Ethylene-tetrafluoroethylene (ETFE) cotelomer iodides and their transformation to surface protection intermediates

Article abstract of DOI:10.1016/j.jfluchem.2014.10.004

A new class of fluorotelomers was synthesized via the cotelomerization of ethylene and tetrafluoroethylene (TFE) with 1H,1H,2H,2H-perfluoroalkyl iodides. The telomerization led to ethylene-tetrafluoroethylene (ETFE) cotelomer iodides with the incorporation of ethylene and TFE in the cotelomer chain in an alternating fashion. By controlling the reaction parameters such as total pressure, temperature, feed ratio of the monomers, initiator feed, and conversion rate, eight-carbon cotelomer iodide or higher cotelomers could be produced preferably. The ETFE cotelomer iodides were transformed to a variety of intermediates such as alcohols, azides, amines and thiols, precursors useful to make surface modification agents.

Full text of DOI:10.1016/j.jfluchem.2014.10.004

Journal of Fluorine Chemistry 169 (2015) 12–23
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Ethylene-tetrafluoroethylene (ETFE) cotelomer iodides and their
transformation to surface protection intermediates
*
*
Weiming Qiu , Anilkumar Raghavanpillai , Peter A. Brown, Wayne R. Atkinson,
Michael F. Vincent, William J. Marshall
Central Research & Development, E. I. duPont de Nemours & Co., Experimental Station, Wilmington, DE 19880, United States
A R T I C L E I N F O
A B S T R A C T
new class of fluorotelomers was synthesized via the cotelomerization of ethylene and
Article history:
A
Received 2 July 2014
tetrafluoroethylene (TFE) with 1H,1H,2H,2H-perfluoroalkyl iodides. The telomerization led to
ethylene-tetrafluoroethylene (ETFE) cotelomer iodides with the incorporation of ethylene and TFE in
the cotelomer chain in an alternating fashion. By controlling the reaction parameters such as total
pressure, temperature, feed ratio of the monomers, initiator feed, and conversion rate, eight-carbon
cotelomer iodide or higher cotelomers could be produced preferably. The ETFE cotelomer iodides were
transformed to a variety of intermediates such as alcohols, azides, amines and thiols, precursors useful to
make surface modification agents.
Received in revised form 7 October 2014
Accepted 8 October 2014
Available online 22 October 2014
Keywords:
Cotelomerization
Tetrafluoroethylene
Perfluoroalkyl iodide
Ethylene-tetrafluoroethylene cotelomer
iodide
Teflon1
Tefzel1
ß 2014 Elsevier B.V. All rights reserved.
1. Introduction
incorporated telomers were suggested as possible non-bioaccu-
mulable intermediates and surface protection agents derived from
Perfluorinated telomer iodides are important intermediates and
widely used for commercial production of surface protection
agents for a variety of surfaces such as textiles, leather, carpet,
paper, stone & tile, and for highly efficient surfactants [1,2]. Most
commercially available fluorinated materials used towards repel-
lency or surfactancy applications contain predominately eight or
more carbons in their perfluoroalkyl chains. While these materials
offer superior performance, concerns have been raised about the
environmental fate of long chain fluorochemicals, especially their
adverse bioaccumulation potential [3]. It is our interest to develop
highly efficient, potentially non-bioaccumulable alternatives for
surface protection and surfactancy applications. Introduction of
hydrocarbon alkylene functionalities to interrupt the perfluor-
oalkyl chain of perfluorinated telomers may lead to likely non-
bioaccumulable alternatives. For example, vinylidine fluoride
these intermediates were shown to provide good surfactant and
repellent properties [4–7].
Polytetrafluoroethylene (PTFE) is a crystalline polymer with a
degree of crystallinity of 40–70% and surface tension of 18.5 mN/
m. The crystallinity is attributed to the ability of the fluoroalkyl
chains to aggregate and self-organize. This phenomenon is seen in
pefluoroalkyl telomers (8 carbon or more) and the polymers
derived from them [8]. In the search of a new class of fluorinated
materials based on fluoro-hydrocarbon chains for surfactancy and
surface protection applications, properties of PTFE (Teflon1) and
its fluoro-hydrocarbon counterpart poly(ethene-co-tetrafluor-
oethylene) (Tefzel1) were compared. Tefzel1 is an ethylene-
tetrafluoroethylene copolymer with mainly alternating ethylene
and TFE units. Properties such as degree of crystallinity, surface
tension, dielectric constant and melting point of Tefzel1 are closer
to that of PTFE (Table 1) [9]. This resemblance in properties
inspired us to investigate the possibility of ETFE cotelomer
intermediates, where the telomer chain is constituted of fluoro-
carbon groups intercepted by hydrocarbon moieties. These fluoro-
hydrocarbon entities may assemble and have the crystalline
properties of Tefzel1, while CF3 groups form organized layers at
*
Corresponding authors. Tel.: +1 302 695 2780/+1 302 695 6846;
fax: +1 302 695 8281.
E-mail addresses: weiming.qiu@dupont.com (W. Qiu),
anilkumar.raghavanpillai@dupont.com (A. Raghavanpillai).
http://dx.doi.org/10.1016/j.jfluchem.2014.10.004
0022-1139/ß 2014 Elsevier B.V. All rights reserved.

W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
13
Table 1
Properties of PTFE and Tefzel1
.
Degree of
Surface
Dielectric
constant
Mp (8C)
crystallinity (%)
tension (mN/m)
PTFE
Tefzel1
40–70
40–60
18.5
22.1
2.1
2.6
327
275
Scheme 2. Cotelomerization of TFE and ethylene with 1H,1H,2H,2H-perfluorobutyl
iodide leading to ETFE cotelomer iodides.
the surface to provide repellency. Schematic representation of
PTFE and corresponding TFE telomer iodide and Tefzel1 and ETFE
cotelomer iodides are shown in Scheme 1.
