Synthesis and polymerisation of fluorinated monomers bearing a reactive lateral group. Part 5 - Radical addition of iodine monobromide to chlorotrifluoroethylene to form a useful intermediate in the synthesis of 4,5,5-trifluoro-4-ene-pentanol

Article abstract of DOI:10.1016/S0022-1139(98)00280-2

The synthesis of the new halogenated alcohol BrCF₂CFClCH₂CHICH₂OH as a precursor of 4,5,5 trifluoro-4-ene pentanol F₂C=CFC₃H₆OH is based on a two-step process. First, the radical addition of iodine monobromide to chlorotrifluoroethylene (CTFE) led to the expected BrCF₂CFClI (I) and ICF₂CFClBr (II), but also to BrCF₂CFClBr (III) and ICF₂CFClI (IV), the amount of which determined by ¹⁹F NMR depended on the reaction conditions: by feeding CTFE into IBr continuously or in batches; photochemical or thermal initiations, and with various initial [IBr]₀/[CTFE]₀ molar ratios. In most cases, isomer (I) was mainly produced. The second step concerned the addition of such a mixture to allyl alcohol yielding the polyhalogenoalcohol with a quantitative conversion of (I). The reactivity of different halogeno end-groups of these isomers toward the allyl alcohol was discussed. Reduction of the iodine atom into hydrogen and the halogenated alcohol was accompanied by that of the bromine atom leading to BrCF₂CFClC₃H₆OH and HCF₂CFClC₃H₆OH (V). Dehalogenation of the former alcohol in the presence of zinc led to F₂C=CFC₃H₆OH while dehydrochlorination of (V) into trifluorovinyl hydroxy monomers was achieved in the presence of potassium hydroxide but in poor yields. Strategies starting from the radical additions of iodine monochloride and of iodine monobromide were compared showing that the former led to better overall yields of trifluorovinyl alcohol than the latter.

Full text of DOI:10.1016/S0022-1139(98)00280-2

Journal of Fluorine Chemistry 93 (1999) 117±127
Synthesis and polymerisation of ¯uorinated monomers bearing a reactive
lateral group. Part 51 ± Radical addition of iodine monobromide to
chlorotri¯uoroethylene to form a useful intermediate in
the synthesis of 4,5,5-tri¯uoro-4-ene-pentanol
a,*
B. Ameduri , B. Boutevin , G.K. Kostov , P. Petrova
a
b
b
Â
ESA 5076 (CNRS), Ecole Nationale Superieure de Chimie, 8 Rue de l'Ecole Normale 34296, Montpellier Cedex 5, France
a
Â
bCenter for Electron Beam Technology and Polymers, University of Bourgas 8010, Bourgas, Bulgaria
Received 19 June 1998; accepted 11 September 1998
Abstract
The synthesis of the new halogenated alcohol BrCF2CFClCH2CHICH2OH as a precursor of 4,5,5 tri¯uoro-4-ene pentanol
F2C=CFC3H6OH is based on a two-step process. First, the radical addition of iodine monobromide to chlorotri¯uoroethylene (CTFE)
led to the expected BrCF2CFClI (I) and ICF2CFClBr (II), but also to BrCF2CFClBr (III) and ICF2CFClI (IV), the amount of which
determined by 19F NMR depended on the reaction conditions: by feeding CTFE into IBr continuously or in batches; photochemical or
thermal initiations, and with various initial [IBr]0/[CTFE]0 molar ratios. In most cases, isomer (I) was mainly produced. The second step
concerned the addition of such a mixture to allyl alcohol yielding the polyhalogenoalcohol with a quantitative conversion of (I). The
reactivity of different halogeno end-groups of these isomers toward the allyl alcohol was discussed. Reduction of the iodine atom into
hydrogen and the halogenated alcohol was accompanied by that of the bromine atom leading to BrCF2CFClC3H6OH and
HCF2CFClC3H6OH (V). Dehalogenation of the former alcohol in the presence of zinc led to F2C=CFC3H6OH while dehydrochlorination
of (V) into tri¯uorovinyl hydroxy monomers was achieved in the presence of potassium hydroxide but in poor yields. Strategies starting
from the radical additions of iodine monochloride and of iodine monobromide were compared showing that the former led to better overall
yields of tri¯uorovinyl alcohol than the latter. # 1999 Elsevier Science S.A. All rights reserved.
Keywords: Chlorotri¯uoroethylene; Iodine monobromide; Radical addition; 19F NMR spectroscopy; Reduction; Functional tri¯uorovinyl monomer
1. Introduction
tri¯uorovinyl monomers [16±18]. However, the last step, the
dechlorination of ClCF2CFCl±R± (where R and de-
Previous papers have demonstrated the high reactivity of
1,2-dichloroiodotri¯uoroethane (ClCF2CFClI) in the telo-
merisation reactions of various ¯uoroole®ns such as viny-
lidene ¯uoride (VDF) [1], tri¯uoroethylene [2,3], 1-chloro-
2,2-di¯uoroethylene [4], chlorotri¯uoroethylene (CTFE)
[4±7], tetra¯uoroethylene [3,8±10], 1,1-di¯uoropropene
[11] or hexa¯uoropropene [6,12]; or the cotelomerisation
of VDF and CTFE [13]. Furthermore, this compound can
undergo radical additions to dienes [14], allyl trialkylsilanes
[15] or functional ole®ns such as allyl acetate [16,17] or allyl
alcohol [18], and also coupling reactions [19].
signate a spacer and a functional group, respectively) did not
exceed 70% yield, even after a pseudo-optimisation of this
reaction [18]. This may arise from the high strength of the
Cl±CF2 bond. It is known that debromination [20] or
dechlorobromination [21,22] are easier and usually gave
high yields of tri¯uorovinylic compounds. Hence, our inter-
est was focused on a similar way of synthesis of tri¯uor-
ovinyl functional monomers from brominated reactants, and
especially, iodine monobromide. Its addition to chlorotri-
¯uoroethylene (CTFE) mainly led to BrCF2CFClI that
reacted with allyl alcohol or allyl acetate. The former
reaction is described in this paper whereas the latter one
will be detailed in a forthcoming paper.
Allyl acetate and allyl alcohol were thus involved in key-
reactions as starting points for the synthesis of functional
In contrast to the addition of iodine monochloride to
CTFE carried out by several authors [7,10,23±27] and
recently optimised [28], that of iodine monobromide to
*Corresponding author. Fax: +33-4-67-14-7220.
1
Part 4, see [18]
0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved.
