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4.2. A typical experimental procedure for the reaction of
HFPO with alcohol or phenol (Table 1, entry 1)
A stainless-steel reactor equipped with a stop valve
(volume: 11.2 ml) was heated under vacuum to remove
moisture. After cooling with liquid N2, hexafluoropropene
oxide (1.0 mmol) and 2,2,3,3,3-pentafluoropropanol
(2.0 mmol) were introduced into the reactor with a vacuum
line. The reactor was warmed up to 150 8C and stirred for
168 h. After the reaction, products were treated with NaF to
remove hydrogen fluoride and fractionated through traps at
À113 and À196 8C with the vacuum line. The structures of
Scheme 4. Reaction of perfluorocyclopropane with CF3CF2CH2OH.
Table 4
Reaction of perfluorocyclopropane with CF3CF2CH2OHa
Entry
1:4
(mmol)
Temperature
Conversion
Yield
of 3 (%)b
(8C)
of 4 (%)
1
2
3
a
1:1
1:1
160
190
190
3
24
28
0
0
the products were determined by GC–MS, 1H NMR and 19
F
10:10
16
NMR spectra. The ratio of the products was determined by
1H NMR and 19F NMR spectra.
Reactions were carried out for 48 h in a stainless-steel reactor (volume:
11.2 ml).
b
Yields were determined by NMR.
4.3. 1,1,1,2,2-Pentafluoro-3-difluoromethoxypropane (3a)
ocyclopropane is known to generate difluorocarbene at
above 160 8C [13,14]. So, perfluorocyclopropane may also
work as a difluorocarbene source to produce the fluorinated
ether in the presence of alcohol. Then, the reactions of
perfluorocyclopropane (4) with 1a were examined to
investigate its influence on the reaction of HFPO with
alcohol (Scheme 4, Table 4). In the reaction at 190 8C and
relatively high pressure, 3a was obtained in 16% yield, but
no 3a was detected under the usual condition of the reaction
of HFPO with the alcohol. Based on the low yield of 3a at
190 8C for 48 h, it was concluded that the influence of
perfluorocyclopropane on the yield of the fluorinated ether in
the reaction of HFPO with alcohol or phenol, is very little.
1H NMR: d 4.27 (2H, t, J = 12.7 Hz, CH2), 6.33 (1H, t,
J = 71.1 Hz, CHF2); 19F NMR: d À84.3 (3F, s, CF3), À87.2
(2F, d, J = 71.1 Hz, CHF2), À124.5 (2F, t, J = 12.7 Hz, CF2).
MS: m/z, 181 (M+ À F), 133 (CF3CF2CH2 ), 81
+
+
(CHF2OCH2 ), 69 (CF3 ), 51 (CHF2 ).
+
+
4.4. 1,1,1-Trifluoro-2-difluoromethoxyethane (3b)
1H NMR: d 4.19 (2H, q, J = 7.8 Hz, CH2), 6.32 (1H, t,
J = 72.8 Hz, CHF2); 19F NMR: d À75.1 (3F, t, J = 7.8, CF3),
À86.7 (2F, d, J = 72.8 Hz, CHF2). MS: m/z, 131 (M+ À F),
+
+
+
+
83 (CF3CH2 ), 81 (CHF2OCH2 ), 69 (CF3 ), 51 (CHF2 ),
33, 31, 29. The measured NMR and MS spectrum data were
consistent with literature [15,16].
3. Conclusion
4.5. 1,1,1,3,3,3-Hexafluoro-2-difluoromethoxypropane (3c)
In conclusions, the insertion reaction of difluorocarbene
to O–H bond proceeded predominantly to give fluorinated
ether in the reaction of HFPO with low nucleophilic alcohol
or phenol, while the insertion reaction and the nucleophilic
attack of alcohol or phenol to HFPO were competition. In
these reactions, the reaction pressure is responsible for the
selectivity and yield of the fluorinated ethers.
1H NMR: d 4.85 (1H, sep, J = 5.7 Hz, (CF3)2CH), 6.45
(1H, t, J = 70.7 Hz, CHF2); 19F NMR: d À74.2 (6F, d,
J = 5.7, CF3), À85.1 (2F, d, J = 70.7 Hz, CHF2). MS: m/z,
199 (M+ À F), 151 ((CF3)2CH+), 149 (M+ À CF3), 113, 79,
+
+
69 (CF3 ), 51 (CHF2 ), 29. The measured NMR spectrum
data were consistent with literature [17].
4.6. Difluoromethoxypentafluorobenzene (3d)
4. Experimental
1H NMR: d 6.63 (1H, t, J = 71.9 Hz, CHF2); 19F NMR: d
À83.5 (2F, d of t, J = 71.9 Hz, 15.8 Hz, CHF2), À152.6 (2F,
m, ArF), À157.2 (1F, m, ArF), À162.2 (2F, m, ArF). MS: m/
4.1. General
+
+
z, 184 (M+ À CF2), 167 (C6F5 ), 155 (C5F5 ), 136, 117, 105,
+
All the organic reagents were purified prior to use.
Hexafluoropropene oxide was used without purification. 1H-
(300 MHz) and 19F NMR (282 MHz) were measured with
JEOL ECA-300S using TMS and CFCl3 as an internal
standard and CDCl3 as a solvent. MS (EI, 70 eV) spectra
were measured using the Shimazu GCMS-QP2010 system
equipped with GC-2010. HRMS (EI, 70 eV) spectra were
measured using Hitachi M-80B.
93, 69, 51 (CHF2 ), 31. The measured 19F NMR spectrum
data were consistent with literature [18].
4.7. 1,1,1,3,3,3-Hexafluoro-2-difluoromethoxy-2-
trifluoromethylpropane (3e)
1H NMR: d 6.67 (1H, t, J = 69.0 Hz, CHF2); 19F NMR: d
À71.1(9F, t, J = 3.0 Hz, CF3), À79.6(2F, dofm,J = 69.0 Hz,