L. Forlani et al.
FULL PAPER
2-Pyridinyl 2,4,6-Trinitrophenyl Ether (11):[18] M.p. 129Ϫ130 °C
(from methanol). Ϫ 13C NMR (75.46 MHz, [D6]DMSO): δ ϭ
111.2, 121.2, 125.1, 141.9, 143.5, 143.8, 144.2, 147.0, 160.6;
(CDCl3): δ ϭ 111.3, 120.8, 124.3, 141.0, 143.1, 144.9, 145.4,
146.8, 160.7.
NMR spectra of crude products resulting from reactions between
all of the hydroxypyridines and 9 are identical to those of the eluted
products. However, the spectral data of 14, 15, and 16 are different
from those of the solid product crystallized from methanol or from
a THF/methanol mixture. All attempts to crystallize 14, 15, and 16
from a number of solvents (dichloromethane, diethyl ether, tetrahy-
drofuran, acetonitrile, light petroleum) failed. Ϫ The 1H NMR and
MS spectra of compounds 10 and 11 are as previously reported.[18]
The yield of 12 was 95%. Ϫ The structures of 12, 14, 15, 16, 18,
and 19 were assigned on the basis of 1H and 13C NMR spectral
data and by comparison with the data by von Philipsborn.[30] The
spectrum of the crude reaction product of 2 is identical to that of
the eluted product and to that after crystallization from MeOH. Ϫ
Under the experimental conditions used, compounds 10, 11, and
12 are stable. In particular, no conversion of 10 into 11 (or of 11
into 10) was observed, even after long reaction times, either in the
absence or in the presence of 1.
N-(2,4,6-Trinitrophenyl)-4-pyridone (12): M.p 174Ϫ176 °C (from
1
methanol). Ϫ H NMR (300 MHz, [D6]acetone): δ ϭ 6.47 (d, J ϭ
7.9 Hz, 2 H), 7.90 (d, J ϭ 7.9 Hz, 2 H), 9.51 (s, 2 H, Ph). Ϫ 13C
NMR (75.46 MHz, [D6]acetone): δ ϭ 119.9, 126.0, 135.2, 140.9,
149.1, 149.2, 178.7. Ϫ MS (EI); m/z (%): 306 [Mϩ] (1), 229 (5), 172
(54),144 (88), 117 (26), 90 (14), 78 (48), 51 (100).
3-Pyridinyl 2,4,6-Trinitrophenyl Ether (14): Oil. Ϫ 1H NMR
(300 MHz, [D6]DMSO): δ ϭ 7.58 (dd, J ϭ 4.3 Hz, J ϭ 4.9 Hz, 1
H, 5-H), 7.70Ϫ7.85 (m, 1 H, 4-H), 8.45Ϫ8.60 (m, 2 H, 2-H and 6-
H), 9.38 (s, 2 H, Ph). Ϫ 13C NMR (75.46 MHz, [D6]DMSO): δ ϭ
123.0, 124.7, 125.7, 137.8, 143.8, 144.3, 145.5 (2 signals overlap),
153.5. Ϫ MS (EI); m/z (%): 306 [Mϩ], 229 (100), 199 (10), 95 (31).
Reaction between the Sodium Salt of 3 and 9: NaH (0.060 g,
2.5 mmol) was added to a vigorously stirred solution of 3 (0.183 g,
1.9 mmol) in 10 mL of anhydrous THF. After 10 min, compound
9 (0.504 g, 1.9 mmol) was slowly added. After 10 min, the solvent
was removed under vacuum and after column chromatography an
oil was obtained. Addition of this oil to a solution of 14 did not
5-Chloro-3-pyridinyl 2,4,6-Trinitrophenyl Ether (15): M.p. 145Ϫ146
°C (from methanol). Ϫ 1H NMR (300 MHz, [D6]DMSO): δ ϭ
7.99Ϫ8.02 (m, 1 H, 4-H), 8.58Ϫ8.61 (m, 2 H, 2-H, 6-H), 9.40 (s, 2
H, Ph). Ϫ 13C NMR (75.46 MHz, [D6]DMSO): δ ϭ 107.37, 123.3,
126.3, 131.8, 136.9, 144.1, 144.2, 144.5, 154.0. Ϫ MS (EI); m/z (%):
342 (3), 340 (9), 139 (8), 128 (5), 112 (11), 102 (29), 100 (100). Ϫ
HRMS for C11H5ClN4O7: calcd. 339.9847; found 339.9853.
1
change its H NMR spectrum.
Kinetics: The choice of solvents was determined by the low solubil-
ity of hydroxypyridines in a number of solvents. Ϫ The reaction at
[9]o ϭ 10Ϫ4 mol dmϪ3 was carried out by monitoring the appear-
ance of the reaction products using UV/Vis spectrophotometry. In
the case of reactions of 1, the reactions were monitored at 3 differ-
ent λ values to determine the quantities of 9, 10, and 11 and to
check the analytical data, taking into account that [9] ϩ [10] ϩ
[11] ϭ [9]o. Ϫ λ values used in the spectrophotometric determina-
tions are as follows:
6-Methyl-3-pyridinyl 2,4,6-Trinitrophenyl Ether (16): M.p. 126Ϫ128
°C (crude product). Ϫ 1H NMR (300 MHz, [D6]DMSO): δ ϭ 2.55
(s, 3 H, Me), 7.39 (d, J ϭ 8.6 Hz, 1 H, 5-H), 7.57 (dd, J ϭ 8.6 Hz,
J ϭ 3.3 Hz, 1 H, 4-H), 8.39 (d, J ϭ3.3 Hz, 1 H, 2-H), 9.36 (s, 2 H,
Ph). Ϫ 13C NMR (75.46 MHz, [D6]DMSO): δ ϭ 23.1, 123.6, 124.1,
125.7, 136.7, 143.6, 143.8, 144.6, 151.7, 154.0. Ϫ MS (EI); m/z (%):
320 (5) [Mϩ], 229 (8), 109 (42), 108 (12), 91 (14), 80 (100). Ϫ
HRMS for C12H8N4O7: calcd. 320.0393; found 320.0387.