P I I : S 0 0 2 2 - 1 1 3 9 ( 9 8 ) 0 0 2 8 0 - 2

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B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
118
CTFE has drawn less attention. Several papers described
this reaction, such as the pioneer work of Haszeldine [23]
who claimed that IBr and CTFE yielded BrCF2CFClI, but
several years later, Chambers et al. [29] showed that this
reaction led to BrCF2CFClBr and two isomers: BrCF2CFClI
and ICF2CFClBr. The formation of both isomers was proved
by irradiating the mixture in the presence of mercury: the
former isomer reacted quickly, leaving the latter one
unchanged. This addition was also mentioned in a patent
[30] but the authors did not indicate the presence of both
isomers and by-products.
Hence, we have planned to perform a deeper investigation
of this reaction to elucidate the above observations and to
quantify the products. The second objective of this paper is
based on the reactivity of these products to allyl alcohol in
order to prepare key intermediates for the synthesis of
functional tri¯uorovinyl monomers. Such monomers were
previously obtained [18,31] from precursors based on the
radical addition of iodine monochloride to CTFE [28]. Thus,
both reactions involving iodine halides are to be compared
as are the reactivities of their products with allyl alcohol.
chlorotri¯uoroethylene (CTFE) without taking into account
the possibility of telomerisation or the reaction mechanism
[23,29].
The radical addition of iodine monobromide to CTFE was
carried out in various ways, IBr being from a commercial
source or generated in situ from a mixture of iodine and
bromine: by either ensuring a continuous bubbling of CTFE
into IBr or the use of a batch process in a Carius tube or an
autoclave. Initiation occurred either thermally or photoche-
mically, and in this latter case, benzophenone was used as
the photoinitiator. These conditions of initiation were sug-
gested from the literature [23,29] or from the previous work
(e.g., those dealing with the radical additions of iodine
monochloride to CTFE [28] or to tri¯uoroethylene [32]).
However, neither redox catalyst nor radical initiator was
used since such systems were not reported to bring any
improvement in the yield or regioselectivity of addition.
The results are listed in Table 1. The amounts of the three
products were determined by gas chromatography, after
identifying ICF2CFClI [8,11,24,28,33] and recently synthe-
sised BrCF2CFClBr [34±36], which have retention times of
11.7 and 6.3 mn, respectively (Fig. 1). In addition, the
presence of the expected I(CTFE)Br was checked by GC/
MS and by 19F NMR spectroscopy. The mass spectrum
con®rms the formation of BrCF2CFClBr and ICF2CFClI by
their characteristic fragments (see Section 4) whereas those
of I(CTFE)Br clearly identify the presence of both isomers:
fragments at 193, 195, 197 and 145, 147 assigned to
2. Results and discussion
The synthesis of new halogenated alcohols was per-
formed in two steps (Scheme 1) which are detailed hereafter.
ꢀ
ꢀ
‡
‡
2.1. Addition of iodine monobromide to
chlorotrifluoroethylene
(BrCF2CFCl) ; and (CFClBr) ; end-groups of (I) and
(II), respectively.
In addition, the 19F NMR spectrum (Fig. 2) provides ®rm
evidence for the existence of these three products and
allowed us to distinguish two isomers for I(CTFE)Br. First,
ICF2CFClI was formed as a minor compound, shown by
According to the literature discussed above, it is clear that
at least two isomers were produced (Scheme 1); but the
authors considered only the monoaddition reaction of IBr to
Table 1
Radical addition of iodine monobromide to chlorotrifluoroethylene (CTFE): experimental conditions and results
Experiment Vessel
no.
Weight of
IBr (g)
Weight of
CTFE (g)
‰IBrŠ0=
‰CTFEŠ
Initiation
Time
(h)
Br(C2F3Cl)I
(%)
BrCF2CFClBr ICF2CFClI Overall
(8C)
(%)
(%)
yield (%)
0
1
2
3
4
5
6
7
8
9
F
in situ
in situ
in situ
in situ
71.0
bubbling
75.0
±
th, 50±70
th, 100
2
2
26
63
74
33
25
23
44
31
20
20
24
0
4
6
n.d.
31a
n.d.
35a
n.d.
n.d.
n.d.
39a
A
<0.77
<0.90
<0.90
1.00
0.77
0.70
0.70
0.97
A
65.0
th, 100
1
55
20
22
5
A
65.0
40.0
th, 90
th, 100
12
72
16
5
55
51
61b
CT
CT
CT
CT
CT
76.4
56.0
th, 90
8
70.4
56.6
th, 80
73
7
37.0
120.0
30.4
69.8
th, 80
5
14
76
75c,d
4
photoch.
Ph2CO, RT
photoch. DPPHe
Ph2CO, RT
1
10
CT
36.5
21.6
0.95
15
72
26
2
8a
F, A, CT, th, photoch. and n.d. mean flask, autoclave, Carius tube, thermal, photochemical and not determined, respectively.
aAfter distillation.
b%BrCF2CFClIˆ58 %ICF2CFClBrˆ3.
cRelative yields determined by 19F NMR.
d%BrCF2CFClIˆ70, %ICF2CFClBrˆ5.
e2,2-Diphenyl-1-picrylhydrazyl.

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B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
119
Scheme 1. Preparation of halogenated alcohols from the products of addition of iodine monobromide to chlorotrifluoroethylene.
three different signals centred at 43.45, 52.27 and
65.85 ppm assigned to the three ¯uorine atoms of an
AMX system. This con®rms the characterisation of Cham-
bers et al. [33]. Second, BrCF2CFClBr was also easily noted
by the characteristic AB part of an ABX system
(ꢀFAˆ 59.13 ppm and ꢀFBˆ 60.85 ppm) and the triplet
(3JFFˆ13.9 Hz) centred at 69.25 ppm. The conditions
used for recording this spectrum allowed us to observe this
triplet only, rather than the expected doublet of doublets
with close coupling constants (13.5 and 14.1 Hz). Finally,
both isomers of I(CTFE)Br are also formed. The major one,
BrCF2CFClI (I), exhibits the following 19F NMR character-

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B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
120
atoms respectively, compared to 163.9 Hz for a chlorine
3
3
atom [17]) and between the JFaFc and the JFbFc
.
The minor isomer, ICF2CFClBr, also had distinct signals.
The AB part of the ABX system, assigned to the ICF2 group,
is a low ®eld shifted compared with that for BrCF2, but high
®eld shifted compared to the same end-group of ICF2CFClI.
The X part (CFClBr group) is represented by a triplet
(3JFFˆ16.1 Hz) centred at 66.20 ppm.
From the integrations of the signals assigned to the
CFClX group (XˆI or Br) of each product centred at
65.85 (CFClI of IV), 66.20 (CFClBr of II), 69.25
(CFClBr of III) and 69.81 (CFClI of I), proportions of
products in the mixture were determined. For example,
experiment 9 (Table 1, Fig. 2) gives the following ratios
of products: ICFClCF2Br (70%), BrCF2CFClBr (24%),
ICF2CFClBr (5%) and ICF2CFClI (1%).
