E. Murotani et al. / Journal of Fluorine Chemistry 128 (2007) 1131–1136
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4. Experimental
4.1. General
1H NMR (internal TMS) and 19F NMR (internal CFCl3)
were obtained with a JEOL AL300 spectrometer. High-
resolution mass spectra were obtained with JEOL SX-102A
coupled to HP-5890 with a 60 m capillary column J&W DB-1
or DB 1301. DSC was obtained with a TA Instruments DSC
Q100. TGA was obtained with a TA Instruments TGA Q500.
Elemental fluorine is a highly toxic and corrosive gas, which
may cause explosion when it meets organic compounds in the
vapor phases, so extreme care must be taken when handling it.
Both the liquid and vapor of hydrogen fluoride (bp 19.5 8C)
evolved during the reaction are also highly corrosive and cause
severe contact burns, so care must be taken! Prior to use, all
hydrocarbon grease must be removed and the apparatus must be
gradually passivated with elemental fluorine. Although the use
of 1,1,2-trichrolotrifluoroethane (R113) is regulated, we have
given experimental examples with it for convenience, because
it is still much more cheaply available than compound 5 for
use as a solvent. Care must be taken to avoid its emission to
the environment. Compound 6 was purchased from Daicel
Chemical Industries, Ltd. (Japan). Other commercially avail-
able materials were used without purification.
Fig. 4. Compound 4.
While feeding 20 vol% fluorine gas at the same flow rate, a
solution of compound 4 (72.0 g, 0.115 mol) in R113 (720 g)
was introduced over a period of 20.6 h. After the introduction of
all the solution, 20 vol% fluorine gas was supplied at the same
flow rate for 1 h. Then, nitrogen gas was fed for 2 h to remove
fluorine gas and volatile compounds from the autoclave to give
a solution of the crude perfluorinated product. The structure of
the obtained compound 3 was determined by 19F NMR (93%
yield).
Compound 3: 19F NMR (282.7 MHz, CDCl3): d À76.4 to
À76.9 (1F of l), À79.1 to À81.6 (2F of c and l, 3F of e, m and n),
À82.0 to À82.3 (8F, a, f and h), À84.1 to À85.1 (1F of c),
À85.6 to À87.5 (2F, i), À120.1 (1F, k), À122.2 to À123.3 (1F of
j), À128.1 to À129.7 (1F of j), À130.2 (2F, b), À132.2 (1F, g),
À145.5 (1F, d) (Fig. 5).
After evaporation of solvent and volatile compounds, crude
perfluorinated ester 3 (93.0 g, 0.108 mol) was charged into a
flask with 0.93 g (0.016 mol) of potassium fluoride powder. The
dispersion was heated at 110 8C and vigorously stirred for 4 h in
an oil bath with a reflux condenser at the top of the flask.
Distillation of the crude solution provided compound 2 (82 8C/
101.3 kPa, 54% yield) and starting acyl fluoride 5. The structure
of compound 2 was confirmed by 19F NMR and GC–MS.
Compound 2: 19F NMR (282.7 MHz, CDCl3): d + 24.1 (1F of
i), À76.6 to À77.1 (1F of l), À80.6 to À81.2 (1F of l, 6F of m and
n), À115.7 to À116.8 (1Fof j), À118.2 (1F, k), À118.5 to À119.6
(1F of j); High-resolution mass spectrum (EI+) 290.9712
([MÀCF3]+, calculated for C6F9O3: 290.9704) (Fig. 6).
4.2. Synthesis of perfluoro (5-methylene-2,2-dimethyl-1,3-
dioxiolane) (1)
To a stirred mixture of 103.2 g (0.705 mol) of 5-
hydroxyethyl-2,2-demethyl-1,3-dioxolane (6) and 59.3 g
(1.411 mol) of sodium fluoride in 1600 g of R-225 (mixture
of CF3CF2CHCl2 and CClF2CF2CHClF) at 0–5 8C was added
dropwise a solution of 421.7 g (0.846 mol) of acyl fluoride 5
over a period of 3 h. After completion of addition, stirring was
continued at room temperature for 20 h. The crude mixture
was filtered, and the liquid was washed once with saturated
NaHCO3 aqueous solution and twice with water, followed by
drying over magnesium sulfate. After filtration, the liquid was
purified by distillation in vacuo (83 8C/1.06 kPa), and ester 4
was obtained (294.5 g, 0.471 mol, 67% yield). The GC purity
was 97%.
Compound 4: 1H NMR (300.4 MHz, CDCl3): d 1.34 (s, 3H,
m or n), 1.41 (s, 3H, m or n), 1.97 (dt, 3J = 6.6 Hz, 6.9 Hz, 2H,
j), 3.59 (dd, 3J = 6.6 Hz, 2J = 7.8 Hz, 1H of l), 4.09 (dd,
3J = 6.0 Hz, 2J = 7.8 Hz, 1H of l), 4.17 (m, 1H, k), 4.53 (m, 2H,
i); 19F NMR (282.7 MHz, CDCl3): d À79.0 to À80.5 (1F of c
and 3F of e), À81.8 to À82.7 (8F, a, f and h), À84.5 to À85.5
(1F of c), À130.1 (2F, b), À132.0 (1F, g), À145.6 (1F, d)
(Fig. 4).
Fig. 5. Compound 3.
Into a 3000 ml autoclave made of nickel, R113 (1700 g) was
charged and stirred at 25 8C. At the outlet of the autoclave, a
packed layer of sodium fluoride pellets and a cooler maintained
at À10 8C were installed in series. Further, a liquid-returning
line was installed to return any condensed liquid from the
cooler to the autoclave. After supplying nitrogen gas for 1 h,
20 vol% F2/N2 was fed for more 1 h at a flow rate of 16.7 L/h.
Fig. 6. Compound 2.