Synthesis of novel perfluoroalkyl ether derivatives

Article abstract of DOI:10.1007/s11164-018-3411-3

A series of novel fluoroether-containing monomers has been designed and prepared based on the commercially available perfluoroalkyl ether acid fluoride. Treating acid fluoride with allyl alcohol, 2-hydroxyethyl methacrylate or N-allylmethylamine allowed for the direct formation of corresponding vinyl-containing fluorinated monomers. High yields of the fluorinated epoxy monomers could be obtained from acid chloride with glycidol; meanwhile, fluorinated diol was prepared from diethanolamine or 3-amino-1,2-propanediol. Moreover, fluorinated monoamine, fluorinated monoalcohol and fluorinated dichloride were also obtained. Most of these fluorinated monomers were liquid at room temperature and exhibited good solubility in common organic solvents.

Full text of DOI:10.1007/s11164-018-3411-3

Res Chem Intermed
https://doi.org/10.1007/s11164-018-3411-3
Synthesis of novel perfluoroalkyl ether derivatives
Xiang Shi1 Hongxin Shi1 Hongke Wu1 HaiMin Shen1
•
•
•
Received: 12 October 2017 / Accepted: 26 March 2018
Ó Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract A series of novel fluoroether-containing monomers has been designed
and prepared based on the commercially available perfluoroalkyl ether acid fluoride.
Treating acid fluoride with allyl alcohol, 2-hydroxyethyl methacrylate or N-allyl-
methylamine allowed for the direct formation of corresponding vinyl-containing
fluorinated monomers. High yields of the fluorinated epoxy monomers could be
obtained from acid chloride with glycidol; meanwhile, fluorinated diol was prepared
from diethanolamine or 3-amino-1,2-propanediol. Moreover, fluorinated mono-
amine, fluorinated monoalcohol and fluorinated dichloride were also obtained. Most
of these fluorinated monomers were liquid at room temperature and exhibited good
solubility in common organic solvents.
Keywords Fluorinated monomers Á Oligomers of hexafluoropropylene
epoxide Á Acylation reactions
Introduction
Water-repellent and oil-repellent films for coating many materials have been
extensively investigated. As is well known, lowering the surface tension of a film
contributes to formulating nonwettable coatings. Notably, one of the most popular
and successful strategies for lowering the surface tension of a film is incorporating a
fluorine-containing group into the polymers [1, 2]. Such low-surface-tension groups
can naturally segregate to the surface, which has been observed by various
analytical methods including contact angle, XPS, static SIMS and neutron
&
Xiang Shi
xiangshi_zmh@163.com
1
School of Chemical Engineering, Zhejiang University of Technology, No. 18 Chaowang Road,
Hangzhou 310032, China
123

X. Shi et al.
reflectivity measurements [3, 4]. Many fluorinated monomers, such as fluorinated
acrylates, fluorinated diols, fluorinated monomalcohols and fluorinated epoxides,
have been synthesized. The copolymerization of fluorinated with nonfluorinated
monomers has produced various fluorinated polymers, which have aroused growing
attention [5–13].
Generally speaking, the surface properties of a fluorinated polymer depend on the
fluorine content of the surface. Fluorinated polymers can be classified into three
types based on the position of the fluorine-containing functional group in the
polymer chain. The quantity of fluorine migrating to the surface of fluorinated
polymer with a fluorinated unit in the main chain does not work well, which can be
attributed to the restricted movement of the entire molecular chains [14–16].
Fluorine in fluorinated polymers with fluorinated side groups or fluorinated
terminating groups can easily segregate to the air–polymer interface, thus promoting
the surface properties of the fluorinated polymer [17–20]. In addition to their surface
properties, fluorinated monomers can also be used for the modification of energy
conversion and storage devices, which are expect to play a major role in the
development of sustainable technologies to alleviate the energy and environmental
challenges we are currently facing [21–23].
Thus far, few studies have been reported on the preparation of fluorinated
monomers with a branched perfluoroalkyl ether pendent group. Compared with the
perfluoroalky group-containing polymer, the flexible ether group can significantly
modify the surface properties of corresponding polymers.
In the light of the above findings, we envisaged that a molecule containing both a
perfluoroalkyl ether group and a reactive functional group should be suitable for
preparing a fluorinated polymer with water repellency, oil repellency and soil
repellency. The design and synthetic process of a number of fluorinated monomers
containing a perfluoroalkyl ether group using acylating reaction has been elaborated
in this study.
Experimental
Chemicals
Perfluoro-2-methyl-3-oxa-hexanoic acid fluoride and perfluoro-2,5-dimethyl-3,6-
dioxa-nonanoic acid fluoride (perfluoroalkyl etheracid fluoride; PFEF) were
purchased from WengJiang Reagent and used as received. Glycidol, dithanolamine,
ethanolamine, 3-amino-1,2-propanediol and 2-hydroxyethyl methacrylate were
bought from Aladdin Reagent and were subjected to vacuum distillation prior to
use. N,N-dimethylformamide, allyl alcohol and ethylenediamine from Shanghai
Lingfeng Chemical Reagent were dried with calcium hydride and purified by
distillation before use. Thionyl chloride was refined by distillation at atmospheric
pressure before use. Dichloromethane, chloroform, triethylamine and tetrahydrofu-
ran were dried through refluxing over sodium benzophenone, which was freshly
distilled prior to use. N-allylmethylamine and trifluoroacetic acid were obtained
from Energy Regent and used as received.
