1388
M.M. Kremlev et al. / Journal of Fluorine Chemistry 128 (2007) 1385–1389
was gently warmed to ambient temperature and was stirred at
ambient temperature for 48 h (compound 2i for 72 h). The
reaction was terminated after signals of AgCF3 were no longer
detected in the 19F NMR spectra. The complete mixture was
filtered from the silver salts. The filtrate was washed with a 5%
aqueous Na2CO3 solution and water. Finally, the organic layer
was dried over MgSO4. Dichloromethane was distilled off and
the remaining residue was distilled under reduced pressure.
Compound 2i was isolated as follows. The reaction mixture
was filtered from the precipitate and dichloromethane was
evaporated under reduced pressure at ambient temperature. The
residue was washed with anhydrous benzene, filtered and dry
HCl gas was bubbled into the filtrate. The precipitate of 4-N,N-
dimethylaminopyridine hydrochloride was filtered off and all
volatiles were removed under reduced pressure. 2i was
crystallized from carefully dried n-hexane.
3.3. Syntheses of 2,2,2-trifluoroethane-1,1-diols (3)
While compound 3d is formed directly upon exposure of a
chloroform solution of 2d to ambient atmosphere, 3i was
prepared as follows. The mixture of 0.22 g (1.0 mmol) of 4-
nitrophenyl(trifluoromethyl)ketone (2i), acetone (5 ml) and
water (1 ml) was stirred for 30 min at ambient temperature. The
solvent was evaporated at reduced pressure and the remaining
residue was crystallized from cyclohexane.
3.3.1. 1-(2-Chloro-pyridin-3-yl)-2,2,2-trifluoroethane-1,1-
diol (3d)
Colourless crystals. Yield 0.70 g (77%), mp 147–149 8C
(glyme). 19F NMR ((CD3)2CO), d: ꢀ83.4 (s, CF3, 1JF,C = 289,
2JF,C = 33); 1H NMR, d: 8.45 (dd, 1H, H-6), 8.34 (dd, 1H, H-4),
7.48 (dd, 1H, H-5), 7.01 (s, 2H, OH, D1/2 ꢂ 4); 13C NMR, d:
150.2 (s, 1C, C-6), 149.6 (s, C-2), 140.1 (s, 1C, C-4), 131.7 (s,
1C, C-3), 122.9 (q, CF3, 1JF,C = 289), 122.1 (s, 1C, C-5), 92.1
(q, C(OH)2, 2JF,C = 33). Anal. calcd. for C7H5ClF3NO2: C 36.9;
H 2.2; N 6.2. Found: C 37.2; H 2.2; N 6.3.
3.2.1. a,a,a–Trifluoro-4-bromoacetophenone (2f)
Colourless liquid. Yield 0.62 g (61%), bp 45–47 8C
(5 ꢁ 10ꢀ2 mbar), lit. bp 95 8C (4 mmHg) [23]. 19F NMR, d:
1
2
1
ꢀ71.6 (s, CF3, JF,C = 291, JF,C = 36); H NMR, d: 7.93 (m,
2H, H-2,6), 7.7 (m, 2H, H-3,5); 13C NMR, d: 179.7 (q, CO,
2JF,C = 36), 132.6 (s, C-3,5), 131.4 (s, C-2,6), 131.0 (s, C-4),
3.3.2. 2,2,2-Trifluoro-1-(4-nitro-phenyl)-ethane-1,1-diol
(3i)
1
128.6 (s, C-1), 116.4 (q, CF3, JF,C = 291).
Yield 0.22 g (93%), mp 79–80 8C. Lit. mp 79–80 8C [13].
1
19F NMR ((CD3)2CO), d: ꢀ84.5 (s, CF3, JF,C = 288,
1
3.2.2. a,a,a,–Trifluoro-4-chloroacetophenone (2g)
2JF,C = 32); H NMR, d: 8.31 (m, 2H, H-3,5), 8.02 (m, 2H,
Colourless liquid. Yield 0.65 g (78%), bp 63–64 8C
(8.7 ꢁ 10ꢀ2 mbar), lit. bp 84 8C (23 mmHg) [24]. 19F NMR,
d: ꢀ71.6 (s, CF3, 1JF,C = 291, 2JF,C = 36); 1H NMR, d: 8.02 (m,
2H, H-2,6), 7.53 (m, 2H, H-3,5); 13C NMR, d: 179.5 (q, CO,
2JF,C = 36), 142.5 (s, C-4), 131.3 (s, C-2,6), 129.6 (s, C-3,5),
H-2,6), 7.03 (m, 2H, OH); 13C NMR, d: 148.7 (s, 1C, C-4),
144.9 (s, C-1), 128.9 (s, 2C, C-2,6), 123.1 (q, CF3, 1JF,C = 288),
122.9 (s, 2C, C-3,5), 92.9 (q, C(OH)2, 2JF,C = 32). Anal. calcd.
for C8H6F3NO4: C 40.5; H 2.5; N 5.9. Found: C 40.2; H 2.6; N
5.9; cf. Ref. [19].
