Formation of polyfluorofluorenes in the reactions of perfluoro-1,1-diphenylalkanes with antimony pentafluoride

Article abstract of DOI:10.1016/j.jfluchem.2017.12.018

Perfluoro-1,1-diphenylethane heated with SbF₅ at 130 °C with further treatment of the reaction mixture with HF-pyridine and then with water, gave perfluorinated 9‐methylfluorene and 9-methyl-1,2,3,4-tetrahydrofluorene. Perfluoro-1,1-diphenylpro

Full text of DOI:10.1016/j.jfluchem.2017.12.018

Accepted Manuscript
Title: Formation of polyfluorofluorenes in the reactions of
perfluoro-1,1-diphenylalkanes with antimony pentafluoride
Authors: Tatyana V. Mezhenkova, Victor M. Karpov, Yaroslav
V. Zonov
PII:
S0022-1139(17)30533-X
DOI:
Reference:
https://doi.org/10.1016/j.jfluchem.2017.12.018
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Please cite this article as: Tatyana V.Mezhenkova, Victor M.Karpov, Yaroslav
V.Zonov, Formation of polyfluorofluorenes in the reactions of perfluoro-
1,1-diphenylalkanes with antimony pentafluoride, Journal of Fluorine
Chemistry https://doi.org/10.1016/j.jfluchem.2017.12.018
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Formation of polyfluorofluorenes in the reactions of perfluoro-1,1-
diphenylalkanes with antimony pentafluoride
Tatyana V. Mezhenkovaa, Victor M. Karpova,, Yaroslav V. Zonova,b
a N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk 630090, Russia
b Novosibirsk State University, Novosibirsk 630090, Russia
Received
05.12.2017
Graphical abstract
R
F
F R
C
1) SbF5, 130 oC
2) HF-Py
F
F
F
F
R = CF3, C2F5, CF(CF3)2
Highlights
 Synthesis and reactions of perfluoro-1,1-diphenylalkanes with antimony pentafluoride.
 Cationic cyclization of perfluoro-1,1-diphenylalkanes into fluorenes.
 Perfluorinated 9-methyl-, 9-ethyl-, 9-isopropylfluorenes were obtained.
Abstract
Perfluoro-1,1-diphenylethane heated with SbF5 at 130 °C with further treatment of the
reaction mixture with HF-pyridine and then with water, gave perfluorinated 9-methylfluorene and
9-methyl-1,2,3,4-tetrahydrofluorene. Perfluoro-1,1-diphenylpropane under similar conditions
formed perfluoro-9-ethylfluorene and perfluoro-9,9-dimethyl-1,2,3,4-tetrahydrofluorene. When
o
perfluoroisobutylbenzene was heated with pentafluorobenzene in SbF5 medium at 130 C, with
further treatment of the reaction mixture with HF-pyridine and then with water, perfluoro-9-
isopropylfluorene was obtained. Perfluorodiphenylmethane heated with SbF5, after treatment of
the reaction mixture with water, gave perfluorobenzophenone; perfluorofluorene or its derivatives
were not found in the mixture.
 Corresponding author. Fax: +7-3832-34-4752. E-mail address: karpov@nioch.nsc.ru (V.M.Karpov)

2
Keywords: Fluorinated; Fluorene; 1,1-Diphenylalkane; Cyclization; Cation; Antimony pentafluoride
1. Introduction
Fluorinated aromatic compounds are essentially important to fundamental organic chemistry
[1–3] and its applications, for example, to materials science, biomedicine and agriculture [1–11].
In particular, fluorine containing fluorenes also receive attention in both fundamental and applied
aspects [11–20]. Of perfluorinated fluorenes, as far as we are aware, only perfluorofluorene [15],
perfluoro-9-phenylfluorene [15], perfluoro-9-methylfluorene [21,22] and perfluoro-9-
ethylfluorene [22] are known.
It has been shown by us earlier that perfluoro-9-methylfluorene along with other compounds
was formed in the reaction of perfluoro-1-phenylindane with antimony pentafluoride [21]. We
proposed that in the intermediate perfluoro-1-(2-tolyl)-1-phenylethan-1-yl cation there occurs
cyclization with elimination of the trifluoromethyl cation to give 9-methylfluorene [21]. It was
interesting to investigate the behavior of perfluoro-1,1-diphenylethane and similar compounds,
which have no CF3-group in the aromatic ring, under the action of SbF5 with the aim to study the
possibility of their cationic cyclization. It should be noted that in the hydrocarbon series
diarylmethyl cations in a strong acid medium can undergo electrocyclization with the formation
of fluorene derivatives [23–25]. In addition to this, 4π-electrocyclization (conrotatory) of
pentadienyl cations to cyclopentenyl cations is known in both hydrocarbon [26, 27] and
fluorocarbon series [28]. This work describes transformations of some perfluoro-1,1-
diphenylalkanes under the action of antimony pentafluoride.
2. Results and discussion
2.1. Reactions of perfluorinated 1,1-diphenylalkanes with SbF5
The heating of perfluoro-1,1-diphenylethane (1) with SbF5 at 130°C with further treatment
of the reaction mixture with Olah’s reagent (HF-pyridine) and then with water, gives a mixture of
perfluorinated 9-methylfluorene (2) and 9-methyl-1,2,3,4-tetrahydrofluorene (3) along with small
amounts of 9-methylfluoren-9-ol (4). When the reaction mixture was treated with water (without
HF pretreatment), compounds 2 – 4, perfluoro-9-methyl-2,3,4,9-tetrahydrofluoren-1-one (5) and
small amounts of perfluoro-9-methyl-2,3,4,4a-tetrahydrofluoren-9-ol (6) were obtained (Scheme
1). The yields of compounds are given for reaction mixtures (19F NMR, GLC).