We are interested in evaluating such ETFE cotelomer iodides
and their derivatives, where the perfluorocarbon groups are
intercepted by ethylene (–CH2CH2–) functional groups. These
intermediates are expected to be fluorine efficient and are
potentially non-bioaccumulable, as incorporation hydrocarbon
functionality limits the occurrence of more than two continuous
CF2 fragments in the fluoroalkyl cotelomers. To our knowledge
medium if necessary. Air was completely removed by repeated
cool, vacuum/nitrogen fill cycles before charging the mixture of
ethylene and TFE to the pressure vessel [Caution! Air must be
removed from the system completely; See experimental part for
important safety precaution for handling TFE-ethylene mixture]. A
series of similar batch cotelomerization reactions were then
performed at different temperatures and pressure by keeping the
same amount of the reactants but varying initiators. The reaction
conditions used for the cotelomerization and the initial results are
summarized in Table 2. The half pressure drop time is used as an
indication of the initial reaction rate for a given reaction. The final
pressure of the reaction provided an indication of the extent of a
reaction (closely associated with the conversion of the reagents
used in the reaction). After the completion of the reaction,
unreacted iodide 1a was removed by reduced pressure distillation,
and the products were analyzed via GC–MS. The products (crude
ETFE cotelomer iodides) obtained from cotelomerization consti-
tutes alternately inserted ETFE cotelomer iodides (such as 2a, 2b
and 2c) as major components, and small amounts of mis-inserted
cotelomer iodides (resulting from the insertion of two or more
molecules of the same alkene next to each other) and additional
by-products which could possibly be longer chain cotelomer
iodides, products derived from the initiator or possible radical
combination products. At lower reaction temperature, using
Luperox1 231 as an initiator, the cotelomerization reaction was
slower (indicated by longer time required for the pressure to drop
by half), leading to a poor conversion as indicated by higher final
pressure and larger quantities of recovered 1a (entries 2–4,
Table 2). Also, at lower reaction temperatures, it was noted that
slightly more 2a was formed as compared to 2b. At 80 8C, using
Vazo164 initiator led to lowest initial rate and yield (entry 6),
whereas, using lauroyl peroxide under similar conditions gave
highest initial rate and yield (entry 5). From these batch reactions,
the ratios of 2a/2b remained within a narrow range of 1.7 to 2.7. As
indicated by the final pressure in Table 2, varying amounts of
unreacted ethylene and TFE were present at the end of the reaction
period. No attempt was made to recover the unreacted ethylene
and TFE. Also, starting material 1a is volatile and may not be
completely recovered (note a, Table 2). Therefore in general, only
75–80% of reaction mass was recovered after the reaction. In the
very conversion reaction (entry 4, Table 2), only about 65%
materials were recovered.
such compounds with
a
general structure of RfCH2CH2
(CF2CF2CH2CH2)nX (where Rf is a perfluoralkyl group, n ¼ 0, X is
halide or any common functional group) are practically unknown.
The only known compounds with these general structures are
C2F5CH2CH2CF2CF2CH2CH3 and C2F5CH2CH2CF2CF2CH2CH2C2F5.
However, these compounds are not obtained via telomerization
and instead prepared in poor yield via the addition of perfluor-
oethyl iodide to CH2 = CHC2F4CH = CH2, followed by reduction
[10]. In this paper, we discuss the cotelomerization of ethylene and
TFE with perfluoroalkylethyl iodide leading to new class of
fluorotelomers [ETFE cotelomer iodides]. The fluorotelomers, thus
generated herein, would be useful intermediates for a variety of
applications including the development of various surface
protection chemicals and surfactants.
2. Results and discussion
2.1. Cotelomerization
Telomerization of alkenes is well-known reaction. Many
telomers, such as TFE telomers [11–14], CTFE telomers [15–17],
vinylidene fluoride telomers [18], trifluoropropylene telomers
[19], and ethylene telomers [20], have been reported. On the other
hand, there are very limited examples related to the cotelomer-
ization that provide fluorinated cotelomer [21]. Some fluorinated
cotelomers are synthesized via a stepwise addition process
[19,22]. Cotelomerization reaction of TFE with other olefins has
not been reported prior to this work. We found cotelomerization of
ethylene and TFE with 1H,1H,2H,2H-perfluorobutyl iodide (1a)
under suitable conditions can lead to ETFE cotelomer iodides
(Scheme 2).
1H,1H,2H,2H-perfluorobutyl iodide (1a) was synthesized in
almost quantitative yields via the reaction of perfluoroethyl iodide
with ethylene. A batch cotelomerization of ethylene and TFE was
first attempted in an autoclave (shaker tube) using a radical
initiator and 1H,1H,2H,2H-perfluorobutyl iodide (1a) as telogen.
The cotelomerization reaction was performed under neat condi-
tions; however, an optional solvent (hexanes) could be used as a
The batch (shaker tube) cotelomerization described above
demonstrated the successful preparation of ETFE cotelomer. In
order to further study the impact of other variables, such as gas
composition and total pressure, the cotelomerization was also
carried out in semi-batch mode, where the initiator, TFE, and
ethylene were allowed to feed independently throughout the
reaction as desired. Total reaction pressure was controlled by
feeding gases when the reagents were consumed. Lauroyl peroxide
was chosen as an initiator for semi-batch cotelomerization because
of the higher reaction rate observed during the batch reaction. In
addition, lauroyl peroxide also has good solubility in 1a, and could
be delivered as a solution using a syringe pump. In the semi-batch
process, iodide 1a was charged to the reactor with or without an
initiator before the vessel was sealed. Ethylene and TFE were then
charged to the reactor from separate feeds to a desired composition
F(CF2CF2)nI
CF2CF2
n
TFE telomer iodides
PTFE
CF2CF2CH2CH2
F(CF2CF2CH2CH2)nI
n
Tefzel®
ETFE cotelomer iodides
Scheme 1. Schematic representation of perfluoroalkyl telomer and ETFE cotelomer.

14
W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
Table 2
Results from batch cotelomerization reaction of 1a (45 g), ethylene (6 g), TFE (25 g), initiator (1.2 g) with total reaction time of 20 h.
Entry
Initiator
Temp. (8C)
Time for half
Final Pressure
(psig)
Recovereda
Total weight
of productsb (g)
2a/2b
pressure drop (min)
1a (g)
1
2
3
4
5
6
Luperox1
P
110
90
80
70
80
80
60
60
61
122
143
200
65
11.8
13.6
14.4
20
49
2.0
1.9
2.2
2.7
2.4
1.7
Luperox1 231
Luperox1 231
Luperox1 231
Lauroyl peroxide
Vazo164
45.7
43
100
>1200
45
30
11.4
20.4
48.2
36.5
360
93
a
1a is very volatile and readily escapes when the system is open to atmosphere, therefore, the recovered 1a is not necessarily the exact same as the remainder from the
reaction.
b
Total weight of products after the removal of 1a.
