PAPER
Nitroso Benzenes and Nitro Benzenes by Oxidation of Anilines
709
1H NMR (CDCl3): d = 7.86 (dm, H-3, H-5), 7.60 (dm, H-2, H-6,
J = 8.6 Hz).
carried out as above; crude and recrystallised yields are given in
Table 1.
2-Chloro-5-nitrosotoluene (2b)
1-Nitro-4-nitrosobenzene (2j)10,23
Yellowish crystals; mp 84–87 °C (MeOH) {lit.23 73–74 °C
(EtOH)}.
Mp 128–130 °C (EtOH) (lit.23 128–130 °C; lit.24 118.5–119 °C).
2-Nitro-5-nitrosotoluene (2k)
1H NMR (CDCl3): d = 2.53 (s, Me-1), 7.59 (d, H-3, J3,4 = 8.3 Hz),
7.68 (dd, H-4, J4,6 = 2.0 Hz), 7.79 (d, H-6).
13C NMR (CDCl3): d = 20.1 (Me-1), 119.3 (C-4), 123.4 (C-6), 130.0
(C-3), 137.7 (C-1), 141.6 (C-2), 164.1 (C-5).
The same procedure as above 1k (1.52g, 10 mmol), MeOH (3 mL),
H2O2 (15 mL, 0.11 mol, 11 equiv) and MoO3 (0.144 g, 1 mmol), 7
d; mp 112–114 °C (EtOH) (lit.24 113 °C).
IR (KBr): 3100, 1610, 1575, 1515, 1345, 1308, 1255, 840, 825
cm–1.
1H NMR (CDCl3): d = 2.74 (s, Me-1), 7.74 (dd, H-4, J3,4 = 8.5 Hz),
7.98 (d, H-6, J4,6 = 2.0 Hz.), 8.13 (d, H-3).
13C NMR (CDCl3): d = 20.0 (Me-1), 117.7 (C-4), 125.8, 126.0 (C-
3,C-6), 135.4 (C-1), 152.3 (C-2), 162.1 (C-5).
1-Bromo-4-nitrosobenzene (2c)
Yellowish crystals; mp 98–100 °C (EtOH) (lit.24 95 °C).
IR (KBr): 3085, 1575, 1475, 1400, 1283, 1253, 1100, 1063, 1010,
853, 805, 705 cm–1.
1H NMR (CDCl3): d = 7.78 (s, 4 H).
13C NMR (CDCl3): d = 122.1 (C-3, C-5), 132.7 (C-2, C-6), 131.7
(C-1); 163.8 (C-4).
Oxidation to Nitro Derivatives 3a,d,j; General Procedure
Oxidation of Nitroso Compounds 2a,d,j
To a stirred suspension at 60 °C of 2a,d,j (10 mmol) in MeOH (7.5
mL) were added H2O2 (5.5 mL, 41 mmol, 4 equiv) and
(NH4)6Mo7O24·4H2O (0.178 g, 1 mmol MoO3). The reaction was
monitored by 1H NMR (CDCl3) and after the given time (see
Table 2) the suspension was diluted with H2O (10 mL), chilled and
(except for 3d, see below) filtered, the solid 3 was washed with H2O
and dried over P2O5 (for yields see Table 2).
Nitrosobenzene (2d)10,26
Reaction at 0 °C; yellowish crystals; mp 76–80 °C (MeOH) (lit.24
67.5–68 °C).
IR,1H NMR and 13C NMR (CDCl3) agreed with the literature.
4-Nitrosotoluene (2e)10
Reaction at 0 °C; yellowish crystals; mp 58–60 °C (lit.24 48.5 °C,
lit.10 47–49 °C).
Oxidation of Anilines 1a,d,j
To a stirred solution of anilines 1a,d,j (10 mmol) in MeOH (10.5
IR (KBr): 3030, 1595, 1500, 1295, 1250, 1160, 1115, 1018, 860,
820, 815, 758 cm–1.
mL) were added H2O2 (8 mL, 60 mmol,
6 equiv) and
(NH4)6Mo7O24·4H2O (0.178 g, 1 mmol MoO3). The solution was
stirred at 20 °C for 1a, 0 °C for 1d, 25 °C for 1f for the given time,
then heated at 60 °C for 6–24 h (see Table 3). Same work-up as
above (for yields see Table 3).
