The surface properties of amine oxides with a fluoroether chain

Article abstract of DOI:10.1016/j.jfluchem.2021.109793

Persistent organic pollutants (POPs) includes long-chained fluorosurfactants, for instance, perfluorooctanonate (PFOA) and perfluorooctanesulfonate (PFOS). In order to find out alternative fluorosurfactants, we synthesized eight amine oxides with a fluoroether chain. Their surface properties were evaluated and compared with perfluoroalkyl and hydrocarbon analogues. The surface tensions at critical micelle concentration (γ_cmc) for the eight amine oxides with a fluoroether chain were at a range from 15.5 to 23.0 mN/m, and γ_cmc of four fluoroether amine oxides were below 17 mN/m comparable to perfluorooctyl analogues (16.4 mN/m) and much lower than perfluorohexyl (20.5 mN/m) and hydrocarbon analogues (24.2 and 24.7 mN/m). The critical micelle concentration (cmc) for the eight amine oxides with a fluoroether chain were 3 to 535 × 10^?4 mol/L. The cmc of four fluoroether amine oxides were 3 to 21 × 10^?4 mol/L (0.2 to 1.0 g/L) comparable to perfluorooctyl (0.4 g/L) and hydrocarbon analogues (4 and 10 × 10^?4 mol/L) and much lower than perfluorohexyl analogue (36.9 g/L). The surface excesses, the limiting molecule areas and the free energies of micellization of amine oxides were calculated. Fluoroether surfactants are promising alternatives for PFOA and PFOS.

Full text of DOI:10.1016/j.jfluchem.2021.109793

Journal of Fluorine Chemistry 246 (2021) 109793
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
The surface properties of amine oxides with a fluoroether chain
,
,*
Longhao Daia, Yong Guob *, Zhaoben Sub, Meiwei Huangb, Qing-Yun Chenb
,
Zhi-Gang Zhaoa *, Chengying Wuc, Qin Sud, Qing Shend
,
a College of Chemistry & Environment Protection Engineering, Southwest Minzu University, Chengdu, 610041, China
b Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, and University of Chinese Academy of Sciences,
345 Lingling Road, Shanghai, 200032, China
c Sanming Hexafluo Chemicals Company, LTD., Fluorinated New Material Industry Park, Mingxi, Sanming, Fujian, 365200, China
d Shanghai Huayi 3F New Materials Co., Ltd., 4600 Longwu Road, Shanghai, 200241, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
Fluoroether
Surfactant
POPs
Persistent organic pollutants (POPs) includes long-chained fluorosurfactants, for instance, perfluorooctanonate
(PFOA) and perfluorooctanesulfonate (PFOS). In order to find out alternative fluorosurfactants, we synthesized
eight amine oxides with a fluoroether chain. Their surface properties were evaluated and compared with per-
fluoroalkyl and hydrocarbon analogues. The surface tensions at critical micelle concentration (γcmc) for the eight
amine oxides with a fluoroether chain were at a range from 15.5 to 23.0 mN/m, and γcmc of four fluoroether
amine oxides were below 17 mN/m comparable to perfluorooctyl analogues (16.4 mN/m) and much lower than
perfluorohexyl (20.5 mN/m) and hydrocarbon analogues (24.2 and 24.7 mN/m). The critical micelle concen-
tration (cmc) for the eight amine oxides with a fluoroether chain were 3 to 535 × 10ꢀ 4 mol/L. The cmc of four
fluoroether amine oxides were 3 to 21 × 10ꢀ 4 mol/L (0.2 to 1.0 g/L) comparable to perfluorooctyl (0.4 g/L) and
hydrocarbon analogues (4 and 10 × 10ꢀ 4 mol/L) and much lower than perfluorohexyl analogue (36.9 g/L). The
surface excesses, the limiting molecule areas and the free energies of micellization of amine oxides were
calculated. Fluoroether surfactants are promising alternatives for PFOA and PFOS.
Amine oxide
PFOA
Alternative
1. Introduction
pollutants (POPs) because they are toxic, persistent, bioaccumulative
and able to transfer to long distance in environment [3]. Although
Amine oxides are amphoteric surfactants, showing nonionic char-
acteristics in neutral or alkaline solutions, and cationic characteristics in
acidic solutions. Amine oxide surfactants have good foaming properties,
wettability, thickening, low toxic and biodegradability, and they cause
less irritation to the skin [1]. Because of these properties, amine oxide
surfactants are widely used in detergents, shampoos, cosmetics and
textile auxiliaries. Amine oxide surfactants are also used as foam
boosters and stabilizers. On the other hand, fluorinated surfactants
usually have high thermal and chemical stability. Furthermore, fluori-
nated surfactants have higher surface activities at lower critical micelle
concentrations (cmc) compared to the traditional surfactants. Therefore,
fluorinated surfactants play a special role in many applications such as
electroplating, fire-fighting foams and repellents [2].
shortening fluorinated segments were proposed to reduce toxicity, the
cmc and the surface tension (γ) will increase with the shortening of the
chain. Fluorosurfactants with high surface activities and environmen-
tally friendly properties are in a high demand in order to replace the
compounds with long-chained perfluoroalkyl groups. We have been
focusing on the risk evaluation of several kinds of emerging fluo-
rosurfactants including their occurrence in environment and livings and
also their toxicities to aquatic organisms and mammals [4–8]. Assisted
by the biological and environmental research, we designed gemini
cationic surfactants with flexible perfluorinated-ether chains last year
[9]. We wish that newly-designed structures with a fluoroether chain
bring more understanding about structural effect on not only surface
property but also bioaccumulative ability. While the alkyl amine oxide
surfactants are well researched,-very few research on fluorinated amine
oxides has been reported [10]. The first fluoroether amine oxide dates
back to 50 years ago [10e]. Commercially available fluoroether
However, according to the Stockholm Convention, long-chained
perfluoroalkyl substances such as perfluorooctanonate (PFOA) and
perfluorooctanesulfonate (PFOS) are classified as organic persistent
* Corresponding author.
E-mail addresses: yguo@sioc.ac.cn (Y. Guo), chenqy@sioc.ac.cn (Q.-Y. Chen), zzg63129@163.com (Z.-G. Zhao).
https://doi.org/10.1016/j.jfluchem.2021.109793
Received 1 February 2021; Received in revised form 8 April 2021; Accepted 8 April 2021
Available online 10 April 2021
0022-1139/© 2021 Elsevier B.V. All rights reserved.

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
surfactants, such as GenX and ADONA, are anionic surfactants using in
fluoropolymer manufacture. Amerduri et al. have developed CH2-con-
taining alternatives based on PVDF [10f,g]. Comparative
structure-property correlations for amine-oxide surfactants with fluo-
roether and fluoroalkyl tail structures are needed.
that at a similar plane in the bulk at cmc. Amin corresponds to the area
per surfactant molecule at air-water interface at cmc [2]. We calculated
Γmax and Amin by using the Gibbs equation
1
dγ
Γm ax = ꢀ
×
2.303 × nRT dlogc
In this article, we report our recent study on perfluoroether amine
oxides and their performance together with a comparison with per-
fluoroalkyl amine oxides and aliphatic amine oxides.
and the equation
1014
NAΓm ax
Am in
=
2. Result and discussion
The “n” was taken as 1 for amine oxide surfactants because they were
looked as a nondissociating molecule in a neutral aqueous solution.
The free energies of micellization (ΔGo) were calculated based on the
equation ΔGo = RTlncmc.