and total pressure. After the reactor was heated to a chosen
reaction temperature, the total pressure was adjusted as needed by
adding more TFE and ethylene. The initiator feed may start at this
stage if no initiator was charged at the beginning. In experiments
where the initiator was charged at the beginning (before the
reactor was closed), additional initiator feed was delayed for a few
hours or no further initiator was added during the reaction. TFE
and ethylene were fed to the reactor constantly either at the same
ratio as the initial feeds or at a different ratio to maintain the
desired total pressure throughout the reaction. The details of
various reaction conditions used for the semi-batch cotelomeriza-
tion are summarized in Table 3. The results and GC analysis of the
crude product resulting from these semi-batch cotelomerization
are summarized in Tables 4 and 5. The semi-batch cotelomeriza-
tion reaction was slow (indicated by low gas uptake) and gave low
conversion (54% recovery of 1a) when performed under low total
pressure of 60 psig (entry 1 in Tables 3 and 4). However, under
these conditions, the reaction gave good selectivity to 2a over
2b. We increased the total pressure to 190 psig (entry 2, Table 3),
the maximum pressure of a TFE and ethylene mixture for our
system to be operated safely, resulting a faster reaction and higher
conversion (14% recovery of 1a). The selectivity between 2a and 2b
became about equal, and in addition, a large amount of 2c was
formed (entry 2, Table 5). Another experiment was then performed
under the same total pressure as described in entry 2, but using less
amount of initiator, larger amount of 1a, and shorter reaction time
(entry 3, Table 3). As expected a low conversion (57% recovery of
1a) with good selectivity to 2a over 2b was the result (entry3,
Table 4). In order to further improve the reaction rate and
selectivity, we investigated increased gas feed molar ratio of TFE/
ethylene to 73:27 at a reduced relative amount of initiator
(compared to total 1a used), (entry 4, Table 3). The reaction
proceeded at very high rate with very low conversion (71%
recovery of 1a), and excellent selectivity to 2a over 2b (entry 4,
Table 4). We then investigated semi-batch cotelomerization
reactions under lower reaction temperature and at 160 psig or
lower total pressure (entries 5–7, Table 3) with no pre-charged
initiator. In these experiments, the initiator was charged only after
the reaction reached the desired temperature and after total
pressure was established. Gas feed ratio of TFE/ethylene (73:27)
was used to establish initial total pressure, and then the feed ratio
was switched to 1:1 to maintain the total pressure during the
reaction. At 150–160 psig total pressure and about 70 8C, the
reaction (entries 5 and 6, Tables 3 and 4) afforded good rate and
good selectivity to 2a over 2b, and good selectivity of perfectly
alternating cotelomers (2a, 2b, and 2c) over mis-inserted
cotelomers (entries 5 and 6, Table 5). It is also worth to note
that only a small amount of the initiator was needed for this
cotelomerization reaction as described in entry 6, where the
reaction was performed using 1000 ppm of initiator. Thus, by
controlling the reaction parameters such as monomer feed,
initiator feed, conversion rate and temperature, the ratio of the
cotelomer chain length was tuned to provide preferably 8 carbon
iodide or higher cotelomers, where ethylene and TFE incorporated
in an alternative fashion.
The reaction mixture obtained from the semi-batch cotelomer-
ization reactions described in Table 3 was analyzed by GC–MS.
Table 5 summarizes GC analysis of the reaction mixture after
Table 3
Reaction conditions for various semi-batch cotelomerization reactions.
Entry
Initially charged
(before close of
the reactor) (g)
Total Pressure (psig),
Lauroyl peroxide (g) in
1a (g) added during the
course of reaction/addition
frequency (mL/min)
Temp (8C)
TFE
Ethylene
charged
Reaction
time (h)
TFE/Ethylene (T/E) mole ratio
charged
1a
Lauroyl
Initially charged
at room temp.
Charged after reaching
peroxide
reaction temp. to adjust
and maintain pressure
1
2
3
4
5
518
11.0
11.0
6.0
20, 53/47
60, 53/47
60, 53/47
3.3, 82/0.2a
75
75
75
75
70
86
397
151
299
330
16
97
38
29
67
7.5
10.5
4.5
518
999
190, 53/47
1.9, 45/6a
60 psig, 53/47
60 psig, 73/27
60 psig, 73/27
190, 53/47
0
1997
850
7.9
160, 73/27
0
4.5
0.0
Adjust: 160, 73/27
Maintain: 160, 50/50
Adjust: 150, 73/27
Maintain: 150, 50/50
Adjust: 100, 73/27
Maintain, 100, 50/50
3.2, 119/1b
14
6
7
1905
1398
0.0
0.0
60 psig, 73/27
50 psig, 73/27
2, 67/5c
70
70
364
512
70
96
16
42
7.5, 225/5d,e
a
b
c
Initiator addition started 3 h after the start of reaction.
Added when system reached 160 psig.
Added when system reached 150 psig.
d
e
5 mL/min for first 5 min then added through the reaction.
addition started when system reached 100 psig.

W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
15
Table 4
Results from the cotelomerization of TFE and ethylene with 1a.
Entry
Recovered
Total solid
TFE uptake in
first 30 min (g)
2a/2b
1a (%)
products (g)
(GC area)
1
2
3
4
5
6
7
54
14
57
71
42
66
50
212
827
370
537
773
841
1150
11
32
20
110
41
38
9
5.1
1
4.6
8.2
2.6
4.5
3
removal of starting material 1a and relative ratios for various
product peaks based on GC area were listed. The GC–MS analysis
reveals that in addition to the desired perfectly alternating
cotelomer iodides varying amounts of mis-inserted oligomers
(insertion of more than one ethylene or TFE unit inserted next each
other in the cotelomer chain) were formed during the cotelomer-
ization. The product ratios of these cotelomer iodides were
influenced by various reaction parameters such as monomer feed
ratio, reaction pressure, reactant and initiator concentration and
reaction time. At a relatively low TFE/ethylene feed ratio (53:47)
(entries 1–3, Table 3), there were no triple TFE inserted product
(FTETTTEI or FTETTTETEI) and only small amounts of double TFE
inserted product (FTETTEI or FTETTETEI & FTETETTEI) were
detected. When TFE/ethylene gas feed ratio was increased from
53:47 to 73:27 (entry 4, Table 3), significant amount of FTETTEI,
and some FTETTTEI, were observed (entry 4, Table 5). In this
reaction, TFE/ethylene ratio of the gas composition in the reactor is
expected to increase further during the course of the reaction as
the consumption of TFE and ethylene at any given time was closer
to 1:1. Higher TFE/Ethylene ratio also appeard to suppress ethylene
double insertion as no FTETEEI and FTEETEI were detected, and
only small amount of FTEEI was observed (entry 4, Table 5). When
TFE/ethylene gas ratio was initially set to 73:27, then gas feed ratio
was adjusted to 50:50 during reactions (entries 5–7, Table 3), the
amount of FTETTTEI was minimized and the amount of FTETTTETEI
was siginificantly reduced. In the meantime, the amounts of
multiple ethylene inserted products were kept as similar or lower
compared with the previous reactions (entries 1–3, Table 5). Again,
higher total reaction pressure led to faster reaction rates as
indicated by TFE uptake in the first 30 min during the reaction
(entries 5–7, Table 4). Thus, it is demonstrated that ETFE cotelomer
iodides can be prepared with good selectivity to perfectly
alternating ones at good reaction rate. Formation of ETFE
copolymers were not observed during the cotelomerization
reaction. The mass spectrometry analysis of several representative
constituents present in the reaction mixture is shown in Fig. 1. All
the coteleomer iodides contain an end group alkyl iodide
(R-CH2CH2I) and no products containing a fluoroalkyl iodide
(R-CF2CF2I) end group were detected. Compounds (2a, 2b, and
FTEETEI), where there was a 2-carbon space between iodine and
fluorinated carbons, gave large molecular ion peaks. Loss of HF
appears to be common for ETFE cotelomer fragmentation. The
peaks resulting from the loss of HF, showed a higher intensity,
generally were the base peak. For 2a, the peak (m/e: 197) was
assigned to the fragment that was formed by breaking the CF2–CF2
bond in the middle of the molecule. That fragment would further
lose HF to form a new fragment with m/e: 177 and 100% relative
intensity. Compounds (PTEEI and FTETEEI), in which there was a
4-carbon space between iodine and fluorinated carbons, gave
very small molecular ion peaks but very large peaks for the
fragment of M+ ꢀ I.
