V.A. Petrov / Journal of Fluorine Chemistry 125 (2004) 531–536
535
–
OCH -group is responsible for the formation of ether 3
2
respectively) using TMS and CFCl as internal standards
3
through intermediate 16. Intermediates 15a–c can be respon-
sible for the formation of diol 12 after acidification of the
reaction mixture. Ratio of products 2, 2a–j to compound 3
formed in the reaction of 1 and alcohols in PTC reactions
depends on the relative rates of the reactions of 1 with
and chloroform-d as a lock solvent. GC and GC/MS analysis
of products were carried out on HP 6890 instrument
using HP FFAP capillary column (30 m) and TC (GC) or
mass-selective (GC/MS) detectors. Hexafluoroisobutene
CH ¼C(CF ) (DuPont), alcohols, solvents and tetrabuty-
2
3 2
À
alkoxide or HO anions. It should be pointed out, that
lammonium hydrogensulfate, methyltricaprylylammonium
R
chloride, Aiquat -336 (Aldrich) were commercially avail-
Scheme 1 explains the formation of adducts 2a–j and 3 only
and it does not explain the real mechanism of the PTC
process, which is probably, by far more complicated. At this
point for example, it is not clear where exactly (in the organic
phase, at the interface or in aqueous phase) the generation of
able and used without further purification. Due to relatively
low boiling point of 1 all reactions were carried out in the
reactor equipped with dry ice condenser to prevent loss of
the epoxide.
1
5a–c and 16 happens and why the preferential formation of
ether 3 over ring opening product 2j is taken place in the
reaction between 1 and iso-propanol. Finding the answers for
these questions might help to understand the real mechanism
of the process, but it will require more detailed investigation
of the mechanism of PTC reaction between 1 and alcohols,
which was not attempted in this of this work.
4.1. Preparation of 2,2-bis(trifluoromethyl)oxirane
(1) [1]
Into vigorously stirred, freshly prepared solution of
NaOCl (prepared by bubbling 15 g of chlorine into the
mixture of 50 ml of 50 wt.% of NaOH in 100 ml of water
at À5 to À3 8C, containing 0.5 g of phase transfer catalyst—
R
Aiquat -336) 40 g (0.24 mol) of hexafluoro-iso-butene
3
. Conclusion
CH ¼C(CF ) was condensed slowly at À2 to þ2 8C. Reac-
2
3
tion mixture was kept at þ2 to þ5 8C till >95% conversion
of olefin was reached (GC), ꢀ1–1.5 h and crude product was
transferred into cold trap (À78 8C) under reduced pressure
The reaction of 2,2-bis(trifluoromethyl)oxirane with vari-
ety of alcohols in the presence of phase transfer catalyst
under basic conditions leads to regioselective ring opening
of hexafluoro-iso-butene epoxide providing easy access to
variety of tertiary fluorinated alcohols ROCH C(CF ) OH.
(300–50 mm Hg), dried over MgSO and distilled to give
4
33 g (0.18 mol, 75%) of liquid 1, bp 42 8C.
1
19
H NMR (CDCl ): 3.3 (s) ppm; F NMR (CDCl ): À73.3
2
3 2
3
3
(
s) ppm; 13C {H} NMR (neat): 46.8 (s), 55.0 (sept, 37 Hz),
126.8 (q, 275 Hz); IR (gas, major): 1404 cm (s), 1388 cm
(s), 1220 cm (s), 1083 cm (s), 997 cm (m), 871 cm
(m), 758 cm
Calcd. for C H F O: C, 26.68, H, 1.12. Found: C, 26.64,
À1
À1
À1
À1
À1
À1
4
. Experimental
19F and 1
H NMR spectra were recorded on Brucker
DRX-400 instruments (400.5524 and 376.8485 MHz,
À1
À1 À1
(w), 690 cm
(m), 636 cm (w). Anal.
4
2 6
H, 1.10.
Table 2
NMR data for new materials
1
a
19
a
Entry number
Compound number
H NMR, d (ppm) (J, Hz)
F NMR , d, ppm (J, Hz)
1
2
3
4
5
6
7
8
9
2
3.5(3H, s), 3.8(2H, sept, 0.8), 4.3(br s)
À77.5(s)
2a
2b
2c
2d
2e
1.1(3H, t), 3.4(2H, q), 3.5 (2H, m), 3.7(2H, m), 3.8(2H, s), 5.9(1H br s) À77.0(s)
3.7(4H, s), 3.8(4H, s), 3.9(2H br s)
À77.2(s)
À77.4(s)
À76.8(s)
3.8(2H, s), 3.9(1H, br s), 4.6(2H, s), 7.4(5H, m)
3.8(1H, br s), 4.2(2H, s), 6.9(2H, d), 7.1(1H, t), 7.3(2H, t)
3.8 (1H, br s), 4.3(2H, s), 4.5(2H, s), 6.9(2H, d), 7.1(1H, t), 7.4(2H, m)
4.2(2H, s), 4.3(2H, q, 10), 7.2 (1H, br s)
b
À73.0(6F, s), À76.3(6F, s)
À75.5(3F, q, 10), À76.6(6F, s)
À62.4(2F, t, 9.5), À77.0(6F, s)
À77.1(6F, s), À124.4(2F, tm, 13),
À138.7(2F, dm, 53.5)
c
2f
2g
2h
3.8(1H, br s), 4.1(2H, t, 9.5), 4.2(2H, s)
3.7(1H, s), 4.0(4H, m), 5.9(1H, tt, 53.5)
1
1
1
0
1
2
2I
d
4.2(1H, hept, 5.8), 4.3(3H, s)
3.6(1H, br s), 4.1(2H, s)
e,f
À74.2 (6F, d, 5.8), À76.8(6F, s)
À76.8(s)
3
12
2.3(1H, br s), 4.0(2H, s), 4.2(1H, br s)
À77.3 (s)
a
b
c
d
e
f
In CDCl
3
solvent.
Isolated product contained 3% of 2e.
13C {H} (neat): 66.6, 67.0(t, 32.5 Hz), 74.0(sept, 30 Hz), 120.81(q, 285 Hz), 121.9 (q, 276 Hz).
13C {H} (neat): 68.3, 75.4 (sept, 36 Hz), 122.2(q, 291 Hz).
Data from [2].
13C {H} (neat): 58.6, 74.9 (sept, 29 Hz), 1222.(q, 287 Hz).