We synthesized tertiary amines from fluorinated esters, carbonyl
fluorides, carbonyl chlorides or acids. The tertiary amines were oxidized
to provide amino oxides for surface properties studies. (Scheme 1)
After we obtained the amine oxides surfactants, the surface tensions
in gradient concentration were measured. The surface tensions at cmc
(γcmc), cmc, the surface excesses (Γmax), the limiting molecule areas
(Amin) and the free energies of micellization (ΔGo) of amine oxides were
calculated and depicted in Table 1.
In the Table 1 and Fig. 1, the γcmc of compounds were in an order as
C61-Oxide 21 > C62-Oxide 24 > C72-Oxide 22 > C73-Oxide 25 >
C82-Oxide 23. The same order was found with cmc of these five sur-
factants. C61-Oxide 21 has been reported with a surface tension of 28.5
mN/m in 1% aqueous solution [10e], which is higher than our result
(18.4 mN/m). The surface tensions and cmc were determined by hy-
drophobic fluorinated chains if hydrophilic groups were same. The
number of fluorinated carbons was prominent on the reducing of γ and
The surface excess Γmax (also written as Γcmc) and the limiting
molecule area Amin (also written as Acmc) were used to characterize the
behavior of surfactant molecules at air-water interface. Γmax is defined
as the concentration of surfactant molecules in a surface plane relative to
Scheme 1. The synthesis of amine oxides with fluoroether, perfluoroalkyl and aliphatic groups.
2

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
Table 1
The surface properties of amine oxides.
Compound
γcmc (mN/m)
cmc
Γmax (× 10ꢀ 10 mol/cm2)
Amin (nm2)
Δ Go (kJ/mol)
Puritya
T (oC)
(× 10ꢀ 4 mol/L)
(g/L)
21
22
23
24
25
26
27
28
29
30
32
33
C61-Oxide
18.4
16.8
15.5
17.0
15.8
20.5
16.4
23.0
21.4
16.6
24.2
24.7
159
21
3
6.9
2.8
3.3
2.8
3.3
0.8
2.4
2.8
2.5
1.0
2.8
3.4
2.4
0.59
0.51
0.60
0.50
2.15
0.68
0.59
0.68
1.63
0.59
0.50
0.69
-10
-15
-20
-12
-16
-6
98%
96%
92%
96%
98%
96%
96%
94%
98%
99%
95%
99%
23
22
22
23
22
24
24
23
22
24
22
22
C72-Oxide
C82-Oxide
C62-Oxide
C73-Oxide
C6-Oxide
1.0
0.2
88
14
891
7
3.9
0.7
36.9
0.4
C8-Oxide
-18
-8
C72-O-Oxide-E
C72-O-Oxide
C72-Oxide-E
CH12-Oxide
C12-Oxide
472
535
19
4
22.8
26.6
0.9
-7
-15
-19
-17
0.1
10
0.2
a
The purity were analyzed by the NMR spectroscopy (see supplementary material)
Fig. 1. The γ-logC curves for fluoroether amine oxides.
Fig. 2. The γ-logC curves for fluoroether amine oxide 22 compared with per-
fluoroalkyl and aliphatic amine oxides.
cmc. Increasing oxygen number on the hydrophobic fluorinated seg-
ments reduced γ and cmc as well. Introducing oxygen atoms into fluo-
rinated chains increased the hydrophobic properties of fluorosurfactants
[11]. Γmax and Amin were calculated by the slope of the γ-logC curves.
The slope of C73-Oxide 25 was smaller than others and its Γmax was
smallest and Amin was largest. This could be explained by the high
flexibility of the oxygen-rich hydrophobic fluorinated chain within
C73-Oxide 25 molecule [9]. The Γmax and Amin of the other four sur-
factants (C61-Oxide 21, C62-Oxide 24, C72-Oxide 22 and C82-Oxide
23) were very close. The trend ofΔGo was based on the trend of cmc. The
order ofΔGo was the same as that for cmc.
in a extremely low solubility and failed to give a low surface tension. The
γ of hydrocarbon 32 and 33 were higher than 24 mN/m, much higher
than that of fluorinated surfactant. The low polarizability and weak
dispersion force for perfluorinated carbon and ether chains with an
enough length can reduce not only surface tension but also cmc [2,12].
The cmc relates to the efficiency and the surface tension relates to
effectiveness [2]. Only fluorinated surfactants can satisfy both re-
quirements to reach low surface tension and low cmc.
An illustration in Scheme 2 may help to understand the air-water
interfacial behavior of the surfactants bearing with various fluorinated
chains. The surface tensions were determined majorly by the length of
perfluoroalkyl or perfluoroether chains. When we discuss the term
“length” here, both backbond and branched chains were considered. As
we discussed above, the effect of two ether bonds on surface tension will
be vaguely equal to that of a difluoromethylene group. So, the surface
tensions were consistent with the apparent lengths when the surfactant
molecules were packing tightly in the air-water interfaces.
In the Table 1 and Fig. 2, we compared fluoroether C72-Oxide 22
with fluorinated amine oxide surfactants (C6-Oxide 26 and C8-Oxide
27) and aliphatic amine oxide surfactants (CH12-Oxide 32 and C12-
Oxide 33). The surface properties of C72-Oxide 22 and C8-Oxide 27
were close. The γcmc for C72-Oxide 22 and C8-Oxide 27 were 16.8 and
16.4 mN/m and the cmc for C72-Oxide 22 and C8-Oxide 27 were 21
and 7 × 10ꢀ 4 mol/L (1.0 and 0.4 g/L), respectively. Surface tension was
determined majorly by the fluorinated segment. The perfluoroalkyl
chain CF3(CF2)6- behaved comparable to the fluoroether chain CF3OCF
(CF3)CF2OCF(CF3)-. One fluorinated carbon worked roughly as two
oxygen atoms within the fluoroether chain. Shortening two carbons in
the perfluoroalkyl chain gave C6-Oxide 26, resulting a sharp increase of
γcmc (20.5 mN/m) and cmc (36.9 g/L). Although the γcmc of CF3(CF2)4-
amine oxide 26 was lower than those of the two hydrocarbon surfactants
CH12-Oxide 32 and C12-Oxide 33, the cmc of aliphatic CH12-Oxide
32 and C12-Oxide 33 were closer to those of fluorinated C72-Oxide 22
and C8-Oxide 27 probably due to the similar hydrophilic-lipophilic
balance (HLB) and lower than that of C6-Oxide 26. Increasing carbon
chain length in compounds 36 CH18-oxide with a C17H35 chain resulted
In Scheme 2, the flexibility of fluorinated chains resulting from the
ether bonds were illustrated. As we all know, silicone surfactants
enhance their surface activities by the multiple flexible ether bonds
[2b]. Fluoroether chains can enhance the surface activities by the same
mechanism. The most extraordinary example is C73-Oxide 25 with the
limiting molecular area of 2.15 nm2, much larger than others. We
contributed the wide Amin of C73-Oxide 25 to the three flexible ether
bonds. While flexibility has an essential influence on Amin, the bulk of
fluorinated groups change the area covered by surfactant molecules
when they are saturated and packing tightly in the interface. The Amin of
C62-Oxide 24, C72-Oxide 22, C8-Oxide 27 and C82-Oxide 23 were
3

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
Scheme 2. An illustration to explain the effect of perfluoroalkyl and fluoroether chain on the surface tension and the limiting molecular area.
reasonable according to this explanation. The large limiting molecular
areas of C61-Oxide 21 and C6-Oxide 26 may be attributed to the lower
surface excess Γmax for higher solubilities of short-chained fluorinated
surfactants in water.
