JOURNAL OF CHEMICAL RESEARCH 2015 103
The organic layer was separated, dried over MgSO4, filtered and
concentrated under reduced pressure. Part of the product was purified
by chromatography on silica gel. Elution with ether:light petroleum
ether 40–60 (25:75) gave the title compound (350 mg, 4%) as a yellow
solid, m.p. 138–139 °C (from ether/light petroleum ether 40–60). λmax
(EtOH)/nm 414 (log ε 4.24) and 276 (4.17); νmax(KBr disc) 3275w,
1617m, 1562m, 1532m, 1486s, 1267s, 1179s, 1153s, 908m, 810m,
764s, 742s, 605s, 572s, 500s and 548m; δH(400 MHz; CDCl3) 2.90
(6H, s), 6.15–6.19 (2H, m), 7.19 (1H, t, J=8.0 and 7.8), 7.30 (2H, d,
J=8.0), 7.39 (2H, t, J=6.8 and 6.8), 8.10 (1H, d, J=9.6) and 9.92 (1H,
s); δC(100.1 MHz; CDCl3) 40.1, 93.2, 104.4, 124.3, 125.2, 128.9, 129.6,
139.2, 145.4 and 155.0 (one peak is missing), m/z (orbitrap ASAP)
258.1237 (M+ +H, 100%) C14H16N3O2 requires 258.1237. When crystals
were being selected for X-ray data collection, the title compound
(as orange plates) and a trace amount of 2,4-bis(phenylamino)
nitrobenzene 4a, as yellow needles (m.p. 146–147°C), were apparent.
2,4-Bis(Phenylamino)nitrobenzene (4b): 2,4-Difluoronitrobenzene
(1.0 g, 6.29 mmol) in aniline (20 mL) was refluxed for 24 h. After
cooling, ether (100 mL) was added and the mixture was extracted with
aqueous HCl (20 mL cHCl:40 mL H2O) to remove excess aniline. The
ether layer was dried over MgSO4 and concentrated under reduced
pressure. The product was purified by chromatography on silica
gel. Ether:light petroleum ether 40–60 (25:75) eluted the main
yellow band contaminated with a red band. The product mixture was
concentrated under reduced pressure to a dark solid and extracted
with ether (30 mL×ꢀ3). This extract was concentrated to a solid under
reduced pressure and then extracted with petroleum ether 40–60
(30 mL×ꢀ3). This extract was concentrated under reduced pressure
to give the title compound (80 mg, 4%) as a fawn (glistening brown/
yellow solid, m.p. 169–170 °C (from ether/light petroleum ether
40–60). Only a small amount of the product was purified. λmax (EtOH)/
nm 410 (log ε 3.97) and 265 (3.77); νmax (KBr disc) 3315w, 3046w,
1621w, 1585s, 1574s, 1537s, 1495s, 1470s, 1408w, 1303w, 1282s, 1205s,
1151s, 816w, 750s, 686s, 583s and 501s; δH(400 MHz; CDCl3) 6.26 (1H,
d, J=6.0), 6.49 (1H, d, J=1.2), 7.01–7.04 (3H, m), 7.11 (1H, t, J=8.4 and
8.0), 7.18–7.19 (2H, m), 7.22 (2H, t, J=5.0 and 5.2), 7.30 (2H, t, J=6.0
and 5.2), 8.05 (1H, d, J=8.0) and 9.77 (1H, s); δC(100.1 MHz; CDCl3)
96.6, 106.6, 121.8, 124.4, 124.6, 125.5, 129.3, 129.5, 129.5, 138.7, 139.3,
145.7 and 150.8; (one peak is missing) m/z (orbitrap ASAP) 306.1236
(M+ +H, 100%) C18H16N3O2 requires 306.1237.
