Polyfluoroalkyl chlorosulfites as new polyfluorinating agents

Article abstract of DOI:10.1023/A:1020788902312

The interaction of polyfluorinated alcohols with triethylamine and the kinetics of the reaction of the resulting triethylamine complexes with thionyl chloride were studied, the mechanism of formation of polyfluoroalkyl chlorosulfites was considered, and the optimal reaction conditions were found. The alkylating power of polyfluoroalkyl chlorosulfites was studied in reactions with alkali metal halides (to obtain polyfluorohaloalkanes), in synthesis of acrylic and methacrylic acid esters, and in synthesis of polyfluoroalkyl ethers (with polyfluoroalkyl 1-adamantyl ethers as example).

Full text of DOI:10.1023/A:1020788902312

Russian Journal of Applied Chemistry, Vol. 75, No. 7, 2002, pp. 1162 1165. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 7,
2002, pp. 1185 1188.
Original Russian Text Copyright
2002 by Rakhimov, Vostrikova.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Polyfluoroalkyl Chlorosulfites as New Polyfluorinating Agents1
A. I. Rakhimov and O. V. Vostrikova
Volgograd State Technical University, Volgograd, Russia
Institute of Chemical Problems of Ecology, Russian Academy of Natural Sciences, Volgograd, Russia
Received January 17, 2002
Abstract The interaction of polyfluorinated alcohols with triethylamine and the kinetics of the reaction
of the resulting triethylamine complexes with thionyl chloride were studied, the mechanism of formation of
polyfluoroalkyl chlorosulfites was considered, and the optimal reaction conditions were found. The alkylating
power of polyfluoroalkyl chlorosulfites was studied in reactions with alkali metal halides (to obtain poly-
fluorohaloalkanes), in synthesis of acrylic and methacrylic acid esters, and in synthesis of polyfluoroalkyl
ethers (with polyfluoroalkyl 1-adamantyl ethers as example).
Polyfluoroalkyl chlorosulfites have been studied
poorly. These compounds were prepared by the reac-
tion of perfluoroalkyl hypochlorites with thionyl
chloride [1 5]
in-ampule glass microreactor was placed in a calori-
metric cell equipped with a device for breaking the
inner ampule (a thin-walled sphere). After the re-
quired temperature was attained, the thin-walled
sphere was broken, and the thermokinetic curve was
recorded with an LKS 4003 device; this curve was
processed to calculate the heat release rate and to
determine the rate constants using the kinetic model.
The heat of formation of the alcohol triethylamine
complex was determined in the bulk at 30 C and
equimolar ratio of the alcohol and amine. Three rep-
licate runs were performed, and the thermokinetic
curves were processed by the trapezium method.
The error of the calorimetric measurements was
3 5%.
RFOCl + SOCl2
RFOS(O)Cl + Cl2.
In a later study [6], these compounds were prepared
by the reaction of polyfluoro alcohols with thionyl
chloride in the presence of triethylamine:
RFOH + SOCl2
RFOSOCl.
In contrast to alkyl chlorosulfites, which are inter-
mediates in reactions of alcohols with thionyl chloride
and readily eliminate SO to form chloroalkanes,
2
The kinetics of formation of polyfluoroalkyl chlo-
rosulfites was studied at 25, 30, and 35 C. The initial
concentrations of the alcohol amine complex and
thionyl chloride were 0.18 M.
polyfluoroalkyl chlorosulfites are stable compounds
distillable without decomposition.
In this work, we studied the interaction of polyflu-
orinated alcohols with triethylamine and the reaction
of the resulting complexes with thionyl chloride, with
the aim to optimize the preparation of polyfluoroalkyl
sulfites, which are of interest as polyfluorinating
agents in syntheses of polyfluorohaloalkanes and of
esters and ethers containing polyfluoroalkyl groups.
Procedures for synthesis and identification of poly-
fluoroalkyl chlorosulfites are reported elsewhere [7].
The reaction was performed in chloroform; the com-
plex of a polyfluorinated alcohol (0.05 mol) with
triethylamine (0.05 mol) was added to a solution of
0.075 mol of thionyl chloride, cooled to 40 C; in the
process, the mixture was not allowed to warm up
above 15 C. After adding the whole amount of the
complex, the mixture was warmed up to 20 C. The
precipitate of triethylamine hydrochloride was filtered
off, excess thionyl chloride was distilled off at atmos-
pheric pressure, and the residue was vacuum-distilled.
The yields and constants of polyfluoroalkyl chlorosul-
fites obtained by the reaction
EXPERIMENTAL
Calorimetric studies were performed with a DAK-
1-2M isothermal differential calorimeter. An ampule-
1
Reported at the 3rd International Conference Chemistry,
Technology, and Applications of Fluoro Compounds (St. Pe-
tersburg, July 6 9, 2001).
1070-4272/02/7507-1162$27.00 2002 MAIK Nauka/Interperiodica