As shown previously [28,33], the diiodinated compound
may undergo a b-scission (or reversion) above 408C leading
back to CTFE and iodine, but from 908C, the CTFE
produced may also react with ICF2CFClI leading to telo-
mers [33] since we have previously shown the high reac-
tivity of the CFClI end-group in the thermal telomerisation
of CTFE [37]. Interestingly, the photochemical induced
reaction enabled drastic decrease of diiodide but with a
non-negligible amount of dibrominated by-product. This
latter product was also observed by Chambers et al. [29] in
20% yield.
Fig. 1. Gas chromatogram of the total product mixture of the addition of
iodine monobromide to CTFE of experiment 2 (the experimental
conditions are in Table 1). A and B represent the peaks assigned to
CTFE and methylene chloride, respectively.
istics: the AB part of an ABX system, assigned to the BrCF2
end-group overlaps with the signal of the same group of
BrCF2CFClBr, giving a doublet (2JFbFaˆ165.9 Hz) of doub-
lets (3JFcFbˆ20.4 Hz) and centred at 58.95 ppm, and a
doublet (2JFaFbˆ165.9 Hz) of doublets (3JFaFcˆ15.1 Hz) at
53.74 ppm. The X part of the ABX system shows a
doublet (3JFcFaˆ15.6 Hz) of doublets (3JFbFcˆ20.2 Hz)
centred at 69.81 ppm. Interestingly, these NMR charac-
teristics show the difference of shapes of signals assigned to
XCF2 and CFClX end-groups (where X is I or Br), the
bulkier iodine atom enhancing the differences between the
The yield obtained from the reaction performed at atmo-
spheric pressure (exp. 1 in Table 1) was quite low whereas
those from thermal initiation in sealed Carius tube were less
than 35%. The best yield observed was for photochemical
induced reaction (exp. 9). However, the yield of this reaction
was worse than that obtained from the addition of iodine
2
coupling constants JFF (188.5 and 165.9 Hz for I and Br
Fig. 2. 19F NMR spectrum of the product of the addition of iodine monobromide to CTFE as experiment 9 (see Table 1) BrCF2CFClI(!), ICF2CFClBr(Á),
BrCF2CFClBr(*) and ICF2CFClI(*).

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B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
121
monochloride to chlorotri¯uoroethylene (leading to 70%
and quantitative yields for photochemical and thermal
initiations, respectively [28]).
ClCF2CFClI and ClCF2CFHI in 95% and 97% yields,
respectively. In both cases, the iodine atom preferred to
add to the less ¯uorinated sides of the ¯uoroalkenes and thus
on the more hindered part of CTFE. This was shown
thermodynamically and con®rms that these reactions are
not controlled by steric effects [32]. In the case of addition
of IBr to CTFE, both these observations are also noted.
Semi-empirical calculations are in progress on the basis of
orbital analysis.
An attempt of the mechanism of the reaction is suggested.
2.2. Mechanism
To our knowledge, the mechanism of this reaction has not
been described previously. It can be ionic:
In order to check whether the mechanism was radical,
2,2-diphenyl-1-picrylhydrazyl (DPPH) was used as radical
scavenger (exp. 10). Table 1 shows that without any DPPH,
the yield was 39% whereas it drastically decreased when
this reaction was performed in the presence of the radical
scavenger.
Hence, although we have no evidence that the mechanism
could be ionic (IBr reacted violently with amines used as
cation scavengers), it is likely that the addition of IBr to
CTFE involves radicals, as that of ICl to CTFE [28] or to
TrFE [32].
d
d‡
d‡
d
BrI ‡ CF2 ˆ CF Cl ! BrCF2CFClI
or radical:
(a) From Brꢀ attack
Initiation
IBr ! Brꢀ ‡ Iꢀ
Brꢀ ‡ F2CˆCFCI ! BrCF2CFCIꢀ
Termination
Á
BrCF2CFCIꢀ ‡ IBr ! BrCF2CFCII ‡Brꢀ ꢁI†
2.3. Addition of Br(CTFE)I to allyl alcohol
ꢁI†
Termination by recombination
Brꢀ ‡ Brꢀ ! Br2
(b) From Iꢀ attack
Initiation
In contrast to Rogozinski et al. [38] who could not react
BrCCl2CHClBr with allyl alcohol, Burton and Kehoe [39],
Ojima and Fuchikami [40], and Hu et al. [21] successfully
added 1,2-dibromo-1-chlorotri¯uoroethane to various ꢁ-
ole®ns in the presence of CuCl/ethanolamine, iron dodeca-
carbonyl and metallic complexes.
IBr ! Iꢀ ‡ Brꢀ
In our experiments, radical addition was chosen to be
initiated by AIBN at 808C (i.e. half life of 1 h) since it led to
the best yields of a similar reaction involving ClCF2CFClI
(yieldˆ81%) [18]. The reaction was monitored by gas
chromatography showing a product having a retention time
longer that those of the reactants. After 4 h and since the
halogenated mixture was not totally consumed, an addi-
tional amount of initiator was introduced as in previous
work [18]. After distillation, pure fractions were charac-
Á
Iꢀ ‡ F2CˆCFCl ! ICF2CFClꢀ
ICF2CFClꢀ ‡ IBr ! ICF2CFClBr ‡Iꢀ ꢁII†
ꢁII†
Termination
Iꢀ ‡ Iꢀ ! I2
As for the radical addition of ICl to CTFE, no CTFE
diadduct was observed (Fig. 1) and thus the propagation
step did not occur.
1
terised by H and 19F NMR.
1
The H NMR spectrum suggests the CH2±CHXCH2OH
According to this radical mechanism, it can be deduced
that if Iꢀ reacts with CTFE, isomer (II) is produced, whereas
the addition of Brꢀ leads to isomer (I). From the experi-
mental work (Table 1), isomer (I) is favoured, probably
because of a higher reactivity of Brꢀ than that of Iꢀ . This
structure (XˆI or Br) as previously observed for
ClCF2CFClCH2CHICH2OH. The signal attributed to the
methylene ꢂ to the hydroxyl function is complex because
this methylene is adjacent to two asymmetric carbons. This
also indicates that halogenated alcohol (I,a) is present as two
diastereoisomers, in equal amounts.
behaviour is similar to those of most telomerisations of
ole®ns with per¯uoroalkyl iodides (RFI) for which RF
ꢀ
The presence of the methylene of the CH2OH end-group
was proved by adding a drop of Cl3CNCO to the NMR tube:
its signal was low ®eld shifted from 3.85 to 4.70 ppm.
reacted preferentially, allowing the formation of I2 by
recombination of Iꢀ , whereas RF RF was not observed [37].