1
128.2 (s, C-1), 116.4 (q, CF3, JF,C = 291).
X-raycrystalstructureanalysisof3i;cf.Ref.[19]:C8H6F3NO4
˚
(FW = 237.135), triclinic, P1, a = 8.734(2) A, b = 9.684(2) A,
˚
¯
˚
3.2.3. a,a,a–Trifluoro-2-fluoroacetophenone (2h)
c = 11.345(2) A, a = 91.82(2)8, b = 103.60(2)8, g = 96.97(2)8,
3
˚
Colourless liquid. Yield 0.55 g (71%), bp 40–42 8C
(9.2 ꢁ 10ꢀ2 mbar), lit. bp 60–62 8C (22 mmHg) [25]. 19F
NMR, d: ꢀ74.8 (d, 3F, CF3, 5JF,F = 16, 1JF,C = 289, 2JF,C = 38),
ꢀ107.7 (m, 1 F, F-2); 1H NMR, d: 7.91 (m, 1H, H-4), 7.70 (m,
1H, H-6), 7.33 (m, 1 H, H-5), 7.25 (m, 1H, H-3); 13C NMR, d:
179.2 (q, CO, 2JF,C = 37), 162.0 (d, C-2, 1JF,C = 263), 137.2 (d,
V = 923.9(3) A , Z = 4, Dcalc. = 1.705 g cmꢀ3, T = 293(2) K. X-
ray intensities were measured on a IPDS I diffractometer (Stoe &
Cie) with graphite-monochromated Mo Ka radiation. The final R
factor was 0.0469 (Rw = 0.1293 for all data) for 4120 reflections
with I > 2s(I). Crystallographic data for the structure have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-642163. Copies ofthe data
canbeobtained,freeofcharge,onapplicationtoCCDC,12Union
Road,CambridgeCB21EZ,UK(fax:+441223336033ore-mail:
3
4
C-6, JF,C = 9), 131.6 (s, C-4), 124.7 (d, C-5, JF,C = 4), 119.6
2
2
(d, C-1, JF,C = 11), 117.4 (d, C-3, JF,C = 22), 116.0 (q, CF3,
1JF,C = 290), cf. Ref. [25].
3.2.4. a,a,a–Trifluoro-4-nitroacetophenone (2i)
Yellow crystals. Yield 0.44 g (50%), mp 44–6 8C (n-
hexane), lit. mp 47 8C [13]. 19F NMR, d: ꢀ71.9 (s, CF3,
1JF,C = 290, 2JF,C = 37); 1H NMR, d: 8.46 (m, 2H, H-3,5), 8.29
(m, 2H, H-2,6), cf. Ref. [13].
Acknowledgement
Financial support of this work by the Deutsche Forschungs-
gemeinschaft (grant 436 UKR 113) is gratefully acknowledged.
3.2.5. 2-Trifluoroacetylfuran (2j)
Colourless liquid. Yield 0.42 g (61%), bp 24 8C
(2.8 ꢁ 10ꢀ2 mbar), lit. bp 129–131 8C [26]. 19F NMR, d:
References
[1] P. Kirsch, Modern Fluoroorganic Chemistry, Wiley-VCH, Weinheim,
1
2
1
2004.
ꢀ73.7 (s, CF3, JF,C = 289, JF,C = 38); H NMR, d: 7.84 (m,
1H, H-5), 7.34 (m, 1H, H-3), 6.71 (‘‘dd’’, 1H, H-4). 13C NMR,
d: 168.5 (q, CO, 2JF,C = 37), 150.2 (s, C-5), 146.8 (s, C-2), 124.2
[2] W.A. Sheppard, C.M. Sharts, Organic Fluorine Chemistry, W.A. Benja-
min, New York, 1997.
[3] J.H. Simons, W.T. Black, R.F. Clark, J. Am. Chem. Soc. 75 (1953) 5621–
5622.
1
(s, C-3), 116.1 (q, CF3, JF,C = 291), 113.2 (s, C-4).