3
ompound was synthesized by the reaction of perfluoroethylbenzene ( ) with C F H in
C
1
7
6
5
the presence of SbF at room temperature [29]. When we hold a mixture of ethylbenzene , C F H
7
5
6 5
and excess of SbF at room temperature, a solution of equimolar amounts of compound and HF
1
5
in antimony pentafluoride was prepared. Heating this solution at 130 oC, with further treatment of
the reaction mixture with HF-pyridine and then with water, leads to the formation of compound ,
2
perfluoro-9-methyl-9-phenyl-1,2,3,4-tetrahydrofluorene ( ) and small amounts of compound .
8
3
When the reaction mixture was treated with water (without HF pretreatment), compounds – ,
2 5 8
were obtained (Scheme 1). Both reaction mixtures also contained compound
unidentified products.
and some
7
The transformations of compound 1 under the action of SbF5 can be rationalized by Scheme
2.
It may be suggested that in cation 10, generated from compound 1 [30], there occurs
cyclization (resonance structure 10a) with further addition of fluoride ion to produce compound
11. The latter isomerizes into compound 12, for example, by elimination–addition of a fluoride
ion. Compound 12 seems to disproportionate to fluorene 2 and tetrahydrofluorene 3. The
mechanism of this process is not clear, but the disproportionation of polyfluorocyclohexadienes in
an SbF5 medium is known [31,32].
The reaction of ethylbenzene 7 with C6F5H resulting in compound 1 and HF seems to be
reversible at 130 °C (Scheme 3). So the reaction mixture contains some amounts of
pentafluorobenzene that can react with compounds 2 or/and 3 to give perfluoro-9-methyl-9-
phenylfluorene (9) or/and compound 8, respectively. Under the reaction conditions, fluorene 9 is
apparently transformed into compound 8.
As mentioned above, in the reaction of compound 1 with SbF5 (in the absence of HF),
fluorene 2 is evidently formed by disproportionation of compound 12, but in the presence of HF,
fluorene 2 is apparently formed by defluorination and/or disproportionation of compound 12. It
appears that compounds 8 and 9 can act as acceptors of fluorine atoms during the defluorination
of compound 12 (cf. defluorination of perfluoro-1,2-dimethylindane [33] and perfluoro-1-methyl-
2-phenylindane [34] in an SbF5 medium with participation of intermediate compounds as acceptors
of fluorine atoms).
In contrast to diphenylethane 1, perfluorodiphenylmethane (13) under the action of antimony
pentafluoride did not give fluorene derivatves. Сompound 13 was synthesized by the reaction of
perfluorotoluene with C6F5H in SbF5 at room temperature [30,35]. Heating compound 13 with an
excess of SbF5 and further treatment of the reaction mixture with water gave
perfluorobenzophenone (14). The same result was obtained when the mixture of perfluorotoluene,

4
C6F5H and SbF5 was held at room temperature (to give 13+HF) and then heated at 200 °C (Scheme
4).
The difference in the behavior of compounds 1 and 13 in their reactions with antimony
pentafluoride seems to be due to a larger positive charge in the benzene rings of cation 10
compared to the perfluorodiphenylmethyl cation (13c). Indeed, in going from the ion 13c to the
ion 10, the participation of the pentafluorophenyl group in charge delocalization considerably
increases [30]. Such consideration is in accordance with the data obtained for electrocyclization
of diarylmethyl cations to fluorene derivatives in the hydrocarbon series [23–25].
The behavior of perfluoro-1,1-diphenylpropane (15) in an SbF5 medium is similar to that of
diphenylethane 1. Compound 15 was synthesized by interaction of perfluoropropylbenzene (16)
with pentafluorobenzene in the presence of SbF5 (Scheme 5). Heating diphenylpropane 15 with
SbF5 at 130 °C with further treatment of the reaction mixture with water, gives a mixture of
perfluorinated 9-ethylfluoren-9-ol (17), 9-ethylfluorene (18), 9,9-dimethyl-2,3,4,9-
tetrahydrofluoren-1-one (19) and 9,9-dimethyl-1,2,3,4-tetrahydrofluorene (20) (Scheme 5).
When the mixture of propylbenzene 16, C6F5H and SbF5 was held at room temperature (to
give 15+HF), then heated at 130 °C compounds 18 and 20 were formed after the treatment of the
reaction mixture with HF-pyridine and then with water. When the reaction mixture was treated
with water (without HF pretreatment), compounds 17 – 20 were obtained (Scheme 5).
A possible route for the formation of compounds 20 and 19 is presented in Scheme 4.
Ethylfluorene 18 exists in SbF5 medium as a salt of perfluoro-9-ethylfluorenyl cation (21) (cation
21 was generated by dissolving of compound 18 in SbF5–SO2ClF). In cation 21, 1,2-shift of the
trifluoromethyl group occurs to give cation 22. Addition of the fluorine anion to cation 22 with
subsequent fluorination form compound 20. The hydrolysis of cation 23 generated from compound
20 leads to the formation of ketone 19.
When perfluoroisobutylbenzene (24) was heated with pentafluorobenzene in SbF5 medium
at 130 °C, with further treatment of the reaction mixture with HF-pyridine and then with water,
perfluoro-9-isopropylfluorene (25) was obtained (Scheme 5). The reaction mixture also contained
some unidentified products. Compound 24 was prepared by the reaction of perfluorotoluene with
perfluoropropene in the presence of SbF5.
When the temperature was lowered to 50 °C, perfluorinated 2-methyl-1,1-diphenylpropane
(26) and 2-methyl-1-phenylpropylidenecyclohexa-2,5-diene (27) along with compound 25 were
formed. The mixture also contained unreacted compound 24 and C6F5H.

