Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 7, pp. 1254−1258.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
P.V. Nikul’shin, A.M. Maksimov, V.E. Platonov, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 7, pp. 1148−1152.
AND INDUSTRIAL ORGANIC CHEMISTRY
Synthesis of Chloro- and ortho-Dichloropolyﬂ uoroarenes
by Pyrolysis of Polyﬂ uoroarenes in the Presence of Chlorine
P. V. Nikul’shin, A. M. Maksimov, and V. E. Platonov
Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Received September 3, 2009
Abstract—Pyrolysis of polyﬂ uoroarenethiols in the presence of chlorine at temperatures of 400–420°C in a ﬂ ow-
through system was used to synthesize chloro- and ortho-dichloropolyﬂ uoroarenes containing perﬂ uorinated
chlorotolyl, xylyl, indanyl, and chloropyridyl groups.
Polyﬂ uorochloroarenes are commonly used to
obtain their functional derivatives, with both chlorine
and ﬂ uorine atoms involved. Of separate interest
are reactions in which chlorine atoms are involved
selectively. To these belong methylation reactions and
primarily, synthesis of polyﬂ uoroaryl organolithium
and organomagnesium reagents  and, recently,
that of polyﬂ uoroaryl organozinc compounds [2, 3].
Polyﬂ uorochloroarenes may be of practical interest as
heat carriers, insulators, and solvents .
To introduce chlorine atoms into polyﬂ uoroarenes,
reactions of electrophilic substitution of hydrogen atoms
by chlorine have been for the most part used . However,
this pathway for synthesis of polyﬂ uorochloroarenes
cannot always produce the desired result, which has
been demonstrated by the example of a failed attempt to
chlorinate 1,2,4,5-tetraﬂ uorobenzene by treatment with
in 65% oleum .
The reaction of hexaﬂ uorobenzene with KF at
450–500°C yields, together with hexaﬂ uorobenzene,
chloropentaﬂ uorobenzene and a mixture of isomeric
dichlorotetraﬂ uoro- and triﬂ uorotrichlorobenzenes .
Recently, a convenient method for introduction
of chlorine atoms into polyﬂ uoroarenes by thermal
replacement of a thiol group easily and selectively
introduced into a polyﬂ uoroarene by reactions of
nucleophilic substitution  with a chlorine atom  was
developed. A number of polyﬂ uoroaromatic compounds
have been synthesized by this method in high yield .
The goal of the present study was to expand the
synthetic capacity of this technique and extend it
to thiol derivatives of 3-chloroheptaﬂ uorotoluene,
perﬂ uoroxylenes, perﬂ uoroindane and its 5-chloro-
derivative, and 3-chlorotetraﬂ uoropyridine. In this
case, it seemed appropriate, in addition to introducing
a chlorine atom into a polyﬂ uoroarene, to develop
a method for synthesis of difﬁ cultly accessible ortho-
dichloro derivatives of polyﬂ uoroaromatic compounds.
H NMR spectra were recorded with
a Bruker AV-300 instrument (282.4 MHz for
300 MHz for
H). Positive chemical shifts correspond
to a downﬁ eld shift of a signal relative to C
TMS; as internal standards served C
(0.04 ppm relative to TMS). IR and UV spectra were
measured on Bruker Vector 22 IR and Hewlett Packard
8453 UV instruments, respectively. The molecular
masses and elemental composition were determined
by mass spectrometry on Finnigan MAT 8200 and
DFS high-resolution instruments (nominal ionization
energies 70 eV). A GLC analysis was made on
a Hewlett Packard HP 5980 instrument equipped with
a 30 m × 0.52 mm/2.6 μm HP-5 quartz capillary column