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Synthesis of novel perfluoroalkyl ether derivatives
General methods and instrumentation
1H NMR (500 MHz), 13C NMR (125 MHz) and 19F NMR(125 MHz) spectra were
1
recorded on a Bruker AV500 spectrometer. Chemical shift values in ppm for H
NMR spectra and 13C NMR spectra were determined referenced to TMS as internal
standard, and those for 19F NMR spectra were referenced to CCl3F as external
standard. FTIR spectra were recorded on a Thermo Electron Nicolet 6700 FTIR
spectrophotometer in the range from 4000 to 600 cm-1. Most of the volatile
fluorinated monomers were analyzed on a GCT Premier gas chromatography time-
of-flight mass spectometer (Waters) with an OV-17 column (3 m 9 3 mm, 50%
phenylmethylpolysiloxane). The detector and injector temperatures were both
250 °C. The analysis was performed at a temperature starting from 50 °C and
reaching 250 °C at a heating rate of 20 °C/min.
Preparation of perfluoroalkyl ether acid chloride
An amount of 117.5 g perfluoro-2,5-dimethyl-3,6-dioxa-nonanoic acid fluoride
(0.35 mol) was added dropwise into 63.1 g water (3.50 mol) under agitation at
room temperature, followed by 6 h of agitation at 50 °C. The two phases could be
carried out separately, and the lower fluorocarbon layer was then transferred to a
separating funnel and extracted 5 times with a saturated sodium chloride solution to
obtain the crude acid, which was then subjected to vacuum distillation, yielding
133.5 g of pure perfluoro-2,5-dimethyl-3, 6-dioxa-nonanoic acid (85%) boiling at
80 °C at 3 mmHg. IR: 1775, 3161, 1439, 1434, 1231, 1150, 993 cm-1
.
The perfluoro-2-methyl-3-oxa-hexanoic acid was prepared from 167.5 g perflu-
oro-2-methyl-3-oxa-hexanoic acid fluoride (0.50 mol) and 90.3 g water (5.00 mol)
using the same method, with a yield of 81%. IR: 1774, 3159, 1438, 1435, 1235,
1150, 993 cm-1
.
Amounts of 80.0 g thionyl chloride (0.67 mol) and 5.0 g DMF were added into a
dry three-neck flask and the mixture was stirred for 0.5 h. Then, 165.4 g pure
perfluoro-2,5-dimethyl-3, 6-dioxa-nonanoic acid (0.33 mol) were added dropwise
into the reaction mixture. The temperature of the reaction mass was then elevated to
80 °C, followed by vigorous stirring. After 5 h, the cloudy mixture was cooled to
room temperature and the liquid separating into two layers was obtained. From this,
the liquid in the lower layer was recovered and distilled to yield 146 g pure
perfluoro-2,5-dimethyl-3,6-dioxa-nonanoyl chloride (yield 75%) boiling at 68 °C at
10 mmHg. IR: 1809, 1241, 994 cm-1
.
The perfluoro-2-methyl-3-oxa-hexanoic acid chloride was prepared in 65% yield
from 109.6 g perfluoro-2-methyl-3-oxa-hexanoic acid (0.33 mol), 80.0 g thionyl
chloride (0.67 mol), and 5.0 g DMF by means of the same procedure, with a yield
of 65%. IR: 1810, 1248, 1156, 992 cm-1
.
Preparation of methyl perfluoroalkyl ether carboxylate
The methyl perfluoroalkyl ether carboxylate was prepared by esterfication of
perfluorinated ether acid fluoride with methanol. A mixed solution of 41.11 g
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X. Shi et al.
anhydrous triethylamine (0.40 mol) in 47.5 g anhydrous methanol (1.48 mol) was
added dropwise into 185 g perfluoro-2,5-dimethyl-3, 6-dioxa-nonanoic acid fluoride
(0.37 mol) in a dry three-neck flask under agitation over a period of 2 h at 0 °C. The
mixture was agitated for another 4 h and the temperature of reaction mass was
maintained at room temperature. Subsequently, the reaction mixture was poured
into a separating funnel. The fluorocarbon layer was washed with sodium
bicarbonate solution and dried over anhydrous sodium sulfate to obtain the crude
product. The crude product was distilled to give 178.43 g methyl perfluoro-2,5-
dimethyl-3,6-dioxa-nonanoate (yield 94%) boiling at 145 °C at 760 mmHg. IR:
2969,1792,1290, 1237, 1145, 1040, 994 cm-1. 1H-NMR (500 MHz, CDCl3): d 3.99
(3H, s, CH3).13C-NMR(125 MHz, CDCl3): d 54.60 (–CH3–).
Methyl perfluoro-2-methyl-3-oxa-hexanoate was prepared in 91% yield from
134.3 g perfluoro-2-methyl-3-oxa-hexanacid fluoride (0.40 mol), 51.2 g anhydrous
methanol (1.60 mol) and 43.7 g anhydrous triethylamine (0.43 mol) using the same
procedure. IR: 2970, 1792, 1292, 1233, 1152, 1040, 993 cm-1
.
1H-NMR
(500 MHz, CDCl3): d 3.96 (3H, s, CH3). 13C-NMR (125 MHz, CDCl3): d 54.57
(CH3).