3. Conclusion
We have synthesized thirteen surfactants including fluoroether,
perfluoroalkyl and aliphatic amine oxides. Their surface properties were
examined and compared. The γcmc and cmc of fluoroether surfactants
can reach as low as 15.5 mN/m and 0.2 g/L. By adjusting oxygen and
carbon number of fluoroether chains, we can provide surfactants with
properties comparable to PFOA-based amino oxides. Oxygen atoms
within fluoroether chain, which can reduce surface tension and cmc, are
hydrophobic. Fluorinated surfactants are irreplaceable for their prop-
erties of both low surface tension and cmc. Modification of surfactants
by fluoroether chains provide a alternative strategy for fluorinated
POPs.
In the Table 1 and Fig. 3, we examined linkage effect by comparing
fluoroether C72-Oxide 22 with ester linkage amine oxides C72-O-Oxide
29 and C72-O-Oxide-E 28 and shorter linkage amine oxides (C72-
Oxide-E 30). Ester linkages increased cmc and γcmc dramatically. By
shortening propylene (-CH2CH2CH2-) to ethylene (-CH2CH2-), slightly
change of C72-Oxide-E 30 in γcmc (16.6 mN/m) and cmc (0.9 g/L) were
found. Due to the lone-pair electron resonance of nitrogen atom and
carbonyl group, amide bonds are normally rigid compared with ester
bonds [12]. The surfactants with amide bonds are less flexible and
consequently have lower entropies compared with the surfactants with
ester bonds, and tend to be pushed out of the bulk aqueous environment
to the air-water interface. Thus, the surface excess of C72-Oxide 22 was
larger than that of C72-O-Oxide 29, and the limiting molecular area of
C72-Oxide 22 was smaller than that of C72-O-Oxide 29 (Table 1). We
also observed higher solubility of C72-O-Oxide 29 and C72-O-Oxide-E
28 than that of C72-Oxide 22 and C72-Oxide-E 30. The high surface
tension and cmc of ester surfactants 28 and 29 could also be attributed
to their solubilities of monomers inside the bulk aqueous solution.
4. Experimental section
4.1. General information
Fluorinated starting materials were provided by Sanming Hexafluo
Chemicals Co., LTD. (see SI), and all other reagents were of AR grade
quality and used without further purification. Chemical shifts are
expressed in parts per million (ppm) with respect to the residual solvent
peak. Chemical shifts for 19F NMR are reported in ppm downfield from
fluorotrichloromethane (CFCl3). 13C NMR was broad-band decoupled
from hydrogen nuclei. Coupling constants are reported as hertz (Hz).
Signal shapes and splitting patterns are indicated as follows: s, singlet; d,
doublet; t, triplet; q, quartet; m, multiplet; br, broad. The resonances
corresponding the N-H protons are not included in the analysis –
possibly due to exchange broadening. HRMS (ESI) data were tested on a
Water Micromass GCT Premier. Surface tensions were obtained with
KRÜSS(DLSB-5L/-20) surface tension meter by Wilhelmy platinum plate
method. Specific test information is recorded in supplementary material.
4.2. Experimental procedures and characterization data for compounds
N-(3-(dimethylamino)propyl)-2,3,3,3-tetrafluoro-2-(per-
fluoropropoxy)propanamide (11) C61-Amine [9]
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 3-dimethylaminopropylamine (20 mmol, 2.04 g,
1 eq.), triethylamine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL).
Then, compound CF3CF2CF2OCF(CF3)COOCH3 (1, 20 mmol, 6.88 g, 1.0
eq.) was slowly dropped in and the mixture was stirred at room tem-
perature for 24 h. After the reaction the solvent was removed by rotary
Fig. 3. The γ-logC curves for amine oxides with different alkyl chain lengths
and different linkage groups.
4

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
evaporation under vacuum. Dichloromethane (50 mL) was added to the
residue. The resulting mixture was washed with saturated brine and
water. The organic phase was separated and then dried over anhydrous
sodium sulfate. After filtration, the solvent was removed by rotary
evaporation under vacuum. The final product was a light-yellow liquid
(8.04 g, 97%) [9]. 1H NMR (400 MHz, CD3OD) δ 3.37 – 3.27 (m, 2H),
2.33 (t, J = 7.6 Hz, 2H), 2.20 (s, 6H), 1.75 – 1.67 (m, 2H). 19F NMR (376
MHz, CD3OD) δ -81.9 (dm, J = 145.9 Hz, 1F), -82.9 (t, J = 7.1 Hz, 3F),
-84.6 (d, J = 1.9 Hz, 3F), -86.2 (dm, J = 149.3 Hz 1F), -131.2 (s, 2F),
-134.0 (dd, J = 19.6, 6.8 Hz, 1F). IR (film) v/cmꢀ 1: 3342.1, 2954.7,
2869.8, 2830.6, 2790.3, 1715.9, 1533.1, 1470.5, 1343.1, 1322.2,
1296.4, 1235.4, 1200.1, 1163.3, 1133.1, 1107.8, 1062.5, 1041.6, 991.0,
809.1, 747.3, 719.8, 628.6, 534.8.
stirring bar was added 3-dimethylaminopropylamine (20 mmol, 2.04 g,
1 eq.), triethylamine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL).
Then, compound CF3OCF2CF2OCF(CF3)COOCH3 (4, 20 mmol, 7.20 g,
1.0 eq.) was slowly dropped in and the mixture was stirred at room
temperature for 24 h. After the reaction the solvent was removed by
rotary evaporation under vacuum. Dichloromethane (50 mL) was added
to the residue. The resulting mixture was washed with saturated brine
and water. The organic phase was separated and then dried over
anhydrous sodium sulfate. After filtration, the solvent was removed by
rotary evaporation under vacuum. The final product was obtained as a
light-yellow liquid (8.26 g, 96%).[9] This compound was obtained as a
light-yellow liquid. 1H NMR (400 MHz, CD3OD) δ 3.34 – 3.30 (m, 2H),
2.33 (t, J = 7.6 Hz, 2H), 2.21 (s, 6H), 1.75 – 1.68 (m, 2H). 19F NMR (376
MHz, CD3OD) δ -57.0 (t, J = 9.0 Hz, 3F), -84.1 (d, J = 1.9 Hz, 3F), -86.2
(dd, J = 146.6, 18.4 Hz, 1F), -90.3 (dd, J = 146.6, 8.3 Hz, 1F), -91.9 (m,
2F), -134.1 (dd, J = 18.1, 7.9 Hz, 1F). IR (film) v/cmꢀ 1: 3342.5, 2954.7,
2869.9, 2830.6, 2790.3, 1723.5, 1533.6, 1470.4, 1285.2, 1224.0,
1149.8, 1114.1, 1061.8, 1041.5, 988.2, 902.2, 795.8, 765.5, 720.7,
681.3, 616.5.
N-(3-(dimethylamino)propyl)-2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-
hexafluoro-2-(trifluoromethoxy)propoxy)propanamide
(12)
C72-
Amine
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 3-dimethylaminopropylamine (20 mmol, 2.04 g,
1 eq.), triethylamine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL).