5
2.2. Generation of perfluoro-1,1-diphenylalk-1-yl cations
When compounds 1, 15 and 26+27 were dissolved in SbF5–SO2ClF, perfluorinated 1,1-
diphenyleth-1-yl (10), 1,1-diphenylprop-1-yl (28) and 2-methyl-1,1-diphenylprop-1-yl (29)
cations were generated (Scheme 7).
The treatment of the solutions of the salts of cations 10, 28 with water leads to the formation
of perfluorinated 1,1-diphenylethanol (30) and 4-(1-phenylethylidene)cyclohexa-2,5-dienone
(31), 1,1-diphenylpropan-1-ol (32) and 4-(1-phenylpropylidene)cyclohexa-2,5-dienone (33),
respectively, together with some amounts of the precursors. Hydrolysis of the salt of cation 29
yielded perfluoro-4-(2-methyl-1-phenylpropylidene)cyclohexa-2,5-dienone (34) as a product of
nucleophile attack at the more sterically available center of delocalized cation 29. Precursors
26+27 and perfluoro-2-methyl-1,1-diphenylpropan-1-ol were not detected in the mixture (19F
NMR).
2.3. Structure of compounds
The structures of the compounds were established by HRMS, elemental analysis and
19
spectral characteristics. Assignment of signals in the F NMR spectra of compounds was made
on the basis of chemical shifts of the signals, their fine structure and integral intensities.
Assignment of signals in the 19F NMR spectra of fluorenes 3, 5, 6, 8, 19, 25 was made by
analogy with fluorenes 2, 4 [21], 17, 18, 20 [22], in the spectra of diphenylalkanes 15, 26, 32 – by
analogy with diphenylalkanes 1 and 30 [29], compound 27 – by analogy with 1-(1-(o-
tolyl)propylidene)cyclohexa-2,5-diene [34], compounds 31–34 – by analogy with 4-(1-(o-
tolyl)propylidene)cyclohexa-2,5-dien-1-one [34].
The structures of the cations were identified by 19F NMR spectra. The peculiarities in the
spectra of cations 21 and 28, 29 agree with those for perfluoro-9-methylfluorenyl cation [21] and
polyfluorinated diphenylmethyl cations [30], respectively.
Compounds 2, 4 [21], 14 [18], 17, 18, 20 [22], 1 and 30 [29] were identified by comparison
of the 19F NMR data with data for authentic samples.
3. Conclusions
We have shown that perfluoro-1,1-diphenylalkanes, existing in an SbF5 medium as the salts
of perfluoro-1,1-diphenylalk-1-yl cations, can give polyfluorinated 9-alkylfluorenes when heated

6
with antimony pentafluoride. The investigations have revealed that the presence of a
perfluoroalkyl group in the cationic centre proved to be a necessary requirement for the cyclization
of the intermediate perfluoro-1,1-diphenylalk-1-yl cations to form fluorene skeleton.
4. Experimental
4.1. General methods
Analytical and spectral measurements were carried out in the Multi-Access Chemical
Service Center of SB RAS. 19F NMR spectra were recorded on a Bruker AV 300 instrument (282.4
MHz). Chemical shifts are given in  ppm from CCl3F (19F), J values in Hz; C6F6 and SO2ClF (–
162.9 and 99.9 ppm from CCl3F) were used as internal standards. The molecular masses of the
compounds were determined by high-resolution mass-spectrometry on a Thermo Electron
Corporation DFS instrument (EI 70 eV). GC-MS: Hewlett Packard G1081A, combined with
Hewlett Packard 5890 with mass selective detector HP 5971 (EI 70 eV). Contents (yields) of
products in the reaction mixtures and the purity of analytical samples (≥97%) were established by
19
GLC and F NMR spectroscopic data. Contents of products are given in mass percent. The
reactions were carried out in a nickel bomb (V = 10 mL).
4.2. Reactions of perfluoro-1,1-diphenylethane (1) with SbF5
1. A mixture of compound 1 (1.18 g, 2.72 mmol) and SbF5 (4.80 g, 22.17 mmol) (molar ratio,
1:8.1 was heated at 130 °C for 15 h and HF-Py (7 mL) was added at –20 °C. The mixture was
kept at 25 °C for 20 h, then poured onto ice, extracted with CHCl3 and dried over MgSO4. The
solvent was distilled off to give 1.0 g of a mixture, containing 38% (yield 41.6%) of compound
2, 42% (38.6%) of 3 and 4% (4.4%) of 4. 0.61 g of a mixture, containing 54% of compound
2 and 42% of 3 was isolated by silica gel column chromatography (CCl4 as eluent). By
repeated chromatography of this mixture on a silica gel column (hexane as eluent) compound
3 (0.11 g) and compound 2 (0.31 g) were isolated.
2. A mixture of compound 1 (2.10 g, 4.84 mmol) and SbF5 (7.70 g, 35.48 mmol) (molar ratio,
1:7.3) was heated at 130 °C for 15 h. The mixture was treated with cold 5% hydrochloric acid,
extracted with CHCl3 and dried over MgSO4. The solvent was distilled off to give 1.54 g of a
mixture, containing 12% (yield 13.2%) of compound 2, 22% (20.2%) of 3, 25% (27.5%) of 4,
19% (18.3%) of 5 and 5% (4.6%) of 6. Compound 6 (0.04 g), compound 4 (0.19 g) and 0.53
g of a mixture, containing 17% of compound 2, 35% of 3 and 38% of 5, were isolated by silica
gel column chromatography (CCl4, then CHCl3 as eluents). By repeated chromatography of
this mixture on a silica gel column (hexane as eluent) product 5 (0.11 g) was isolated.