A
proposed mechanistic explanation for the alternating
insertion reaction of ethylene and TFE during cotelomerization

16
W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
Fig. 1. MS analysis of representative ETFE cotelomers.
with 1H,1H,2H,2H-perfluorobutyl iodide is presented in
Scheme 3. The preferred pathway is represented in bold. A
radical (Rꢁ) in the system (from the initiator or other radical
intermediates) reacted with the iodide (1) to form the
hydrocarbon radical 3 which reacted with TFE faster than
ethylene to form a fluorocarbon radical 4 as a major intermedi-
ate. The fluorocarbon radical 4 reacted with ethylene faster than
with TFE and resulted hydrocarbon radical 5 as major interme-
diate species. The radical 5 further reacted with TFE faster than
ethylene and the sequence continue until the radical terminates.
It has been reported that the k(CF2 = CF2)/k(CH2 = CH2) rate ratio
for addition of methyl radical (ꢁCH3) is about 9.5, but is 0.1 for
addition of trifluoromethyl radical (ꢁCF3)[9]. This reaction rate
difference between the hydrocarbon or fluorocarbon radical
species and corresponding complementary olefinic species is
responsible for the formation of the desired alternating ETFE
cotelomers [23,24]. The intermediate radical species involved in
the telomerization process can pick up an iodine atom at any
stage of the reaction sequence to form the corresponding ETFE
cotelomer iodides.
Scheme 3. Alternating insertion reaction during cotelomerization.

W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
17
Scheme 4. Reaction pathway to form 1a and FTEEI.
Scheme 5. Cotelomerization of TFE and ethylene with 1a0 leading ETFE cotelomer iodides.
The iodides of the type 2a, where the hydrocarbon end was
terminated with iodine, were seen as the major product, and
fluorocarbon iodides of the type 9 were not seen in the reaction
mixture. It was speculated that fluorocarbon iodide (9) formed
during the process was much more reactive and dissociated faster
to the corresponding radical intermediate 4, which underwent
reaction through the preferred pathway with ethylene. It was
consistent with the observation that reaction of pentafluoroethyl
iodide with ethylene forms quantitative yield of 1a. The impurity,
ethylene double insertion product, 1H,1H,2H,2H,3H,3H,4H,4H-
perfluorohexyl iodide (FTEEI), was about a fraction of one percent
in the reaction mixture, even though the reaction was carried out
under excess ethylene. Therefore, the ratio of ra/rb could be very
large and the radical 3 reacted with pentafluoroethyl iodide much
faster than with ethylene (Scheme 4). Thus, in our cotelomeriza-
tion, any fluoroalkyl iodide type of 9 would quickly react with
hydrocarbon radical type of 3.
pure 2a upon solvent removal followed by vacuum distillation. The
solid fraction left from the acetonitrile extraction, further extracted
with hot tetrahydrofuran led to a preferential extraction of ETFE
cotelomer iodide 2b. The remaining solid fraction consisted of
higher ETFE cotelomer iodides. The crude ETFE cotelomer iodides
(2) and individually isolated 2a and 2b were used for downstream
Table 6
Product distribution of cotelomerization of ethylene and TFE with 1a0.
Rt
ID
GC area % Structure of the cotelomer iodide
10.2
5.48 FBEEI
F
F
F
F
F
F
I
F
F
F
ETFE cotelomers with 1H,1H,2H,2H-perfluorohexyl iodide (1a0)
were similarly prepared in a shaker tube, wherein, ethylene and
TFE were cotelomerized with iodide 1a0 at 80 8C using Vazo1
64 initiator for 20 h, to provide corresponding cotelomers (Scheme
5). The reaction mixture obtained from cotelomerization was
analyzed by GC–MS after the removal of the unreacted 1a0. GC area
ratios of various identified products and their structure are
summarized in Table 6.
5.95 10a
57
6.84 FBETTEI 4.8
7.74 FBETEEI 4.4
7.80 FBEETEI 1.6
2.2. Isolation of ETFE cotelomer iodides
The key cotelomers, 2a and 2b, were successfully isolated and
characterized. Mixtures obtained from the telomerization process
were subjected to distillation to remove unreacted 1a. After
removing the starting material, the crude mixture of ETFE
cotelomer iodides [F(CF2CF2CH2CH2)nI] mainly constituted iodide
fractions n = 2 (2a), 3 (2b) and small amounts of higher or mis-
inserted cotelomers. This crude mixture could be used for
downstream chemistry to produce surface protection intermedi-
ates. However, it is also possible to isolate individual ETFE
cotelomer iodide components via fractional distillation or a
selective sequence of extractions followed by distillation. The
isolation process is schematically outlined in Scheme 6. Extraction
of the crude mixture with acetonitrile preferentially removes ETFE
cotelomer iodide 2a along with impurities. This extract provided
8.15 10b
9.92 10c
17
5.2

18
W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
Scheme 6. Isolation of ETFE cotelomers and individual components.
˚
chemistry to develop surface protection intermediates. Similarly,
from the crude product obtained from the cotelomerization of
ethylene and TFE with 1H,1H,2H,2H-perfluorohexyl iodide (1a0),
the product 10a was isolated as a single component.
0.1 A. It is believed that the individual C–F. . .H–C short contact may
be weak (1–2 kJ/mol [29–31], but the sum of these short contact
may be sufficient to help organizing a three-dimensional packing
to yield a CF3 layer (Fig. 4). It is known that perfluoroalkyl chains
form helical structures due to electrostatic repulsion of fluorine
atoms in the relative 1,3-positions on the chain [32]. However,
ETFE cotelomer formed a non-helical conformation (Fig. 5),
partially due to short contact between fluorine atom and hydrogen
atom in the relative 1,3-positions on the chain.
