Chemistry Reference
In-Depth Information
were washed with 0.1 n HCl (10 mL), 10% sodium hydrogen carbonate solution
(10 mL), and finally with water. The mixture was then dried over sodium sulfate
and concentrated to give 0.19 g of the product (79%).
3,3,3-Trinitropropyl carbamate 122 was prepared via the corresponding chloro-
formate 121 using triphosgene [65].
NO
2
NO
2
O
(CCl
3
O)
2
CO
O
2
N
O
2
N
O
2
N
OH
O
2
N
O
Cl
CH
2
Cl
2
, Py, 0°C
120
121
NO
2
O
NH
4
OH
- 10 °C
O
2
N
O
2
N
O
NH
2
122
Typical procedure. 3,3,3-Trinitropropyl carbamate 122 [65]: To a stirred mixture of
triphosgene (1.8 g, 6 mmol) and 3,3,3-trinitropropanol (3.1 g, 16 mmol) in di-
chloromethane (10 mL) at 0
C, a solution of pyridine (1.5 mL, 19 mmol) in
dichloromethane (5 mL) was added dropwise. After 24 h at room temperature, the
reaction mixture was cooled to
10
C, whereupon concentrated ammonium hy-
droxide (30%, 2 mL, 32 mmol) was added dropwise with stirring. The precipitated
solid was removed by filtration and the filtrate was extracted with water and dilute
hydrochloric acid. The volatiles were removed to give 2.75 g of product, which was
chromatographed on silica gel 40 (eluting first with dichloromethane and then
with dichloromethane/acetone, 80:20) to yield 0.65 g of solid; mp 82-84
C.
Phosgene reacts with oximes to form O-(chloroformyl)oximes 124, which, on ad-
dition of antimony pentachloride, undergo smooth Beckmann rearrangement with
loss of carbon dioxide to give the nitrilium salts 125 almost quantitatively [66].
With oxygen or nitrogen nucleophiles, O-(chloroformyl)oximes 124 form symmetri-
cal and unsymmetrical oxalyl derivatives.
O
COCl
2
, CH
2
Cl
2
-15 to 23°C, 1-2h
R
1
R
1
N
N
O
Cl
OH
R
2
R
2
56-88 %
124
123
SbCl
5
, CH
2
Cl
2
R
1
CNR
2
SbCl
6
- 40 to 23°C, 1-2 h
95-100 %
125
R
1
, R
2
= Me, Ph
