Reaction of fluoroolefins with sulfur chlorides in hydrogen fluoride-boron trifluoride system

Article abstract of DOI:10.1016/S0022-1139(01)00530-9

The reaction of tetrafluoroethylene (1), perfluorovinyl ether (3), hexafluoropropene (5), and 2-H-pentafluoropropene (7) with sulfur chlorides in anhydrous HF/BF₃ system has been studied. The reaction with S₂Cl₂ at 40-100°C produces a mixture of the corresponding di- and trisulfides along with smaller amounts of sulfenyl- and thiosulfenyl chlorides. In case of 7 the use of BF₃ catalyst results higher yields and selectivity of the process under milder conditions. The reaction of 5 and SCl₂ in HF/BF₃ at 100°C is selective, gives (CF₃)₂CFSCl, isolated in 65% yield.

Full text of DOI:10.1016/S0022-1139(01)00530-9

Journal of Fluorine Chemistry 112 ,2001) 325±327
Reaction of ¯uoroole®ns with sulfur chlorides in hydrogen
¯uoride±boron tri¯uoride system
Viacheslav A. Petrov*,1
DuPont Central Research and Development Experimental Station, P.O. Box 80328, Wilmington, DE 19880-0328, USA
Received 6June 2001; accepted 31 August 2001
Dedicated to Dr. Karl Christe on the occasion of his 65th birthday
Abstract
The reaction of tetra¯uoroethylene ,1), per¯uorovinyl ether ,3), hexa¯uoropropene ,5), and 2-H-penta¯uoropropene ,7) with sulfur
chlorides in anhydrous HF/BF3 system has been studied. The reaction with S2Cl2 at 40±100 8C produces a mixture of the corresponding di-
and trisul®des along with smaller amounts of sulfenyl- and thiosulfenyl chlorides. In case of 7 the use of BF3 catalyst results higher yields
and selectivity of the process under milder conditions. The reaction of 5 and SCl2 in HF/BF3 at 100 8C is selective, gives ,CF3)2CFSCl,
isolated in 65% yield. # 2001 Elsevier Science B.V. All rights reserved.
Keywords: Tetra¯uoroethylene; Hexa¯uoropropene; Per¯uorovinyl ether; 2-H-penta¯uoropropene; Sulfur monochloride; Sulfur dichloride; Hydrogen
¯uoride; Boron tri¯uoride
1. Introduction
producing a mixture of polysul®des general formulae
,FSO2CFXCF2)2Sx [17±19]. The reaction of ¯uoroole®ns
with SF4/HF/S2Cl2 system [20,21] results in the formation of
the mixture of per¯uoroalkyl polysul®des. Unfortunately,
this process requires use of substantial amount of toxic and
relatively expensive sulfur tetra¯uoride. There is a growing
interest in recent years in per¯uorinated sul®des, since these
materials has been proposed for use as components of
azeotropic refrigerant compositions [22] and solvents for
polymerization of ¯uoroole®ns [23].
Per¯uoroalkyl polysul®des can be also used as feedstock
for the preparation of derivatives of per¯uorinated sulfonic
acids [21].
In search of simple and relatively inexpensive synthesis of
per¯uoroalkyl polysul®des the reaction of S2Cl2 and SCl2
with ¯uoroole®ns in anhydrous hydrogen ¯uoride as a
solvent was investigated.
Poly¯uoroalkyl sulphides and polysul®des is important
group of ¯uorinated materials used for the synthesis of
variety of sulfur-containing compounds. Partially ¯uori-
nated sul®des and polysul®des can be prepared by variety
of methods, including the reaction of the corresponding
sulfenyl chlorides with unsaturated or aromatic compounds
[1], per¯uoroalkyl iodides and metal salts of thiols [2,3],
radical addition of poly¯uorinated disul®des [4], sulfenyl-
[1,5] and thiosulfenyl- [6] chlorides to ole®ns. Among
methods for preparation of per¯uororinated polysul®des
are reaction of sulfur with per¯uoroalkyl iodides [7,8],
¯uoroole®ns [9±11], per¯uorinated carbanions [12] and
Lewis acid catalyzed oxidative addition of sulfur to ¯uor-
oole®ns [13±15]. Thermal addition of sulfur chlorides to
poly¯uoroole®ns [16] provides simple and direct route
to perhalogenated polysul®des, however it proceeds at ele-
vated temperature and is limited to production of sul®des
containing at least two chlorine substituents in the molecule.
