Organofluorine Sulfur-containing Compounds: V. Joint Pyrolysis with Chlorine or Bromine of Polyfluoroarenethioles, Polyfluorohetarenethioles, and Their Derivatives

Abstract

Joint pyrolysis with chlorine and bromine of polyfluoroarenethiols, -hetarenethiols, and their derivatives at 300-650°C furnished polyfluorocompounds containing chlorine and bromine.

Synthesis of 1,2-dichlorotetrafluoro- and 1,2,4-trichlorotrifluorobenzenes

“…The reaction resulted in introduction of a sulfanyl group into the 4-position (Scheme 5), in keeping with the substitution direction observed in the reaction of I with sodium methoxide [10]. The subsequent replacement of the sulfanyl group in 3,4-dichlorotrifluorobenzenethiol (X) by chlorine was accomplished by analogy with the procedures reported in [4,27], and trichloro derivative II was obtained in 90% yield.…”

“…The reaction of V with KSH gave 2,5-dichlorotrifluorobenzenethiol (XI), and pyrolysis of the latter in the presence of chlorine afforded 84% of II (Scheme 6). Compound V was syn-SYNTHESIS OF 1,2-DICHLOROTETRAFLUORO-AND 1,2,4-TRICHLOROTRIFLUORO... RUSSIAN thesized in a similar way from 4-chloro-2,3,5,6-tetrafluorobenzenethiol (XII) [4] which was prepared [28] in turn from accessible chloropentafluorobenzene [2]. Taking into account that compound X or XI is necessary for the preparation of II we believed it reasonable to develop a more practical and convenient procedure for the synthesis of this compound.…”

“…As a result, we obtained arene II in 90% yield (Scheme 7). Presumably, the SH group in the initial thiols is replaced by chlorine through intermediate formation of isomeric dichlorotrifluorobenzenesulfenyl chlorides by analogy with the formation of chloropolyfluoroarenes in the pyrolysis of polyfluoroarenethiols in the presence of chlorine [4] (Scheme 8).…”

“…The mixture of trichlorotrifluorobenzenes contained mainly 1,3,5-trichlorotrifluorobenzene (~69%) together with 1,2,3-and 1,2,4-isomers (~18 and 13%, respectively); only 1,3,5-trichlorotrifluorobenzene was isolated as individual substance from that mixture [3]. We recently developed a procedure for the synthesis of 1,4-dichlorotetrafluorobenzene by pyrolysis of 4-chlorotetrafluorobenzenethiol in the presence of chlorine [4].…”

New polyfluorinated aromatic and aza-aromatic diselenides, selenyl chlorides, non-symmetric selenides and selenoxides

“…Starting 2,3,5,6-tetrafluoro-1-chlorobenzene [14], 2,3,5,6-tetrafluoroanisole [15], N,N-dimethyl-2,3,5,6-tetrafluoroaniline [16], 2,4,6-trifluoropyridine and 2,3,4,6-tetrafluoropyridine [17], and pentafluoropyridine [18] were described before.…”