Y. Cheburkov, G.J. Lillquist / Journal of Fluorine Chemistry 118 (2002) 123–126
125
quantitative purposes. GC/MS analysis was performed using
an HP 5890 Series 2 gas chromatograph with a 105 m ꢀ
0:32 mm Rtx-5 capillary column to introduce the sample to a
Finnigan SSQ-700 mass spectrometer. The samples were
ionized using chemical ionization with methane as the
reagent gas. A gas chromatograph HP 5890 Series 2 with
J&W Scientific fused silica capillary column DB 210
(30 m ꢀ 0:325 mm) with FID detector was used for GC
analysis.
are stable and do not lose gaseous acyl fluoride at atmo-
spheric pressure and may be stored in a polyethylene bottle
for many days.
The reaction of perfluorinated acyl fluoride with the
mixture of triethylamine trihydrogenfluoride and triethyla-
mine in solvents (diglyme, acetonitrile, THF, dichloro-
methane, etc.) is an exothermic process and needs
cooling. The perfluoroalcohol–triethylamine adduct may
be prepared without solvent, which may be added to the
adduct if necessary. The following adducts were prepared:
3.1. Reaction of triethylamine with hydrogen fluoride
ꢁ CF3OHÁNEt3, 19F NMR (CD3CN): À33.18 (CF3, vb), 1H
NMR: 11.37 (H, b), 3.00 (CH2, q), 1.22 (CH3, t).
ꢁ CF3CF2CF2OHÁNEt3, 19F NMR (diglyme): À81.16 (CF3,
An excess of triethylamine (4.347 g, 43.0 mmol) was
added to liquid HF (0.664 g, 33.2 mmol) at À78 8C. The
resulting solid and liquid mixture was melted and unreacted
triethylamine was separated after cooling as an upper liquiÀd
layer to give 2.519 g of white solidÀmixture of Et3NHþ HF2
1
s), À126.44 (CF2, s), À45.8 (OCF2, vb); H NMR: 11.8
(H, b), 2.80 (CH2, q), 1.05 (CH3, t).
ꢁ (CF3)2CFCF2OHÁNEt3, 19F NMR (CD3CN): À72.79
1
(CF3, d), À180.72 (CF, h), À51 (CF2, vb); H NMR:
1
19F NMR (CD3CN): À152.70 (F2 , s, b), H NMR: 11.09
12.46 (H, b), 2.87 (CH2, q), 1.17 (CH3, t).
(NHþ) and Et3NHþ FÀ 19F NMR: À126.12 (FÀ, s, b). Cross-
correlation of fluorine and proton signal intensities gives: HF
as H2F2 41.41% (F NMR), Et3N 45.62% (H NMR) and HF
as HF 12.97% (F NMR), which corresponds 77 mol%
triethylammonium bifluoride and 23 mol% triethylammo-
nium monofluoride mixture.
The NMR spectrum of C3F7OHÁNEt3 was originally run in a
Teflon NMR tube at 22 8C and then run at À45, À20, 50,
75 and 100 8C with no resolution of the broad OCF2 signal.
The combined proton and fluorine NMR spectral data
showed no acid fluoride at any temperature. The sample
contains a minor amount of perfluoropropionic acid at the
5 mol% level and several very minor impurities, which
increase to about 5 mol% at 75 and 100 8C. One of these
increasing impurities appears to be the aminoketone
C2F5COCH=CHN(C2H5)2.
3.2. Reaction of triethylamine with triethylamine
trihydrogenfluoride
To 0.963 g (5.98 mmol) of triethylamine trihydrogen-
fluoride was added 1.207 g (11.9 mmol) triethylamine.
Immediately a white crystalline solid formation was
observed. The mixture was heated until all solid was melted
to give the layered liquid material, which after cooling and
separation gave 1.266 g (8.97 mmol) of solid triethylamo-
nium bifluoride (100% yield) and 0.878 g (8.69 mmol) of
unreacted triethylamine.
3.4. Heptafluoropropylmethyl ether (3M HFE 301)
A mixture of pentafluoropropionyl fluoride (7.25 g,
44 mmol), Aldrich triethylamine trihydrogenfluoride
(2.41 g, 15 mmol) and triethylamine (3.0 g, 30 mmol) was
heated at 35–40 8C for 30 min in ACE GLASS Inc. pressure
tube until homogenization was completed. To the clear
liquid at 0 8C was added dimethylsulfate (5.81 g, 46 mmol)
and 0.19 g Adogen and the whole mixture agitated at 45–
47 8C for 5.5 h. In vacuum (25 Torr) from the reactor dis-
tilled out low boiling material in cold trap (À78 8C) contain-
ing 1.1 g of ethanol. The trap content washed H2O and dried
MgSO4 to give 8.33 g a mixture of (GC (%)): 68%
C3F7OCH3 MS (CI): 201 [50 ðM þ 1Þþ], 181 [100 (M–
F)þ], (calculated yield 6.15 g, 70%); 2.5% C2F5COOCH3,
(calculated yield 0.2 g, 2.6%) and 28% C2F5COOC2H5
(calculated yield 2.36 g, 28%).
3.3. Reaction of triethylammonium fluoride with
perfluorinated acid fluorides (typical experiment)
To a suspension of triethylamine trihydrogenfluoride
(0.33 mol) and triethylamine (0.67 mol) perfluoroacyl fluor-
ide (1 mol) was added while cooling. The addition without
solvent may be accomplished simply by pouring liquid acyl
fluoride into the amines mixture at a temperature lower than
its boiling point. Usually gaseous acyl fluoride was con-
densed in a trap and poured at À70 8C into a mixture of
triethylamine and its trihydrogenfluoride in an ACE GLASS
Inc. heavy-wall glass pressure tube with Ace-Thred PTFE
cap, FETFE ‘‘O-ring’’ and magnetic bar stirrer. After
leaving the tube reactor to warm to room temperature, the
acyl fluoride gradually reacts with the amines mixture to
give a clear and slightly colored solution. To accomplish the
adduct formation the reaction mixture may be heated at
40 8C for 10–15 min. The products are crystalline solid at
approximately 0 8C and liquid at room temperature. They
3.5. Methyltrifluoromethyl ether (HFE 134a)
Carbonyldifluoride from a steel cylinder was bubbled
through the agitated mixture of triethylamine trihydrogen-
fluoride (1.67 g, 10 mmol) and triethylamine (2.10 g,
21 mmol) in 2.71 g diglyme in a two-neck flask with a
condenser at 0 8C and end bubbler. The exothermic reaction
was ended when an excess of the carbonylfluoride began to