Then, compound CF3OCF(CF3)CF2OCF(CF3)COOCH3 (2, 20 mmol, 8.20
g, 1.0 eq.) was slowly dropped in and the mixture was stirred at room
temperature for 24 h. After the reaction the solvent was removed by
rotary evaporation under vacuum. Dichloromethane (50 mL) was added
to the residue. The resulting mixture was washed with saturated brine
and water. The organic phase was separated and then dried over
anhydrous sodium sulfate. After filtration, the solvent was removed by
rotary evaporation under vacuum. The final product was a light-yellow
liquid (8.84 g, 92%). 1H NMR (400 MHz, CD3OD) δ 3.38 – 3.30 (m, 2H),
2.34 (t, J = 7.6 Hz, 2H), 2.22 (s, 6H), 1.77 – 1.69 (m, 2H). 19F NMR (376
MHz, CD3OD) δ -55.0 (m, 3F), -80.8 (m, 1F), -81.5 (m, 3F), -84.1 (dd, J
= 6.4, 1.5 Hz, 3F), -84.5 (m, 1F), -133.9 (m, 1F), -147.8 (m, 1F). 13C
NMR (100 MHz, CD3OD): δ 157.8 (m), 56.6, 43.9, 38.1, 25.9, carbons
corresponding to the CF3OCF(CF3)CF2OCF(CF3)- group cannot be
identified due to C-F coupling. HRMS-ESI (m/z) calcd for
2-(2-(difluoro(trifluoromethoxy)methoxy)-1,1,2,2-tetra-
fluoroethoxy)-N-(3-(dimethylamino)propyl)-2,3,3,3-tetra-
fluoropropanamide (15) C73-Amine [9]
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 3-dimethylaminopropylamine (20 mmol, 2.04 g,
1 eq.), triethylamine (30 mmol, 3.04 g, 1.5 eq.) and tert-butyl methyl
ether (10 mL). Then, compound CF3OCF2OCF2CF2OCF(CF3)COF (5, 20
mmol, 8.28 g, 1.0 eq.) was slowly dropped in and the mixture was stirred
at room temperature for 4 h. After the reaction the solvent was removed
by rotary evaporation under vacuum. Dichloromethane (50 mL) was
added to the residue. The resulting mixture was washed with saturated
brine and water. The organic phase was separated and then dried over
anhydrous sodium sulfate. After filtration, the solvent was removed by
rotary evaporation under vacuum. The final product was obtained as a
light-yellow liquid (9.71 g, 94%) [9]. 1H NMR (400 MHz, CD3OD) δ 3.40
– 3.32 (m, 2H), 2.42 (t, J = 7.6 Hz, 2H), 2.28 (s, 6H), 1.82 – 1.75 (m, 2H).
19F NMR (376 MHz, CD3OD) δ -55.3 (m, 2F), -58.7 (t, J = 8.8 Hz, 3F),
-84.1 (d, J = 1.5 Hz, 3F), -86.7 (m, 1F), -90.1 (m, 1F), -91.7 (q, J = 21.1,
10.5 Hz, 2F) -134.0 (dd, J = 18.4, 7.9 Hz, 1F). IR (film) v/cmꢀ 1: 3336.3,
2956.5, 2871.2, 2832.1, 1714.9, 1534.2, 1471.0, 1390.5, 1309.5,
1219.9, 1108.1, 1040.7, 989.3, 964.1, 869.4, 794.7, 765.3, 720.6,
647.1.
C
12H14F13N2O3 [M + H]+: 481.0791 found: 481.0793. IR (film) v/cmꢀ 1
:
3342.6, 2955.0, 2869.7, 2830.6, 2790.8, 1724.6, 1533.7, 1471.0,
1239.0, 1161.4, 1106.3, 1077.6, 1062.6, 1041.8, 982.1, 892.7, 809.2,
765.6, 739.1, 683.9, 643.8, 534.3.
N-(3-(dimethylamino)propyl)-2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-
hexafluoro-2-(perfluoroethoxy)propoxy)propanamide (13) C82-Amine
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 3-dimethylaminopropylamine (20 mmol, 2.04 g,
1 eq.), triethylamine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL).
Then, compound CF3CF2OCF(CF3)CF2OCF(CF3)COOCH3 (3, 20 mmol,
9.20 g, 1.0 eq.) was slowly dropped in and the mixture was stirred at
room temperature for 24 h. After the reaction the solvent was removed
by rotary evaporation under vacuum. Dichloromethane (50 mL) was
added to the residue. The resulting mixture was washed with saturated
brine and water. The organic phase was separated and then dried over
anhydrous sodium sulfate. After filtration, the solvent was removed by
rotary evaporation under vacuum. The final product was obtained as a
light-yellow liquid (9.76 g, 92%). 1H NMR (400 MHz, CD3OD) δ 3.38 –
3.32 (m, 2H), 2.34 (t, J = 7.4 Hz, 2H), 2.22 (s, 6H), 1.77 – 1.69 (m, 2H).
19F NMR (376 MHz, CD3OD) δ -81.3 (m, 3F), -84.2 (m, 3F), -80.7 – -84.7
(m, 2F), -87.0 (m, 2F), -88.3 (d, J = 15.8 Hz, 3F), -133.8 (dd, J = 19.6,
7.1 Hz, 1F), -146.4 (t, J = 22.0 Hz, 1F). 13C NMR (100 MHz, CD3OD): δ
157.8 (d, J = 26 Hz), 56.6, 43.9, 38.1, 25.9, carbons corresponding to
the CF3CF2OCF(CF3)CF2OCF(CF3)- group cannot be identified due to C-F
coupling. HRMS-ESI (m/z) calcd for C13H14F15N2O3 [M + H]+:
531.0759, found: 531.0754. IR (film) v/cmꢀ 1: 3342.8, 2955.5, 2870.6,
2831.5, 2790.8, 1716.5, 1533.7, 1470.9, 1305.5, 1235.2, 1153.5,
1125.3, 1090.3, 1041.7, 981.8, 916.4, 825.6, 805.8, 765.2, 743.5,
720.6, 691.2, 646.0, 523.5.
N-(3-(dimethylamino)propyl)-2,2,3,3,4,4,5,5,6,6,6-undeca-
fluorohexanamide (16) C6-Amine [13]
3-dimethylaminopropylamine (20 mmol, 2.04 g, 1 eq.), triethyl-
amine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL) was added into a
100 mL three necked round-bottom flask. The mixture was stirred
evenly at room temperature. Then, compound CF3CF2CF2CF2CF2COOH
(6, 20 mmol, 6.28 g, 1.0 eq.) was slowly dropped in and the mixture was
stirred at room temperature for 24 h. The solvent was removed by rotary
evaporation under vacuum. The final product was obtained as a light-
yellow liquid (7.65 g, 96%). 1H NMR (400 MHz, CD3OD) δ 2.92 (t, J
= 6.8 Hz, 2H), 2.44 (t, J = 7.2 Hz, 2H), 2.24 (s, 6H), 1.79 – 1.72 (m, 2H).
19F NMR (376 MHz, CD3OD) δ -82.5 (m, 3F), -118.0 (m, 2F), -123.8 (m,
4F), -127.5 (m, 2F). IR (film) v/cmꢀ 1: 3429.6, 2959.5, 2835.0, 1685.8,
1471.6, 1394.6, 1350.1, 1237.8, 1204.7, 1146.6, 1106.8, 1083.0, 867.9,
827.5, 807.9, 747.6, 732.5, 713.8, 655.7, 566.3, 530.4.