7
3. Pentafluorobenzene (0.63 g, 3.75 mmol) was added to a solution of ethylbenzene 7 (1.07 g,
10.08 mmol) in SbF5 (6.47 g, 29.82 mmol) (molar ratio, 1:2.7:8). The mixture was kept at 25
°C for 20 h, then heated at 130 °C for 15 h and treated as in 4.2. (1) to give 1.1 g of a mixture,
containing 54% (yield 40.1%) of compound 2, 4% (2.5%) of 3 and 22% (10.4%) of 8.
Compound 2 (0.27 g) and compound 8 (0.08 g) were isolated by silica gel column
chromatography (hexane as eluent).
4. Pentafluorobenzene (0.92 g, 5.47 mmol) was added to a solution of ethylbenzene 7 (1.42 g,
13.37 mmol) in SbF5 (8.64 g, 39.82 mmol) (molar ratio, 1:2.4:7.3). The mixture was kept at
22 °C for 17 h, then heated at 130 °C for 15 h and treated as in 4.2. (2) to give 1.72 g of a
mixture, containing 25% (yield 21.9%) of compound 2, 3% (2.2%) of 3, 24% (21.1%) of 4,
2% (1.5%) of 5 and 16% (8.9%) of 8.
4.2.1. Perfluoro-9-methyl-1,2,3,4-tetrahydrofluorene (3)
19
Liquid. F NMR:  –76.0 (dm, 3F, CF3), –102.9 (dm, 1FA, CF2-1) and –125.3 (dm, 1FB,
CF2-1), –109.9 (dm, 1FA, CF2-4) and –118.1 (dm, 1FB, CF2-4), –126.2 (dm, 1FA, CF2-2) and
–141.4 (dm, 1FB, CF2-2), –128.9 (dm, 1FA, CF2-3) and –143.0 (dm, 1FB, CF2-3), –131.1 (ddddd,
1F, F-5), –132.3 (qddd, 1F, F-8), –145.0 (ddd, 1F, F-6), –145.6 (ddd, 1F, F-7), –185.5 (m, 1F,
F-9); JA1,B1 = 301, JA2,B2 = 277, JA3,B3 = 274, JA4,B4 = 309, JA4,5 = 15, JB4,5 = 40, J5,6 = J7,8 = 21, J5,7 =
8, J5,8 = 15, J6,7 = 17, J6,8 = 9, JCF3-F(8) = 22.5. HRMS, m/z: calcd. for C14F16 471.9739; found
471.9743.
4.2.2. Perfluoro-9-methyl-2,3,4,9-tetrahydrofluoren-1-one (5)
Liquid. 19F NMR:  –75.5 (dd, 3F, CF3), –115.0 (dd, 1FA, CF2-4) and –116.1 (dd, 1FB, CF2-
4), –126.8 (m, 1FA, CF2-2) and –128.3 (m, 1FB, CF2-2), –133.3 (m, 1FA, CF2-3) and –134.5 (m,
1FB, CF2-3), –127.5 (ddddd, 1F, F-5), –132.3 (qddd, 1F, F-8), –141.7 (ddd, 1F, F-7), –144.4 (ddd,
1F, F-6), –189.5 (q, 1F, F-9); JA2,B2 = 290, JA3,B3 = 270, JA4,B4 = 310, JA4,5 = 28, JB4,5 = 30, J5,6
=
20, J5,7 = 10, J5,8 = 15, J6,7 = 17, J6,8 = 9, J7,8 = 21, JCF3-F(8) = 19, JCF3-F(9) = 12. HRMS, m/z: calcd.
for C14F14O 449.9720; found 449.9727.
4.2.3. Perfluoro-9-methyl-2,3,4,4a-tetrahydrofluoren-9-ol (6)
19
Liquid. F NMR:  –77.7 (dm, 3F, CF3), –112.3 (dm, 1FA, CF2-2) and –126.4 (dm, 1FB,
CF2-2), –119.0 (dm, 1FA, CF2-3) and –138.3 (dm, 1FB, CF2-3), –121.4 (m, 1F, F-1), –123.5 (dm,
1FA, CF2-4) and –131.1 (ddm, 1FB, CF2-4), –134.7 (dddd, 1F, F-5), –135.8 (qddd, 1F, F-8),
–144.3 (ddd, 1F, F-6), –146.5 (ddd, 1F, F-7), –165.3 (m, 1F, F-4a); JA2,B2 = 292, JA3,B3 = 274,