2.3. Crystalline ETFE cotelomer iodides
The crude ETFE iodides (2) were solid at room temperature. The
individually isolated ETFE iodide components 2a and 2b were also
solids at room temperature. The distilled 2a was crystallized from
hexane and had a melting point of 75–77 8C. In comparison, linear
hydrocarbon iodide with 16 carbons (C16H33I) is still a liquid at
room temperature (with mp. 22 8C) [25]. A number of eight carbon
fluoroalkyl iodides containing hydrocarbon spacers [C6F13CH2CH2I,
C4F9(CH2)4I, and C2F5(CH2)6I] were liquids at room temperature
[20,26,27]. Other than the examples discussed here, the only other
example of an 8-carbon iodide with melting point above room
temperature is C4F9CH2CF2CH2CH2I (mp. 41–43 8C), about 30 8C
lower than that of ETFE cotelomer iodide, 2a [28].
2.4. Surface protection derivatives from ETFE cotelomer iodides
We were particularly interested in developing new ETFE
cotelomer based surface protection derivatives analogous to
various fluorotelomer derivatives. It is possible to synthesize a
variety of new ETFE cotelomer based intermediates utilizing
simple chemistries outlined in Scheme 7. All these derivatives
could be further transformed to monomers, polymers, or
surfactants useful as surface protection chemicals.
The X-ray structure revealed significant inter- and intra-
molecular short contact of C–F. . .H–C (Figs. 2 and 3), that is the
distances between F and H (linked by blue or red lines) are smaller
than the sum of van der Waals radii of F and H atoms by more than
On paper, these transformations appeared simple as the well-
known chemistry used for the transformation of telomer iodides
to corresponding derivatives such as telomer alcohols, azides,
amines, thiocaynates, thiols, sulfides, sulfonic acids, isocyanates
Fig. 2. Inter-molecular interactions. (For interpretation of the references to color in
Fig. 3. Inter-molecular interactions. (For interpretation of the references to color in
this figure legend, the reader is referred to the web version of this article.)
this figure legend, the reader is referred to the web version of this article.)

W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
19
Fig. 4. Packing of iodide 2a. The CF3 groups form in layers around cell edges a = 0 and
Fig. 5. Non-helical conformation of iodide 2a.
the iodines form layers around the middle of the cell at a = 1/2.
etc. could be extended to ETFE cotelomer iodides with minor
modification [33–38]. However, there are major difficulties
associated with, particularly with regard to the poor solubility
of the ETFE cotelomer iodides in some of the organic solvents used
as medium for these transformations. So not all the transforma-
tions outlined in Scheme 7 have been attempted and a few
important transformations that lead to corresponding alcohols,
amines, thiocyanates, thiols, etc were performed. ETFE cotelomer
iodides 2a, 2b, and 10a were hydrolyzed to corresponding alcohols,
11a, 11b and 12a, via a reaction with N-methylformamide at
150 8C for 19 h followed by acid treatment in ethanol [33] or with
oleum (15% SO3) at 60 8C followed by hydrolysis as shown in
Scheme 8 [34].
via the cotelomeric azides 14 followed by reduction using
hydrazine hydrate and Ni-Raney (Scheme 9). The transformation
of the iodide to the azide was initially attempted under phase-
transfer conditions, as described in the literature for telomer
iodides [36]. However, this reaction failed to give good yield of the
azide and only 10% conversion was observed. This was attributed
to the poor solubility of the ETFE cotelomer iodide in the reaction
medium. We then attempted this transformation using DMF,
acetone or acetonitrile as solvents under heating conditions (80–
90 8C), which yielded the ETFE-azides 14 in quantitative yields. The
thermogravimetric analysis of the cotelomeric azides showed
decomposition of the contents at 129 8C. The transformation of the
azide to the amine 15 was also performed using a mixed solvent
system comprising of 1:1 water and ethanol, using hydrazine
hydrate/Ni-Raney to provide 87% isolated yield of the amine.
The crude ETFE cotelomer iodide (2) which contains 2a and 2b
as major components was transformed to corresponding thiol 16
by refluxing with thiourea followed by basic hydrolysis of the
The ETFE cotelomer iodide, 2a, was converted to the corre-
sponding thiocyanate 13a in high yield by the treatment with
potassium thiocyanate (Scheme 8a) [35].
The crude ETFE cotelomer iodide (2) which contains 2a and 2b
as major components was transformed to corresponding amine 15
Scheme 7. Various possible transformations of ETFE cotelomer iodides.
Scheme 8. Preparation of ETFE cotelomer alcohols.

20
W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
Scheme 8a. Preparation of ETFE cotelomerthiocyanate.
Scheme 9. Transformation of ETFE cotelomer iodides to corresponding azides and amines.
intermediate thiouronium salt using sodium hydroxide [37]. The
reaction was slow in ethanol presumably due to the poor solubility
of the ETFE cotelomer iodide in that solvent. However, refluxing
the reaction mixture for a prolonged period of time (36 h) provided
>95% conversion (Scheme 10).
3. Conclusions
A
new class of fluorotelomers was synthesized via the
cotelomerization of ethylene and TFE with 1H,1H,2H,2H-perfluor-
oalkyl iodides. The telomerization led to ethylene-tetrafluoroethy-
lene (ETFE) cotelomer iodides with the incorporation of ethylene
and TFE in the cotelomer chain in an alternating fashion. By
controlling the reaction parameters such as monomer feed,
initiator feed, conversion rate and temperature, the ratio of the
cotelomer chain length could be tuned to provide preferably to
eight carbon iodide or higher cotelomers. Unlike TFE telomer
iodides, the ETFE cotelomer iodides were crystalline solids. The
ETFE cotelomer iodides were transformed to a variety of useful
surface protection intermediates such as alcohols, thiocyanates,
azides, amines, and thiols in high yield.
We also extended this chemistry to the synthesis of an ETFE
cotelomer hydroxyethyl sulfide 17 by the displacement of ETFE
cotelomer iodide with 2-mercaptoethanol in t-butanol in presence
of sodium hydroxide (Scheme 11). Similarly, an ETFE cotelomer
aminoethyl sulfide 18 was derived from ETFE cotelomer iodides by
the displacement reaction with 2-aminoethanethiol under similar
conditions. Elimination products, olefins C2F5CH2CH2CF2
CF2CH = CH2 or C2F5(CH2CH2CF2CF2)2CH = CH2, were not observed
under these reaction conditions. The isolated yield of ETFE
cotelomer hydroxyethyl sulfide 17 was 77%. Similarly, reaction
of ETFE cotelomer iodides and 2-aminoethanethiol in presence of
sodium hydroxide provided ETFE cotelomer aminoethyl sulfide 18
in 89% isolated yield (Scheme 11).