N-(3-(dimethylamino)propyl)-2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentade-
cafluorooctanamide (17) C8-Amine [14]
3-dimethylaminopropylamine (20 mmol, 2.04 g, 1 eq.), triethyl-
amine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL) was added into
100 ml three necked round-bottom flask. Stir the mixture evenly at room
temperature. Then, compound CF3(CF2)6COOH (7, 20 mmol, 8.28 g, 1.0
eq.) was slowly dropped in and the mixture were stirred at room tem-
perature for 24 h. The solvent was removed by rotary evaporation under
vacuum. The final product was obtained as a white solid (8.99 g, 94%).
1H NMR (400 MHz, CD3OD) δ 2.90 (t, J = 7.2 Hz, 2H), 2.42 (t, J = 7.2
N-(3-(dimethylamino)propyl)-2,3,3,3-tetrafluoro-2-(1,1,2,2-tetra-
fluoro-2-(trifluoromethoxy)ethoxy)propanamide (14) C62-Amine [9]
To a 100 mL three-necked round-bottom flask containing a magnetic
5

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
Hz, 2H), 2.22 (s, 6H), 1.74 (m, 2H). 19F NMR (376 MHz, CD3OD) δ -82.5
(m, 3F), -118.0 (m, 2F), -122.7 (m, 2F), -123.1 (m, 2F), -123.6 (m, 2F),
-123.9 (m, 2F), -127.4 (m, 2F). IR (film) v/cmꢀ 1: 2960.6, 2836.1,
1686.1, 1472.9, 1394.2, 1360.4, 1240.9, 1206.3, 1149.0, 1102.1,
1013.1, 812.9, 746.6, 721.9, 700.0, 663.8, 641.5, 560.8, 530.4.
2-(dimethylamino)ethyl2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexa-
159.5 (d, J = 26 Hz), 58.3, 45.4, 38.8, carbons corresponding to the
CF3OCF(CF3)CF2OCF(CF3)- group cannot be identified due to C-F
coupling. HRMS-ESI (m/z) calcd for C11H10F13N2O3 [M – H]–: 465.0489,
found: 465.0488. IR (film) v/cmꢀ 1: 3350.1, 2955.1, 2869.2, 2830.1,
2781.8, 1716.0, 1520.0, 1463.6, 1356.2, 1235.5, 1162.2, 1107.5,
1077.4, 1054.8, 981.9, 893.0, 846.7, 808.9, 773.3, 739.1, 684.1, 619.6,
536.0.
fluoro-2-(trifluoromethoxy)propoxy)propanoate (18) C72-O-Amine-E
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 2-(dimethylamino)ethan-1-ol (80 mmol, 7.13 g, 4
eq.), methanol (10 mL). Then, compound CF3OCF(CF3)CF2OCF(CF3)
COF (8, 20 mmol, 7.96 g, 1.0 eq.) was slowly dropped in and the mixture
was stirred at room temperature for 24 h. After the reaction the solvent
was removed by rotary evaporation under vacuum. Ethyl acetate (50
mL) was added to the residue. The resulting mixture was washed with
saturated brine and water. The organic phase was separated and then
dried over anhydrous sodium sulfate. After filtration, the solvent was
removed by rotary evaporation under vacuum. The final product was
obtained as a white viscous solid (8.04 g, 86%). 1H NMR (400 MHz,
CD3OD) δ 3.67 (t, J = 5.6 Hz, 2H), 2.57 (t, J = 6.0 Hz, 2H), 2.34 (s, 6H).
19F NMR (376 MHz, CD3OD) δ -54.9 (m, 3F), -81.8 (m, 3F), -80.4 – -84.9
(m, 2F), -83.9 (m, 3F), -126.5 (m, 1F), -147.8 (m, 1F). 13C NMR (100
MHz, CD3OD): δ 162.4 (m), 61.9, 59.6, 45.4, carbons corresponding to
the CF3OCF(CF3)CF2OCF(CF3)- group cannot be identified due to C-F
coupling. HRMS-EI (m/z) calcd for C11H10F13NO4 [M – H]–: 467.0397,
found: 467.0393. IR (film) v/cmꢀ 1: 3675.9, 3412.4, 2839.4, 1697.4,
1464.5, 1403.7, 1355.8, 1232.3, 1157.9, 1040.3, 980.7, 892.7, 820.1,
771.4, 738.9, 682.9, 653.0, 619.6, 537.3.
N,N-dimethyl-3-(2,3,3,3-tetrafluoro-2-(perfluoropropoxy)prop-
anamido)propan-1-amine oxide (21) C61-Oxide [10e]
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3CF2CF2OCF(CF3)C(O)NHCH2CH2CH2N(CH3)2 (11,
5
mmol, 2.07 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at 50
◦C for 12 h. The organic extract was concentrated by rotary evaporation
under vacuum. The final product was obtained as a white viscous liquid
(2.09 g, 97%). 1H NMR (400 MHz, CD3OD) δ 3.42 (t, J = 6.8 Hz,2H),
3.32 (m, 2H), 3.16 (s, 6H), 2.15 – 2.07 (m, 2H). 19F NMR (376 MHz,
CD3OD) δ -81.8 (dm, J = 149.7 Hz, 1F), -82.9 (t, J = 7.5 Hz, 3F), -84.0 (d,
J = 1.9 Hz, 3F), -86.2 (dm, J = 149.3 Hz 1F), -131.1 (m, 2F), -134.0 (dd,
J = 19.2, 6.4 Hz, 1F). 13C NMR (100 MHz, CD3OD): δ 159.5 (d, J = 27
Hz), 69.2, 58.6 (d, J = 3 Hz), 38.8, 24.2, carbons corresponding to the
CF3CF2CF2OCF(CF3)- group cannot be identified due to C-F coupling.
HRMS-ESI (m/z) calcd for C11H14F11N2O3 [M + H]+: 431.0823, found:
431.0813. IR (film) v/cmꢀ 1: 3261.9, 2810.1, 1709.2, 1544.3, 1477.0,
1451.4, 1323.0, 1234.7, 1165.6, 1134.9, 1072.0, 991.6, 927.8, 886.1,
809.2, 747.9, 721.0, 630.3, 536.6.