8
JA4,B4 = 267, JB4,5 = 65, J5,6 = J7,8 = 21, J5,7 = 7, J5,8 = 16.5, J6,7 = 19, J6,8 = 8, JCF3-F(8) = 17. HRMS,
m/z: calcd. for C14HF15O 469.9782; found 469.9784.
4.2.4. Perfluoro-9-methyl-9-phenyl-1,2,3,4-tetrahydrofluorene (8)
19
Liquid. F NMR:  –65.9 (bm, 3F, CF3), –101.1 (dm, 1FA, CF2-1) and –123.4 (dm, 1FB,
CF2-1), –108.4 (dm, 1FA, CF2-4) and –117.0 (ddm, 1FB, CF2-4), –126.0 (dm, 1FA, CF2-2) and
–141.1 (dm, 1FB, CF2-2), –129.8 (dm, 1FA, CF2-3) and –142.7 (dm, 1FB, CF2-3), –132.6 (ddddd,
1F, F-5), –134.8 (qddd, 1F, F-8), –138.2 (m, 1F, F-ortho), –139.9 (m, 1F, F-ortho), –146.8 (ddd,
1F, F-7), –147.9 (ddd, 1F, F-6), –149.7 (tt, 1F, F-para), –158.6 (m, 1F, F-meta), –160.2 (m, 1F,
F-meta); JA1,B1 = 298, JA2,B2 = 276, JA3,B3 = 273, JA4,B4 = 306, JA4,5 = 16, JB4,5 = 40, J5,6 = J7,8 = 20,
J5,7 = J6,8 = 7, J5,8 = 16, J6,7 = 18, JCF3-F(8) = 49, Jmeta,para = 21, Jortho,para = 5. HRMS, m/z: calcd. for
C20F20 619.9675; found 619.9668.
4.3. Reactions of perfluorodiphenylmethane (13) with SbF5
1. A mixture of compound 13 (0.73 g, 1.9 mmol) and SbF5 (5.02 g, 23.13 mmol) (molar ratio,
1:12.2) was heated at 200 °C for 10 h. The mixture was treated with cold 5% hydrochloric
acid, extracted with CH2Cl2 and dried over MgSO4. Distillation of the solvent gave 0.59 g of
compound 14 (19F NMR spectrum).
2. Pentafluorobenzene (0.98 g, 5.83 mmol) was added to a solution of perfluorotoluene (1.25 g,
5.30 mmol) in SbF5 (8.01 g, 36.91 mmol) (molar ratio, 1.1:1:7). The mixture was kept at 22
°C for 5 h, then heated at 200 °C for 10 h and treated as in the previous experiment to give
1.76 g of compound 14 (19F NMR spectrum).
4.4. Preparation of perfluoro-1,1-diphenylpropane (15)
A mixture of compound 16 (2.17 g, 6.46 mmol), C6F5H (1.19 g, 7.08 mmol) and SbF5 (7.00
g, 32.26 mmol) (molar ratio, 1:1.1:5) was stirred at 25 °С for 4 h. The mixture was treated with
anhydrous HF (15 mL), then poured onto ice, extracted CH2Cl2 and dried over MgSO4. The solvent
was distilled off to give 2.81 g of a solid product, containing 86% (yield 77%) of compound 15.
Crystallization from CH2Cl2 – hexane gave 2.02 g of compound 15. Colorless solid, mp 68–69 оС
19
(CH2Cl2 – hexane). F NMR:  –79.1 (d, 3F, CF3), –121.4 (quind, 2F, CF2), –136.6 (m, 4F, F-
ortho), –148.9 (tt, 2F, F-para), –160.5 (m, 4F, F-meta), –163.2 (m, 1F, CFCF2CF3); JCF ,ortho = 21,
2
JCF ,CF = 15, JCF ,CF = 8, Jmeta,para = 21, Jortho,para = 5. HRMS, m/z: calcd. for C15F16 483.9739; found
3
2
483.9733. Anal. Calcd for C15F16: C, 37.21; F, 62.79%. Found: C, 36.84; F, 63.12%.

9
4.5. Reactions of perfluoro-1,1-diphenylpropane (15) with SbF5
1. A mixture of compound 15 (1.11 g, 2.29 mmol) and SbF5 (3.73 g, 17.19 mmol) (molar ratio,
1:7.5) was heated at 130 °C for 15 h, then it was treated as in 4.2.(2) to give 0.68 g of a
mixture, containing 65% (yield 43.4%) of compound 17, 2% (1.3%) of 18, 15% (8.9%) of 19
and 4% (2.3%) of 20. Compound 17 (0.38 g) and compound 19 (0.075 g) were isolated by
silica gel column chromatography (CCl4, then CHCl3 as eluents).
2. Pentafluorobenzene (0.86 g, 5.12 mmol) was added to a solution of propylbenzene 16 (1.57
g, 13.06 mmol) in SbF5 (8.11 g, 37.37 mmol) (molar ratio, 1:2.6:7.3). The mixture was kept
at 23 °C for 10 h, then heated at 130 °C for 15 h and treated as in 4.2. (2) to give 1.9 g of a
mixture, containing 51% (yield 46.7%) of compound 17, 25% (22.8%) of 18, 3% (2.4%) of
19 and 4% (3.1%) of 20.
3. Pentafluorobenzene (0.62 g, 3.69 mmol) was added to a solution of propylbenzene 16 (1.25
g, 10.40 mmol) in SbF5 (6.43 g, 29.63 mmol) (molar ratio, 1:2.8:8). The mixture was kept at
23 °C for 10 h and heated at 130 °C for 15 h, then HF-Py (6 mL) was added. The mixture was
kept at 25ºC for 20 h and treated as in 4.2. (1) to give 1.48 g of a mixture, containing 68%
(yield 60.6%) of compound 18 and 8% (6.1%) of 20. By silica gel column chromatography
(hexane as eluent) 0.76 g of compound 18 was isolated.
4.5.1. Perfluoro-9,9-dimethyl-2,3,4,9-tetrahydrofluoren-1-one (19)
19
Liquid. F NMR:  –64.8 (d, 6F, 2CF3), –114.1 (dm, 2F, CF2-4), –127.6 (m, 2F, CF2-2),
–128.1 (tddd, 1F, F-5), –129.1 (septddd, 1F, F-8), –133.9 (m, 2F, CF2-3), –141.4 (ddd, 1F, F-7), –
145.6 (ddd, 1F, F-6); J4,5 = 33, J5,6 = 21, J5,7 = J6,8 = 9, J5,8 = 15, J6,7 = 18, J7,8 = 20, JCF3-F(8) = 22.
HRMS, m/z: calcd. for C15F16O 499.9688; found 499.9687.
4.5.2. Perfluoro-9-ethylfluorenyl cation (21)
Compound 18 (0.11 g, 0.25 mmol) was dissolved in SbF5 (1.04 g, 4.8 mmol) (molar ratio,
19
1:19), then SO2ClF (0.21 g) was added at 0 °C and F NMR spectrum of the solution was
measured at 20 °C. The spectrum contained signals of cation 21 in the absence of the signals of
precursor 18. The solution was poured into water and extracted with CHCl3. The extract was dried
over MgSO4 and the solvent was distilled off to give 0.09 g of a mixture, containing compounds
17 and 18 in the ratio 71:29 (19F NMR spectrum). Cation 21. 19F NMR:  –80.4 (m, 3F, CF3), –
72.8 (td, 2F, F-1,8), –92.6 (dm, 2F, F-3,6), –109.0 (m, 2F, F-4,5), –112.0 (t, 2F, CF2), –143.2 (m,
2F, F-2,7); JCF2-F(1) = JCF2-F(8) = 59, J1,3 = J6,8 = 45.