Preparation of bis(2-chloroethyl)amine
To a mechanically stirred solution of 63.7 g diethanolamine (0.60 mol) in
anyhydrous chloroform (250 mL), 221.0 g thionyl chloride (1.85 mol) were added
dropwise at room temperature. The reaction mixture was later heated to reflux,
followed by vigorous stirring. Then, 3 h later, the reaction mixture was cooled to
0 °C. The precipitate was then filtered, washed with diethyl ether, and dried under
an infrared lamp to obtain 78.1 g white solid bis(2-chloroethyl)amine hydrochloride
with a yield of 72%. 1H NMR (500 MHz, CD3OD): d 4.91 (2H, s,-NH2), 3.96 (4H,
t, –N–CH2), 3.54 (4H, t, –CH2–Cl).
An amount of 17.8 g bis(2-chloroethyl)amine hydrochloride (0.10 mol) was
added to 200 mL dichloromethane to form a suspension. Later, 120 mL aqueous
solution of sodium hydroxide (1 moL/L) were added and stirred at room
temperature for 6 h. The dichlormethane layer was separated, dried over anhydrous
sodium sulfate, and concentrated to obtain the crude product, which was distilled
under reduced pressure to acquire the pure bis (2-chloroethyl)amine, with a yield of
70%. 1H NMR (500 MHz, CDCl3): d 3.60 (4H, t, J = 4.40 Hz, –CH2–Cl), 2.94 (4H,
t, –N–CH2), 1.88 (1H, s, -NH).
General procedures for the synthesis of fluorinated monomers
Procedure A To a magnetic stirred solution of 15.6 g triethylamine (0.15 mol) and
10.10 g allyl alcohol (0.17 mol) in anhydrous chloroform (150 mL) in a dry three-
neck flask, 74.90 g perfluoro-2,5-dimethyl-3,6-dioxa-nonanoyl fluoride (0.15 mol)
were added dropwise over a period of 3 h under agitation at 0 °C. The reaction
mixture was stirred for a further 12 h, with the temperature of reaction mass being
maintained at room temperature. Distilled water was added to extract the
triethylammonium fluoride and the unreacted allyl alcohol at the end of the
123

Synthesis of novel perfluoroalkyl ether derivatives
reaction. The chloroform layer was dried over anhydrous sodium sulfate, and the
major portion of the chloroform was distilled off in the vacuum of a water-jet pump
over water. Additionally, the crude product was obtained and distilled under
reduced pressure to give the pure product.
Procedure B To a mechanically stirred solution of 12.5 g triethylamine
(0.12 mol) and 51.6 g perfluoro-2,5-dimethyl-3,6-dioxa-nonanoyl chloride
(0.10 mol) in anhydrous dichloromethane (100 mL) in a dry three-neck flask,
8.25 g glycidol (0.12 mol) were added dropwise under agitation at - 10 °C and the
mixture was stirred for 2 h. Then, the cryopump was removed, andthe mixture
allowed to stand at room temperature for 5 h. The subsequent procedures exactly
followed those in procedure A.
Procedure C An amount of 61.5 g methyl perfluoro-2,5-dimethyl-3,6-dioxa-
nonanoate (0.12 mol) was added dropwise into 15.4 g ethylenediamine (0.25 mol)
at room temperature under a nitrogen atmosphere. The reaction mixture was stirred
at room temperature for 24 h. Later, 400 mL chloroform and 100 mL water were
added into the mixture, the chloroform layer was collected and dried over anhydrous
sodium sulfate, then evaporated, and the residue was distilled under reduced
pressure to obtain the pure product.
Procedure D An amount of 21.0 g pre-distilled diethanolamine (0.20 mol) was
added in 200 mL DMF under mechanical stirring, and then 51.5 g perfluoro-2,5-
dimethyl-3,6-dioxa-nonanoyl chloride (0.10 moL) were added dropwise into the
mixed solution at - 20 °C under a nitrogen atmosphere. After being stirred for 3 h,
the cryopump was removed, and the reaction mixture was allowed to stand for 24 h
at room temperature. The reaction mixture was acidified with hydrochloric acid;
meanwhile, the solvent was removed under reduced pressure. Subsequently, the
crude product was further purified by column chromatography using silica gel with
methanol and chloroform as eluent.
Procedure E An amount of 9.13 g pre-distilled 3-amino-1,2-propanediol
(0.10 mol) was added in a dry round-bottomed flask fitted with a stirrer,
thermometer and drop funnel, and then 51.4 g methyl perfluoro-2,5-dimethyl-3,6-
dioxa-nonanoate (0.10 mol) were added dropwise from the funnel. The reaction
mixture was stirred for 6 h at 65 °C and then cooled to room temperature and the
unreacted methyl perfluoroalkyl ether carboxylate and methanol was removed under
reduced pressure The crude product was purified by column chromatography as
described above under Procedure D.
Procedure F Amounts of 6.0 g trifluoroacetic acid and 30 g water were added to
61.0 g glycidyl perfluoro-2,5-dimethyl-3,6-dioxa-nonanoate (0.11 mol). The mix-
ture was stirred vigorously for 24 h at room temperature. Next, 400 mL chloroform
were added to the mixture, then the chloroform layer was washed with sodium
bicarbonate solution and dried over anhydrous sodium sulfate. The chloroform was
removed on a rotary evaporator, and the residue was purified by distillation under
reduced pressure.
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X. Shi et al.