POLYFLUOROALKYL CHLOROSULFITES AS NEW POLYFLUORINATING AGENTS
1163
Table 1. Physicochemical characteristics of polyfluoroalkyl chlorosulfites H(CF2CF2)nCH2OS(O)Cl
3
n
Yield, %
Empirical formula
bp, C/P, mm Hg
d240, g cm
n2D0
1
2
3
84.2
82.0
80.0
C3H3F4SO2Cl
C5H3F8SO2Cl
C7H3F12SO2Cl
61/40
99/50
101/10
1.611
1.783
1.787
1.3704
1.3580
1.3428
H(CF2CF2)nCH2OH N(C2H5)3 + SOCl2
ing mechanism of nucleophilic substitution of chlorine
in the thionyl chloride molecule:
H(CF2CF2)nCH2OSOCl + (C2H5)3N HCl, n = 1 3,
+
[
+
SOCl2
R
]
FO NHEt 3
are listed in Table 1.
O
Polyfluorinated alcohols virtually do not react with
thionyl chloride in the absence of triethylamine. If
triethylamine is added to a mixture of alcohol and
thionyl chloride, the yield of alkyl chlorosulfite does
not exceed 15%. The highest yield (80 84%) is at-
tained when the complex of a polyfluorinated alcohol
with triethylamine, prepared in advance, is added to
thionyl chloride. Therefore, using microcalorimetry
+
[
Cl NHEt3
]
RFO
S
Cl
RFOS(O)Cl + [NHEt3]+Cl .
This mechanism is confirmed by the kinetic data.
Using the kinetic model, we processed experimental
heat release curves [8] and determined the rate con-
stants and the effective activation energy of the reac-
tion. For the reaction of thionyl chloride with FA1
triethylamine, the second-order rate constants are as
1
and IR and H NMR spectroscopy, we studied the
interaction of polyfluorinated alcohols with triethyl-
amine.
1
1
The thermal effect of the interaction of polyfluo-
rinated alcohols with triethylamine was estimated
microcalorimetrically. The heat of interaction with tri-
follows (l mol s ): 0.020 at 25 C, 0.025 at 30 C,
and 0.027 at 35 C. The effective activation energy is
1
31.77 kJ mol .
1
ethylamine is 19.9 kJ mol for 2,2,3,3-tetrafluoro-1-
We have studied the alkylating power of polyfluo-
1
propanol (FA1) and 20.7 kJ mol for 2,2,3,3,4,4,5,5-
octafluoro-1-pentanol (FA2).
T
(b)
(a)
Complexation causes significant changes in the IR
spectra of polyfluorinated alcohols. The stretching
1
vibration band of the OH group at 3620 cm sharply
decreases in intensity, and a new medium-intensity
1
band appears at 2600 2700 cm , which is split in
several bands (Fig. 1). These changes are due to for-
+
mation of a salt, H(CF CF ) CH O NH(C H ) .
T
(c)
(d)
2
2 n
2
2 5 3
The conclusions made from the IR spectra are con-
1
firmed by the H NMR spectra of FA2 solutions in
CCl . Interaction of FA2 with triethylamine causes a
4
downfield shift of the hydroxyl proton signal by
2.49 ppm. Triethylamine is a stronger proton acceptor
than acetone, as with acetone, under similar condi-
tions, the OH proton signal is shifted downfield by
only 1.86 ppm. Thus, the complexation is favored by
the acid properties of polyfluorinated alcohols and
high basicity of triethylamine.
1
1
, cm
, cm
Fig. 1. IR spectra in CCl of (a, b) 2,2,3,3-tetrafluoroprop-
4
anol and (c, d) 1 : 1 2,2,3,3-tetrafluoropropanol triethyl-
amine complex. Cell thickness 0.18 mm. (T) Transmission
and ( ) wave number. Concentration, M: (a, c) 0.4 and
(b, d) 0.2.
Based on the data on complexation with triethyl-
amine, we optimized the conditions for preparing
polyfluoroalkyl chlorosulfite. We suggest the follow-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 7 2002