In addition, the greater formation of BrCF2CFClBr (III),
as compared with ICF2CFClI (IV), is in good agreement
with scheme (a) which generates more Br2.
We have previously demonstrated that the addition of
iodine monochloride to CTFE [28] or to tri¯uoroethylene
(TrFE) [32] was through a radical mechanism. Both these
reactions led to the major formation of two isomers,
1
However, H NMR spectroscopy was not able to con®rm
the formation of (I,a), (II,a), (II,a0) and (III,a) products. The
19F NMR spectrum exhibits three signals, only: that centred
at 61.90 ppm (the AB part of an ABX system, BrCF2) and
two doublets of quartets assigned to the CFCl groups of both
2
diastereoisomers. The JFF coupling constant of the XCF2
end-group was 154.7 Hz let us assume that this was for

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B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
122
Fig. 3. 13C NMR spectrum of BrCF2CFClCH2CHICH2OH (expansion of the 106±128 ppm zone; BrCF2 (*, Ã) and CFCl (*, ‡)).
XˆBr. It is rather close to that of the ClCF2 end-group
2.4. Reduction of iodohalogenated alcohol I; a
(2JFFˆ169.3 Hz) in ClCF2CFClCH2CHICH2OAc [17].
Finally, the 13C NMR spectrum con®rms the formation of
(I,a) only. Indeed, the XCF2 end-group signals (in the 105±
140 ppm range) are in excellent agreement with the
BrCF2CFCl structure as shown in Fig. 3. This is also in
agreement with the values of the 1JCF coupling constants in
BrCF2 and ICF2 end-groups being 312 and 367 Hz, respec-
tively [36].
The attempt to perform the selective reduction of the
iodine atom of BrCF2CFClCH2CHICH2OH (I; a) was car-
ried out in the presence of an equimolar amount of tributyl-
stannane at 5±208C as done previously [18]. The reaction
was monitored by gas chromatography, the retention time of
I; a being 8.36 min. After 3 h, a ®rst peak having a retention
time of 6.19 min appeared while that of the alcohol I; a
decreased. After 8 h, the signal assigned to the iodinated
alcohol was absent whereas that at 6.19 min. increased,
while another signal at 4.50 min. was observed. Both these
products were distilled, the heavier one (RTˆ6.19 min)
having the expected BrCF2CFClC3H6OH (I; b) structure
as shown by the high ®eld shift of the CHI group
(ꢀˆ4.50 ppm) to 1.90 ppm in the 1H NMR spectrum
(assigned to the central methylene group of I; b). The 19F
NMR characteristics show the presence of two groups of
signals; that centred at 62 ppm being unchanged from that
of the iodinated precursor, whereas only one doublet
In order to con®rm that the reactivity of BrCF2CFClI is
higher than that of BrCF2CFClBr towards alkenes,
BrCF2CFClBr was reacted with allyl alcohol in the presence
of AIBN. A similar reaction was performed [39,40] using
metal complexes but to our knowledge, AIBN was not
previously used to initiate such a reaction. In similar con-
ditions as above, the reaction occurred but in a poor yield
(10% after distillation of BrCF2CFClCH2CHBrCH2OH
(III,a)). Such a product was co-injected with the total
product mixture of the reaction described above for GC,
and the corresponding signal of (III,a) having a retention
time of 7.39 min appeared close to that of (I,a)
(RTˆ8.36 min). The peak assigned to (III,a) was observed
on the gas chromatogram of I,a but in a very low amount (ca.
5%).
3
(3JFcFaˆ30.7Hz) of quartets (3JFcFb ˆ JFcH ˆ 10:3 Hz)
was present proving the loss of the second asymetric carbon,
observed in I; a.
1
The H NMR spectrum of the second product exhibits,
The low reactivity of BrCF2CFClBr is based on the rather
high bond dissociation energy of the C±Br bond in the
CFClBr end-group. Even its radical addition on allyl acetate
(shown to be more reactive than allyl alcohol in telomer-
isation reactions [41]) at 928C initiated by dibenzoyl per-
oxide led to 15% yield, only, after 10 h with an additional
amount of initiator every 3 h. Under the same conditions, the
addition of ClCF2CFClI to such an w-acetoxy monomer was
almost quantitative after 5 min [17].
beside the same signals observed for the above product, a
triplet (2JHF ˆ 54:8 Hz) of doublets (3JHF ˆ 3:2 Hz) char-
acteristic of a HCF2 end-group. This shows that tributyl-
stannane ef®ciently reduced the bromine atom to a proton,
even at rather mild temperatures.
The 19F NMR spectrum shows an interesting triplet
(3JFcH ˆ 10:4 Hz) of doublets (3JFcFa ˆ 10:7 Hz) of
doublets (3JFcFb ˆ 9:7 Hz) of doublets (3JFcH ˆ 3:3 Hz)
centred at 125.3 ppm and an expected AB part at

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B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
123
130.3 ppm assigned to the CFCl and HCF2 groups,
respectively.
ducts (including two I(CTFE)Br isomers) were produced
whatever the way of initiation without any formation of
diadduct, the photochemical induced reaction is the best
since it minimised the amount of by-products X(CTFE)X
(XˆI and Br) and afforded the best overall yields. However,
these yields were worse than those obtained from radical
addition of iodine monochloride. Although no evidence for
an ionic mechanism could be given, the radical character of
this reaction was noted, similar to those of the addition of
ICl to CTFE and to tri¯uoroethylene. When the mixture of
products formed reacted with allyl alcohol, only
BrCF2CFClI was ef®cient leading to BrCF2CFClCH2CHI-
CH2OH in fair yields. The poor reactivity of BrCF2CFClBr
(present in the mixture) towards allyl alcohol was shown by
its direct addition to allyl alcohol in the same initiation
conditions, but leading to 10% yield, only. Its reduction in
the presence of tributyl stannane produced two derivatives:
BrCF2CFClC3H6OH (I; b) and HCF2CFClC3H6OH (I; b0),
the unexpected latter compound coming from the reduction
of the bromine to hydrogen. Both these alcohols have been
used as precursors of 4,5,5-tri¯uoro-4-ene pentanol (I; c):
the former underwent a dechlorobromination in the pre-
sence of zinc in fair yield, in contrast to the latter which only
reacted with dif®culty in the presence of base.
The yields of BrCF2CFClC3H6OH (I; b) and
HCF2CFClC3H6OH (I; b0) were 50 and 29%, respectively.
A similar reaction performed with a two-fold excess of
hydride led to the selective formation of (I; b0) in 55% yield
after distillation.