Allyl perfluoro-2-methyl-3-oxa-hexanoate (1a, FP2_Ally)
Colorless liquid, yield 75%, bp 78 °C(10 mmHg). IR: 1781, 1643, 1332, 1285,
1
1235, 1152, 1038, 993 cm-1. H NMR (500 MHz, CDCl3): d 5.97–5.89 (1H, m, –
CH=C), 5.47–5.38 (2H, m, –C=CH2), 4.89–4.83 (2H, m, –O–CH2–).13C NMR
(125 MHz, CDCl3): d 69.06 (–O–CH2–), 129.29 (–CH–), 121.22 (=CH2). 19F NMR
(500 MHz, CDCl3): d - 80.05 (m, 1F, CF3CF2CF2), - 82.09 (m, 3F, OCF(CF3)),
- 87.09 (m, 1F, CF3CF2CF2), - 82.89 (m, 3F, CF3CF2CF2), - 130.30 (s, 2F,
CF3CF2CF2), -132.06 (t, 1F, OCFCF3). GC–MS (m/z): 69[CF3]?, 169 [C3F7]?,
370 [M-e]?.
Allyl perfluoro-2,5-dimethyl-3,6-dioxa-nonanoate (2a, FP3_Ally)
Colorless liquid, yield 83%, bp 90 °C (10 mmHg). IR: 1787, 1648, 942, 1283, 1239,
1147, 1038, 994 cm-1. 1H NMR (500 MHz, CDCl3): d 5.97–5.89 (1H, m, –CH=C),
5.47–5.39 (2H, m, –C=CH2), 4.90–4.82 (2H, m, –O–CH2–).13C NMR (125 MHz,
CDCl3): d 69.09 (–O–CH2–), 129.38 (–CH–), 121.35 (=CH2). 19F NMR (500 MHz,
CDCl3): d - 79.0 (m, 2F, CF2OCF(CF3)COO), - 79.6 (m, 3F, CF2OCF(CF3)-
CF2O), - 80.5 (t, 3F, CF3CF2CF2), - 81.4 (m, 3F, CF2OCF(CF3)COO), - 85.6
(m, 2F, CF3CF2CF2), - 128.9 (s, 2F, CF3CF2CF2), - 129.0 (s, 1F, CF2OCF(CF3)-
COO), - 131.0 (m, 1F, CF2OCF(CF3)CF2). GC–MS (m/z): 69 [CF3]?, 169
[C3F7]?, 508 [M-(CH2=CH2)]?, 536 [M-e]?.
Methacrylic acid-b-(perfluoro-2-methyl-3-oxa-hexanoyl) acetate (1b, FP2_HEMA)
Colorless liquid, yield 87%, bp 94 °C (3 mmHg). IR: 2968, 1789, 1727, 1640, 1235,
1152, 992 cm-1. 1H NMR (500 MHz, CDCl3): d 6.11 (1H, s, –C(CH3)=CH2), 5.62
(1H, s, –C(CH3)=CH2), 4.69–4.62 (2H, m, –O–CH2), 4.44–4.43 (2H, m, –COO–
CH2–), 1.93 (3H, s, –C(CH3)=C). 13C NMR (125 MHz, CDCl3): d 167.23 (C=C–
C=O), 135.55 (C=CH2), 126.46 (C=CH2), 66.06 (–COO–CH2–), 61.55 (–O–CH2),
17.62 (–CH3). GC–MS (m/z): 41 [CH2CH=CH2]?, 69 [CF3]?, 169 [C3F7]?, 442 [M-
e]?.
Methacrylic acid-b-(perfluoro-2,5-dimethyl-3,6-dioxa-nonanoyl) acetate (2b,
FP3_HEMA)
Colorless liquid, yield 94%, bp 104 °C (3 mmHg). IR: 2967, 1789, 1728, 1640,
1240, 1147, 993 cm-1. 1H NMR (500 MHz, CDCl3): d 6.10 (1H, s, –C(CH3)=CH2),
5.61 (1H, s, -C(CH3)=CH2), 4.43–4.41 (2H, m, –O–CH2), 4.43–4.41 (2H, m, –
COO–CH2–), 1.92 (3H, s, –C(CH3)=C). 13C NMR (125 MHz, CDCl3): d 168.84
(C=C–C=O), 135.54 (C=CH2), 126.36 (C=CH2), 66.08 (–COO–CH2–), 61.36 (–O–
CH2), 17.86 (–CH3). GC–MS (m/z): 41 [CH2CH=CH2]?, 69 [CF3]?, 169 [C3F7]?,
335 [C3F7OCF(CF3)CF2]?, 523 [M-OCOCH(CH3)=CH2]?, 608 [M-e]?.
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Synthesis of novel perfluoroalkyl ether derivatives
N-methyl-N-allyl-perfluoro-2-methyl-3-oxa-hexanamide (1c, FP2_NAlly)
Colorless liquid, yield 78%, bp 52 °C (3 mmHg). IR: 1687, 1648, 1235, 1146, 1105,
991, 933 cm-1 1H NMR (500 MHz, CDCl3): d 5.79–5.69 (1H, m, –CH=C),
.
5.29–5.19 (2H, m, –C=CH2), 4.24–3.89 (2H, m, –N–CH2–),3.03, 3.14, 3.13 (3H, t,
N–CH3). 13C NMR (125 MHz, CDCl3): d 35.26 (N–CH3), 52.78 (–N–CH2–),
118.36 (=CH2), 131.13 (–C=). GC–MS (m/z): 69 [CF3]?, 169 [C3F7]?, 368 [M-
CH3]?, 383 [M-e]?.