1164
RAKHIMOV, VOSTRIKOVA
Table 2. Polyfluoroalkyl acrylates and methacrylates
where n = 1, 2, 3; R = H, CH .
3
The yield of acrylates and methacrylates in this
case is appreciably higher than in the known proce-
dure [9] (Table 2).
Yield,
%
bp, C/P,
mm Hg
d240,
g cm
R
n
n2D0
3
H
1
2
3
2
3
76.2
34.0*
76.0
38.5*
76.1
45.2*
76.4
56.0*
76.5
50.8*
56/60
75/110
85/40
1.2860 1.3666
1.2858 1.3668
1.4460 1.3462
1.4884 1.3460
1.5802 1.3402
1.5974 1.3400
1.4210 1.3578
1.4106 1.3580
1.5360 1.3506
1.5390 1.3500
Polyfluoroalkyl chlorosulfites readily react with
alcohols in dioxane to form the corresponding ethers.
For example, previously unknown polyfluoroalkyl
1-adamantyl ethers were prepared by the reaction of
1-adamantol with polyfluoroalkyl chlorosulfites:
H
84/40
H
110/40
107/40
100/40
87/40
104/20
112/40
CH3
CH3
Ad OH + H(CF2CF2)nCH2OS(O)Cl
Ad OCH2(CF2CF2)nH,
where n = 1, 2.
* Data of [9].
Adamantyl polyfluoroalkyl ethers are colorless
liquids readily distillable in a vacuum (Table 3). The
composition and structure of these compounds were
Table 3. Polyfluoroalkyl 1-adamantyl ethers
Ad OCH2(CF2CF2)nH
1
determined by elemental analysis and by IR and H
NMR spectroscopy.
Analytical data, %*
Yield, bp, C/P,
n
n2D0
The IR spectra of the ethers exhibit a very strong
absorption at about 2916 cm assigned to the stretch-
%
mm Hg
1
C
H
F
ing vibrations of the methylene and methine groups
and at about 1124 cm assigned to the ether C O
stretching vibrations.
1
58.02
58.65
49.00
49.20
6.70 28.21
6.77 28.57
4.60 41.03
4.92 41.53
1
2
76
75
86/2
1.4440
1.4233
1
106/2
The H NMR data for 1-adamantyl alkyl ethers are
given in Table 4.
1
* Numerator: found; denominator: calculated.
The H NMR spectra of 1-[2,2,3,3-tetrafluoroprop-
oxy]adamantane and 1-[2,2,3,3,4,4,5,5-octafluoropen-
toxy]adamantane contain characteristic proton signals
of the adamantane moiety [10]. The - ( 1.56 ppm)
and -protons ( 1.68 ppm) give narrow signals. The
signal of the -protons is broad ( 2.12 ppm). The
signal of the methylene protons in the polyfluoroalkyl
moiety is a triplet with a coupling constant of 12 Hz.
The proton signal of the hydrofluoromethyl group is
a triplet of triplets with a coupling constant of 6 Hz.
roalkyl chlorosulfites in the reactions with alkali metal
halides, carboxylic acid salts, and alcohols.
Polyfluoroalkyl chlorosulfites react with alkali
metal halides (KF, LiCl, KBr, KI) in diethylene glycol
to form the corresponding polyfluorohaloalkanes in
75 90% yield:
H(CF2CF2)nCH2OS(O)Cl + MX
+ MCl + SO2,
H(CF2CF2)nCH2X
According to the predictions of the medicobiologi-
cal activity, perfluoroalkyl 1-adamantyl ethers show
promise as antidepressants and tranquilizers.
where n = 1, 2, 3; X = F, Cl, Br, I; M = K, Li, Na.
The advantages of the synthesis of polyfluorohalo-
alkanes by substitution of the chlorosulfite group in
alkyl chlorosulfites are the use of low-toxic chemicals,
versatility, and high yield of the reaction products.
CONCLUSIONS
(1) A procedure was developed for synthesis of
polyfluoroalkyl chlorosulfites by the reaction of thio-
nyl chloride with complexes of polyfluorinated alco-
hols with triethylamine.
By the reaction of alkyl chlorosulfites with potassi-
um (meth)acrylate, we prepared the corresponding
polyfluoroalkyl (meth)acrylates:
(2) Complexation in the system polyfluorinated
alcohol triethylamine was studied by microcalorim-
etry and IR and H NMR spectroscopy, and the salt-
CH2=C(R)COOH + H(CF2CF2)nCH2OS(O)Cl
CH2=C(R)COOCH2 (CF2CF2)nH,
1
like structures of the complexes were suggested.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 7 2002