10
4.6. Synthesis of perfluoroisobutylbenzene (24)
A mixture of perfluorotoluene (10.74 g, 45.5 mmol), SbF5 (6.47 g, 29.8 mmol) and
perfluoropropene (9.43 g, 62.9 mmol) (molar ratio, 1:0.66:1.38) in a sealed glass ampoule was
kept at 25 °C for 250 h. The mixture was treated with water; the organic layer was separated and
dried over MgSO4 to give 13.5g of a mixture containing compound 24 and perfluorotoluene in the
ratio 4:1 (19F NMR). Distillation yielded 7.92 g of compound 24, bp 153–154 °С. 19F NMR:  –
73.7 (td, 6F, 2CF3), –100.1 (dtsept, 2F, CF2), –137.2 (m, 2F, F-ortho), –146.5 (tt, F, F-para), –
160.3 (m, 2F, F-meta), –184.3 (tsept, 1F, CF(CF3)2); JCF ,CF = 22, JCF ,ortho = 20, JCF ,CF = 11, JCF ,CF
2
2
2
3
3
= 6, Jmeta,para = 21, Jortho,para = 6. HRMS, m/z: calcd. for C10F14 385.9771; found 385.9772.
4.7. Reactions of perfluoroisobutylbenzene (24) with C6F5H in the presence of SbF5
1. Pentafluorobenzene (0.47 g, 2.8 mmol) was added to a solution of compound 24 (1.09 g, 2.8
mmol) in SbF5 (4.89 g, 22.5 mmol) (molar ratio, 1:1:8). The mixture was kept at 23 °C for 21
h and heated at 130 °C for 15 h, then HF-Py (6 mL) was added. The mixture was kept at 23
°C for 24 h, then poured onto ice, extracted with CHCl3 and dried over MgSO4. Unreacted
C6F5H and compound 24 (in part) were distilled off along with the solvent to give 1.1 g of a
mixture, containing 58% (yield 45.6%) of compound 25 and 19% (19.2%) of 24. Compound
25 (0.34 g) was isolated by silica gel column chromatography (hexane as eluent).
2. A mixture of compound 24 (1.38 g, 3.57 mmol), C6F5H (0.66 g, 3.93 mmol) and SbF5 (3.87
g, 17.83 mmol) (molar ratio, 1:1.1:5) was heated at 55 °C for 28 h. The mixture was treated
as in the previous experiment to give 1.21 g of a mixture, containing 17% (yield 11.6%) of
compound 25, 15% (9.5%) of 26, 30% (19.0%) of 27 and 31% (27.2%) of 24. By silica gel
column chromatography (hexane as eluent) 0.33 g of a mixture of isomers 27 (conformers A
and B in the ratio 58:42) and 26 in the ratio 64:36 was isolated.
4.7.1. Perfluoro-9-isopropylfluorene (25)
Colorless solid, mp 80.5–82 °С (hexane). 19F NMR:  –73.0 (m, 6F, 2CF3), –132.8 (m, 2F, F-
4,5), –133.3 (m, 2F, F-1,8), –146.1 (m, 2F, F-3,6), –151.3 (m, 2F, F-2,7), –170.9 (m, 1F,
CF(CF3)2), –173.7 (m, 1F, F-9). HRMS, m/z: calcd. for C16F16 495.9739; found 495.9733. Anal.
Calcd for C16F16: C, 38.73; F, 61.27%. Found: C, 38.57; F, 61.39%.
4.7.2. Perfluoro-1,1-diphenylisobutane (26)

11
Mixture with isomer 27 (26:27 = 36:64). Compound 26. 19F NMR:  –71.5 (m, 6F, 2CF3), –
136.3 (bm, 4F, F-ortho), –149.1 (m, 2F, F-para), –160.4 (m, 4F, F-meta), –164.3 (m, 1F, F-1), –
175.9 (quinm, 1F, CF(CF3)2); JCF,ortho = 52. GC-MS, m/z: 534 [M]+ for 26. HRMS, m/z: calcd. for
C16F18 533.9707; found 533.9709 (for the mixture of 26+27).
4.7.3. Perfluoro-2-methyl-1-phenylpropylidenecyclohexa-2,5-diene (27)
CF3
CF3
F3C
F3C
F C
C
C F
C
2
3
4
F
F
F
F
6
5
A
B
Mixture with isomer 26 (26:27 = 36:64). Compound 27 (conformers A:B = 58:42). 19F NMR,
conformer A:  –71.7 (m, 6F, 2CF3), –110.0 (m, 2F, CF2), –134.1 (dm, 1F, F-2), –137.5 (m, 2F,
F-ortho), –141.4 (m, 1F, F-6), –148.8 (m, 1F, F-para), –149.7 (m, 1F, F-3), –150.9 (m, 1F, F-5),
–156.1 (dm, 1F, CF(CF3)2), –160.9 (m, 2F, F-meta); JCF-F(2) = 148; conformer B: 
–70.8 (dm, 6F, 2CF3), –109.0 (m, 2F, CF2), –138.7 (septm, 1F, F-2), –139.2 (m, 2F, F-ortho),
–141.3 (m, 1F, F-6), –149.8 (m, 1F, F-para), –150.4 (m, 1F, F-3), –151.7 (m, 1F, F-5), –151.7 (m,
1F, CF(CF3)2), –161.6 (m, 2F, F-meta); JCF3-F(2) = 48. GC-MS, m/z: 534 [M]+ for 27. HRMS, m/z:
calcd. for C16F18 533.9707; found 533.9709 (for the mixture of 26+27).
4.8. Generation of perfluoro-1,1-diphenylalk-1-yl cations
1. Compound 1 (0.11 g, 0.25 mmol) was dissolved in SbF5 (1.12 g, 5.16 mmol) (molar ratio,
19
1:20), then SO2ClF (0.20 g) was added at 0 °C and F NMR spectrum of the solution was
measured at 20 °C. The spectrum contained the signals of cation 10 in the absence of the
signals of precursor 1. The solution was poured into water and extracted with CHCl3. The
extract was dried over MgSO4 and the solvent was distilled off to give 0.09 g of a mixture,
containing compounds 1, 30 and 31 in the ratio 21:72:7 (19F NMR spectrum). From 0.59 g of
a similar mixture, obtained in another experiment, 0.025 g of compound 31 was isolated by
silica gel column chromatography (CCl4 as eluent).
2. An analogous procedure was used to generate cation 28 (19F NMR spectrum) from compound
15 (0.12 g, 0.25 mmol) and SbF5 (1.11 g, 5.12 mmol) (molar ratio, 1:20) in SO2ClF (0.17 g).
The solution was treated as in the previous experiment to give a mixture (0.10 g) containing
compounds 15, 32 and 33 in the ratio 29:47:24 (19F NMR spectrum). From 0.65 g of a similar