4-Amino-2-(phenylamino)nitrobenzene (5): 2,4-Difluoronitrobenzene
(0.500 g, 3.14 mmol) and aniline (585 mg, 6.2 mmol) in EtOH (8 mL)
were heated in a Teflon-lined Parr digestion bomb at 150 °C for
8 h. After cooling, the ethanol was removed by pipette then EtOH
(4 mL) and cNH3/H2O (4 mL) was added. After sealing, the mixture
was heated at 150 °C for 15 h. On cooling the mixture was mixed
with DCM (50 mL) and extracted with H2O (50 mL), then dried
over MgSO4, concentrated under reduced pressure and purified by
chromatography on silica gel. Elution with ether:light petroleum
ether 40–60 (25:75) gave the title compound (325 mg, 45%) as orange
blocks, m.p. 123–124 °C (from ether/light petroleum ether 40–60).
λmax (EtOH)/nm 398 (log ε 4.05) and 277 (3.85); νmax (KBr disc) 3467w,
3433w, 3381w, 3346w, 3231w, 1612s, 1589s, 1561s, 1492vs, 1415s,
1273s, 1255s, 1214s, 1164s, 801s, 751vs, 690vs and 562s; δH(400 MHz;
CDCl3) 3.90–4.45 (2H, s), 6.04 (1H, dd, J=9.6 and 2.4), 6.19 (1H, d,
J=2.4), 7.21 (1H, t, J=7.4 and 7.6), 7.25 (2H, d, J=5.6), 7.39 (2H, t,
J=7.8 and 7.2), 8.05 (1H, d, J=9.2) and 9.83 (1H, s); δC(100.1 MHz;
CDCl3) 95.8, 106.8, 125.0, 125.3, 125.7, 129.5, 129.6, 138.7, 146.1
and 153.7; m/z (orbitrap ASAP) 230.0920 (M+ +H, 100%) C12H12N3O2
requires 230.0924. Fine yellow needles (3 mg, 0.3%) of compound 4a
were characterised by an X-ray single crystal structure determination,
and had an identical unit cell to the material found as an impurity in
compound 3.
sealing, the mixture was heated at 150 °C for 15 h. On cooling the
mixture was mixed with DCM (50 mL), extracted with H2O (50 mL),
then dried over MgSO4, concentrated under reduced pressure and
purified by chromatography on silica gel. Elution with ether:light
petroleum ether 40–60 (25:75) gave the title compound (590 mg, 66%)
as a yellow solid, m.p. 75–76 °C (from ether/light petroleum ether
40–60). λmax (EtOH)/nm 409 (log ε 4.42) and 276 (4.18); νmax (KBr disc)
3419w, 3329w, 1626m, 1613m, 1558m, 1411m, 1352m, 1262s, 1164s,
1105s, 962s, 804s, 756s, 548vs and 527vs; δH(400 MHz; CDCl3) 0.90
(3H, t, J=7.2), 1.34 (2H, s, J=7.2), 1.55 (2H, p, J=7.6), 3.04 (2H, t,
J=6.8), 6.03 (1H, d, J=10.0), 6.12 (1H, s), 7.20 (1H, t, J=6.4 and 6.8),
7.27 (2H, t, J=6.8 and 6.0), 7.40 (2H, t, J=6.8 and 6.4), 8.05 (1H, d,
J=9.6) and 9.97 (1H, s); δC(100.1 MHz; CDCl3) 13.7, 20.1, 31.0, 43.0,
92.8, 106.1, 124.7, 125.4, 129.2, 129.6, 138.9, 146.2 and 154.1 (one peak
is missing); m/z (orbitrap ASAP) 286.1552 (M+ +H, 100%) C16H20N3O2
requires 286.1550.
4-Benzylamino-2-(phenylamino)nitrobenzene (7): 2,4-Difluoro-
nitrobenzene (0.5 g, 3.14 mmol) and aniline (585 mg, 6.2 mmol) in
EtOH (8 mL) were heated in a Teflon-lined Parr digestion bomb at
150 °C for 8 h. After cooling, the EtOH was removed by pipette and
then EtOH (4 mL) and benzylamine (672 mg, 6.28 mmol) were added.