N-methyl-N-allyl-perfluoro-2,5-dimethyl-3,6-dioxa-nonanamide (2c, FP3_NAlly)
Colorless liquid, yield 82%, bp 68 °C (3 mmHg). IR: 1687, 1648, 1238, 1146, 1105,
993, 935 cm-1 1H NMR (500 MHz, CDCl3): d 5.80–5.70 (1H, m, –CH=C),
.
5.29–5.19 (2H, m, –C=CH2), 4.24–3.91 (2H, m, –N–CH2–), 3.15, 3.14, 3.04(3H, t,
N–CH3).13C NMR (125 MHz, CDCl3): d 35.30 (N–CH3), 52.87 (–N–CH2–),
118.45 (=CH2), 131.05 (–C=). GC–MS (m/z): 69 [CF3]?, 169 [C3F7]?, 534 [M-
CH3]?, 549 [M-e]?.
Glycidyl perfluoro-2-methyl-3-oxa-hexanoate (1d, FP2_PO)
Colorless liquid, bp 68 °C (3 mmHg). IR: 3020, 1789, 1238, 1147, 1038, 993 cm-1
.
1H NMR (500 MHz, CDCl3): d 4.68–4.63 (1H, m, –COO–CH2), 4.27–4.23 (1H,
m,–COO–CH2), 3.26–3.23 (1H, m,–O–CH–), 2.89–2.86 (1H, m, –O–CH2–),
2.68–2.66 (1H, m, –O–CH2–). 13C NMR (125 MHz, CDCl3): d 68.87 (–COO–
CH2), 47.98 (–O–CH–), 44.09 (–O–CH2). GC–MS (m/z): 169 [C3F7]?, 386 [M-e]?.
Glycidyl perfluoro-2,5-dimethyl-3, 6-dioxa-nonanoate (2d, FP3_PO)
Colorless liquid, bp 76 °C (3 mmHg). IR: 3018, 1789, 1383, 1238, 1147, 1038,
993 cm-1 1H NMR (500 MHz, CDCl3): d 4.70–4.61 (1H, m, –COO–CH2),
.
4.30–4.23 (1H, m, –COO–CH2), 3.28–3.24 (1H, m, –CH2–CH–O–), 2.91–2.88 (1H,
m, –O–CH2–), 2.70–2.68 (1H, m, –O–CH2–). 13C NMR (125 MHz, CDCl3): 68.83
(–COO–CH2), 48.00 (–O–CH–), 44.33 (–O–CH2). GC–MS (m/z): 169 [C3F7]?, 552
[M-e]?.
N-(2-hydroxyethyl)-perfluoro-2-methyl-3-oxa-hexanamide (1e, FP2_MEA)
Soild, yield 82%, bp 112 °C (3 mmHg). IR: 3335, 1709, 1547, 1232, 1135,
991 cm-1.1H NMR (500 MHz, DMSO): d 9.51 (1H, s, –NH–), 4.79 (1H, s, –OH),
3.48–3.44 (2H, m, –CH2–O–), 3.34–3.23 (2H, m, –N–CH2–).13C NMR (125 MHz,
DMSO): d 40.23 (–NH–CH2–), 60.75 (–CH2–OH). GC–MS (m/z): 69 [CF3]?, 169
[C3F7]?, 328 [M-(CH2CH2OH)], 356 [M-OH]?, 373 [M-e]?.
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N-(2-hydroxyethyl)-perfluoro-2,5-dimethyl-3,6-dioxa-nonanamide (2e, FP3_MEA)
Soild, yield 79%, bp 127 °C (3 mmHg). IR: 3422, 1709, 1532, 1236, 1158,
994 cm-1. 1H NMR (500 MHz, DMSO): d 9.40 (1H, s, –NH–), 4.75 (1H, s, –OH),
3.53–3.38 (2H, m, –CH2–O–), 3.29–3.24 (2H, m, –N–CH2–).13C NMR (125 MHz,
CD3OD): d 42.36 (–NH–CH2–), 58.80 (–CH2–OH). GC–MS (m/z): 169 [C3F7]?,
509 [M-CH2O]?, 539 [M-e]?.
N-(2-aminoethyl)-perfluoro-2-methyl-3-oxa-hexanamide (1f, FP2_EA)
Colorless viscous liquid, yield 66%, bp 110 °C (3 mmHg). IR: 3326, 3178, 1708,
1
1547, 1233, 1165, 992 cm-1. H NMR (500 MHz, CDCl3): d 7.59 (1H, s, –NH–),
3.43–3.36 (2H, m, –N–CH2–), 2.90–2.88 (2H, t, –CH2–N–), 1.27 (2H, s, –NH2).13C
NMR (125 MHz, CDCl3): d 42.49 (–NH–CH2–), 40.23 (–CH2–NH2). GC–MS (m/
z): 169 [C3F7]?, 354 [M-NH3]?, 371 [M-H]?.
N-(2-aminoethyl)-perfluoro-2,5-dimethyl-3,6-dioxa-nonanamide (2f, FP3_EA)
Colorless viscous liquid, yield 74%, bp 120 °C (3 mmHg). IR: 3340, 3192, 1707,
1
1545, 1237, 1155, 994 cm-1. H NMR (500 MHz, CDCl3): d 7.38 (1H, s, –NH–),
3.45–3.38 (2H, m, –N–CH2–), 2.92–2.90 (2H, t, –CH2–N–), 1.31 (2H, s, –NH2). 13
C
NMR (125 MHz, CDCl3): d 42.40 (–NH–CH2–), 40.23 (–CH2–NH2). GC–MS (m/
z): 169 [C3F7]?, 519 [M-NH3]?, 537 [M-H]?.