4-Benzoylnitrosobenzene (2f)
Yellowish crystals; mp 120–122 °C (EtOH).
IR (KBr): 3100, 3050, 1645, 1592, 1524, 1403, 1314, 1302, 1276,
1260, 1105, 940, 923, 876, 870, 822, 788, 740, 695, 685 cm–1.
1H NMR (CDCl3): d = 7.53 (tm, 2 H, Arm, Jo,m = 7.4 Hz ), 7.66 (tm,
H, Arp, Jm,p = 7.6 Hz), 7.83 (dm, 2 H, Aro), 8.00, 8.02 (2 d, H-2, H-
6, H-3, H-5, J2,3 = 8.8 Hz).
13C NMR (CDCl3): d = 120.4 (C-3, C-5), 128.6 (2 Cm), 130.1, 131,0
(2 Co, C-2,C-6), 133.3 (Cp), 136.5 (C), 142.7 (C-1), 164.0 (C-4),
195.5 (CO).
4-Chloronitrobenzene (3a)26
Pale yellow crystals; mp 81–82 °C (lit.24 83–84 °C).
Nitrobenzene (3d)28
The dark organic phase was separated, the aqueous phase was dilut-
ed with H2O (10 mL) and extracted with CH2Cl2 (3 × 1 mL), organ-
ic phases were combined and distilled to give 3d.
Yellow oil; Eb6 68 °C (lit.24 Eb10 85 °C); nD20 1.5518 (lit.24 1.5530).
Anal Calcd for C13H9NO2 (211.22): C, 73.92; H, 4.30; N, 6.63.
Found: C, 73.6; H, 4.1; N, 6.8.
4-Dinitrobenzene (3j)13a,26,28
Crude product isolated as yellow crystals (83–85%) containing 5%
of tetranitroazoxybenzene (Method 1) and 11% (Method 2), which
was purified by sublimation (130 °C, 4–10 Torr, 2 h, containing 2%
azoxyderivative).
Methyl 4-nitrosobenzoate (2g)23,27
After 24 h, MeOH (6 mL) and H2O (4 mL) were added; yellowish
crystals; mp 145–150 °C (EtOAc) (lit.23 130 °C, lit.24 128.5–
129.5 °C)
Pale yellow crystals; mp 172–174 °C (lit.24 173–174 °C).
4-Nitrosoanisole (2h)23
Reaction carried out at 0 °C in two phases with addition of hexane
(20 mL) for 16 h. The hexane phase was decanted and the aqueous
phase extracted with hexane (4 × 20 mL), the combined hexane
phases were evaporated at 30 °C and the resulting green resin (0.97
g, 63%) recrystallised from hexane at –30 °C; green crystals;
mp 20–21 °C (hexane) (lit.23 22 °C, lit.24 23 °C).
Acknowledgement
The support of the Centre National de la Recherche Scientifique
(UMR-7015) is gratefully acknowledged. We thank also Prof. J.
Streith for his interest in this work and the diploma student Isabelle
Guy for her cooperation.
13C NMR (CDCl3): d = 55.9 (OMe-1), 113.8 (C-2, C-6), 124.2 (C-
3, C-5), 164.0, 165.6 (C-4), C-1).
References
Nitronitrosobenzenes 2j,k; Typical Procedure
(1) Seidenfaden, W. In Houben–Weyl, Methoden der
organischen Chemie, 4th ed., Vol 10/1; Müller, E., Ed.;
Thieme: Stuttgart, 1971, 1053–1058.
(2) Langley, W. D. In Org. Synth., Coll. Vol. 3; Horning, E. C.,
Ed.; Wiley & Sons: New York, 1955, 334–336.
To a stirred suspension of 1j (1.38 g, 10 mmol) in MeOH (3 mL) at
25 °C were added H2O2 (10 mL, 75 mmol, 7.5 equiv) and MoO3
(0.144 g, 1 mmol). After 2.5–3 d the ochre suspension was diluted
with MeOH (3 mL) and H2O (2 mL); after 10 d the work-up was
Synthesis 2004, No. 5, 706–710 © Thieme Stuttgart · New York