After sealing, the mixture was heated at 150 °C for 15 h. On cooling
the mixture was mixed with DCM (50 mL) and extracted with H2O
(50 mL), then dried over MgSO4, concentrated under reduced pressure
and purified by chromatography on silica gel. Elution with ether:light
petroleum ether 40–60 (25:75) gave the title compound (621 mg,
62%), as golden plates, m.p. 168–169 °C (from ether/light petroleum
ether 40–60). λmax (CH2Cl2)/nm 384 (log ε 4.08) and 281 (3.97); νmax
(KBr disc) 3316s, 1618s, 1592s, 1577s, 1504s, 1493s, 1408w, 1323s,
1271s, 1215s, 1139vs, 816s, 746s, 695s, 687s, 639m, 613m, 587s,
566s, 545s, 501s and 452s; δH(400 MHz; CDCl3) 4.27 (2H, s), 4.8–5.1
(1H, s, br), 6.09 (1H, s), 7.10 (2H, d, J=7.6), 7.17 (1H, t, J=7.4), 7.22
(2H, d, J=7.2), 7.27–7.34 (6H, m), 8.06 (1H, d, J=8.4) and 9.97 (1H,
s); δC(100.1 MHz; CDCl3) 47.3, 93.3, 106.1, 124.4, 125.2, 127.2, 127.7,
128.9, 129.1, 129.5, 137.4, 138.8, 145.9 and 153.7 (one peak is missing);
m/z (orbitrap ASAP) 320.1391 (M+ +H, 100%) C19H18N3O2 requires
320.1394.
2,4-Bis(butylamino)nitrobenzene (8): 2,4-Difluoronitrobenzene
(0.5 g, 3.14 mmol) and butylamine (1.0 mL) in EtOH (8 mL) were
sealed in a Teflon-lined Parr bomb and heated at 150 °C for 15 h. On
cooling, the mixture was mixed with DCM (50 mL), extracted with
H2O (50 mL), then dried over MgSO4, concentrated under reduced
pressure and purified by chromatography on silica gel. Elution with
ether:light petroleum ether 40–60 (25:75) gave the title compound
(757 mg, 84%) as a yellow solid, m.p. 58–59 °C (from ether/light
petroleum ether 40–60). λmax (EtOH)/nm 409 (log ε 4.19) and 268
(3.33); νmax (KBr disc) 3316w, 2860w, 2956w, 2929w, 1616vs, 1579s,
1543s, 1460m, 1399m, 1252vs, 1165vs, 1129vs, 819vs, 786m, 750s,
669m, 651m, 589s and 561s; δH(400 MHz; CDCl3) 0.66–0.71 (6H,
m), 1.12–1.21 (4H, m), 1.31–1.45 (4H, m), 2.89 (2H, t, J=7.2 and 7.2),
2.94 (2H, t, J=7.2 and 7.2), 4.30–4.70 (1H, s, br), 5.35 (1H, d, J=2.0),
5.64 (1H, dd, J=9.2 and 2.4), 7.70 (1H, d, J=9.6) and 8.25 (1H, s, br);
δC(100.1 MHz; CDCl3) 13.8, 20.2, 20.3, 30.8, 31.0, 42.6, 43.0, 89.9,
105.1, 123.4, 129.1, 148.7 and 154.5 (one methyl group is missing);
m/z (orbitrap ASAP) 266.1863 (M+ +H, 100%), C14H24N3O2 requires
266.1863.
We thank the EPSRC National Mass Spectrometry Service
Centre (University of Swansea) for the high-resolution mass
spectra and the EPSRC National Crystallography Service
(University of Southampton) for the X-ray data collections.
4-Butylamino-2-(phenylamino)nitrobenzene (6): 2,4-Difluoro-
nitrobenzene (0.5 g, 3.14 mmol) and aniline (585 mg, 6.2 mmol) in
EtOH (8 mL) were heated in a Teflon-lined Parr digestion bomb at
150 °C for 8 h. After cooling, the EtOH was removed by pipette. Then
EtOH (4 mL) was added and an excess of butylamine (1.0 mL). After
Received 27 December 2014; accepted 10 January 2015
Paper 1403109 doi: 10.3184/174751915X14223549608222
Published online: 13 February 2015