Monoglyceride perfluoro-2-methyl-3-oxa-hexanoate (1g, FP2_GO)
Colorless liquid, yield 82%, bp 110 °C (3 mmHg). IR: 3445, 2963, 1787, 1454,
1
1228, 1154, 993 cm-1. H NMR (500 MHz, CDCl3): d 4.56–4.52 (1H, m, -COO-
CH2), 4.49–4.45 (1H, m, –COO–CH2), 4.20–4.16 (1H, m, –CH), 3.69–3.60 (2H, m,
–CH2OH).13C NMR (125 MHz, CDCl3): d 69.17 (–CH–OH), 67.52 (COO–CH2),
44.60 (–CH2–OH). GC–MS (m/z): 169 [C3F7]?, 373 [M-CH2OH]?.
Monoglyceride perfluoro-2,5-dimethyl-3,6-dioxa-nonanoate (2g, FP3_GO)
Colorless liquid, yield 85%, bp 122 °C (3 mmHg). IR: 3450, 2970, 1788, 1454,
1
1238, 1149, 994 cm-1. H NMR (500 MHz, CDCl3): d 4.57–4.53 (1H, m, –COO–
CH2), 4.48–4.43 (1H, m, –COO–CH2), 4.19–4.14 (1H, m, -CH), 3.68–3.58 (2H, m,
–CH2OH). 13C NMR (125 MHz, CDCl3): d 69.16 (–CH–OH), 67.52 (COO–CH2),
44.66 (–CH2–OH). GC–MS(m/z): 169 [C3F7]?, 539 [M-CH2OH]?.
N-(2,3-dihydroxypropyl)-perfluoro-2-methyl-3-oxa-hexanamide (1h, FP2_APDO)
Colorless viscous liquid, yield 71%. IR: 3344, 3081, 2949, 2888, 1708, 1545, 1234,
1
991 cm-1. H NMR (500 MHz, CD3OD): d 4.86 (3H, s, –NH–, –OH), 3.83–3.73
(1H, m, –CHOH), 3.57–3.46 (2H, m, –CH2OH), 3.57–3.46 (1H, m, –N–CH2–),
3.38–3.32 (1H, m, –N–CH2–).13C NMR (125 MHz, CD3OD): d 44.04 (–NH–CH2–),
123

Synthesis of novel perfluoroalkyl ether derivatives
65.17 (–CH2–OH), 71.34 (–CH–OH). ESI–MS (m/z): 426 [M ? Na]?, 448 [M-
H ? 2Na]?.
N-(2,3-dihydroxypropyl)-perfluoro-2,5-dimethyl-3,6-dioxa- nonanamide (2h,
FP3_APDO)
Colorless viscous liquid, yield 74%, IR: 3345, 3084, 2949, 2888, 1707, 1543, 1236,
1
994 cm-1. H NMR (500 MHz, CD3OD): d 4.88 (3H, s, –NH–, –OH), 3.80–3.74
(1H, m, –CHOH–), 3.56–3.45 (2H, m, –CH2OH), 3.56–3.45 (1H, m, –N–CH2–),
3.39–3.32 (1H, m, –N–CH2–). 13C NMR (125 MHz, CD3OD): d 43.83 (–NH–CH2–),
64.97 (–CH2–OH), 71.18 (–CH–OH). ESI–MS (m/z): 570 [M ? H]?, 592
[M ? Na]?.
N,N-bis(2-hydroxyethyl)-perfluoro-2-methyl-3-oxa-hexanamide (1i, FP2_DEA)
Colorless viscous liquid, yield 52%, IR: 3397, 2923, 1719, 1488, 1272, 1194,
975 cm-1 1H NMR (500 MHz, CHCl3): d 4.23–4.20 (2H, t, –N(–CH2–)2),
.
3.24–3.22 (2H, t, –N(–CH2–)2), 3.60–3.57 (4H, m, –(CH2–O–)2). 13C NMR
(125 MHz, CDCl3): d 62.15, 59.78 (–CH2–OH), 46.56, 45.34 (–N–CH2–). ESI–MS
(m/z): 418 [M ? H]?.
N,N-bis(2-hydroxyethyl)-perfluoro-2,5-dimethyl-3,6-dioxa-nonanamide (2i,
FP3_DEA)
Colorless viscous liquid, yield 49%, IR: 3395, 2923, 1724, 1532, 1272, 1194,
975 cm-1 1H NMR (500 MHz, CHCl3): d 4.25–4.21 (2H, t, –N(–CH2–)2),
.
3.26–3.24 (2H, t, –N(–CH2–)2), 3.64–3.58 (4H, m, –(CH2–O–)2). 13C NMR
(125 MHz, CDCl3): d 62.04, 59.38 (–CH2–OH), 46.34, 45.12 (–N–CH2–). ESI–
MS(m/z): 584 [M ? H]?.
N,N-bis(2-chloroethyl)-perfluoro-2-methyl-3-oxa-hexanamide (1j, FP2_DECl)
Colorless liquid, yield 72%, bp 80 °C(3 mmHg). IR: 2970, 1686, 1234, 1146,
994 cm-1 1H NMR (500 MHz, CHCl3): d 4.09–3.62 (8H, m). 13C NMR
.
(125 MHz, CDCl3): d 52.73, 51.66 (–CH2–Cl), 41.12, 39.88 (–N–CH2–). GC–MS
(m/z): 169 [C3F7]?, 404 [M-CH2Cl]?, 418 [M-Cl]?, 453 [M-e]?.