2.5. Dehalogenation of BrCF2CFClC3H6OH (I; b)
The debromochlorination of I; b into 4,5,5-tri¯uoro-4-ene
pentanol I; c was performed in the presence of activated zinc
in anhydrous DMF. The reaction was carried out at 908C and
monitored by GC, the respective retention times for the
tri¯uorovinyl and halogenated alcohol being 2.75 and
6.19 min. After 6 h, the conversion of I; b was 90% and
after work up, the total product mixture was distilled giving
66% yield of I; c. This hydroxy monomer was characterised
1
by NMR. The H NMR spectrum exhibits 19 bands of an
interesting doublet (3JHFˆ22.5 Hz) of doublets
(4JHFˆ2.4 Hz) of doublets (4JHFˆ3.9 Hz) of triplets
(3JHHˆ6.7 Hz) assigned to the methylene group adjacent
to the tri¯uorovinyl end-group. In addition, it shows signals
similar to those of the I; b precursor, as expected. The 19F
NMR spectrum clearly identi®es the three signals assigned
to the ¯uorine atoms, centred at 106.1, 125.2 and
174.6 ppm.
The overall yield of I; c via photochemical initiation of
the ®rst step and dehalogenation step was 8.3% whereas that
from the dehydrochlorination of I; b0 was 1%. The poor
overall yield of the ®rst step accompanied by the formation
of two by-products is thus a limiting step. Such yields are
much lower than that (40%) obtained for the synthesis of the
same tri¯uorovinyl pentanol via a similar route starting from
the photochemical addition of iodine monochloride to
CTFE and a dechlorination as the ®nal step.
2.6. Dehydrochlorination of HCF2CFClC3H6OH (I; b0)
This reaction was performed in the presence of an
equimolar amount of methanolic potassium hydroxide.
As above, the reaction was monitored by GC (the retention
times of I; b0 and I; c were 4.50 and 2.75 min., respectively)
and was shown to be rather slow, since after 14 h only 40%
of I; b0 was consumed. A two-fold excess of potassium
hydroxide did not increase the yield of I; c but seemed to
produce a further dehydrochlorination leading to II; d or
II; d0 with an internal double bond. This was shown in the 1H
NMR spectrum by the presence of small signals at 6.2 ppm.
However, the absence of signal at 8.1 ppm may indicate that
II; d0 was not produced since it should lead to an aldehyde by
tautomeric equilibrium. The 19F NMR spectrum allowed
identi®cation of the three ¯uorine atoms of I; c as shown
above. This tri¯uorovinyl alcohol was not distilled but its
yield was deduced from GC (12%). The low yield of this
reaction presumably results from the high bond dissociation
energy of the C±H bond of the HCF2 end-group.
Hence, the following decreasing reactivity series can be
proposed:
1. for the radical addition of X±Y onto CTFE: Br2>I-
Cl>IBr
2. for the radical addition of X(C2F3Cl)Yonto allyl alcohol:
ClCF2CFClI>BrCF2CFClI>>BrCF2CFClBr.
4. Experimental
4.1. General comments
Chlorotri¯uoroethylene (CTFE) was kindly given by
Solvay S.A. whereas all other reactants were supplied by
Aldrich (except AIBN from Merck) and did not require
puri®cation prior to use.
Thermal reactions (exp. 5±8) and the reaction in the
presence of a radical scavenger (2,2-diphenyl-1-picrylhy-
drazyl, DPPH) were carried out in Carius tubes (thickness:
3 mm; outside diameter: 30 mm; length: 205 mm).
The photochemically initiated reactions were performed
in big borosilicate Carius tubes (thickness: 3 mm; outside
diameter: 50 mm; length: 310 mm) under irradiation of a
3. Conclusion
The preparation of 4,5,5-tri¯uoro-4-ene pentanol was
achieved from a four-step procedure. The ®rst step involved
the radical addition of iodine monobromide to CTFE,
initiated thermally or photochemically. Although four pro-

Â
B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
124
mercury lamp Philips HPK 125 W located 15±20 cm from
the vertical tube, the reaction mixture being stirred magne-
tically.
4.2.1. 1,2-Dibromotrifluorochloroethane (III)
BrCF2CFClBr ꢀ: 59.90 (AB part of ABX system
2
ꢀFaˆ 59.13 ppm, ꢀFbˆ 60.85 ppm, JFaFbˆ166.8 Hz,
3
The autoclave used in this work was made of Hastelloy
(HC 276) having a volume of 200 ml, equipped with a valve,
a manometer, a rupture disk, and a magnet bar for stirring.
Gas chromatography/mass spectrometry analyses were
performed with a Hewlett-Packard apparatus composed of a
chromatograph type 5972 coupled to a mass detector type
2567 with quadrupole scanning at 90 eV. The BPX5 column
was 25 m long and 0.19 mm in inner diameter. The oven
temperature was raised from 1008C to 2308C at a heating
3JFaFcˆ13.5 Hz, JFbFcˆ14.1 Hz, BrCF2); 69.25 (X part,
3
t, JFFˆ13.9 Hz, CFClBr).
ꢀ
MS m/z: 79/20 and 81/19 (Br) ; 116/18 (C2F3Cl); 145/
‡
ꢀ
25, 147/32, 149/9 (CFClBr) ; 176/6, 178/7 (C2BrF2Cl);
‡
ꢀ
195/75, 197/100, 199/19 (BrCF2CFCl) ; 239/2, 241/3,
‡
ꢀ
243/2 (M±Cl) ; 274/2, 276/3, 278/3 M
ꢀ
‡
‡
4.2.2. 1,2-Diiodotrifluorochloroethane (IV)
ICF2CFClI ꢀ: AB part of ABX system ꢀFaˆ 43.45 ppm,
ꢀFbˆ 52.27 ppm, 2JFaFbˆ188.5 Hz, 3JFaFcˆ16.1 Hz,
3JFbFcˆ18.9 Hz, ICF2; 65.85 (X part, dd, 3JFcFaˆ16.0 Hz,
1
rate of 58C min 1. Helium was the eluent at 0.12 ml min
and the injection temperature was 2208C.
3
After reaction, the products were worked-up with an
alkaline sodium bisulphite solution and analysed by gas
chromatography (GC) using a Delsi apparatus (model 330)
equipped with an SE-30 column, 3 mÂ1/8 in (i.d.). The
nitrogen pressure at the entrance to the column was main-
tained at 0.6 bar and the detector and injector temperatures
were 2608C and 2558C, respectively. The temperature pro-
gramme started from 508C and reached 2508C at a heating
rate of 158C min 1. The GC apparatus was connected to a
Hewlett-Packard integrator (model 3390) which automati-
cally calculated the area of each peak on the chromatogram.