Several years ago it was reported that the reaction of
¯uoroole®ns with sulfur chlorides in ¯uorosulfonic acid
as a solvent proceeds at signi®cantly lower temperature
2. Results and discussion
Sulfur monochloride rapidly reacts with tetra¯uoroethy-
lene ,1) in anhydrous HF as a solvent in the presence of BF3
catalyst producing in a high yield the mixture in which
sulfenyl chloride 2b, disul®de 2c and trisul®de 2d are iden-
ti®ed as major components ,NMR, GC/MS). Surprisingly,
crude reaction mixture contains a noticeable amount of
* Tel.: ‡1-302-695-1958; fax: ‡1-302-695-8281.
E-mail address: viacheslav.a.petrov@usa.dupont.com ,V.A. Petrov).
1 Publication no 8203.
0022-1139/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 1 1 3 9 , 0 1 ) 0 0 5 3 0 - 9

326
V.A. Petrov / Journal of Fluorine Chemistry 112 12001) 325±327
Table 1
Reaction of fluoroolefins with sulfur chlorides in HF/BF3
Entry Reagents ,g) Temperature Time Crude
Composition ,%)
,8C)
,h)
product ,g)
1
2
3
4
5
6
7
8
9
1 ,50), S2Cl2 ,31), BF3 ,10), HF ,100)
1 ,50), S2Cl2 ,31), BF3 ,10), HF ,100)
1 ,50), S2Cl2 ,31), BF3 ,10), HF ,100)
20
40
70
12
12
12
12
8
Trace
54
2a ,7), 2b ,2), 2c ,33), 2d ,49), 2e ,3), 2f ,4), others ,2)
2a ,12), 2b ,2), 2c ,23), 2d ,51), 2e ,3), 2f ,5), others ,4)
3 ,7) 4a ,3), 4b ,9), 4c ,16), 4d ,58), others ,7)
4a ,55), 4c ,30), 4b ,15)
57
3 ,66), S2Cl2 ,26), BF3 ,10), HF ,100) 100
4c, 4da ,36), Cl2 ,6)
5 ,50), S2Cl2 ,26), BF3 ,10), HF ,100) 100
b
5 ,60), SCl2 ,26), BF3 ,10), HF ,100) 100
70
10±25
40
77
12
12
12
12
5 ,6), 6a ,2), 6b ,33), 6c ,57), 6d ,2)
41
5 ,6), 6a ,6), 6b ,72), 6c ,6), others ,10); isolated yield of 6bÐ65%
8a ,10), 8b ,38), 8c ,37), 8d ,11), others ,4)
8a ,4), 8b ,87), 8c ,7), others ,2); isolated yield of 8bÐ67%
7 ,52), S2Cl2 ,26), HF ,100)
7 ,52), S2Cl2 ,26), BF3 ,10), HF ,100)
70
50
48
71
a Ratio 30:70, respectively.
b Distilled SCl2.
monochlorodisul®de 2e and -trisul®de 2f ,3±4%), along with
smaller amount of thiosulfenyl chloride 2a ,see Table 1,
entries 2 and 3)
surprisingly, disulfide 4c under reaction conditions remained
unchanged.
hv
4c ‡ 4d ‡ Cl2À5 to 25 ꢀC;8 h
!
4a ‡ 4b ‡ 4c
,3)
40À70ꢀ
BF3;HF
CF2ˆCF2 ‡ S2Cl2 ! C2F5SSCl ‡ C2F5SCl ‡ ꢁC2F5†2S2
2a
2b
Hexafluoropropene ,5) reacts with S2Cl2 at elevated tem-
perature ,Table 1, entry 6) with formation of mixture in
which compounds 6b and 6c are major components, along
with smaller amount of 6a and 6d
2c
‡ ꢁC2F5†2S3 ‡ ClCF2CF2S2C2F5
2e
2d
‡ ClCF2CF2S3C2F5
,1)
2f
100 ꢀC;12 h
CF3CFˆCF2 ‡ S2Cl2
!
ꢁCF3†2CFSSCl
HF;BF3
This result is in a sharp contrast to the data obtained for the
reaction of 1 with SF4/HF/S2Cl2 system leading to mixture
of 2a, 2b, and 2d in ratio 23:45:32, after 4 h at 80 8C [21].
