G Model
CRAS2C-3754; No. of Pages 9
8
D. Habibi, M. Nasrollahzadeh / C. R. Chimie xxx (2013) xxx–xxx
was controlled by addition or removal of water from the
ultrasonic bath. The temperature of the water bath was
controlled at about 25–30 8C.
4.5.4. N-(4-Chlorophenyl) formamide
Mp 100–102 8C (lit. [32] 99.8–101.1 8C); H NMR
(300 MHz, CDCl ): 7.02–7.67 (m, 4H), 8.34 (s, 1H),
.65 (s, 1H) (Table 2, entry 6).
1
3
d
H
8
4.2. Caution
4
.5.5. N-(4-Bromophenyl) formamide
Mp 116–118 8C (lit. [Aldrich] 117–121 8C); H NMR
(90 MHz, CDCl ): 6.31 (s, 1H), 6.52–7.46 (m, 4H), 8.61 (s,
1H) (Table 2, entry 7).
1
Although formic acid is often used as a source for a
formyl group and hydride ion in organic synthesis, it is
nonetheless toxic material and appropriate safety
precautions should be taken.
3 H
d
a
4
.5.6. N-(2,5-dichlorophenyl) formamide
À1
4.3. General experimental procedure for the synthesis of N-
Mp 148–151 8C; FTIR (Nujol, cm ): 3240, 2888, 1707,
phenyl formamide (the mole ratio of amine to HCOOH, 1:1)
1673, 1588, 1527, 1447, 1416, 1278, 1262, 1150, 1124, 1093,
1
1
049, 906, 872, 829, 799, 736; H NMR (300 MHz, CDCl
9.70 (d, 1H), 8.52(s, 1H), 7.75(s, 1H), 7.32(d, 1H, J = 8.3), 7.07
(d, 1H, J = 8.4); Anal. calcd for C NOCl : C, 44.24; H, 2.62;
3 H
): d
A mixture of formic acid (1 mM) and aniline (1 mM) was
irradiated by ultrasound for 5 h at room temperature
H
7 5
2
(Table 1). During stirring, a white crystalline solid was
N, 7.33. Found: C, 43.93; H, 2.53; N, 7.41 (Table 2, entry 8).
separated out. After completion (as monitored by TLC), the
solid was separated and characterized by NMR, FT-IR,
elemental analysis (CHN), and melting point measurement
4.5.7. N-(2-Methylphenyl) formamide
1
Mp 60–62 8C [37]; H NMR (90 MHz, acetone-d
6
):
d
H
(Table 2, entry 1).
8.41 (s, 1H), 7.95 (d, 1H), 6.98–7.29 (m, 4H), 2.29 (s, 3H)
Table 2, entry 9).
(
4.4. Typical procedure for the N-formylation of amines (the
mole ratio of amine to HCOOH, 1:2.5)
4.5.8. N-(4-Methylphenyl) formamide
1
Mp 52–54 8C (lit. [43] 50–54 8C); H NMR (300 MHz,
CDCl ): 2.29 (S, 3H), 6.98–8.32 (m, 4H), 8.62 (s, 1H), 8.89
A mixture of formic acid (2.5 mM) and amine (1 mM)
was irradiated by ultrasound for an appropriate time at
room temperature (Table 2). After completion (as mon-
3 H
d
(s, 1H) (Table 2, entry 10).
itored by TLC), H
2
O was added and the organic layer was
4.5.9. N-(2,4-Dimethylphenyl) formamide
extracted with EtOAc to afford the pure product (Table 2).
The physical data (mp, IR, NMR) of known compounds
were found to be identical to those reported in the
literature [19,26–42]. The formation of formamides was
confirmed by IR spectra, which showed two characteristic
Mp 114–118 8C (lit. [Aldrich] 114–118 8C); FTIR (KBr,
cm ): 3167, 3073, 2923, 2877, 1686, 1656, 1608, 1510,
À1
1469, 1375, 1314, 1256, 1217, 1121, 1036, 932, 900, 868,
1
828, 794, 721, 603; H NMR (300 MHz, DMSO-d
6
):
d
H
2.28
(s, 3H), 2.29 (s, 3H), 7.66 (d, 1H, J = 8.7), 8.43 (d, 1H, J = 15.5)
(Table 2, entry 11).
