J. CHEM. RESEARCH (S), 1998 193
2,2-Di¯uoro-4-iodooctane 7.ÐHex-1-ene 6 (1.35 g, 0.016 mol), 1,1-
di¯uoro-1-iodoethane 4 (1.5 g, 0.008 mol) and a catalytic amount of
azobisisobutyronitrile (0.1 g) in benzene (5 mL) were stirred under
re¯ux during 17 h. The solvent was evaporated and the
compound was eluted with pentane on a silica gel thin-layer plate
with pentane as eluent to give 2,2-di¯uoro-4-iodooctane 7 (1.8 g,
0.0065 mol) in 82% yield. ꢀF 91.5 (1 F, d*quint*d, JFF 241.3 Hz,
FA), 87 (1 F, d*d*q*d, FB). ꢀH 1.47 (CH3CF2, t, J 18.5 Hz), 2.71
(CF2CHAHB, d*d*d*d, JHAFB 20.2, JHAHB 15.4, JFAHA=13.4,
JHAH4 6.0 Hz), 2.54 (CF2CHAHB, d*d*d*d, JFAHB 18.5, JHAHB
15.4 Hz, JHBFB 10.5 Hz, JHAH4 6.0 Hz); 4.11 (CH(4)I, q*d, J = 7 Hz,
JHAH4 6.0 Hz), 1.4±1 (6 H, m), 0.75 (3 H, m) (Found: C, 35.14; H,
5.71. C8H15F2I requires C, 34.8; H, 5.48%).
eciency of this addition is in agreement with the known
reactivity order RCH2CH2Á < RCH2CF2Á < F3CÁ.12
In conclusion, the iodide 4 can be prepared easily in a
two-step procedure. This iodide is a useful synthon for the
preparation of more elaborated ¯uorinated compounds.4
Experimental
1H NMR spectra (dH) were recorded on a Bruker AM 300 spec-
trometer and are expressed in ppm down®eld from tetramethylsilane
(solvent: CDCl3). 19F NMR spectra (dF) were recorded in ppm
down®eld from chlorotri¯uoromethane. We thank 3 M for provid-
ing us with tri¯ic acid and Atochem for 1,1-di¯uoroethylene.
1,1-Di¯uoroethyl Tri¯uoromethanesulfonate 3.ÐA thick-walled
This work enters in the frame of the European TMR pro-
gram `Fluorine as a unique tool for engineering molecular
properties'.
Received, 25th September 1997; Accepted, 2nd December 1997
Paper E/7/06939A
glass bottle ®lled with tri¯uoromethanesulfonic acid
2 (24 g,
0.16 mol) was placed in a Parr apparatus. A 5 mbar vacuum was
applied. The bottle was shaken for 3 h under 3.9 atm pressure of
1,1-di¯uoroethylene 1. Then, the bottle was opened. 19F and 1H
NMR analysis of the product 3 so obtained (32.2 g; 0.15 mol;
94%) showed that it was pure. Distillation gave a boiling point
of 70±72 8C. ꢀH 1.9 (t, JHF 15 Hz); ꢀF 75 (3 F, t, JFF 5.9 Hz);
58 (2F, q*q).
1,1-Di¯uoro-1-iodoethane 4.ÐSodium iodide (15 g, 0.1 mol) and a
catalytic amount of tetrabutylammonium bromide were stirred in
pentan-3-one (25 mL) for 20 min. Then, 1,1-di¯uoroethyl tri¯uoro-
methanesulfonate (4.5 g, 0.021 mol) was added dropwise. The
stirring was maintained for 12 h. After ®ltration, the organic phase
was evaporated under vacuum and condensed in a dry ice±acetone-
cooled trap. Then, distillation in a Fisher apparatus gave 1,1-
References
1 M. J. Tozer and T. F. Herpin, Tetrahedron, 1996, 52, 8619.
2 M. Hauptschein, A. H. Fainberg and M. Braid, J. Org. Chem.,
1958, 23, 322.
3 R. N. Haszeldine and J. E. Osborne, J. Chem. Soc., 1956, 61.
4 C. S. Rondesvelt, J. Org. Chem., 1977, 42, 1985.
5 T. Gramstad and R. N. Haszeldine, J. Chem. Soc., 1957, 4069.
6 Y. Katsuhara and D. D. Desmarteau, J. Org. Chem., 1980, 45,
2441.
7 R. D. Chambers, in Fluorine in Organic Chemistry, Wiley, New
York, 1973, p. 142.
8 R. L. Hansen, J. Org. Chem., 1965, 30, 4322.
9 Y. Kobayashi, T. Yoshida and I. Kumadaki, Tetrahedron Lett.,
1979, 3865.
10 S. L. Taylor and J. C. Martin, J. Org. Chem., 1987, 52, 4147.
11 We thank Dr. Blazejewski for the preparation of authentic
samples from tri¯uoromethyl tri¯ate and phenyllithium or
1-pyrrolidinocyclohex-1-ene.
12 M. D. Bartberger, W. R. Dolbier, J. Lusztyk and K. U. Ingold,
Tetrahedron, 1997, 53, 9857.
di¯uoro-1-iodoethane
4 (2.48 g, 0.013 mol) in 62% yield. bp
45±48 8C (lit.,4 45 8C), ꢀH 2.55 (t, JFH 19.1 Hz), ꢀF 26.5 (q, JFH
19.1 Hz).
1-Bromo-1,1-di¯uoroethane 5.ÐThe same experiment was
repeated with sodium bromide. The conversion rate was about
75%. The bp of 1-bromo-1,1-di¯uoroethane is 14 8C3 but the major
part of the product evaporated during the distillation. ꢀH 2.22 (t);
ꢀF 38 (q, JFH 15.9 Hz).