2-(dimethylamino)propyl2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexa-
fluoro-2-(trifluoromethoxy)propoxy)propanoate (19) C72-O-Amine
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 3-(dimethylamino)propan-1-ol (100 mmol, 10.3
g, 4 eq.), methanol (10 mL). Then, compound CF3OCF(CF3)CF2OCF(CF3)
COF (8, 25 mmol, 9.95 g, 1.0 eq.) was slowly dropped in and the mixture
was stirred at room temperature for 24 h. After the reaction the solvent
was removed by rotary evaporation under vacuum. Ethyl acetate (50
mL) was added to the residue. The resulting mixture was washed with
saturated brine and water. The organic phase was separated and then
dried over anhydrous sodium sulfate. After filtration, the solvent was
removed by rotary evaporation under vacuum. The final product was
obtained as a white viscous solid (10.11 g, 84%). 1H NMR (400 MHz,
CD3OD) δ 3.57 (t, J = 6.4 Hz, 2H), 2.45 (t, J = 7.6 Hz, 2H), 2.26 (s, 6H),
1.74 – 1.65 (m, 2H). 19F NMR (376 MHz, CD3OD) δ -54.9 (m, 3F), -81.9
(m, 3F), -81.6 – -84.2 (m, 2F), -83.9 (m, 3F), -126.6 (m, 1F), -147.9 (m,
1F). 13C NMR (100 MHz, CD3OD): δ 162.3 (d, J = 26 Hz), 61.4, 57.8,
45.3, 30.8, carbons corresponding to the CF3OCF(CF3)CF2OCF(CF3)-
group cannot be identified due to C-F coupling. HRMS-EI (m/z) calcd for
N,N-dimethyl-3-(2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexafluoro-2-
(trifluoromethoxy)propoxy)propanamido)propan-1-amine oxide (22)
C72-Oxide
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3OCF(CF3)CF2OCF(CF3)C(O)NHCH2CH2CH2N(CH3)2 (12,
5 mmol, 2.40 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at
50 ◦C for 18 h. The organic extract was concentrated by rotary evapo-
ration under vacuum. The final product was obtained as a white viscous
liquid (2.43 g, 98%). 1H NMR (400 MHz, CD3OD) δ 3.43 (t, J = 6.8
Hz,2H), 3.31 (m, 2H), 3.15 (s, 6H), 2.14 – 2.06 (m, 2H). 19F NMR (376
MHz, CD3OD) δ -54.9 (m, 3F), -81.0 (m, 3F), -80.3 – -84.9 (m, 2F), -84.4
(m, 3F), -133.9 (m, 1F), -147.8 (m, 1F). 13C NMR (100 MHz, CD3OD): δ
159.5 (d, J = 26 Hz), 69.2, 58.7 (d, J = 4 Hz), 38.8, 24.2, carbons
corresponding to the CF3OCF(CF3)CF2OCF(CF3)- group cannot be
identified due to C-F coupling. HRMS-ESI (m/z) calcd for
C
12H14F13N2O4 [M + H]+: 497.0741, found: 497.0736. IR (film) v/
cmꢀ 1: 3226.1, 2804.3, 1709.6, 1541.4, 1455.9, 1161.7, 1070.9, 1026.3,
981.8, 892.8, 809.2, 773.4, 739.0, 684.0, 644.5, 535.5.
C12H12F13NO4 [M + H]+: 481.0553, found: 481.0551. IR (film) v/cmꢀ 1
:
1695.4, 1667.6, 1411.6, 1232.5, 1159.1, 1042.2, 981.2, 892.9, 821.8,
771.5, 739.3, 683.4, 654.7, 539.2.
N,N-dimethyl-3-(2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexafluoro-2-
(perfluoroethoxy)propoxy)propanamido)propan-1-amine oxide (23)
C82-Oxide
N-(2-(dimethylamino)ethyl)-2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexa-
fluoro-2-(trifluoromethoxy)propoxy)propanamide (20) C72-Amine-E
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added N,N-dimethylethane-1,2-diamine (20 mmol, 1.76
g, 1 eq.), triethylamine (30 mmol, 3.04 g, 1.5 eq.) and methanol (10 mL).
Then, compound CF3OCF(CF3)CF2OCF(CF3)COOCH3 (2, 20 mmol, 8.20
g, 1.0 eq.) was slowly dropped in and the mixture was stirred at room
temperature for 24 h. After the reaction the solvent was removed by
rotary evaporation under vacuum. Dichloromethane (50 mL) was added
to the residue. The resulting mixture was washed with saturated brine
and water. The organic phase was separated and then dried over
anhydrous sodium sulfate. After filtration, the solvent was removed by
rotary evaporation under vacuum. The final product obtained as a light-
yellow liquid (8.77 g, 94%). 1H NMR (400 MHz, CD3OD) δ 3.42 (t, J =
6.4 Hz, 2H), 2.47 (t, J = 7.6 Hz, 2H), 2.26 (s, 6H). 19F NMR (376 MHz,
CD3OD) δ -55.0 (m, 3F), -81.0 (m, 3F), -80.4 – -84.9 (m, 2F), -84.3 (m,
3F), -134.0 (m, 1F), -147.8 (m, 1F). 13C NMR (100 MHz, CD3OD): δ
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3CF2OCF(CF3)CF2OCF(CF3)C(O)NHCH2CH2CH2N(CH3)2
(13, 5 mmol, 2.65 g, 1 eq.), and ethanol (50 mL). The reaction mixture
was stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15
mmol, 1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred
at 50 ◦C for 12 h. The organic extract was concentrated by rotary
evaporation under vacuum. The final product was obtained as a white
viscous liquid (2.68 g, 98%). 1H NMR (400 MHz, CD3OD) δ 3.39 (t, J =
7.2 Hz, 2H), 3.30 (m, 2H), 3.14 (s, 6H), 2.13 – 2.04 (m, 2H). 19F NMR
(376 MHz, CD3OD) δ -81.5 (m, 3F), -80.7 – -84.8 (m, 2F), -84.1 (m, 3F),
-87.0 (m, 2F), -88.2 (d, J = 13.9 Hz, 3F), -133.8 (dd, J = 19.9, 7.1 Hz,
1F), -146.4 (t, J = 21.8 Hz, 1F). 13C NMR (100 MHz, CD3OD): δ 159.4 (d,
J = 26 Hz), 69.2, 58.6 (d, J = 3 Hz), 38.7, 24.2, carbons corresponding to
the CF3CF2OCF(CF3)CF2OCF(CF3)- group cannot be identified due to C-F
coupling. HRMS-ESI (m/z) calcd for C13H14F15N2O4 [M + H]+:
547.0709, found: 547.0693. IR (film) v/cmꢀ 1: 3250.5, 2806.1, 1708.4,
6

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
1541.1, 1476.8, 1455.1, 1307.1, 1234.9, 1153.6, 1090.3, 1070.0,
1026.2, 981.7, 927.9, 885.5, 825.7, 805.9, 765.3, 743.6, 721.4, 691.5,
645.0, 521.9.
was added CF3CF3CF3CF2CF2CF2CF2C(O)NHCH2CH2CH2N(CH3)2 (17,
5 mmol, 2.49 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at
50 ◦C for 18 h. The organic extract was concentrated by rotary evapo-
ration under vacuum. The final product was obtained as a white viscous
solid (2.42 g, 97%). 1H NMR (400 MHz, CD3OD) δ 3.48 (t, J = 6.8 Hz,
2H), 3.17 (s, 6H), 2.92 (t, J = 6.8 Hz, 2H), 2.08 (m, 2H). 19F NMR (376
MHz, CD3OD) δ -82.5 (m, 3F), -118.1 (m, 2F), -122.8 (m, 2F), -123.2 (m,
N,N-dimethyl-3-(2,3,3,3-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-(tri-
fluoromethoxy)ethoxy)propanamido)propan-1-amine oxide (24) C62-
Oxide
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3OCF2CF2OCF(CF3)C(O)NHCH2CH2CH2N(CH3)2 (14, 5
mmol, 2.15 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at
50 ◦C for 12 h. The organic extract was concentrated by rotary evapo-
ration under vacuum. The final product was obtained as a white viscous
liquid (2.14 g, 96%). 1H NMR (400 MHz, CD3OD) δ 3.41 (t, J = 7.2 Hz,
2H), 3.31 (m, 2H), 3.16 (s, 6H), 2.14 – 2.07 (m, 2H). 19F NMR (376 MHz,
CD3OD) δ -57.0 (t, J = 9.6 Hz, 3F), -84.0 (d, J = 2.3 Hz, 3F), -86.3 (dd, J
= 146.6, 18.4 Hz, 1F), -90.2 (dd, J = 146.6, 8.3 Hz, 1F), -91.9 (m, 2F),
-134.0 (dd, J = 18.4, 7.9 Hz, 1F). 13C NMR (100 MHz, CD3OD): δ 159.6
(d, J = 27 Hz), 69.2, 58.7 (d, J = 3 Hz), 38.8, 24.0, carbons corre-
sponding to the CF3OCF2CF2OCF(CF3)- group cannot be identified due
to C-F coupling. HRMS-ESI (m/z) calcd for C11H14F11N2O4 [M + H]+:
447.0772, found: 447.0761. IR (film) v/cmꢀ 1: 3254.2, 2810.0, 1709.0,
1541.3, 1452.0, 1398.6, 1223.4, 1150.1, 1068.4, 1026.8, 984.6, 967.7,
903.0, 795.8, 721.9, 681.3, 616.9.
