Regioselective Synthesis of para-Bromo Aromatic Compounds
J. Chin. Chem. Soc., Vol. 52, No. 3, 2005 561
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strate ring do not oxidize with this reagent, whereas a Br2
molecule can oxidize this group.
1162, 1022, 903, 834 cm-1, H-NMR (acetone-d6 / TMS): d
3.90 (s, 3H), 7.07 (d, 1H), 7.78 (t, 2H), 10.38 (s, 1H).
4: p-Bromo-N,N-dimethyl Aniline, m.p. 52 °C, IR
(paraffin): 2926, 2853, 1864, 1716, 1597, 1501, 1457, 1353,
1311, 1226, 1190, 1165, 1125, 1063, 947, 816 cm-1, 1H-NMR
(acetone-d6 / TMS): d 2.78 (s, 6H), 6.67-7.19 (dd, 4H).
5: p-Bromo-N,N-diethyl Aniline, b.p. 215 °C, IR
(neat): 2971, 2892, 1718, 1591, 1499, 1396, 1355, 1266,
1194, 1156, 1078, 1011, 920, 804 cm-1, 1H-NMR (acetone-d6 /
TMS): d 1.07 (t, 6H), 3.27 (q, 4H), 6.63-7.16 (dd, 4H).
6: p-Bromo Phenol, m.p. 70 °C, IR (paraffin): 3454,
3207, 2888, 1770, 1728, 1606, 1434, 1372, 1306, 1231, 1174,
1139, 1089, 1059, 968, 860, 817 cm-1, 1H-NMR (acetone-d6 /
TMS): d 6.86-7.22 (dd, 4H), 8.40 (br, 1H).
7) Aromatic rings containing the –NH2, -NHR, or -NR2
group do not undergo classical bromination, partly because
the strongly basic nitrogen ties up the Lewis acid needed for
ionization of the bromine molecule, whereas by our method,
these types of compounds are brominated selectively.
8) The starting material is recovered easily and can be
reused many times without reducing the yield.
EXPERIMENTAL SECTION
IR and 1H-NMR spectra were recorded using a Shimadzu
435-U-04 spectrophotometer (KBr pellets) and a 90 MHz
Jeol FT-NMR spectrometer, respectively. 1H-NMR chemical
shifts were measured relative to TMS (int; 1H).
7: 3-Bromo Para-N,N-Dimethyl-Amino benzalde-
hyde, m.p. 70 °C, IR (paraffin): 2923, 2853, 1749, 1661,
1601, 1530, 1457, 1375, 1231, 1164, 1065, 937, 812 cm-1,
1H-NMR (acetone-d6 / TMS): d 3.05 (s, 6H), 6.70- 6.80 (d,
1H), 7.61-7.80 (t, 2H), 9.68 (s, 1H).
Regioselective Synthesis of para Bromo-N,N-dimethyl-
aniline; Typical Procedure
8: p-Bromo Benzamide, m.p. 191 °C, IR (NUJOL
MULL): 3480, 3000, 1690, 1400, 1200, 1100, 1050, 840
cm-1, 1H-NMR (DMSO-d6 / D2O): d 7.51-7.94 (q, 4H).
9: 1-Bromo Naphthalene, m.p. 50 °C, IR (paraffin):
3190, 2925, 2855, 1774, 1728, 1604, 1463, 1377, 1307, 1289,
In a 250 mL round-bottomed flask, 6.55 g (29 mmol) of
N-bromophthalimide and 30 mL of Et2O were placed. The
flask was cooled in ice-water and added, with stirring, 3.68
mL (29 mmol) of N,N-dimethylaniline dropwise. The mix-
ture was stirred for 10 minutes at room temperature. Then the
flask was cooled; by this time all of the solid should have
risen to the surface of the liquid. The phthalimide was filtered
under suction. The solvent was removed on a water bath, and
the para bromo-N,N-dimethylaniline was collected as a sin-
gle product. The yield of product, m.p. 53-54 °C, was 5.22 g
(90%).
1141, 1093, 1052, 903, 863 cm-1, H-NMR (acetone-d6 /
1
TMS): d 7.18-7.71 (m, 6H).
10: 4-Bromo-1-Naphthylamine, m.p. 101 °C, IR
(NUJOL MULL): 3300, 1720, 1530, 1480, 1330, 1050, 920,
810 cm-1, 1H-NMR (acetone-d6 / TMS): d 3.90 (br, 2H), 6.43-
8.35 (m, 6H).
11: 9-Bromo Anthracene, m.p. 97 °C, IR (paraffin):
3049, 2964, 2861, 1678, 1623, 1525, 1454, 1378, 1310, 1260,
1151, 1012, 952, 920, 884, 838, 808 cm-1, H-NMR (ace-
All of the bromo products were characterized by their
physical constants, comparison with authentic samples, and
by their IR and NMR spectra.13
1
tone-d6 / TMS): d 7.59-8.49 (m, 9H).
Received November 19, 2004.
REFERENCES
DATA OF THE PRODUCTS
1: p-Bromo Anisole, b.p. 217 °C, IR (neat): 3107,
1713, 1591, 1490, 1356, 1218, 1092, 1013, 968, 908, 832
cm-1, 1H-NMR (acetone-d6 / TMS): d 3.64 (s, 3H), 6.74- 7.26
(dd, 4H).
1. Muathen, H. A. J. Org. Chem. 1992, 57, 2740.
2. Katritzky, A. R.; Li, J.; Stevens, C. V.; Ager, D. J. Org. Prep.
Proced. Int. 1994, 26, 439.
3. Conte, V.; Difuria, F.; Moro, S. Tetrahedron Lett. 1994, 35,
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4. Dinesh, C. U.; Kumar, R.; Pandey, B. J. Chem. Soc., Chem.
Commun. 1995, 611.
5. Smith, K.; Bahzad, D. Chem. Commun. 1996, 467.
2: p-Bromo Acetanilide, m.p. 173 °C, IR (paraffin):
3304, 3192, 2855, 1670, 1603, 1536, 1465, 1372, 1313, 1259,
1041, 966, 825 cm-1, 1H-NMR (acetone-d6 / TMS): d 2.08 (s,
3H), 7.47 (q, 4H), 9.31 (br, 1H).
3: 5-Bromo orthoanisaldehyde, m.p. 120 °C, IR (par-
affin): 3076, 2843, 1732, 1599, 1483, 1393, 1287, 1246,