JOURNAL OF CHEMICAL RESEARCH 2011 309
was heated to 75 °C with stirring to dissolve compound 6 then treated
with 1.34 equivalents of potassium dichromate (535 mg, 1.82 mmol)
and heated for a further 2–3 h. The reaction mixture turned red. The
mixture was cooled, filtered through a fine No 4 sinter then washed
with water. The precipitated material was extracted by agitation using
a spatula on the sinter 6–7 times or more with small quantities of
methanol. These washings were combined then concentrated and col-
umned on conventional flash silica. The column is run with a fume
hood on. Methanol elutes front running brown material and allows the
compound to be loaded onto the column with a number of washings
from a flask. 20% aqNH3/MeOH (prepared from concentrated aque-
ous NH3 and MeOH) firstly elutes a blue layer. This is followed by a
long purple band of the title compound (25 mg, 5 %) as a purple solid
with golden sheen, m.p. > 220 °C; λmax (ethanol)/nm 225 (log ε 4.7),
280 (4.7) and 552 (4.75); νmax (KBr)/cm-1 2700–3500br, 1600s, 1500s,
1380s, 1350s, 1320s, 1190s, 1020–1120br, 880m, 830m, 750m, 700m,
680w, 610m and 500w; δH(400 MHz; CDCl3) 5.90 (1H, d, J = 1.6),
6.20 (1H, d, J = 1.6), 7.02 (1H, m), 7.05 (2H, d, J = 7.4), 7.20 (3H, m),
7.35 (1H, m), 7.41 (2H, d, J = 7.4), 7.65 (1H, d, J = 7.4), 7.71 (2H, m),
7.79 (1H, d, J = 9) and 7.86 (1H, d, J = 9.4); δC(100.1 MHz; CDCl3)
93.2, 93.7, 120.3, 121.7, 121.8, 125.0, 127.2, 129.0, 130.6, 131.0,
133.0, 133.7, 135.9, 136.1, 136.4, 137.2, 137.5, 138.4, 152.5 and
158.1; m/z (Orbitrap ASAP) 363.1601 (M) C24H19N4 requires
363.1604.
3-Phenylamino-5-(o-toluyl)-7-amino-8-methylphenazinium sulfate
(11): N-Phenyl-p-phenylenediamine 9 (250 mg, 1.36 mmol) and two
equivalents of o-toluidine (291 mg, 2.72 mmol) were added to water
(250 mL) treated with a small amount of concentrated sulfuric acid
(five drops, 0.25 mL). The mixture was heated to 75 °C with stirring
to dissolve compound 1 then treated with 1.34 equiv. of potassium
dichromate (535 mg, 1.82 mmol, 1.34 equiv.) and heated for a further
2–3 h. The reaction mixture turned red. The mixture was cooled,
filtered through a fine No 4 sinter and then washed with water. The
precipitated material was extracted on the sinter 6–7 times or more
with small quantities of methanol. These washings were combined
then concentrated and columned on conventional flash silica. The
column is run with a fume hood on. Methanol elutes front running
brown material and allows the compound to be loaded onto the
column with a number of washings from a flask. 20% aqNH3/MeOH
(prepared from concentrated aqNH3 and MeOH) firstly elutes a blue
band. This is followed by a long purple band of the title compound
(34 mg, 6 %) as a purple solid with golden sheen, m.p. > 220 °C;
λmax (ethanol)/nm 229 (log ε 4.29), 280 (log ε 4.50), 554 (4.60); νmax
(KBr)/cm−1 3000–3500vs, 1620s, 1580s, 1540s, 1500s, 1460s, 1350s,
1320s, 1190s, 1130s, 830w, 750w, 700w and 620w; δH(400 MHz;
CDCl3) 1.90 (3H, s), 2.38 (3H, s), 6.06 (1H, s), 6.29 (1H, d, J = 1.6),
7.14 (3H, d, J = 8.22), 7.32–7.27 (3H, m), 7.40 (1H, d, J = 7.04), 7.50
(1H, m), 7.65 (2H, d, J = 3.91), 7.84 (1H, s), 8.00 (1H, d, J = 9.00);
δC(100.1 MHz; CDCl3) 15.4, 16.2, 92.9, 93.1, 120.4, 121.8,121.9,
125.2, 127.3, 128.8, 129.2, 131.1, 132.4, 132.5, 133.2, 135.0, 135.4,
135.5, 136.1, 137.9, 138.6, 152.6 and 158.3 (one CH resonance is
missing); m/z (Orbitrap ASAP) 391.1925 (M+) C26H23N4 requires
391.1917.
aniline was not available to react). The spectroscopic properties were
identical with those of published material (checked by 1H NMR).
Aniline (2 mL, 0.0215 mol) and aniline sulfate (0.5 g, 1.76 mmol)
were sealed in a 23 mL PTFE Parr digestion bomb and heated at
220 °C for 48 h. After work up the title compound was obtained
(294 mg, 16%) from 2 mL of aniline.
Aniline (1 mL, 0.011 mol), o-toluidine (1 mL, 0.009 mol) and ani-
line hydrochloride (1 g, 0.0077 mol) were sealed in a 23 mL PTFE
Parr digestion bomb and heated at 220 °C for 48 h. After work up
diphenylamine was obtained (427 mg, 47%) from 1 mL of aniline.
We are grateful to the EPSRC mass spectrometry service
centre for mass spectra and to the editor and referee’s for
carefully checking this manuscript.
Received 10 March 2011; accepted 23 April 2011
Paper 1100614 doi: 10.3184/174751911X13052165053977
Published online: 1 June 2011
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Diphenyl amine (7);36 general procedure: Aniline (10 mL,
0.108 mol) and aniline hydrochloride (5.0 g, 0.039 mol) were sealed
in a 45 mL PTFE Parr digestion bomb and heated at 220 °C for 48 h.
TLC analysis showed a clean reaction which had not yet gone to
completion. After cooling the mixture was suspended in CH2Cl2 and
extracted with dilHCl (x2) which removes remaining aniline. The
organic layer was dried with MgSO4 and filtered through a small pad
of silica. This was effective in removing baseline impurities. The solu-
tion was concentrated under reduced pressure to an oil which quickly
crystallised to give the title compound as a pale yellow solid (3.7 g,
40%) from 10 mL of aniline(assuming that the hydrochloride salt of