2F), -123.7 (m, 2F), -123.9 (m, 2F), -127.5 (m, 2F). IR (film) v/cmꢀ 1
:
3034.9, 1659.9, 1456.4, 1397.9, 1363.0, 1323.1, 1238.3, 1204.2,
1146.2, 1104.5, 1017.9, 815.9, 736.3, 722.7, 666.1, 642.0, 560.5,
530.5.
N,N-dimethyl-2-((2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexafluoro-2-
(trifluoromethoxy)propoxy)propanoyl)oxy)ethan-1-amine oxide (28)
C72-O-Oxide-E
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3OCF(CF3)CF2OCF(CF3)C(O)OCH2CH2N(CH3)2 (18, 5
mmol, 2.34 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at
50 ◦C for 18 h. The organic extract was concentrated by rotary evapo-
ration under vacuum. The final product was obtained as a white viscous
solid (2.32 g, 96%). 1H NMR (400 MHz, CD3OD) δ 4.01 (m, 2H), 3.47 (m,
2H), 3.26 (s, 6H). 19F NMR (376 MHz, CD3OD) δ -54.9 (m, 3F), -81.5 (m,
3F), -81.6 – -84.1 (m, 2F), -83.7 (m, 3F), -126.5 (m, 1F), -147.8 (m, 1F).
13C NMR (100 MHz, CD3OD): δ 162.4 (m), 72.6, 59.2, 57.5, carbons
corresponding to the CF3OCF(CF3)CF2OCF(CF3)- group cannot be
identified due to C-F coupling. HRMS-EI (m/z) calcd for C11H10F13NO5
[M]+: 483.0346, found: 483.0348. IR (film) v/cmꢀ 1: 3427.5, 2820.1,
1689.7, 1401.2, 1235.3, 1158.5, 1092.6, 1040.1, 981.7, 893.2, 820.5,
771.4, 739.4.
1,1,1,3,3,5,5,6,6,8-decafluoro-N,N-dimethyl-9-oxo-8-(tri-
fluoromethyl)-2,4,7-trioxa-10-azatridecan-13-amine oxide (25) C73-
Oxide
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3OCF2OCF2CF2OCF(CF3)C(O)NHCH2CH2CH2N(CH3)2
(15, 5 mmol, 2.48 g, 1 eq.), and ethanol (50 mL). The reaction mixture
was stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15
mmol, 1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred
at 50 ◦C for 18 h. The organic extract was concentrated by rotary
evaporation under vacuum. The final product was obtained as a white
viscous liquid (2.48 g, 97%). 1H NMR (400 MHz, CD3OD) δ 3.44 – 3.34
(m, 4H), 3.21 (s, 6H), 2.14 – 2.04 (m, 2H). 19F NMR (376 MHz, CD3OD) δ
-55.2 (m, 2F), -58.7 (t, J = 9.0 Hz, 3F), -84.1 (d, J = 1.9 Hz, 3F), -86.6
(dd, J = 146.3, 18.4 Hz, 1F), -90.2 (dd, J = 146.3, 7.9 Hz, 1F), -91.7 (m,
2F), -134.0 (dd, J = 18.8, 8.7 Hz, 1F). 13C NMR (100 MHz, CD3OD): δ
159.7 (d, J = 27 Hz), 68.9, 58.1 (d, J = 3 Hz), 38.6, 24.1, carbons
corresponding to the CF3OCF2OCF2CF2OCF(CF3)- group cannot be
identified due to C-F coupling. HRMS-ESI (m/z) calcd for
N,N-dimethyl-3-((2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexafluoro-2-
(trifluoromethoxy)propoxy)propanoyl)oxy)propan-1-amine oxide (29)
C72-O-Oxide
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3OCF(CF3)CF2OCF(CF3)C(O)OCH2CH2CH2N(CH3)2 (19, 5
mmol, 2.41 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at
50 ◦C for 18 h. The organic extract was concentrated by rotary evapo-
ration under vacuum. The final product was obtained as a white viscous
solid (2.44 g, 98%). 1H NMR (400 MHz, CD3OD) δ 3.62 (t, J = 6.0 Hz,
2H), 3.41 (t, J = 7.6 Hz, 2H), 3.17 (s, 6H), 2.08 – 1.98 (m, 2H). 19F NMR
(376 MHz, CD3OD) δ -54.9 (m, 3F), -81.5 (m, 3F), -81.6 – -84.2 (m, 2F),
-83.8 (m, 3F), -126.6 (m, 1F), -147.9 (m, 1F). 13C NMR (100 MHz,
CD3OD): δ 162.3 (m), 70.0, 60.4, 58.5, 28.0, carbons corresponding to
the CF3OCF(CF3)CF2OCF(CF3)- group cannot be identified due to C-F
coupling. IR (film) v/cmꢀ 1: 3237.6, 2807.7, 1694.3, 1405.6, 1232.5,
1157.6, 1092.1, 1039.6, 980.8, 892.5, 820.0, 770.9, 738.8, 682.9,
653.5, 537.3.
C
12H14F13N2O5 [M + H]+: 513.0690, found: 513.0677. IR (film) v/
cmꢀ 1: 3265.4, 2812.7, 1708.2, 1541.2, 1478.5, 1450.9, 1392.3, 1312.0,
1216.0, 1111.3, 1035.5, 964.5, 870.3, 794.5, 721.0, 646.8.
