The formation of 1,2,3,4-tetrafluoronaphthalene in the co-pyrolysis of pentafluorobenzenesulphonyl chloride or pentafluoronitrobenzene with butadiene

Article abstract of DOI:10.1016/S0022-1139(99)00081-0

Co-pyrolysis of pentafluorobenzenesulphonyl chloride or pentafluoronitrobenzene with butadiene in a flow system at 500-635°C gave 1,2,3,4-tetrafluoronaphthalene.

Full text of DOI:10.1016/S0022-1139(99)00081-0

Journal of Fluorine Chemistry 96 (1999) 191±192
The formation of 1,2,3,4-tetra¯uoronaphthalene in the
co-pyrolysis of penta¯uorobenzenesulphonyl chloride or
1
penta¯uoronitrobenzene with butadiene
*
V.E. Platonov , O.I. Osina, A.M. Maksimov, V.G. Kolechkina
N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division of Russian Academy of Sciences, 9 Academician Lavrentjev ave.,
Novosibirsk 630090, Russian Federation
Received 17 December 1998; accepted 1 April 1999
Abstract
Co-pyrolysis of penta¯uorobenzenesulphonyl chloride or penta¯uoronitrobenzene with butadiene in a ¯ow system at 500±6358C gave
,2,3,4-tetra¯uoronaphthalene. # 1999 Elsevier Science S.A. All rights reserved.
1
Keywords: 1,2,3,4-Tetra¯uoronaphthalene; Co-pyrolysis; Butadiene; Penta¯uorobenzenesulphonyl chloride; Penta¯uoronitrobenzene
1
. Introduction
GC±MS data are consistent with 4-vinyl cyclohexene and
1
,5-cyclooctadiene.
The co-pyrolysis of compound III with butadiene in the
1
,2,3,4-Tetra¯uoronaphthalene (I) was obtained by the
thermolysis of tetra¯uorobenzobicycloocta[2.2.2]triene (II)
1±3]. The latter was synthesized by the interaction of
tetra¯uorobenzyne with benzene [1±3]. Generation of tetra-
uorobenzyne in its turn was realised by the decomposition
presence of copper or brass also gives tetra¯uoronaphtha-
lene I in 30±33% yields (see Table 1).
[
It is probable that penta¯uorophenyl radical, generated by
the thermolysis of compounds III and IV [4,5] or the high-
temperature interaction of the ®rst with copper (cf. [6]),
takes part in the formation of the compound I by reacting
with butadiene in the following manner:
¯
of penta¯uorophenylmagnesium chloride or bromide [1,2],
as well as penta¯uorophenyl lithium [3].
In this work, another route to tetra¯uoronaphthalene I is
described from the co-pyrolysis of penta¯urobenzenesul-
phonyl chloride (III) or penta¯uoronitrobenzene (IV) with
butadiene (see Table 1).
Yield of compound I in the co-pyrolysis of sulphonyl
chloride III with butadiene may run to 40%. In this reaction,
the formation of C H F (V), penta¯uorobenzene, chlor-
1
0 6 4
openta¯uorobenzene also occurred as the minor products
yield of each is approximately 2±4%). According to gas
chromatography±mass spectrometry (GC±MS) data, the
reaction mixture contains un¯uorinated products as well.
(
Intramolecular closure of the intermediate allyl radical
A) with subsequent elimination of H and HF from the s-
(
complex (B) apparently would lead to tetra¯uoronaphtha-
lene I. Copper could facilitate the elimination of a chlorine
atom from compound III with subsequent generation of a
penta¯uorophenyl radical (cf., for example, the action of
copper on R SO Cl [6]).
*
1
Corresponding author. Fax: +7-3832-34-4752.
Presented at the 12th European Symposium on Fluorine Chemistry,
Freie Universit aÈ t Berlin, Berlin, Germany, 29 August±2 September 1998,
Abstracts, p. PII-88.
f
2
0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 1 1 3 9 ( 9 9 ) 0 0 0 8 1 - 0