4. Experimental
The ETFE cotelomer alcohols, amines, thiols, hydroxyethyl
sulfides and aminoethyl sulfides could be transformed to their
corresponding acrylates or acylamides, the key ingredient mono-
mers useful for making fluoroacrylic copolymer repellents. The
alcohols could also be transformed ethoxylates or phosphates or
urethanes, candidates widely used as surfactants and coating
additives. In addition, a variety of chemistries described on Scheme
7 could be performed to create a library of ETFE cotelomer
intermediates that in turn provide surface protection agents
suitable for variety of applications. In addition, the cotelomeriza-
tion chemistry described here could be extended for the
cotelomerization of 1H,1H,2H,2H-perfluoroalkyl iodides with
ethylene and a variety of fluorinated alkenes is currently under
our investigation. These intermediates are expected to be fluorine
efficient and potentially non-bioaccumulable as incorporation
hydrocarbon functionality limits the occurrence of more than two
continuous CF2 fragments in the ETFE cotelomers.
4.1. General
All solvents and reagents, unless otherwise indicated, were
purchased from commercial sources and used directly as supplied.
TFE and perfluoroalkyl iodides were obtained from E.I. du Pont de
Nemours and Company, Wilmington, DE. 1H and 19F NMR spectra
were recorded on a Brucker DRX400 or 500 Spectrometer. Chemical
shifts have been reported in ppm relative to an internal reference
(CFCl3 or TMS). All melting points reported were uncorrected. GC
analysis was performed on an Agilent 5890 using a DB 5 column and
FID detector, oven temperature: hold at 50 8C for 2 min, increase
20 8C/min to 280 8C and hold at 280 8C for 5 min.
Caution! A 1:1 mixture of ethylene and TFE is extremely
hazardous and may be ignited at 60 8C and >60 psig pressure. Use
of such a mixture should be restricted within these limits for
operation, or in an operation system (e.g. autoclave) that can
withstand the peak pressure in case the mixture does ignite.
4.2. Ethylene-tetrafluoroethylene cotelomerization with
1H,1H,2H,2H-perfluorobutyl iodide under batch process
A
400 mL shaker tube was charged with 1H,1H,2H,2H-
perfluorobutyl iodide (1a, 45 g) and Vazo164 (1.0 g). After cool
evacuation, ethylene (6.0 g) and TFE (25.0 g) were added. The
resulting mixture was heated to 80 8C for 20 h. The unreacted
1H,1H,2H,2H-perfluorobutyl iodide was recovered by vacuum
distillation at room temperature. The remaining solid was
extracted with CH3CN (3 times 100 mL). The CH3CN extracts were
concentrated and distilled at reduced pressure to give pure
iodide 1,1,2,2,5,5,6,6-octahydroperfluoro-1-iodooctane. The solid
remaining after CH3CN extraction was extracted with warm
tetrahydrofuran. The tetrahydrofuran extract was concentrated
and dried to give 1,1,2,2,5,5,6,6,9,9,10,10-dodecahydroperfluoro-
1-iodododecane. The solid remaining after tetrahydrofuran
extraction was mainly iodides of formula C2F5(CH2CH2CF2CF2)n
Scheme 10. Transformation of ETFE cotelomer iodides to corresponding thiols.
Scheme 11. Transformation of ETFE cotelomer iodides to corresponding
hydroxyethyl and aminoethyl sulfides.

W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
21
CH2CH2I (wherein n = 3 and higher cotelomers), which have very
low solubility in common solvents.
4.6. Preparation of 1,1,2,2,5,5,6,6-octahydroperfluoro-1-octanol, 11a
by NMF method
The products 1,1,2,2,5,5,6,6-octahydroperfluoro-1-iodooctane
and 1,1,2,2,5,5,6,6,9,9,10,10-dodecahydroperfluoro-1-iododode-
cane were characterized by 1H NMR and 19F NMR as shown
below: 1,1,2,2,5,5,6,6-octahydroperfluoro-1-iodooctane: mp. 75–
A mixture of 1,1,2,2,5,5,6,6-octahydroperfluoro-1-iodooctane,
2a (136.9 g) and N-methylformamide (NMF) (273 mL) was heated
reaction to 150 8C for 19 h. The reaction mixture was washed with
water (4 ꢂ 500 mL) to give a residue. A mixture of this residue,
ethanol (200 mL), and concentrated hydrochloric acid (1 mL) was
gently refluxed (85 8C bath temperature) for 2.5 h. The reaction
mixture was washed with water (2 ꢂ 200 mL), diluted with
dichloromethane (200 mL), dried over sodium sulfate overnight.
The dichloromethane solution was concentrated and distilled at
reduced pressure to give 11a (60.8 g, yield 61%)
77 8C. 1H NMR (CDCl3)
(m, 2H, CH2I). 19F NMR (CDCl3)
d 2.33 (m, 4H, CH2), 2.68 (m, 2H, CH2), 3.24
d
ꢀ85.9 (s, 3F, CF3), ꢀ115.8 (m, 4F,
CF2), ꢀ119.2 (m, 2F, CF2).; 1,1,2,2,5,5,6,6,9,9,10,10-dodecahydro-
perfluoro-1-iodododecane: mp. 125–128 8C. 1H NMR (acetone-d6)
d
2.46 (m, 8H, CH2), 2.77 (m, 2H, CH2), 3.37 (m, 2H, CH2I). 19F NMR
(acetone-d6)
(m, 2F, CF2), ꢀ119.5 (m, 2F, CF2).
d
ꢀ86.7 (bs, 3F, CF3), ꢀ117.1 (m, 6F, CF2), ꢀ117.3
4.3. Ethylene-tetrafluoroethylene cotelomerization with
4.7. Preparation of 1,1,2,2,5,5,6,6,9,9,10,10-dodecahydroperfluoro-1-
1H,1H,2H,2H-perfluoroethyl iodide under semi-batch process.
dodecanol, 11b
A one gallon reactor was charged with 1H,1H,2H,2H-perfluor-
obutyl iodide (1a, 850.0 g). After cool evacuation, TFE/ethylene in a
ratio of 73:27 were added until pressure reached 60 psig. The
reaction was then heated to 70 8C. More TFE and ethylene in a ratio
of 73:27 were added until pressure reached 160 psig. A lauroyl
peroxide solution (4.0 g lauroyl peroxide in 150.0 g of 1a) was
added in 1 mL/min rate. Gas feed ratio was adjusted to 1:1 of
ethylene and TFE and the total pressure was kept at 160 psig. The
initiator feed was stopped after about 1 h and total about lauroyl
peroxide (3.2 g) in of 1a (119.0 g) was added to the reaction. After
about 67.0 g of ethylene was added, both ethylene and TFE feeds
were stopped. The reaction was heated at 70 8C for another 8 h. The
volatiles were removed by vacuum distillation at room tempera-
ture. A solid of the ETFE cotelomer iodides 2 (773.0 g) was obtained.