16.0 Hz, JFcFbˆ19.1 Hz, CFClI).
ꢀ
MS m/z: 66/10, 68/3 (CFCl) ; 116/60, 118/28 (C2F3Cl);
‡
ꢀ
127/53 (I) ; 177/5 (CF2I) ; 193/12 (CFClI) ; 243/82,
ꢀ
ꢀ
‡
‡
‡
ꢀ
245/32 (ICFClCF2) ; 254/100 (I2)
‡
4.2.3. Chloroiodo-2-bromotrifluoroethane (I)
BrCF2CFClI ꢀ: 56.20(AB part of ABX system,
ꢀFaˆ 53.74,
ꢀFbˆ 58.95,
2JFaFbˆ165.9 Hz,
3
3JFaFcˆ15.1 Hz, JFbFcˆ20.4 Hz, BrCF2); 69.81(X part,
3
3
dd, JFcFaˆ15.6 Hz, JFcFbˆ20.2 Hz, CFClI).
Its mass spectrum also exhibits fragments coming from
isomer II.
1
The products were characterised by H and 19F NMR
ꢀ
ꢀ
‡ ‡
MS m/z: 50/12 (CF2) ; 66/21, 68/9 (CFCl) ; 79/8, 80/
ꢀ ꢀ ꢀ
spectroscopy at room temperature (ca. 238C). 19F NMR and
1H NMR spectra were recorded on Bruker AC-200, 250
or WM-360 instruments, using deuterated chloroform
and tetramethyl silane or CFCl3 as solvent and internal
references, respectively. The letters s, d, t, qi and m desig-
nate singlet, doublet, triplet, quintet and multiplet, respec-
tively.
‡
‡
‡
18 (Br) ; 116/80, 118/20 (C2F3Cl) ; 127/100 (I) ; 145/
ꢀ
20, 147/23, 149/7 (CFClBr) ; 193/11, 195/85, 197/99, 199/
‡
ꢀ
22 (BrCF2CFCl) ; 206/12, 208/20 (IBr); 243/13, 245/5
‡
ꢀ
(CF2CFClI) ; 287/4, 289/4 (BrCF2CFI)
ꢀ
‡
‡
4.2.4. Chlorobromo-2-iodotrifluoroethane (II)
ICF2CFClBr ꢀ: AB part of an ABX system:
2
4.2. Radical addition of iodine monobromide to CTFE
ꢀFaˆ 50.95 ppm, ꢀFbˆ 54.15 ppm, JFaFbˆ188.1 Hz,
3
3JFaFcˆ15.7 Hz; JFbFcˆ18.8 Hz;
66.20(X part, t,
The weights of reactants are given in Table 1. Hereafter is
presented the experimental procedure for experiment 9.
A Carius tube equipped with a magnet bar and contain-
ing 120.02 g (0.58 mol) of iodine monobromide, 2.5 g
(13.7 mmol) of benzophenone and 300.0 g of methylene
chloride was frozen and degassed before 69.75 g
(0.60 mol) of CTFE was condensed at 808C. After sealing,
the tube was exposed to a UV lamp at room temperature
for 14 h.
3JFFˆ16.1 Hz).
The mixture was dif®cult to purify because of close
boiling points between BrCF2CFClBr (Bpˆ918C [36])
and IC2F3ClBr (Bpˆ828C/195 mm Hg [23] or 120.18C/
768 mm Hg [29]), but ICF2CFClI decomposed at these
temperatures [28,33].
The distillation of the gross (from exp. 9) led to 73.2 g
(0.226 mol) of a red liquid (yieldˆ39%) Bpˆ1108C.
It was necessary to dilute IBr with methylene chloride
and to pour the solution into the Carius tube rather than
melting the reactant before introduction in the tube.
Although the overall yield was similar (37%), the latter
procedure led to a partial decomposition of IBr into iodine
and bromine and consequently gave an increase of by-
products (BrCF2CFClBr, 40% and ICF2CFClI, 15%) with
a decrease of I(C2F3Cl)Br (45%) (Table 1).
4.3. Radical addition of (I)‡(II)‡(III)‡(IV) to allyl
alcohol
In a three-necked round-bottom ¯ask equipped with a
condenser and a device with a nitrogen ¯ow, were intro-
duced 73.2 g (0.23 mol) of Br(C2F3Cl)I and 15.1 g
(0.26 mol) of allyl alcohol. The mixture was heated under
stirring up to 808C and 1.3 g (7.9 mmol) of AIBN were
added. The reaction mixture was stirred at this temperature
for 4 h after which 1.3 g of AIBN was added and the
medium was left stirring for 4 h more. After distillation
The gross was characterised by 19F NMR in CDCl3
(Fig. 2), the spectrum of which indicates the presence of
4 products, 2 being isomers.

Â
B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
125
of unreacted starting materials, 56.7 g (0.149 mol) of a
brown viscuous liquid was redistilled.
Bp 95±998C/0.02 mm Hg. Yieldˆ64.7%.
The mixture was heated up to 808C and 0.25 g (1.5 mmol)
of AIBN was added every 15 min for 1 h. Then the reaction
was left stirring for 6 additional hours. After distillation
under reduced pressure, was obtained 3.8 g (0.011 mol,
10.4% yield) of a colourless liquid which crystallised in
the cold room. Bpˆ74±778C/0.15 mm Hg (Tm ˆ188C).
1H NMR (CDCl3) ꢀ: 2.90 (m, CFClCH2, 2H); 3.15 (broad
s, low ®eld shifted to 7±9 ppm with Cl3CNCO, OH, 1H);
3.82 (m, shifted to 4.63 ppm in the presence of Cl3CNCO,
CH2OH, 2H); 4.53 (m, CHBr, 1H).
4.3.1. 2-Iodo-4-chloro-5-bromo-4,5,5-trifluoropentanol
1H NMR (CDCl3) ꢀ:2.45 (broad s, shifted with dilution
and with Cl3CNCO, CH2OH, 1H); 2.95 m, CFClCH2, 2H);
3.85 (m, shifted to 4.70 with Cl3CNCO, CH2OH, 2H);
4.50 m, CHI, 1H).
