Molecules 2016, 21, 1738
6 of 8
In particular handling of concentrated and fuming nitric acid (HNO ) needs special precautions
3
and safety equipment. Furthermore, all nitrated compounds should be treated as potential explosives.
3
.1. General Nitration Procedures
3
.1.1. Method A
The carbamate (115 mmol) was added portion wise to stirred nitric acid (100%; 28 g; 444 mmol).
The solution was evaporated to dryness on a steam bath. The product solidified on cooling; it was
dried in vacuo and recrystallized from toluene (absolute. ethanol can also be used) to give the product.
3
.1.2. Method B
Using a dry ice/acetone bath acetic anhydride (25 mL) was cooled to
◦
−
15 C. Fuming nitric acid
◦
(
18.5 g; 13.2 mL; 298 mmol) was added dropwise keeping the temperature between
A mixture of the carbamate (24.0 mmol) and about 12.5 mL of Ac O was added slowly at
vigorous stirring. The mixture was allowed to warm up to 0 C and maintained at 0–4 C for 10 h.
The reaction mixture was poured on ice and stirred for a couple of minutes. Extraction with DCM,
−
10 and
−
15 C.
◦
−
15 C with
2
◦
◦
washing with 10% NaHCO , drying (MgSO ) and evaporation yielded the product.
3
4
3
.1.3. Method C
A solution of the carbamate (115 mmol) in 72 mL Ac O was added slowly with stirring to a cooled
2
◦
(
5–10 C) suspension of finely-ground Cu(NO )
·
(H O) (10.5 g; 43 mmol) in 85 mL Ac O. After 1 h,
3
2
2
3
2
an additional portion of finely-ground Cu(NO ) ·(H O) (10.5 g; 43 mmol) was added. The resulting
3
2
2
3
◦
mixture was cooled to 0–5 C (ice/water) and stirred for another 4 h while slowly being heated to room
temperature. The mixture was filtered through Celite 545. Water (50 mL) was added, and the water
phase was extracted with DCM (3
×
50 mL) to get rid of additional dissolved copper salts. Drying
(
MgSO ) and evaporation gave a crystalline compound that was recrystallized from toluene to give
4
the product.
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.2. Spectral Data
3
-Nitrooxazolidin-2-one (
9
): Oxazolidin-2-one (
8
) was nitrated using Methods A, B and C to give
9
as
◦
1
◦
13
off-white crystals. m.p. 109–110 C (literature. m.p. 108–109.5 C). C-NMR (100 MHz, CDCl3):
δ
1
45.22, 60.18, 147.45. H-NMR (400 MHz, CDCl ):
δ
4.39 (2H, d, J = 7.2 Hz), 4.32 (2H, J = 7.2 Hz). IR:
3
−
1
3
006, 1794, 1565 cm
.
4
,4-Dimethyl-3-nitrooxazolidin-2-one (11): 4,4-dimethyloxazolidin-2-one (10) was nitrated using Methods
◦
1
◦
13
A, B and C to give 11 as white crystals. m.p. 121–122 C (lit. m.p. 124 C). C-NMR (100 MHz, CDCl3):
δ
1
22.02, 62.92, 72.18, 147.65. H-NMR (400 MHz, CDCl ):
δ
4.11 (6H, s), 1.68 (2H, s). IR: 3005, 2992,
3
−
1
2
949, 1772, 1565 cm
.
3-Nitrobenzo[d]oxazol-2(3H)-one (14): Benzo[d]oxazol-2(3H)-one (13) was nitrated using Methods A,
B and C to give 19 as white crystals, slightly yellow. m.p. was not determined, as the compound
1
3
decomposed on the apparatus. C-NMR (100 MHz, CD OD):
δ
109.32, 114.93, 130.11, 132.73, 141.52,
3
1
1
1
45.38, 153.99. H-NMR (400 MHz, CD OD):
δ
8.44 (2H, d, J =1.8 Hz), 8.86 (2H, d, J = 1.8 Hz). IR: 3103,
3
−
1
798, 1637, 1543 cm
-(Chloromethyl)-3-nitrooxazolidin-2-one (16): 5-(chloromethyl)oxazolidin-2-one (15) was nitrated using
Methods A, B and C to give 21 as white crystals. m.p. was not determined, as the compound
decomposed on the apparatus. 1 C-NMR (100 MHz, CDCl3):
400 MHz, CDCl3): 3.69–3.80 (2H, m), 4.25 (1H, dd, J = 5.9 Hz, J = 4.3 Hz), 4,42 (dd, J = 8.5 Hz,
J = 4.3 Hz), 4.81–4.87 (1H, m). IR: 3025, 2968, 2929, 2853, 1804, 1571 cm
.
5
3
1
δ
42.77, 47.50, 70.14, 146.45. H-NMR
(
δ
−
1
.