12
mixture, obtained in another experiment, 0.08 g of compound 33 and 0.21 g of compound 32
were isolated by silica gel column chromatography (CCl4, then CHCl3 as eluents).
3. An analogous procedure was used to generate cation 29 (19F NMR spectrum) from isomers
26 and 27 (36:64, 0.13 g, 0.24 mmol) and SbF5 (1.04 g, 4.79 mmol) (molar ratio, 1:20) in
SO2ClF (0.22 g). The solution was treated as in the previous experiment to give 0.12 g
compound 34 (conformers A and B in the ratio 52:48).
4.8.1. Perfluoro-1,1-diphenyleth-1-yl cation (10)
19F NMR:  –60.2 (quin, 3F, CF3), –88.0 (tt, 2F, F-para), –104.6 (m, 4F, F-ortho), –146.9 (m, 4F,
F-meta); JCF ,ortho = 19, Jmeta,para = 21, Jortho,para = 34, cf. [30].
3
4.8.2. Perfluoro-1,1-diphenylprop-1-yl cation (28)
19F NMR:  –75.8 (m, 3F, CF3), –101.9 (quin, 2F, CF2), –87.2 (tt, 2F, F-para), –104.2 (m, 4F,
F-ortho), –146.9 (m, 4F, F-meta); JCF ,ortho = 29, Jmeta,para = 22, Jortho,para = 34.
2
4.8.3. Perfluoro-2-methyl-1,1-diphenylprop-1-yl cation (29)
19F NMR:  –66.5 (m, 6F, 2CF3), –70.7 (tt, 1F, F-para), –96.4 (m, 2F, F-ortho), –105.5 (tt,
1F, F-para’), –114.0 (m, 2F, F-ortho’), –144.3 (m, 2F, F-meta), –149.7 (m, 2F, F-meta’), –155.5
(m, 1F, CF(CF3)2); Jmeta,para = 23, Jortho,para = 44, Jmeta’,para’ = 22, Jortho’,para’ = 22.
4.8.4. Perfluoro-4-(1-phenylethylidene)cyclohexa-2,5-dienone (31)
CF3
2
C
3
F
F
6
O
5
Yellow viscous liquid. 19F NMR:  –58.4 (dm, 3F, CF3), –130.0 (qdd, 1F, F-2), –134.5 (dd,
1F, F-6), –139.1 (m, 2F, F-ortho), –145.7 (d, 1F, F-5), –146.1 (d, 1F, F-3), –148.7 (tt, 1F, F-para),
–160.5 (m, 2F, F-meta); JCF3-F(2) = 47, J2,6 = J5,6 = 7, J2,3 = 6, Jmeta,para = 21, Jortho,para = 3. HRMS,
m/z: calcd. for C14F12O 411.9752; found 411.9748. Anal. Calcd for C14F12O: C, 40.80; F, 55.32%.
Found: C, 40.63; F, 54.79%.
4.8.5. Perfluoro-1,1-diphenylpropan-1-ol (32)
19
Colorless solid, mp 71–72 °С (CH2Cl2 – hexane). F NMR:  –76.9 (m, 3F, CF3), –117.7
(quin, 2F, CF2), –138.2 (m, 4F, F-ortho), –150.8 (tt, 2F, F-para), –160.9 (m, 4F, F-meta); JCF ,ortho
2

