Generation of Interhalogen Fluorides
J . Org. Chem., Vol. 64, No. 4, 1999 1097
stirred for 1.5 h. Workup was with 0.2-0.3 mL of 5% aqueous
sodium bicarbonate followed by 20 µL of 1.0 M chlorobenzene
in carbon tetrachloride as internal standard. The aqueous
layer was extracted with methylene chloride. The combined
organic layers were dried over anhydrous magnesium sulfate,
and the mixture was analyzed by GC.
and 5.29 ppm). The iodofluoroproduct 3 did survive GC, GC-
1
MS, and H and 19F NMR analysis but decomposed during 13
C
data collection. The following data were obtained.
2-Ch lor o-1-flu or otetr a h yd r op yr a n (1). trans: GC-MS
(m/z) 140 (M+, 0.8), 138 (M+, 0.2), 92 (7), 90 (21), 75 (12), 64
(16), 63 (52), 55 (100), 54 (23), 53 (13). HRMS MH+ calcd for
1
Ha loflu or in a tion w ith Tr ieth yla m in e Tr ih yd r oflu o-
r id e a n d Alk yl Hyp oh a lites (ROX; R ) t-Bu , X ) Cl or
Br ; R ) CH3, X ) Cl; or NIS). To a round-bottom flask at 0
°C was added with stirring 0.011 mol hypohalite (25 mL of
0.44 M t-BuOBr13a in methylene chloride or hexane; or 20 mL
of solvent (Table 1) followed by 7.8 mL of 1.4 M t-BuOCl in
methylene chloride or hexane)13a,15 or 2.48 g of NIS in 20 mL
methylene chloride, was added 0.863 g (0.010 mol) 2-methyl-
2-pentene and 1.612 g (0.010 mol) (C2H5)3N‚3HF. The mixture
was stirred for 30 min at 0 °C and then worked up as described
above. Analysis by GC gave yields (85% from t-BuOBr; 50%
from t-BuOCl) with chlorobenzene as internal standard cor-
rected for flame response. Solvent was removed under vacuum,
and bulb-to-bulb distillation at 6-10 Torr, oil bath at 50-70
°C, gave 3-bromo-2-fluoro-2-methylpentane or 3-chloro-2-fluoro-
2-methylpentane that was greater than 90% pure by GC.
Iodofluorination of 2-methyl-2-pentene was carried out with
(C2H5)3N‚3HF and NIS12c in 85% yield, greater than 95% pure
by GC. Analysis by 19F NMR showed that the minor isomers
(3-fluoro-2-halo-2-methylpentanes) were less than 1% for each
reaction. The following data were obtained.
C5H9OFCl 139.0326; found 139.0321. H NMR δ 1.48 (dm, J
) 16.2 Hz, 1H), 1.99 (dm, J ) 16.2 Hz, 1H), 2.09-2.24 (m,
1H), 2.27-2.40 (m, 1H), 3.80 (dm, J ) 11.5 Hz, 1H), 3.95 (dd,
J ) 11.5 and 2.8 Hz, 1H), 4.08 (m, 1H), 5.51 (d, J ) 51.0 Hz,
1H). 19F δ -127.3 (d, J ) 51.0 Hz). 13C δ 18.9 (s), 25.8 (s), 53.5
(d, J ) 39 Hz), 62.1 (s), 106.6 (d, J ) 220 Hz). cis: GC-MS
140 (M+, 1), 138 (M+, 0.3), 92 (6), 90 (20), 75 (12), 64 (15), 55
1
(100), 55 (22), 53 (15). H NMR δ 5.56 (dd, J ) 53.2 and 2.0
Hz) other protons covered by trans. 19F δ -152.5 (dd, J ) 53.2
and 24.3 Hz).
2-Br om o-1-flu or otetr a h yd r op yr a n (2). trans:16 GC-MS
(m/z) 184 (M+, 3), 182 (M+, 3), 136 (28), 134 (29), 108 (31), 106
(30), 55 (100), 53 (18), 51 (9). 1H NMR δ 1.47 (dm, J ) 16.2
Hz, 1H), 1.99 (dm, J ) 16.2 Hz, 1H), 2.08-2.25 (m, 1H), 2.29-
2.44 (m, 1H), 3.78 (dm, J ) 11.5 Hz, 1H), 3.97 (ddd, J ) 12.0,
11.5 and 2.5 Hz, 1H), 4.15 (m, 1H), 5.57 (brd.d, J ) 52.0 Hz,
1H). 19F δ -123.0 (brdd, J ) 52.0 Hz). 13C δ 19.7 (s), 26.2 (s),
48.8 (d, J ) 37 Hz), 62.1 (s), 106.6 (d, J ) 220 Hz). cis: GC-
MS (m/z) 184 (M+, 0.6), 182 (M+, 0.6), 136 (29), 134 (30), 108
(28), 106 (29), 55 (100), 53 (21), 51 (7). 19F NMR δ -149.3 (dd,
J ) 52.6 and 25.8 Hz).