1
92
V.E. Platonov et al. / Journal of Fluorine Chemistry 96 (1999) 191±192
Table 1
Co-pyrolysis of polyfluoroaromatic compounds with butadiene
a
Run
Starting
compound (g)
Temperature
(8C)
Time
(min)
Metal addition
(shaving) (g)
Yield of reaction
mixture (g)
Content of (I) according
to GLC (%)
Yield of (I) according
to GLC (%)
1
2
3
4
5
6
7
8
III, 6.6
III, 8
500±550
510±560
510±530
510±555
550±570
550±585
570±610
620±635
7
25
20
25
21
40
60
30
Copper, 12
2.0
2.6
3.1
3.0
7.1
7.6
11.8
3.2
75
77
22
55
33
63
56
38
30
33
14
20
Brass, 12
III, 8.4
IV, 8.9
III, 9.9
III, 17.2
III, 22
III, 6.4
±
±
±
±
±
±
b
31
37
40
30
a
Gas was fed at the rate of 10 l/h.
b
Solid product, 1.8 g, was filtered off from the reaction mixture. According to GLC content of I is 96%.
Tetra¯uoronaphthalene I was also obtained by pyrolysis
of compound II in a ¯ow system at 5308C in accordance
mixture was distilled with steam, treated by CH Cl , dried
2 2
over MgSO and analysed by GLC methods. The results of
4
with [3]. IR-, 19F, H, C NMR spectra of compound I
1
13
experiments are given in Table 1.
obtained by the two methods agree with each other. Formula
2
Compound I was isolated from the reaction mixture after
evaporation of the solvent. The precipitate was ®ltered off
and recrystallized from ethanol, m.p. 110±1118C (m.p. 110±
1118C [7]). Found (%): C 60.0; H 2.0; F 38.5; Mol. weight
200.0248 (MS), C H F . Calculated (%): C 60.0; H 2.0; F
C H F is ascribed on the basis of mass spectrometry data
1
0 6 4
(
found: M 202.0363; calculated: M 202.0406) of the mix-
ture of compounds I and V which was isolated by distillation
of reaction mixture (run 7, Table 1).
10 4 4
The 19F, H and 13C NMR spectra were recorded on a
1
38.0; Mol. weight 200.0249. F NMR (ꢀ, ppm): F 11.09;
19
1
2
F 2.44 (F 11.82; F 3.05 [8]). H NMR (ꢀ, ppm): H 7.95;
1
2
1
5
Bruker WP-200SY and Bruker AC-200 instruments operat-
ing at 188.2, 200 and 50.3 MHz in CDCl (10% solution of
6
H 7.53 (H 8.05; H 7.64 [8]).
5
6
3
individual compounds). Internal standards were hexa¯uor-
obenzene and hexamethyldisiloxane. The IR spectra were
recorded on a UR-20 instrument for solid samples as KBr
pellets at a concentration of 0.25%. Molecular weights and
molecular formulae of compounds were determined mass-
spectrometrically on a Finnigan-MAT-8200 instrument. The
nominal energy of ionizing electrons was 70 eV. GLC
analyses were performed on a LHM-72 instrument with a
thermal conductivity detector with a linear temperature
program of 108C/min. The carrier gas was helium with a
Acknowledgements
We gratefully thank the Siberian Division of Russian
Academy of Sciences (Grant IG SO RAN-97-N2) for
®nancial support.
References
¯
ow rate of 10 ml/min. The stainless steel columns
4
000Â4 mm in dimensions (the solid carrier chromosorb
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[
[
[
[
[
[
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MS analyses were performed with a Hewlett-Packard 5890/
II apparatus (70 eV) using a 30 m capillary column coated
with an HP5 oil. A typical experimental procedure was as
follows. The starting poly¯uoroaromatic compound was
passed dropwise in a stream of butadiene through a quartz
tube (400Â20 mm) placed into an electric oven which was
heated to certain temperature (see Table 1). The reaction
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(
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2
Description of the structure will be published.