N,N-bis(2-chloroethyl)-perfluoro-2,5-dimethyl-3, 6-dioxa-nonanamide (2j,
FP3_DECl)
Colorless liquid, yield 76%, bp 96 °C(3 mmHg). IR: 2972, 1685, 1238, 1152,
993 cm-1 1H NMR (500 MHz, CHCl3): d 4.10–3.63 (8H, m). 13C NMR
.
(125 MHz, CDCl3): d 52.91, 51.79 (–CH2–Cl), 41.18, 39.95 (–N–CH2). GC–MS
(m/z): 169 [C3F7]?, 570 [M-CH2Cl]?, 584 [M-Cl]?, 619 [M-e]?.
123

X. Shi et al.
Results and discussion
Synthesis of fluorinated monomers
PFEF, perfluoroalkyl ether acid chloride (PFEC) and methyl perfluoroalkyl ether
carboxylate (PFEM) are the desirable starting materials for synthesizing respective
fluorinated monomers. Furthermore, the functionalized fluorinated monomers can
be typically synthesized by the reactions of PFEF, PFEC or PFEM with the
corresponding alcohols or amines. The chemical structures of the target compounds
are shown in Schemes 1 and 2, while the formulas and corresponding abbreviations
for the prepared fluorinated monomers are presented in Table 1.
Preparation of PFEC and PFEM
PFEC is the more reactive acylating agent for many organic reactions. Unfortu-
nately, it is not available from commercial sources. Thus, it can be prepared from
the corresponding acid by chlorination with thionyl chloride. However, such a
reaction is associated with a greatly diversified yield, ranging from low to excellent.
Treating acid with thionyl chloride would generally not give rise to perfluoroalkyl
ether carbonyl chloride at elevated temperatures. In addition, a higher yield of
carbonyl chloride could be obtained using thionyl chloride in the presence of DMF.
Differences in the yields could be attributed to the chlorinating regents in the
reaction. The actual chlorinating reagent was the Vilsmeier reagent formed from the
reaction of DMF with thionyl chloride. It was a superior chlorinating reagent for
preparing perfluoroalkyl ether carbonyl chloride from the corresponding acid.
PFEM could be obtained in a single step by means of the reaction of anhydrous
methanol with the corresponding PFEF in the presence of triethylamine. Impor-
tantly, the generated triethylamine hydrofluoride was immiscible with PFEM, which
could be further purified through vacuum distillation; thus, the colorless liquid could
be obtained: IR: 2939, 2939, 1477, 1835, 1229, 1171, 1035, 846 cm-1.1H NMR
(500 MHz, CDCl3): d 0.76 (9H, q, –CH3), 2.58 (6H, t, –N–CH2), 9.22 (3H, s, HF).
Triethylamine trihydrofluoride, the obtained by-product, is a good fluorinating
reagent widely used in organic fluorination reactions [24–26].
Synthesis of O-functionalized fluorinated monomers
The O-functionalized fluorinated monomers (1a–b, 2a– b, 1d, 2d) are typically
synthesized in the manner of the reaction of PFEF or PFEC with a slightly excessive
amount of the corresponding alcohols, and with triethylamine being served as an
acid acceptor. However, large discrepancies can be seen in the reactions of vinyl-
containing alcohols and glycidol with PFEF. Treating vinyl-containing alcohols
with PFEF or PFEC could directly result in corresponding vinyl-containing
fluorinated monomers, which could be incorporated into the polymer through
radical copolymerization. However, the reaction of glycidol with PFEF gives rise to
several by-products which are difficult to separate. The structures of these by-
123

Synthesis of novel perfluoroalkyl ether derivatives
Scheme 1 Synthesis route of fluorinated monomers
Scheme 2 Synthesis route of monoglyceride perfluoroalkyl ether carboxylate
products were characterized using infrared spectroscopy (Fig. 1). As shown in
Fig. 1, the typical absorption peak of hydroxyl group can be observed at 3385 cm-1
,
resulting from the ring-opening of the epoxide compound. The instability of the
strained three-membered ring in the epoxy compound was responsible for such a
phenomenon. The hydrogen fluoride and triethylamine trihydrofluoride formed in
the reaction had increased the susceptibility of the ring-opening reaction by
nucleophiles. It is concluded that the ring-opening reaction between glycidol and
PFEF indeed takes place.
It was discovered in this study that ring-opening of the epoxide moiety, which
was the side reaction, could be efficiently prevented using PFEC as the acylating
agent with excessive triethylamine as the acid acceptor. No ring-opening by-
products were observed; moreover, the triethylamine hydrochloride could be
removed through filtration. Glycidyl perfluoroalkyl ether carboxylate could be
obtained at a yield of over 70% under such conditions. Monoglyceride
123

