfl uoropropylene (Scheme 23 ) [ 12 ].…”

“…It is worth to note that the replacement of fl uorine atoms in 3,5,6-trifl uoro-1,2,4-triazine 18 by action of bis(trifl uoromethyl)amino anion (the latter can be obtained from perfl uoro-2-azapropene and cesium fl uoride) provides a mixture of mono-, diand trisubstituted perfl uorodimethylamino-1,2,4-triazines 96-98 (Scheme 41 ) [ 12 ]. Incorporation of perfl uoroisopropyl groups into trifl uoro-1,2,4-triazine takes place smoothly in the reaction of 18 with hexafl uoropropene and cesium fl uoride without of any solvent [ 12 ]. When the reaction is carried out at 125 °С for 25 min a mixture of 5-perfl uoroisopropyl-derivative 100 and 3,5-di-and 3,5,6-tri (perfl uoroisopropyl)-1,2,4-triazines 101, 102 are formed (Scheme 43 ), while the formation of trisubstituted derivative 102 (yield 52 %) takes place on heating at 110 °С for 2 h.…”

A novel and efficient synthetic route to perfluoroisobutyronitrile from perfluoroisobutyryl acid

“…[1][2][3] On-going research in General Electric (GE), America has led to the emergence of some new insulating gases like CF 3 I, c-C 4 F 8 , i-C 5 F 10 O, and i-C 4 F 7 N. There are handful reports about the synthesis of i-C 4 F 7 N, furthermore most of them aren't practical to apply in industry. [4][5][6][7][8][9][10][11] The gas i-C 4 F 7 N, when mixed with CO 2 , exhibits excellent properties, which surely be one of the rst choices to replace SF 6 . Besides, the GWP of i-C 4 F 7 N is only 2210, which is far lower than that of SF 6 .…”