POLYFLUOROALKYL CHLOROSULFITES AS NEW POLYFLUORINATING AGENTS
1165
Table 4. 1H NMR spectra of 1-adamantyl alkyl ethers
4
3
5
4
5
4
2
1
3
(CF )nH
OCH 2
2
5
3
Chemical shift , ppm
3
Coupling constant, Hz
n
1
2
4
5
JHCF
JHCCF
J2HCH
2
4
5.78 t.t
5.84 t.t
3.64 t
3.74 t
1.56 s
1.56 s
2.12 s
2.12 s
1.66 s
1.68 s
52
52
6
6
12
12
(3) A mechanism of formation of polyfluoroalkyl
chlorosulfites was suggested, involving bimolecular
nucleophilic substitution of chlorine by the polyfluo-
roalkoxy group in thionyl chloride in its reaction with
the polyfluorinated alcohol triethylamine complex.
Fox, W.R., J. Am. Chem. Soc., 1969, vol. 91, no. 6,
pp. 1310 1313.
3. Eserrard, V., J. Chem. Soc., 1964, pp. 5480 5482.
4. Young, D.E. and Fox, W.B., Inorg. Nucl. Chem. Lett.,
1971, no. 7, pp. 1033 1035.
5. Young, D.E., Anderson, L.R., and Fox, W.B., Inorg.
Chem., 1971, vol. 10, no. 12, pp. 2810 2812.
6. De Marco, R.A., Kovacina, T.A., and Fox, W.B.,
J. Fluorine Chem., 1975, vol. 6, pp. 3 104.
7. Rakhimov, A.I. and Vostrikova, O.V., Zh. Org. Khim.,
(4) Polyfluoroalkyl chlorosulfites efficiently alky-
late carboxylic acid salts (alkyl acrylates and meth-
acrylates were obtained) and alcohols (with 1-adaman-
tol as example); they can also be used for preparing
polyfluorohaloalkanes by the reactions with metal
halides.
1999, vol. 35, no. 5, pp. 815 816.
8. Vostrikova, O.V., Synthesis and Properties of Poly-
fluoroalkyl Chlorosulfites, Cand. Sci. Dissertation,
Volgograd, 1999.
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RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 7 2002