A mixture of 1,1,2,2,5,5,6,6,9,9,10,10-dodecahydroperfluoro-1-
iodododecane, 2b (65.6 g) and NMF (135 mL) was heated to 150 8C
for 4 h. The reaction mixture was washed with water (ꢃ1 L) to give
a solid product. This solid product was added ethanol (150 mL) and
concentrated hydrochloric acid (1 mL) to the solids and heated at
reflux (ꢃ85 8C) for 19 h. The reaction mixture was poured into
water (500 mL) and the resulting solid was washed with water
(3 ꢂ 300 mL), dried on vacuum to give 11b (50.8 g, yield 98%, mp.
112–115 8C). 1H NMR (CDCl3)
d
1.52 (bs, 1H, OH), 2.34 (m, 10H,
CH2s), 3.97 (dq, J = 6 Hz, J = 6 Hz, CH2O). 19F NMR (CDCl3)
(s, 3F, CF3), ꢀ114.2 (m, 2F, CF2), ꢀ115.8(m, 4F, CF2s), ꢀ116.1 (m, 2F,
CF2), ꢀ119.2 (m, 2F, CF2).
d
ꢀ85.9
4.8. Preparation of alcohol 12a [C2F5(C2F4CH2CH2)2OH] by oleum
method
4.4. Cotelomerization of ethylene and TFE with 1H,1H,2H,2H-
perfluorohexyl iodide under batch process
A 250 mL flask was charged with C2F5(C2F4CH2CH2)2I, 10a
(12 g) and oleum (15% SO3, 125 mL) at room temperature. The
resulting mixture was stirred at 60 8C for 2 h. A Na2SO3 solution
(4 g in 100 mL) was added to the reaction mixture slowly at 60 8C
bath between 65 and 90 8C internal temperatures. The resulting
mixture was heated to 90 8C for 30 min. The liquid was decanted.
The solid was dissolved in ether (150 mL) and washed with Na2SO3
(1 M, 20 mL), water (2 ꢂ 20 ml), NaCl (sat., 20 mL), dried over
Na2SO4, concentrated and dried on vacuum to give a residue 9.5 g,
which was further purified by distillation to give the alcohol, 12a,
A 400 mL shaker tube was charged with 1H,1H,2H,2H-perfluor-
ohexyl iodide (1a0, 75.0 g), Vazo1 64 (1.5 g). After cool evacuation,
ethylene (6.0 g) and TFE (25.0 g) were added. The resulting mixture
was heated to 80 8C for 20 h. A wet solid was obtained. Combined
reaction mixtures from 8 identical cotelomerization experiments
were distilled under vacuum to recover unreacted 1a0 at room
temperature. The remaining solid was then extracted with acetoni-
trile (4 ꢂ 750 mL). The combined acetonitrile extracts were concen-
tratedto givea solid (418.6 g), which was further distilled at reduced
pressure to give purer product (>90% purity, and major impurities in
this product were FBEEI, FBETTEI, and FBETEEI), C2F5(C2F4CH2CH2)2I,
6.2 g, bp. 65–79 8C at 2 torr. 1H NMR (CDCl3)
6H), 3.97 (t, J = 7 Hz, 2H). 19F NMR (CDCl3)
d
1.58 (s, 1H), 2.36 (m,
d
ꢀ81.5 (tt, J = 9.5, 3 Hz,
3F), ꢀ114.1 (m, 2F), ꢀ115.4 (m, 2F), ꢀ116.0 (m, 2F), ꢀ124.8 (m, 2F),
10a, mp. 72–74 8C. 1H NMR (CDCl3)
(m, 2H). 19F NMR (CDCl3)
ꢀ115.7 (m, 4F), ꢀ124.7 (m, 2F), ꢀ126.4 (m, 2F).
d2.36 (m, 4H), 2.68 (m, 2H), 3.24
ꢀ81.5 (tt, J = 10, 3 Hz, 3F), ꢀ115.3 (m, 2F),
ꢀ126.4 (m, 2F).
d
4.9. Preparation of alcohol 13a [F(C2F4CH2CH2)2SCN]
4.5. Preparation of 1,1,2,2,5,5,6,6-octahydroperfluoro-1-octanol, 11a
by oleum method
A mixture of the iodide 2a (8.9 g), KSCN (2.5 g) and acetone
(30 mL) was refluxed for 5 h. After being cooled to room
temperature, the reaction mixture was poured into water
(200 mL). The solid was collected by filtration and washed with
water (2 ꢂ 40 mL), dried on vacuum to give 13a (a white solid,
7.1 g, 96% yield). MS (m/e) 333 (M+, 100%), 255 (24%), 235 (30%),
A mixture of 1,1,2,2,5,5,6,6-octahydroperfluoro-1-iodooctane,
2a (10.0 g) and oleum (15% SO3, 20 mL) was heated to 60 8C for
1.5 h. A K2SO3 solution (1.5%, in ice–water 150 mL) was added to
the reaction mixture while cooled with an ice–water bath. The
resulting mixture was heated to 100 8C for 30 min. After being
cooled to room temperature, a solid was precipitated. The liquid
was decanted and the solid was dissolved in ether (200 mL) and
washed with water (2 ꢂ 50 mL), saturated NaCl (50 mL), dried over
anhydrous Na2SO4, concentrated and dried on vacuum to give a
solid product, 11a (7.0 g, yield, 96%, mp 48–49 8C). 1H NMR (CDCl3)
306 (11%), 197 (49%), 177 (91%), 77 (92%). 1H NMR (CDCl3)
(m, 4H), 2.55 (m, 2H), 3.10 (m, 2H). 19F NMR
d
2.28
d
ꢀ85.9 (s, 3F), ꢀ114.7
(m, 2F), ꢀ115.4 (m, 2F), ꢀ119.2 (t, J = 17 Hz, 2F).
4.10. Synthesis of azide 14 [F(CF2CF2CH2CH2)nN3]
Crude ETFE cotelomer iodides 2 [F(CF2CF2CH2)nI, wherein n = 2,
3 were major components in about 2:1 ratio] (10.0 g) was added to
a solution of sodium azide (2.03 g) in acetonitrile (90 mL) and
water (34 mL). The mixture was allowed to heat at 90 8C until the
d
1.51 (t, 1H, J = 6 Hz, OH), 2.34 (m, 6H, CH2), 2.47 (m, 2H, CH2), 3.97
(dq, J = 6 Hz, J = 6 Hz, CH2O). 19F NMR (CDCl3)
ꢀ85.9 (bs, 3F, CF3),
ꢀ114.1 (m, 2F, CF2), ꢀ116.0 (m, 2F, CF2), ꢀ119.2 (m, 2F, CF2).
d

22
W. Qiu et al. / Journal of Fluorine Chemistry 169 (2015) 12–23
reaction was determined complete by gas chromatography. By
36 h, complete conversion of the iodides to azides was observed.