That difference may be a result of either longer reaction time
,12 h versus 4 h) or higher temperature of the work-up step
of the process, which includes treatment of crude reaction
mixture with water ,see Section 3). The composition of
crude product in the reaction of 1 and S2Cl2 does not change
significantly at higher temperature ,70 8C, 12 h), however at
ambient temperature the reaction is quite slow producing
only trace amount of product ,see Table 1, entry 1).
The reaction between sulfur monochloride and vinyl ether
3 proceeds at higher temperature ,100 8C, 12 h) leading after
treatment of the reaction mixture with water to a mixture of
4a±c and trisul®de 4d ,Table 1, entry 4).
5
6a
‡ ꢁCF3†2CFSCl ‡ ‰ꢁCF3†2CFŠ2S3 ‡ ‰ꢁCF3†2CFŠ2S4
6b
6c
6d
,4)
Interestingly, the reaction of 5 with distilled SCl2 is much
more selective, leading to predominant formation of sulfenyl
chloride 6b isolated in 65% yield
100 ꢀ
5 ‡ SCl2
!
C;12 h6b ꢁyield 65%†
,5)
HF;BF3
It should be pointed out that this result is in a good agree-
ment with data of [18], where the formation of correspond-
ing sulfenyl chloride as a major product was observed in the
reaction of SCl2 with 5 in HOSO2F as a solvent.
The effect of catalyst ,boron tri¯uoride) was studied in the
reaction of 2-H-penta¯uoropropene ,7) and S2Cl2. In the
absence the reaction is slow even at 70 8C and produces a
mixture of disul®de 8b, trisul®de 8c, tetrasul®de 8d and
,CF3)2CH2 ,8a) ,Table 1, entry 8)
100 ꢀ
CF3OCFˆCF2 ‡ S2Cl2
!
C;12 hCF3OCF2CF2SSCl
4a
HF;BF3
3
‡ CF3OCF2CF2SCl ‡ ꢁCF3OCF2CF2†2S2
4b
4c
‡ ꢁCF3OCF2CF2†2S3
,2)
70 ꢀC;12 h
4d
CF3CHˆCF2 ‡ S2Cl2
!
ꢁCF3†2CH2
HF
7
8a
The structures of 4a±d were established from data 19F NMR
and GS/MS spectroscopy. The proposed structure of pro-
ducts and orientation of addition to a double bond are in
good agreement with published data on the orientation
of addition of electrophiles to 3 [24]. The chlorination
under mild conditions of the mixture 4c and 4d leads to
complete conversion of 4d into a mixture of 4a and 4b, but
‡ ‰ꢁCF3†2CHŠ2S2‡‰ꢁCF3†2CHŠ2S3‡‰ꢁCF3†2CHŠ2S4
8b
8c
8d
,6)
However, the same reaction in the presence of BF3 catalyst
proceeds rapidly at 50 8C leading significantly higher
weight of crude product ,71 g versus 46g, respectively)

V.A. Petrov / Journal of Fluorine Chemistry 112 12001) 325±327
327
and predominant formation of disulfide 8b ,isolated in 67%
yield),alongwithsmallamountsof8aand8c,Table1,entry9).
Compound 2f: proposed structureÐClCF2CF2S3CF2CF3;
‡
‡
MS: 350 [M , C4ClF9S3 , for Cl35].
Compound 4a: bp 110±112 8C; CF3OCF2CF2SSCl; 19F
NMR: À55.93 ,3F, t; 9 Hz), À87.38 ,2F, m), À94.86,2F, s);
ꢀ
7 ‡ S2Cl2
!
50 C;12 h8a ‡ 8b ‡ 8c ꢁisolated yield of 8b 67%†
,7)
HF;BF3
‡
‡
MS: 284 [M , C3ClF7OS2 , for Cl35].
Compound 4b: bp 58±59 8C; CF3OCF2CF2SCl; 19F
NMR: À55.80 ,3F, t; 9 Hz), À87.40 ,2F, m), À97.67 ,2F,
‡
‡
3. Experimental
t, 3 Hz); MS: 252 [M , C3ClF7OS , for Cl35].
Compound4c: ,CF3OCF2CF2)2S2; 19F NMR: À55.88,3F),
‡
‡
1
19F and H NMR spectra were recorded on a QE-300
,General Electric) instrument using CFCl3 as internal stan-
dard or chloroform-d or acetone-d6 as a lock solvent. Mass-
spectra were recorded at 70 eV for EI using Hewlett-Packard
5985B GC/MS instrument.