19F NMR (CDCl3) ꢀ: 61.90 (AB part of an ABX system,
2
3
ꢀAˆ 61.5, JFaFbˆ154.8Hz, JFaFxˆ11.5 Hz; ꢀBˆ 62.3,
19F NMR (CDCl3) ꢀ : 62.08 (AB part of an ABX
2JFbFaˆ154.7 Hz, 3JFbFxˆ18.5 Hz, BrCF2, 2F); 116.2(dq,
system, ꢀAˆ 61.64, JFaFbˆ155.6 Hz, JFaFcˆ11.3 Hz;
2
3
3JFxHˆ35.5 Hz, JFxFaˆ11.0 Hz, BrCF2CF, 1F of one
ꢀBˆ 62.47, JFaFbˆ155.6 Hz, JFbFcˆ13.2 Hz); 117.08
3
2
3
3
3
3
diastereoisomer); 118.74(dq, JFxHˆ25.5 Hz, JFxFb
ˆ
(X part of the ®rst diastereoisomer, dq, JFcFa ˆ11.1Hz,
16.8 Hz, 1F of the other diastereoisomer).
3JFcHˆ32.6Hz); 118.53 (X part of the second diastereo-
13C NMR (CDCl3) both diastereoisomers have been
characterised but their concentrations being identical, the
assignments of the signals are arbitrary.
isomer, dq, JFcFbˆ13.2 Hz, JFcHˆ26.9 Hz).
4.5. Reduction of I; a by tributylstannane
3
3
Isomer
A
ꢀ: 119.29 (ddd, 1JCFaˆ313.0 Hz,
2
1JCFbˆ313.0Hz, JCFxˆ34.9 Hz, BrCF2); 111.10 (ddd,
An ampoule saturated with argon and equipped with a
septum, contained 51.0 g (0.13 mol) of I; a. It was cooled in
an ice bath and then 38.9 g (0.13 mol) of tributylstannane
were added dropwise via a syringe. After complete addition,
the solution was left stirring 30 mn and then the ice bath was
withdrawn. The mixture was left reacting at room tempera-
ture for 10 additional hours to ensure complete conversion
of I; a. After distillation, 6.65 g (0.038 mol) of a colourless
liquid was obtained (yieldˆ29%). Bpˆ83±868C/25 mm
Hg.
1JCFxˆ258.6, JCFaˆ2JCFbˆ29.6 Hz, CFCl); 68.19 (s,
2
2
CH2OH); 42.38 (d, JCFxˆ19.9 Hz, CH2CFCl); 26.04 (s,
CHI).
Isomer B ꢀ: 118.79 (ddd, JCFaˆ1JCFbˆ313.0 Hz,
1
2JCFxˆ35.0 Hz, BrCF2); 110.49 (ddd, JCFxˆ260.6 Hz,
1
2JCFaˆ2JCFbˆ29.3 Hz, CFCl); 66.91 (d, JCFˆ4.0 Hz,
4
2
CH2OH); 42.09 (d, JCFxˆ19.8 Hz, CFClCH2); 22.97 (s,
CHI).
4.4. Radical addition of 1,2-dibromo-2-
chlorotrifluoroethane to allyl alcohol
4.5.1. 4-Chloro-4,5,5-trifluoropentanol (I; b0)
1H NMR (CDCl3) ꢀ: 1.90(qi, 3JHHˆ6.2 Hz, CH2CH2OH,
2H); 2.23(m, CFClCH2, 2H); 2.75 (broad singlet, shifted
with dilution or in the presence of Cl3CNCO); 3.68 (t,
shifted to 4.50 ppm in the presence of Cl3CNCO,
4.4.1. Synthesis of 1,2-dibromo-2-chlorotrifluoroethane
The addition of bromine to CTFE was performed in a
Carius tube containing a magnet bar and 35.0 g (0.22 mol)
of bromine. After cooling and degassing under vacuum,
33.0 g (0.28 mol) of CTFE was carefully transferred into the
vessel at about 808C. At higher temperatures ( 35±608C),
CTFE reacted with bromine as noted by a white smoke. The
tube was then sealed and allowed to progressively warm up
to 208C. The heat evolution was reduced by immersing the
vessel in an acetone/liquid nitrogen bath, while the orange
mixture progressively turned colourless on reacting. Then,
the mixture was warmed up to room temperature and stirred
for an additional hour. Finally, the tube was frozen into
liquid nitrogen, opened and the total product mixture was
distilled to give 29.8 g (0.15 mol) of a colourless liquid
(yieldˆ69%), Bpˆ918C (lit. val. [23]: 92±92.58C; [35]
92.58C).
2
3JHHˆ6.6 Hz, CH2OH, 2H); 5.81 (td, JHFˆ54.8 Hz,
3JHFˆ3.2 Hz, HCF2, 1H).
19F NMR (CDCl3) ꢀ: 125.33(tddd, X part of an ABX
3
3
3
system, JFcHˆ10.4 Hz, JFcFaˆ10.7 Hz, JFcFbˆ9.7 Hz,
3JFcHˆ3.3 Hz, CFcCl, 1F);
130.30 (AB part,
3JFaFcˆ10.6 Hz,
ꢀFaˆ 129.35,
2JFaFbˆ284.4 Hz,
2JFaHˆ55.0 Hz,
ꢀFbˆ 131.28,
2JFbFaˆ283.7 Hz,
3JFbFcˆ9.9 Hz, JFbHˆ55.0 Hz) 16.5 g (0.064 mol) of a
second pure fraction was distilled (colourless liquid) Bp,
90±928C/21 mm Hg (yieldˆ49.6%).
2
4.5.2. 4-Chloro-4,5,5-trifluoro-5-bromopentanol (I; b)
1H NMR (CDCl3) ꢀ: 1.93(qi, 3JHHˆ6.3 Hz, CH2CH2OH,
2H); 2.29 (m, CFClCH2, 2H); 3.10 (broad singlet, shifted
with dilution or with Cl3CNCO, OH, 1H); 3.64 (t,
3JHHˆ6.4 Hz, low ®eld shifted to 4.6 ppm in the presence
of Cl3CNCO, CH2OH, 2H).
4.4.2. Preparation of 4-chloro-2,5-dibromo-4,5,5-
trifluoropentanol
In a three-necked round-bottomed ¯ask swept by an
argon ¯ow and equipped with a condenser and a thermo-
meter were introduced 31.0 g (0.109 mol) of BrCF2CFClBr
and 6.60 g (0.109 mol) of allyl alcohol.
19F NMR (CDCl3) ꢀ: (AB part of an ABX system
2
3
ꢀFAˆ 61.65, JFaFbˆ155.2 Hz, JFaFxˆ30.5 Hz, ꢀFB
ˆ
2
3
62.85, JFaFbˆ155.2 Hz, JFbFxˆ10.3 Hz); 118.32 (X
part, dq, JFxFaˆ30.7 Hz, JFxFbˆ3JFcHˆ10.3 Hz, Fx).
3
3

Â
B. Ameduri et al. / Journal of Fluorine Chemistry 93 (1999) 117±127
126
A similar reaction using 56.7 g (0.15 mol) of I; a and
1H NMR (CDCl3): mixture of signals assigned to I; b0 to
I; c and complex multiplet at 6.2.