X. Shi et al.
Method
Table 1 Synthesis of fluorinated monomers
Compound
Formula
Abbreviation
Solvent
1a
2a
1b
2b
1c
2c
1d
2d
1e
2e
1f
C6F11O3–C3H5
FP2_ALLY
FP3_ALLY
FP2_HEMA
FP3_HEMA
FP2_NALLY
FP3_NALLY
FP2_PO
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CH2Cl2
CH2Cl2
THF
A
A
A
A
A
A
B
B
A
A
B
B
F
C9F17O4–C3H5
C6F11O3–C6H9O2
C9F17O4–C6H9O2
C6F11O2–C4H8N
C9F17O3–C4H8N
C6F11O3–C3H5O
C9F17O4–C3H5O
C6F11O2–C2H6N
C9F17O3–C2H6N
C6F11O2–C2H7N2
C9F17O3–C2H7N2
C6F11O2–C3H7O3
C9F17O3–C3H7O3
C6F11O2–C3H8NO2
C9F17O3–C3H8NO2
C6F11O2–C4H10NO2
C9F17O3–C4H10NO2
C6F11O2–C4H8NCl2
C9F17O3–C4H8NCl2
FP3_PO
FP2_MEA
FP3_MEA
FP2_EA
THF
None
2f
FP3_EA
None
1g
2g
1h
2h
1i
FP2_GO
None
FP3_GO
None
F
FP2_APDO
FP3_APDO
FP2_DEA
FP3_DEA
FP2_DECl
FP3_DECl
None
E
None
E
DMF
D
D
A
A
2i
DMF
1j
CH2Cl2
CH2Cl2
2j
2927
3385
744
1787
994
1149
1237
4000
3500
3000
2500
2000
1500
1000
500
Wavenumber (cm-1)
Fig. 1 FTIR spectra of byproducts from glycidol and PFEF
123

Synthesis of novel perfluoroalkyl ether derivatives
perfluoroalkyl ether carboxylate (1g, 2g) was prepared form the ring-opening of the
synthesized epoxy monomer with water using trifluoroacetic acid (TFAA) as the
catalyst (see Scheme 2).
Synthesis of N-functionalized fluorinated monomers
N-functionalized fluorinated monomers were prepared by means of the reaction of
PFEF, PFEC or PFEM with the corresponding amines. Treatment of ethanolamine
with PFEF allowed for the controlling of the chemoselective N-acylation over O-
acylation at 0 °C. However, the reactions proceeded in a quite distinct way with the
amino alcohol of diethanolamine. PFEC could react with diethanolamine, which
allowed for producing the expected products (1i, 2i); however, no desired products
were obtained from the reaction of PFEF with diethanolamine. The potential
intramolecular hydrogen bonding (N–HÁÁÁO) causing poor nucleophilicity of
diethanolamine might be responsible for such a result, which thus hindered the
reaction of PFEF with diethanolamine. PFEC had a relatively higher electrophilicity
compared with its corresponding homologues, which made it sufficiently reactive to
react with diethanolamine. Additionally, it was found in this study that the hydroxyl
groups of diethanolamine had been replaced by chlorine to form bis(2-
chloroethy1)amine. The N,N-bis(2-chloroethyl)-substituted perfluoroalkyl ether
carboxamide (1j, 2j) had been successfully prepared at low temperature (to reduce
self-condensation of the amine) using PFEF as acylating reagent. Such a
replacement had enhanced the nucleophilicity of the amino-nitrogen, making it
sufficiently reactive to react with PFEF to form the amide. The synthesized N,N-
bis(2-chloroethyl)-perfluoroalkyl ether carboxamide (1j, 2j) had two electrophilic
sites, which could polmerize with monomers that had two nucleophilic sites. The
ethylenediamine contains two almost identically reactive sites which were available
for combination with the acylating reagent. To synthesize N-(2-aminoethyl)-
perfluoroalkyl ether carboxylamide (1f, 2f), controling the chemoselective mono-
amide formation had played a key role in the course of the synthesis and the reaction
could not be sufficiently controlled using PFEC or PFEF as the acylating agent.
Therefore, an efficiently chemoselective mono-amidation reaction was developed in
this study with PFEM as the acylating agent. The high nucleophilicity of amino-
nitrogen in 3-amino-1,2-propanediol made it sufficiently reactive to react with
PEFM to synthesize N-(2, 3-dihydroxypropyl)-perfluoroalkyl ether carboxamide
(1h, 2h). Furthermore, it was found in the current study that N-methyl-N-allyl-
perfluoroalkyl ether carboxamide (1c, 2c) and N-(2-hydroxyethyl)-perfluoroalkyl
ether carboxamide (1e, 2e) could also be obtained in high yields by the reactions of
PFEM with N-allylmethylamine or 2-aminoethanol.
Properties of fluorinated monomers
Twenty derivatives of perfluoroalkyl ether carbonyl compounds were prepared in
the current study, 12 of which are reported for the first time. Most of these
compounds were liquid at room temperature. As has been reported, the melting
point of an organic compound is mainly determined by three factors, the
123

X. Shi et al.
intermolecular force, the molecular symmetry and the degree of conformational
freedom of the molecule [27]. The low melting point could be attributed to the
higher flexibility of the branched perfluoroalkyl ether chain structures, which could
be achieved by the increased degree of conformational freedom and the decreased
molecular symmetry.
Of the synthesized fluorinated monomers, the ester linkage-containing monomers
showed superb solubility in common organic solvents such as dichloromethane,
chloroform, alcohols, esters and ethers. In contrast, the amide linkage-containing
monomers had good solubility in alcohols, ethers and amides. Surprisingly,
compounds 1i and 2i were soluble in water, which could be used as surfactants that
exhibited strong foamability.
Conclusions
In summary, 20 derivatives of perfluoroalkyl ether carbonyl compounds have been
synthesized and characterized in this study based on perfluoroalkyl ether acid
fluoride. Most of these prepared fluoroether-containing monomers are liquid at room
temperature, and display excellent solubility in common organic solvents.
Moreover, these fluorinated monomers, which have been designed containing at
least one functional group, can be strategically used for preparing fluorinated
polymers.
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