The mixture was cooled to room temperature and the bulk of the
acetonitrile evaporated under vacuum. The resulting slurry was
extracted with methylene chloride (3 ꢂ 60 mL). The organic layer
washed with water (2 ꢂ 80 mL), brine (1 ꢂ 80 mL) and dried over
anhydrous MgSO4. Evaporation of the solvent and vacuum drying
provided the cotelomer azides 14 [F(CF2CF2CH2CH2)nN3] as a white
solid (6.0 g). GC–MS: 2 major peaks correspond to n = 2 and
n = 3 alcohols [(m/e) 480] in about 2:1 ratio. 1H NMR (CDCl3):
d
3.40 (t, J = 6.8 Hz, OCH2), 2.81 (t, J = 6.8 Hz, SCH2), 2.79 (m, SCH2),
2.35 (bm, CF2CH2’s).
4.14. Synthesis of aminoethyl sulfide 18
[F(CF2CF2CH2CH2)nSCH2CH2NH2]
To a solution of 2-aminoethanethiol (1.39 g) and sodium
hydroxide (0.720 g) in tert-butanol (10 mL) heated to 80 8C was
slowly added to crude ETFE cotelomer iodide 2 [F(CF2CF2CH2CH2)nI
wherein n = 2,3 were major components in about 2:1 ratio] (5 g),
The mixture was allowed to heat at 80 8C for 12 h and the reaction
was determined complete by gas chromatography. The mixture
was cooled to ambient temperature and the precipitated product
was filtered and washed repeatedly with cold water followed by a
mixture of 1:1 methylene chloride and hexane. The white solid was
dried under vacuum to obtain the ether amines 18,
n = 3 azides in about 2:1 ratio: 1H NMR (CDCl3):
d 3.52 (bt,
J = 6.0 Hz, N–CH2), 2.29 (bm, CF2–CH2’s).
4.11. Synthesis of amine 15 [F(CF2CF2CH2CH2)nNH2]
An ETFE cotelomer azide mixture 14 [F(CF2CF2CH2CH2)N3,
wherein n = 2, 3 were major components in about 2:1 ratio]
(2.25 g), and Ni-Raney (0.032 g) was added to a solution ethanol
(5 mL) and water (5 mL). To the stirring mixture was slowly added
hydrazine hydrate (0.328 g). After the addition was complete, the
mixture was progressively heated to 60 8C and stirred at 60 8C for
12 h. The reaction mixture was cooled to room temperature and
methylene chloride (30 mL) was added and stirred for 10 min. The
resulting mixture was filtered and washed with water (2 ꢂ 20 mL)
and brine (1 ꢂ 20 mL). Evaporation of the solvent followed by
recrystallization from methylene chloride/hexane provided the
amine 15 [F(CF2CF2CH2CH2)nNH2] as a light brown solid (1.9 g).
GC: 2 major peaks correspond to n = 2 and n = 3 amines (about 2:1
[F(CF2CF2CH2CH2)nSCH2CH2NH2] as
(3.9 g). GC–MS: 2 major peaks corresponded to n = 2 [(m/e) 351]
and n = 3 amines [(m/e) 479] in about 2:1 ratio. 1H NMR (CDCl3):
a mixture of cotelomers
d
3.04 (t, J = 6.0 Hz, NCH2), 2.79 (t, J = 6.6 Hz, SCH2), 2.76 (t, J = 6.6 Hz,
SCH2), 2.37 (bm, CF2CH2’s).
4.15. Crystallography
X-ray data for 2a were collected at ꢀ100 8C using a Bruker 1K
CCD system equipped with a sealed tube molybdenum source and
a graphite monochromator. The structures were solved and refined
using the Shelxtl software package, [39] refinement by full-matrix
least squares on F2, scattering factors from Int. Tab. Vol. C
Tables 4.2.6.8 and 6.1.1.4. Crystallographic data (excluding
structure factors) for the structures in this paper have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication nos. CCDC #1010680. Copies of the
data can be obtained, free of charge, on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK, (fax: +44 1223 336033 or
deposit@ccdc.cam.ac.uk).
ratio). 1H NMR (CDCl3):
CF2–CH2’s).
d 3.05 (bt, J = 6.0 Hz, NH2–CH2), 2.29 (bm,
4.12. Synthesis of thiol 16 F(CF2CF2CH2CH2)nSH
Crude ETFE cotelomer iodides 2 [F(CF2CF2CH2CH2)nI, wherein
n = 2,3 were major components in about 2:1 ratio] (10.0 g) were
added to a solution of thiourea (2.03 g) in absolute ethanol
(100 mL) kept at 70 8C. The mixture was continued to heat at 80 8C
until the reaction was determined complete by the disappearance
of iodide by gas chromatography. By 36 h, 98% consumption of the
iodide was observed. The mixture was concentrated and treated
with a solution of sodium hydroxide (1.92 g) in water (5 mL). The
mixture was stirred overnight at ambient temperature and then
heated to boiling for 30 min. The reaction mixture was then cooled
to ambient temperature and 5% sulfuric acid was added drop wise
until solution was acidic. The mixture was then extracted with
methylene chloride (3 ꢂ 50 mL), the organic layer dried over
anhydrous MgSO4 and evaporated to obtain the cotelomeric thiols
16 [F(CF2CF2CH2CH2)nSH] as a white solid (5.8 g). GC–MS: 2 major
peaks corresponded to n = 2 [(m/e) 308] and n = 3 thiols [(m/e)
Acknowledgements
We gratefully acknowledge Charles K. Taylor of DuPont for
helpful insight into this research.
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slowly added to crude ETFE cotelomer iodides
2
[F(CF2CF2CH2CH2)n (wherein n = 2,3 were major components in
about 2:1 ratio] (5 g). The mixture was allowed to heat at 80 8C for
12 h and the reaction was determined complete by gas chroma-
tography. The mixture was cooled to ambient temperature and the
precipitated product was filtered and washed repeatedly with cold
water followed by a mixture of 1:1 methylene chloride and hexane.
The product was dried under vacuum to obtain the cotelomeric
alcohol F(CF2CF2CH2CH2)nSCH2CH2OH (17) as a white solid (3.4 g)
.GC–MS: 2 major peaks corresponded to n = 2 [(m/e) 352] and
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