λ ϭ 360, ε ϭ 300, 1000, 700 for 9, 10, and 11, respectively;
λ ϭ 380, ε ϭ 130, 1000, 230 for 9, 10, and 11, respectively;
λ ϭ 400, ε ϭ 30, 850, 70 for 9, 10, and 11, respectively;
λ ϭ 360, ε ϭ 13.000 for 12.
3-Hydroxypyridinium Picrate: M.p. 202Ϫ203 °C. This product was
made by mixing a saturated (methanol) solution of picric acid with
a
solution of 3-hydroxypyridine. Ϫ
1H NMR (300 MHz,
[D6]DMSO): δ ϭ 7.90Ϫ8.10 (m, 2 H, 4-H and 5-H), 8.40Ϫ8.55 (m,
2 H, 2-H and 6-H), 8.70 (s, 2 H, Ph), 11.40Ϫ11.70 (br. s, 2 H, OH
and NH).
From the analytical data, kobs values were calculated, as an initial
rate, by using conventional procedures. Table 2 reports some se-
lected experimental data.
3-Hydroxy-1-methylpyridinium Picrate (18): M.p. 197Ϫ199 °C
(from methanol) ref.[53] 202Ϫ203.
Ϫ
1H NMR (300 MHz,
[D6]DMSO): δ ϭ 4.38 (s, 3 H, NϪCH3), 7.90Ϫ8.10 (m, 2 H, 4-H
and 5-H), 8.45Ϫ8.60 (m, 2 H, 2-H and 6-H), 8.68 (s, 2 H, Ph),
11.00Ϫ12.00 (br. s,
Table 2. Reactions between 1-chloro-2,4,6-trinitrobenzene (9) and
hydroxypyridines at 30 °C
1 H, OH). Ϫ
13C NMR (75.46 MHz,
[D6]DMSO): δ ϭ 47.8, 124.1, 125.1, 128.2, 130.8, 133.7, 136.4,
141.8, 156.6, 160.8. Ϫ C12H10N4O8 (338.2): calcd. C 42.61, H 2.98,
N 16.56; found C 42.55, H 3.02, N 16.50. Ϫ λ ϭ 360, ε ϭ 13.000.
[2P]o ϫ 103 [mol dmϪ3 [a]
]
0.841 1.12 1.40 1.73 2.37 3.15
3.00 3.21 3.28 3.30 3.10 3.02
3.60 3.25 3.37 3.72 3.40 3.68
koNbs ϫ 104 [sϪ1 mol dmϪ3
koObs ϫ 104 [sϪ1 mol dmϪ3
]
]
[2P]o ϫ 103 [mol dmϪ3 [a]
]
5.05 6.31 7.15 26.1 52.2
3.02 3.00 3.24 3.20 3.35
3.58 3.77 3.68 3.41 3.54
5-Hydroxy-1,2-dimethylpyridinium Picrate (19): M.p. 190 °C (from
methanol). Ϫ H NMR (300 MHz, [D6]DMSO): δ ϭ 2.65 (s, 3 H,
koNbs ϫ 104 [sϪ1 mol dmϪ3
koObs ϫ 104 [sϪ1 mol dmϪ3
]
]
1
CϪCH3), 4.25 (s, 3 H, NϪCH3), 7.85Ϫ7.96 (m, 2 H, 3-H and 4-
H), 8.55Ϫ8.60 (m, 1 H, 6-H), 8.69 (s, 2 H, Ph), 11.45Ϫ11.65 (br. s,
1 H, OH). Ϫ 13C NMR (75.46 MHz, [D6]DMSO): δ ϭ 18.5, 45.5,
124.1, 125.1, 129.4, 131.7, 133.6, 141.8, 146.0, 154.6, 160.7. Ϫ
C13H12N4O8 (352.3): calcd. C 44.33, H 3.43, N 15.90; found C
44.45, H 3.47, N 15.80.
[a]
Solvent ϭ tetrahydrofuran; [9]o ϭ 4.0·10Ϫ4 [mol dmϪ3].
The KT value related to 1, in THF, was calculated by described
procedures.[45,48] Values of [1] ranged from 7·10Ϫ4 to 1·10Ϫ5 mol
dmϪ3. Compound 1: λmax ϭ 306 (ε ϭ 4.0·103); 2-methoxypyridine:
λ ϭ 306 (ε ϭ 1); 1-methyl-2-pyridone: λmax ϭ 306 (ε ϭ 4.45·103).
2,4,6-Trinitroanisole (20): M.p. 68 °C.[31]
Ϫ
1H NMR (300 MHz,
N-(2,4,6-Trinitrophenyl)-2-pyridone (10):[18] M.p. 194Ϫ195 °C (from
[D6]DMSO): δ ϭ 4.15 (s, 3 H, OCH3), 9.18 (s, 2 H, Ph). Ϫ 13C
methanol). Ϫ 13C NMR (75.46 MHz, [D6]DMSO): δ ϭ 107.5, NMR (75.46 MHz, [D6]DMSO): δ ϭ 64.8, 124.6, 141.4, 143.8,
120.3, 124.6, 131.5, 136.9, 142.8, 147.0, 147.2, 160.3.
1180
150.7.
Eur. J. Org. Chem. 2001, 1175Ϫ1182