N,N-dimethyl-3-(2,2,3,3,4,4,5,5,6,6,6-undecafluorohexanamido)
propan-1-amine oxide (26) C6-Oxide [13]
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3CF2CF2CF2CF2C(O)NHCH2CH2CH2N(CH3)2 (16, 5 mmol,
1.99 g, 1 eq.), and ethanol (50 mL). The reaction mixture was stirred
evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol, 1.70 g,
3.0 eq.) was slowly dropped in and the mixture was stirred at 50 ◦C for
18 h. The organic extract was concentrated by rotary evaporation under
vacuum. The final compound product was obtained as a white viscous
liquid (1.97 g, 95%). 1H NMR (400 MHz, CD3OD) δ 3.51 (t, J = 6.4 Hz,
2H), 3.19 (s, 6H), 2.98 (t, J = 6.4 Hz, 2H), 2.18 – 2.09 (m, 2H). 19F NMR
(376 MHz, CD3OD) δ -82.5 (m, 3F), -118.1 (m, 2F), -123.8 (m, 4F),
-127.5 (m, 2F). 13C NMR (100 MHz, CD3OD): δ 162.9 (t, J = 24 Hz),
70.1, 58.8, 39.0, 23.6, carbons corresponding to the CF3CF2CF2CF2CF2-
N,N-dimethyl-2-(2,3,3,3-tetrafluoro-2-(1,1,2,3,3,3-hexafluoro-2-
(trifluoromethoxy)propoxy)propanamido)ethan-1-amine oxide (30)
C72-Oxide-E
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CF3OCF(CF3)CF2OCF(CF3)C(O)NHCH2CH2N(CH3)2 (20, 5
mmol, 2.33 g, 1 eq.), and ethanol (50 mL). The reaction mixture was
stirred evenly and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol,
1.70 g, 3.0 eq.) was slowly dropped in and the mixture was stirred at
50 ◦C for 18 h. The organic extract was concentrated by rotary evapo-
ration under vacuum. The final product was obtained as a white viscous
liquid (2.41 g, 98%). 1H NMR (400 MHz, CD3OD) δ 3.79 (t, J = 6.4 Hz,
2H), 3.44 (t, J = 8.0 Hz, 2H), 3.17 (s, 6H). 19F NMR (376 MHz, CD3OD) δ
-54.9 (m, 3F), -81.5 (m, 3F), -84.0 – -84.9 (m, 2F), -84.4 (m, 3F), -134.0
(m, 1F), -147.8 (m, 1F). 13C NMR (100 MHz, CD3OD): δ 159.5 (m), 68.1,
59.0 (d, J = 4 Hz), 36.1, carbons corresponding to the CF3OCF(CF3)
group cannot be identified due to C-F coupling. IR (film) v/cmꢀ 1
:
3058.3, n 1686.2, 1479.1, 1458.8, 1395.4, 1350.5, 1235.6, 1204.6,
1149.5, 1106.9, 1084.1, 1061.8, 994.7, 953.5, 868.5, 827.4, 808.7,
748.0, 732.7, 714.4, 656.0, 566.4, 531.3.
N,N-dimethyl-3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadeca-
fluorooctanamido)propan-1-amine oxide (27) C8-Oxide [14]
To a 100 mL round-bottom flask containing a magnetic stirring bar
7

L. Dai et al.
Journal of Fluorine Chemistry 246 (2021) 109793
CF2OCF(CF3)- group cannot be identified due to C-F coupling. HRMS-ESI
(m/z) calcd for C11H10F13N2O4 [M – H]–: 481.0438, found: 481.0438. IR
(film) v/cmꢀ 1: 3208.5, 2799.1, 1715.5, 1541.4, 1478.1, 1456.5, 1235.3,
1161.9, 1073.4, 1043.9, 982.1, 893.1, 809.1, 773.6, 739.5, 684.1,
620.8, 535.0, 469.9.
g, 1 eq.), and ethanol (50 mL). The reaction mixture was stirred evenly
and heated to 50 ◦C. Then, hydrogen peroxide (20 mmol, 2.28 g, 4.0 eq.)
was slowly dropped in and the mixture was stirred at 50 ◦C for 12 h. The
organic extract was concentrated by rotary evaporation under vacuum.
The final compound product was obtained as a white solid (1.87 g,
97%). 1H NMR (400 MHz, CD3OD) δ 3.31 – 3.21 (m, 4H), 3.15 (s, 6H),
2.16 (t, J = 8.0 Hz, 2H), 2.05 – 1.98 (m, 2H), 1.64 – 1.53 (m, 2H), 1.38-
1.16 (m, 28H), 0.88 (t, J = 6.8 Hz, 3H). IR (film) v/cmꢀ 1: 3325.6,
2916.7, 2849.0, 1643.7, 1550.8, 1467.5, 1378.6, 1274.1, 1258.8,
1242.3, 1223.7, 1208.8, 1123.1, 1066.0, 1010.3, 936.3, 869.4, 720.1,
616.7, 488.3, 427.1.
N-(3-(dimethylamino)propyl)dodecanamide (31) CH12-Amine [1a]
To a 100 mL three-necked round-bottom flask containing a magnetic
stirring bar was added 3-dimethylaminopropylamine (20 mmol, 2.04 g,
1 eq.), chloroform (10 mL). Then, compound C11H23COCl (9, 20 mmol,
4.38 g, 1.0 eq.) was slowly dropped in and the mixture was stirred at
room temperature for 24 h. After the reaction the solvent was removed
by rotary evaporation under vacuum. Dichloromethane (50 mL) was
added to the residue. The resulting mixture was washed with saturated
brine and water. The organic phase was separated and then dried over
anhydrous sodium sulfate. After filtration, the solvent was removed by
rotary evaporation under vacuum. The final product was obtained as a
white solid (5.12 g, 90%). 1H NMR (400 MHz, CD3OD) δ 3.18 (t, J = 6.8
Hz, 2H), 2.36 (t, J = 7.6 Hz, 2H), 2.25 (s, 6H), 2.16 (t, J = 7.2 Hz, 2H),
1.75 – 1.53 (m, 4H), 1.36 – 1.21 (m, 18H), 0.89 (t, J = 6.4 Hz, 3H). IR
(film) v/cmꢀ 1: 3294.1, 2925.0, 2854.2, 2815.3, 2764.3, 1645.5, 1556.4,
1464.8, 1383.9, 1263.3, 1154.9, 1099.6, 1042.0, 721.7.
Appendix A. Supplementary data
Supplementary material related to this article can be found, in the
online version, at doi
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
3-dodecanamido-N,N-dimethylpropan-1-amine oxide (32) CH12-
Oxide [1a]
The support by the National Natural Science Foundation of China
(Nos. 21737004, 21672239, and 21421002), Science and Technology
Service Network Plan of Chinese Academy of Science (KFJ-STS-QYZX-
068) is gratefully acknowledged.
To a 100 mL round-bottom flask containing a magnetic stirring bar
was added CH3(CH2)10C(O)NHCH2CH2CH2N(CH3)2 (31, 5 mmol, 1.42
g, 1 eq.), and ethanol (50 mL). The reaction mixture was stirred evenly
and heated to 50 ◦C. Then, hydrogen peroxide (15 mmol, 1.70 g, 3.0 eq.)
was slowly dropped in and the mixture was stirred at 50 ◦C for 24 h. The
organic extract was concentrated by rotary evaporation under vacuum.
The final product was obtained as a white viscous solid (1.46 g, 97%). 1H
NMR (400 MHz, CD3OD) δ 3.35 – 3.23 (m, 4H), 3.15 (s, 6H), 2.18 (t, J =
7.6 Hz, 2H), 2.08 – 1.98 (m, 2H), 1.64 – 1.54 (m, 2H), 1.36 – 1.21 (m,
18H), 0.89 (t, J = 6.4 Hz, 3H). IR (film) v/cmꢀ 1: 3331.2, 3103.9, 2915.3,
2848.2, 1643.7, 1545.9, 1472.6, 1462.5, 1425.1, 1403.3, 1375.1,
1360.4, 1328.4, 1306.9, 1273.5, 1250.3, 1232.8, 1224.3, 1210.3,
1121.0, 1066.1, 1027.6, 1009.5, 976.6, 935.5, 864.6, 786.2, 770.5,
754.2, 729.2, 719.6, 689.7, 615.0, 561.6, 514.0, 489.8, 427.8.
N,N-dimethyldodecan-1-amine oxide (33) C12-Oxide [1b]
Supplementary materials
Supplementary material associated with this article can be found, in
the online version, at doi:10.1016/j.jfluchem.2021.109793.
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