87.3 g (0.30 mol) of SnBu3H led to an almost complete
conversion of I; b after 14 h and I; b0 (14.6 g, 0.083 mol) was
produced only (yieldˆ55%).
Acknowledgements
4.6. Dehalogenation of I; b
The authors would like to express their gratitude to the
Â
Â
Ministere Franc,ais de l'Enseignement Superieur et de la
Recherche for an associate professor position at ENSC
Montpellier (to GK) and for a grant administrated by the
Centre International des Etudiants et Stagiaires (to PP).
Financial support and gift of chlorotri¯uoroethylene from
Solvay were also greatly appreciated. The authors also
thank Prof. A. Fruchier (Head for NMR of ENSCM) for
helpful discussions.
In a three-necked round-bottomed ¯ask swept by an
argon ¯ow and equipped with a condenser was introduced
via a septum 30 ml of dry DMF. Under vigorous stirring,
6.7 g (0.103 mol) of zinc activated by 1 ml of acetic acid and
1 ml of acetic anhydride were placed in the ¯ask and then
the slurry was heated up to 908C. 8.7 g (0.034 mol) of I; b
was then added dropwise and the temperature was main-
tained at 908C, 6 h after complete addition. At this stage, the
reaction, monitored by GC, showed that about 90% of I; b
had reacted. After cooling, the excess of zinc was ®ltered
off, the total product mixture was heated with HCl 10% and
the ¯uorinated part extracted with diethyl ether. 4,5,5-tri-
¯uoro-4-ene pentanol (I; c) was recti®ed after distillation of
the solvent. 3.15 g (0.022 mol) of a colourless liquid was
obtained. Bpˆ48±508C/21 mm Hg (lit. val. [42]: 958C/
155 mmHg). Yieldˆ66%.
References
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(1958) 846.
[2] M.M. Kremlev, L.I. Moklyachuck, Yu.A. Fialkov, L.M. Yagupol'skii,
Zh. Org. Khim. 20 (1984) 1162.
[3] A.K. Anhudinov, R.M. Ryazanova, S.V. Sokolov, J. Org. Chem.
USSR 10 (1974) 2520.
1H NMR (CDCl3) ꢀ: 1.80 (qi, 3JHHˆ6.8 Hz, CH2CH2OH,
[4] M.M. Kremlev, P.G. Cherednichenko, L.I. Moklyachuck, L.M.
Yagupol'skii, Zh. Org. Khim. (English transl.) 16 (1980) 822,
(Chem. Abst. 113, 39872).
2H);
2.38
(dddt,
3JHFˆ22.5 Hz,
4JHFˆ2.4 Hz,
4JHFˆ4.0 Hz, 3JHHˆ6.8 Hz, CFCH2, 2H); 3.15 (broad sing-
let, shifted with dilution or with Cl3CNCO, OH, 1H); 3.66
3
[5] J.E. Fearn, D.W. Brown, L.A. Wall, J. Polym. Sci. Part A, 4 (1966)
131.
(t, shifted to 4.40 ppm with Cl3CNCO, JHHˆ6.3 Hz,
[6] M. Hauptschein, M. Braid, F.E. Lawlor, J. Amer. Chem. Soc. 79
(1957) 2549.
CH2OH).
19F NMR (CDCl3) ꢀ: 106.1 (ddt, JFFgemˆ88.4 Hz,
2
[7] R.N. Haszeldine, J. Chem. Soc. (1955) 4291.
[8] I.L. Knunyants, L. Chai-Yuan, V.V.S. Shokina, Doklady. Akad. Nank
SSSR 136 (1961) 610.
3JFFˆ32.0 Hz, JFHˆ2.5 Hz); 125.2(ddt, JFFˆ88.4 Hz,
4
2
3JFFˆ113.6 Hz, JFHˆ3.9); 174.6(ddt, JFFˆ32.0 Hz,
4
3
3JFFˆ113.6 Hz, JFHˆ22.5 Hz).
[9] A.E. Fiering, B.E. Smart, Z.Y. Yang, US Patent 5 326 917 (to E.I. du
Pont de Nemours and Co.) 05-07-1994.
3
13C NMR (CDCl3) ꢀ: 21.9(dd, 2JCFˆ22.4 Hz,
[10] J.E. Fearn, J. Res. Nat. Bur. Stand. 754 (1971) 41.
[11] P. Tarrant, M.R. Lilyquist, J. Amer. Chem. Soc. 77 (1955) 3640.
[12] A.D. Kirchenbaum, A.G. Streng, M. Hauptschein, J. Chem. Soc. 75
(1953) 3141.
3JCFˆ2.2 Hz,
CFCH2);
28.2
CH2CH2OH); 61.2 (s, CH2OH); 128.5 (ddd,
(d,
3JCFˆ2.3 Hz,
1JCFˆ233.8 Hz, 2JCFˆ53.7 Hz, 2JCFˆ15.8 Hz, CF);
153.2
(ddd,
1JCFˆ272.5 Hz,
1JCFˆ285.9 Hz,
[13] M. Hauptschein, M. Braid, US Patent 3 091 648 (1963).
[14] G. Zhao, J. Yang, W.Y. Huang, J. Fluorine Chem. 86 (1997) 89.
[15] T. Fuchikami, I. Ojima, Tetrahedron Lett. 25 (1984) 307.
[16] T.I. Gorbunova, M.I. Kodess, A.V. Podol'skii, V.I. Saloutin, Zh.
Obshch. Khim. 61 (1991) 2364 (Chem. Abstr., 116 (1992) 151082).
2JCFˆ47.0 Hz, F2C).
4.7. Dehydrochlorination of I; b0
Â
[17] B. Ameduri, B. Boutevin, G. Kostov, P. Petrova, J. Fluorine Chem.
89 (1998) 167.
Â
[18] B. Ameduri, B. Boutevin, G. Kostov, P. Petrova, J. Fluorine Chem.,
In a two-necked round-bottomed ¯ask equipped with a
condenser was re¯uxed a mixture composed of 10.3 g
(0.06 mol) of I; b0 and 3.27 g (0.06 mol) of potassium
hydroxide dissolved in 30 ml of methanol. The reaction
was monitored by GC which showed the slight decrease of
the peak attributed to I; b0 (RTˆ4.50 min.) and the presence
of a signal with a RT of 2.75 min. Another experiment
requiring a two-fold excess of KOH showed the presence of
another signal at 2.83 min assigned to a ¯uorinated com-
pound containing an internal double bond (probably II; d).
The 19F NMR spectrum shows similar signals at 106.1,
125.2 and 174.6 ppm as above with multiplets centred at
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