13
= 22, Jmeta,para = 21. HRMS, m/z: calcd. for C15HF15O 481.9782; found 481.9779. Anal. Calcd for
C15HF15O: C, 37.37; H, 0.21; F, 59.11%. Found: C, 37.25; H, 0.32; F, 58.76%.
4.8.6. Perfluoro-4-(1-phenylpropylidene)cyclohexa-2,5-dienone (33)
19
Yellow solid, mp 78–79 °C (CH2Cl2 – hexane). F NMR:  –80.0 (dm, 3F, CF3), –104.2
(dm, 2F, CF2), –127.7 (tqdd, 1F, F-2), –133.6 (dd, 1F, F-6), –138.4 (m, 2F, F-ortho), –145.2 (d,
1F, F-3), –145.7 (d, 1F, F-5), –148.6 (tm, 1F, F-para), –160.6 (m, 2F, F-meta); JCF2-F(2) = 68,
JCF3-F(2) = 29, J2,3 = 5, J2,6 = 7.5, J5,6 = 7, Jmeta,para = 21. HRMS, m/z: calcd. for C15F14O 461.9720;
found 461.9716. Anal. Calcd for C15F14O: C, 38.98; F, 57.55%. Found: C, 38.61; F, 57.89%.
4.8.7. Perfluoro-4-(2-methyl-1-phenylpropylidene)cyclohexa-2,5-dienone (34)
CF3
CF3
F3C
F3C
F C
C
C F
C
2
3
F
F
F
F
6
O
O
5
A
B
Yellow solid, mp 94.5–96 °С (hexane). 19F NMR (conformers A:B = 52:48), conformer A:
 –71.4 (m, 6F, 2CF3), –124.6 (dm, 1F, F-2), –133.0 (dd, 1F, F-6), –137.2 (m, 2F, F-ortho),
–145.1 (d, 1F, F-3), –145.6 (d, 1F, F-5), –148.0 (m, 1F, F-para), –155.2 (dm, 1F, CF(CF3)2),
–160.3 (m, 2F, F-meta); JCF-F(2) = 152, J2,3 = 5, J2,6 = J5,6 = 7; conformer B:  –70.5 (dm, 6F, 2CF3),
–129.8 (septdd, 1F, F-2), –132.7 (dd, 1F, F-6), –138.9 (m, 2F, F-ortho), –146.3 (d, 1F, F-3), –
146.7 (d, 1F, F-5), –148.7 (m, 1F, F-para), –151.4 (m, 1F, CF(CF3)2), –160.9 (m, 2F, F-meta);
JCF3-F(2) = 48, J2,3 = J5,6 = 6, J2,6 = 7. HRMS, m/z: calcd. for C16F16O 511.9688; found 511.9684.
Anal. Calcd for C16F16O: C, 37.52; F, 59.48%. Found: C, 37.66; F, 59.35%.
Acknowledgement
The authors gratefully acknowledge the Russian Foundation for Basic Researches (project
no. 16-03-00348) for financial support. The authors are grateful to the Multi-Access Chemical
Service Center of SB RAS for spectral and analytical measurements.

14
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16
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17
HO
CF3
F
CF3
F CF3
C
CF3
F
1) SbF5, 130 oC
2) HF-Py
F
F
F
F
+
+
F
F
F
F
1
3) H2O
4
2
3
yield (19F NMR, GLC):
4%
42%
39%
CF3
CF3
HO
F
O
1) SbF5, 130 oC
2) H2O
2
+
3
+
4
+
+
F
F
F
F
F
13%
20%
28%
5
6
18%
5%
CF3
C6F5
F
2) HF-Py
2
+
3
+
F
3) H2O
CF2CF3
F
8
40%
3%
C6F5H
SbF5, r.t.
1) SbF5
130 oC
10%
1 + HF
2) H2O
7
2
+
3
+
4
+
5
+
8
22%
2%
21%
2%
9%
Scheme 1. Reaction of perfluoro-1,1-diphenylethane with SbF5.
CF3
F
CF3
F
CF3
F CF3
C
+
C
SbF5
F
F
F
+
F
F
F
F
F
-
-F
2
3
10
1
SbF5
CF3
CF3
CF3
CF3
F
CF3
F
+
SbF5
-
F
F
F
+
F
F
F
F
F
F
F
F
+
F
F
F
F
F
10a
11
12
Scheme 2. The mechanistic pathway of the reaction of perfluoro-1,1-diphenylethane with SbF5.

18
CF3
C6F5
F
CF3
C6F5
F
CF2CF3
F
+
C6F5H
HF
+
F
F
9
8
7
SbF5
-HF
C6F5H, SbF5
-HF
CF3
F
CF3
F
F CF3
C
SbF5
F
F
+
F
F
F
F
2
3
1
Scheme 3. The mechanistic pathway of the reaction of perfluoro-1,1-diphenylethane with SbF5
in the presence of HF.
F
C
+
_
SbF5 SO2
F
F
[30, 35]
13c
H2O
O
C
F F
C
CF3
F
1) SbF5, 200 oC
2) H2O
1) SbF5, 200 oC
2) H2O
C6F5H
F
F
13 + HF
F
F
SbF5, r.t.
13
14
Scheme 4. The heating of perfluoro-1,1-diphenylmethane with SbF5.

19
2) HF-Py
3) H2O
18
+
20
6%
CF2CF2CF3
61%
C6F5H
1) SbF5
130 oC
15 + HF
F
SbF5, r.t.
2) H2O
16
17 + 18 + 19 +
20
yield (19F NMR, GLC):
1) C6F5H, SbF5, 25 oC
47%
23%
2%
3%
2) HF
3) H2O
CF2CF3
F
CF3
HO
CF2CF3
F
F3C
F
CF3
F
F3C
F
F CF2CF3
C
O
1) SbF5, 130 oC
F
F
F
F
F
F
+
+
+
2) H2O
15
17
18
1%
19
20
43%
9%
2%
H2O
+
CF3
CF2
+
CF3
F2C
CF3
F3C
+
- [F]
H2O
SbF5
SbF5
F
F
F
F
F
F
F
18
20
19
21
22
23
Scheme 5. Synthesis and reaction of perfluoro-1,1-diphenylpropane with SbF5.

20
CF(CF3)2
CF2CF(CF3)2
CF3
F
1) C6F5H, SbF5, 130 oC
CF2=CFCF3
SbF5, r.t.
F
F
24
+
F
F
2) HF-Py
3) H2O
25,
24
yield (19F NMR, GLC):
46%
19%
CF(CF3)2
F CF(CF3)2
C
C
1) C6F5H, SbF5, 55 oC
F
F
F
24
25
+
+
24
F
+
2) HF-Py
3) H2O
26
27
12%
10%
19%
27%
Scheme 6. Synthesis and reaction of perfluoroisobutylbenzene with C6F5H.
Scheme 7. Generation and hydrolysis of perfluoro-1,1-diphenylalk-1-yl cations.