3-Ch lor o-2-flu or o-2-m eth ylp en ta n e: GC-MS (m/z) 138
(M+, 0.03), 103 (M - Cl, 0.2), 102 (M - HCl, 0.5), 87 (6), 61
(M - C3H6F, 100), 60 (27), 59 (10), 41 (33), 39 (14). 1H NMR δ
0.96 (t, J ) 7.6 Hz, 3H), 1.76 (d, J ) 22.3 Hz, 6H), 1.90 (m,
2H), 4.28 (m, 1H). 19F NMR (282 MHz) δ -139.5 (hept. d, J )
22 and 10 Hz).
2-Iod o-1-flu or otetr a h yd r op yr a n (3). trans: GC-MS (m/
z) 230 (M+, 21), 154 (26), 127 (20), 103 (89), 84 (6), 83 (17), 73
1
(11), 59 (12), 56 (7), 55 (100), 53 (28), 47 (16). H NMR δ 1.52
(dm, J ) 13.0 Hz, 1H), 1.91 (qt, J ) 13.0 and 4.1 Hz, 1H),
2.19 (qd, J ) 13.0 and 3.9 Hz, 1H), 2.66 (dm, J ) 13.0 Hz,
1H), 3.69 (ddd, J ) 12.4, 12.2 and 1.9 Hz, 1H), 4.18 (dd, J )
12.4 and 5.0 Hz, 1H), 5.11-5.26 (m, 2H). 19F δ -122.9 (dd, J
) 51.4 and 4.7 Hz). cis: GC-MS (m/z) 230 (M+, 60), 154 (26),
127 (22), 103 (90), 84 (13), 83 (41), 73 (12), 56 (17), 55 (100),
53 (33), 47 (16). 19F δ -143.4 (dd, J ) 51.0 and 28.0 Hz).
Rela tive Ra tes. Meth od A (for gen er a tin g XF fr om
(C2H5)3N‚3HF or XeF 2). A stock solution of 0.0780 M 2-meth-
yl-2-pentene, 0.0780 M 1-hexene, and 0.0390 M n-heptane as
internal standard was prepared in methylene chloride. One
milliliter of this stock solution was placed in a 3 mL dry plastic
vial with stirring bar at 0°. To this stirred mixture were added
0.060 mmol of the halogen and the interhalogen or 0.060 mmol
of each reagent needed to generate the interhalogen (Table
1). The reaction was stirred at 0° for 30 min, and then 1.0 mL
of 5% aqueous sodium bicarbonate solution was added to
quench the reaction. The organic layer was separated and
dried with anhydrous MgSO4. Relative concentrations of the
unreacted alkenes were determined by GC analysis corrected
for flame response.17 The following data were obtained.
Halogen source (rel rate 2-methyl-2-pentene/1-hexene): Br2
(20 ( 4), Cl2 (1.6 ( 0.2), NIS-(C2H5)3N‚3HF (16 ( 3), NBS-
(C2H5)3N‚3HF (33 ( 4), t-BuOBr-(C2H5)3N‚3HF (10 ( 4),
t-BuOBr-XeF2 (16 ( 3), t-BuOCl-XeF2 (60 ( 10), t-BuOCl-
(C2H5)3N‚3HF (4 ( 1), NCS-(C2H5)3N‚3HF (3 ( 1).
3-Br om o-2-flu or o-2-m eth ylp en ta n e: GC-MS (m/z) 184
and 182 (M+, 0.1), 103 (M - Br, 17), 83 (21), 61 (M - C3H6F,
1
100), 60 (47), 59 (24), 41 (85), 39 (44). H NMR δ 1.11 (t, J )
7.0 Hz, 3H), 1.48 (d, J ) 22 Hz, 3H), 1.54 (d, J ) 22 Hz, 3H),
1.59-1.74 (m, 2H), 3.86 (ddd, J ) 11.2, 9.0 and 2.4 Hz, 1H).