À86.41 ,2F, m), À94.83 ,2F); MS: 434 [M , C6F14O2S2 ].
Compound4d:,CF3OCF2CF2)2S3;19FNMR:À55.88,3F),
‡
‡
À87.43 ,2F, m), À95.76,2F); MS: 466[ M , C6F14O2S3 ].
Compound 8c: [,CF3)2CH]2S3; 19F NMR: À66.40
,6F, d; 7 Hz); 1H NMR: 4.00 ,hept., 7 Hz); MS: 398
‡
‡
[M , C6H2F12S3 ].
3.1. Reagents
Compound 8d: [,CF3)2CH]2S4; 19F NMR: À66.80
,6F, d; 7 Hz); 1H NMR: 4.00 ,hept., 7 Hz); MS: 430
‡
‡
S2Cl2, SCl2, BF3 ,Aldrich), tetra¯uoroethylene, hexa¯uor-
opropene, per¯uoromethylvinyl ether ,DuPont), 2-H-penta-
¯uoropropene ,PCR) were commercially available and were
used without further puri®cation. Technical SCl2 ,Aldrich)
was puri®ed by distillation ,residual amount of S2Cl2 < 3%).
Compound 8a was identi®ed by comparison with authentic
sample. Compounds 2a±d [14,15,21], 6a±d [14,15,21], 8b
[M , C6H2F12S4 ].
Acknowledgements
Author thanks Dr. C.G. Krespan for helpful discussions
and R. Smith Jr. for technical support.
1
[25] were identi®ed by comparison of 19F and H NMR
References
spectra data with reported literature values. Compounds
2d, 2f, 4a±d, 8c and 8d were not isolated, but identi®ed in
mixture by GC/MS or 19F NMR spectroscopy ,see below).
Caution: Hydrogen ¯uoride is toxic and causes severe
chemical burns. It should be handled by trained personnel
only.
[1] A.Y. Sizov, A.K. Kolomiets, A.V. Fokin, Uspekhi Khimii 61 ,940)
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fluoroolefins 1typical procedure)
[6] N.R. Zack, J.M. Shreeve, J. Chem. Soc., Perkin Trans. 1 ,1975) 614.
[7] M. Hauptschein, A.V. Grosse, J. Am. Chem. Soc. 73 ,1951) 5461.
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0.25 mol for SCl2) was loaded in 400 ml Hastelloy shaker
tube. The reactor cooled down to À50 8C and charged with
100 g of HF, 0.3±0.5 mol of the corresponding ¯uoroole®n
and 10 g BF3 and kept at 20±100 8C for 12 h. At ambient
temperature water ,200 ml) is injected into shaker tube ,this
step is exothermic and since the inside temperature of reactor
at this step was not controlled, temperature of the reaction
mixture could exceed 70±80 8C). The reactor was unloaded
at 25 8C, organic layer separated, dried with MgSO4 and
analyzed. Reaction conditions are given in Table 1.
[9] C.G. Krespan US Patent 3,099,688 ,1963) to DuPont.
[10] C.G. Krespan, W.R. Brasen, J. Org. Chem. 27 ,1962) 3995.
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3.1.2. Chlorination of mixture 4c, 4d
[19] A.Y. Sizov, V.M. Rogovick, A.F. Kolomiets, A.V. Fokin, Izv. AN
SSR. Ser. Khim. ,1996) 1745.
The mixture of 36g of mixture 4c, 4d ,ratio 30:70) and
15 g of chlorine was kept in a ¯ask with dry-ice condenser
under irradiation using sun lump. In 8 h temperature of the
reaction mixture went from À5 to 25 8C. Reaction mixture
was washed with water, dry over MgSO4 and crude product
,28 g) was analyzed. Reaction conditions and ratios of
reactants and products are given in Table 1.
[20] N.N. Muratov, N.M. Mohamed, B.N. Kunshenko, L.A. Alekseeva,
L.M. Yagupol'skii, Zh. Org. Khim. 22 ,1986) 862.
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Compound 2d: proposed structureÐClCF2CF2S2CF2CF3;
‡
MS: 318 [M , C4ClF9S2 , for Cl35].
[25] W.J. Middleton, W.H. Sharkey, J. Org. Chem. 30 ,1965) 1384.
‡