À1
peaks, one between 3300 and 3400 cm (secondary NH)
À1
and the other between 1640 and 1680 cm (N-formyl,
1
C5O). The H NMR spectra of the N-formamides showed
4.5.10. N-(4-Acetylphenyl) formamide
1
one amide NH proton signal and another the signal of the
aldehyde proton.
Mp 104–107 8C [37,40]; H NMR (90 MHz, acetone-d
6
):
H
d 2.42 (s, 3H), 7.65 (d, J = 8.8 Hz, 2H), 7.86 (d, J = 9.0 Hz,
2H), 8.32 (s, 1H), 9.42 (s, 1H) (Table 2, entry 13).
1
13
The elemental analysis (CHN), IR, H NMR and C NMR
data of the unknown formamides (Table 2, entries 8 and
1
1
4) and H NMR data of the known compounds (Table 2,
4.5.11. N-(3-fluorophenyl) formamide
À1
entries 1–7, 9–13 and 15–21) are given below.
Mp 59–61 8C; FTIR (KBr, cm ): 3279, 3221, 3163, 3092,
3055, 3010, 2881, 1693, 1675, 1608, 1560, 1486, 1452,
4.5. Spectral data of some compounds
1400, 1339, 1319, 1283, 1260, 1180, 1151, 1125, 1069,
1
1000, 975, 911, 892, 818, 797, 736, 694, 655; H NMR
4
.5.1. N-Phenyl formamide
(90 MHz, CDCl ): 7.42–8.33 (m, 4H), 8.89 (d, 1H,
J = 10.6), 10.49 (s, 1H) (Table 2, entry 14).
3
d
H
1
Mp 46–48 8C (lit. [32] 46.3–47.8 8C); H NMR (90 MHz,
CDCl ): 7.61–7.12 (m, 5H), 8.29 (s, 1H, cis), 8.66 (d, 1H,
3
d
H
trans), 8.99 (brs, 1H, cis), 9.38 (brs, 1H, trans) (Table 2,
entry 1).
4.5.12. 4-Phenylpiperazine-1-carbaldehyde
À1
Mp 82–84 8C; FTIR (KBr, cm ): 2916, 2814, 1654, 1632,
1599, 1499, 1447, 1405, 1385, 1366, 1350, 1334, 1283,
4
.5.2. N-(2-Chlorophenyl) formamide
1254, 1239, 1197, 1149, 1092, 1057, 1033, 1007, 916, 766,
1
1
Mp 76–80 8C (lit. [Aldrich] 76–80 8C); H NMR (90 MHz,
693; H NMR (300 MHz, CDCl
1H), 6.92–7.33 (m, 5H, Ar–H), 3.72–3.16 (m, 8H); C NMR
(500 MHz, CDCl ): 161.2, 151.4, 129.7, 121.4, 117.6,
0.9, 49.8, 46.0, 40.4 (Table 2, entry 16).
3 H
): d 10.35 (s, 1H), 8.55 (s,
1
3
6 H
acetone-d ): d 6.95–8.36 (m, 5H), 8.93 (s, 1H) (Table 2,
entry 2).
3
d
C
5
4
.5.3. N-(4-Nitrophenyl) formamide
Mp 196–197 8C (lit. [41] 194–195 8C); H NMR (90 MHz,
acetone-d ): 7.91 (d, J = 8.7 Hz, 2H), 8.25 (d, J = 9.0 Hz,
H), 8.49 (s, 1H), 9.77 (s, 1H) (Table 2, entry 3).
1
4.5.13. N-Benzyl formamide
Mp 60–62 8C (lit. [38] 60–62 8C); H NMR (90 MHz,
CDCl ): 6.86–8.52 (m, 4H), 9.29 (s, 1H) (Table 2, entry 17).
1
6
d
H
2
3 H
d
Please cite this article in press as: Habibi D, Nasrollahzadeh M. An ultrasound-promoted green approach for the N-