19F NMR (282 MHz) δ -136.2 (hept. d, J ) 22 and 9 Hz).
2-F lu or o-3-iod o-2-m eth ylp en ta n e: GC-MS (m/z) 230
(M+, 2), 186 (0.3), 155 (1), 127 (5), 83 (34), 61 (M - C3H6F,
1
100), 59 (11), 43 (24), 41 (44), 39 (21). H NMR δ 1.06 (t, J )
7.2 Hz, 3H), 1.53 (d, J ) 21.5 Hz, 3H), 1.56 (d, J ) 21.5 Hz,
3H), 1.61-1.88 (m, 2H), 3.98 (ddd, J ) 11.3, 8.5 and 2.3 Hz,
1H). 19F NMR (282 MHz) δ -131.3 (hept. d, J ) 21.5 and 8.5
Hz).
F r om m eth ylen ecycloh exa n e, 1-Ch lor om eth yl-1-flu o-
r ocycloh exa n e was isolated by preparative GC with
a
3
Hewlett-Packard 700 (TC) gas chromatograph with a 6′ × /8′′
stainless steel column of 10% Carbowax 20 M on 80/100
Chromosorb W-H. P. The product was >90% pure by analyti-
cal GC analysis, and the following data were obtained: GC-
MS (m/z) 150 (M+, 0.1), 101 (78), 81 (100), 41 (30), 39 (28), 27
+
(24). HRMS MNH4 calcd for C7H12ClFNH4 168.0955; found
1
168.0957. H NMR (60 MHz) δ 1.00-2.20 (m, 10H), 3.58 (d, J
) 18.0 Hz, 2H). 13C (75.4 MHz) δ 21.7, 25.1, 32.9 (d, J ) 22
Hz), 50.7 (d, J ) 29 Hz), 117.3 (d, J ) 337 Hz). 19F NMR (282
MHz) δ -159.3 (m).
Meth od
B (for F 2 a n d ClF fr om F 2). In a typical
experiment, 200 mL of the stock solution was transferred to a
300-cc 316-ss Parr Instrument Co. magnetically stirred reactor.
A sample of the stock solution was analyzed in triplicate. The
reactor was cooled to -2 or -3 °C under a nitrogen atmo-
sphere. A mixture of the gas [ClF in N2 (ca. 6% v/v), F2 in N2
(ca. 5% v/v)] was then added to the reaction mixture with
vigorous stirring while the reaction temperature was main-
tained at -3 °C for reaction with F2 and at -2 °C for reaction
with ClF. The mole ratio of ClF or F2 to alkenes was 0.71:1.
Ha loflu or in a tion of 3,4-Dih yd r o-2H-P yr a n w ith Tr i-
eth yla m in e Tr ih yd r oflu or id e. To 500 mg (5.94 mmol) of 3,4-
dihydro-2H-pyran in 75 mL of dry methylene chloride at 0 °C
was added with stirring 6.54 mmol of NXS (X ) Cl, Br, or I),
followed by the dropwise addition of 2.39 g (14.8 mmol) of
(C2H5)3N‚3HF. The reaction was stirred for 30 min at 0° and
then poured into ice-cold aqueous 2% sodium bicarbonate. The
organic layer was washed several times with cold 2% sodium
bicarbonate until the aqueous layer was basic. The organic
layer was dried over anhydrous MgSO4 and filtered, and the
solvent was removed on a rotary evaporator at room temper-
ature. Bulb-to-bulb distillation at room temperature (20-0.1
Torr) gave 1 (trans/cis 80:20), which was greater than 95%
pure by GC (major contaminant was unreacted 3,4-dihydro-
2H-pyran). Products 2 and 3 decomposed during bulb-to-bulb
distillation but did survive solvent removal at room temper-
ature. Products 2 and 3 contained succinimide (singlets at 2.72
(16) Mass spectral and NMR data are similar to ours.14f 2-Bromo-
1-fluorotetrahydropyran could not be purified by our attempted distil-
lation or column chromatography.14f
(17) Relative rate calculated as described in our earlier study.
Heasley, V. L.; Louie, T. J .; Luttrull, D. K.; Millar, M. D.; Moore, H.
B.; Nogales, D. F.; Sauerbrey, A. M.; Shevel, A. B.; Shibuya, T. Y.;
Stanley, M. S.; Shellhamer, D. F.; Heasley, G. E. J . Org. Chem. 1988,
53, 2199.