Org. Synth. 1933, 13, 84
[Carbamic acid, methylnitroso-, ethyl ester]
Submitted by W. W. Hartman and Ross Phillips.
Checked by Louis F. Fieser and J. T. Walker.
Caution! See the discussion in Org. Synth. 1973, Coll. Vol. 5, 842 with regard to potential hazards associated with the title compound.
To 206 g. (2 moles) of ethyl N-methylcarbamate (p. 278)
and 600 cc. of ordinary ethyl ether
in a 5-l. flask
is added, along with 200 g. of ice, 650 g. (9 moles) of 96 per cent sodium nitrite (Note 1)
dissolved in 1 l. of cold water. The flask is provided with a stopper
carrying a thermometer
, a tube to lead off evolved nitric oxide
, and a separatory funnel
with an extension tube reaching to the bottom of the flask. A solution of 1.2 kg. (6.7 moles) of cold 35 per cent nitric acid, prepared by pouring 600 g. (426 cc.) of concentrated acid
onto 600 g. of ice, is then cautiously added through the funnel in the course of one and one-half hours. The flask is given an occasional swirl to ensure some mixing, but most of the stirring is done by the evolved gases. Ice is added as required to keep the temperature below 15°. The ether
layer first becomes pale red and gradually changes to a blue-green. As soon as the color has changed to green, the ether
layer is separated (Note 2)
, washed twice with cold water, and then with cold potassium carbonate
solution until carbon dioxide
is no longer evolved. The solution is dried with solid potassium carbonate
, and the ether
is distilled from a water bath
using a 1-l. flask with a 30-cm. column
arranged for vacuum distillation. The vacuum is applied as soon as most of the ether
has been removed, and the flask is heated gently so that the temperature of the liquid does not exceed 45–50° (Note 3)
until the pressure has been reduced below 20 mm. The yield of nitrosomethylurethane
boiling at 59–61/10 mm.
is 200 g.
per cent of the theoretical amount). The density is 1.133 at 20°.
A large excess of sodium nitrite
is required to give a satisfactory yield. This may be due to reaction according to the following equations:
Nitric oxide (NO)
is lost during the reaction. It is not thought advisable to use this by passing in oxygen
because of the danger of an explosion, or by passing in air because of the loss of material by evaporation.
irritates the skin.
According to the literature, nitrosomethylurethane
explodes when attempts are made to distil it at normal pressure.
has been prepared by treating ethyl methylcarbamate
with sodium nitrite
and sulfuric acid
and by passing the gases generated from arsenious oxide
and nitric acid
into an ethereal solution of ethyl methylcarbamate
This preparation is referenced from:
Chemical Abstracts Nomenclature (Collective Index Number);
Nitric oxide (NO)
potassium carbonate (584-08-7)
sulfuric acid (7664-93-9)
ethyl ether (60-29-7)
nitric acid (7697-37-2)
sodium nitrite (7632-00-0)
carbon dioxide (124-38-9)
ethyl methylcarbamate (105-40-8)
Carbamic acid, methylnitroso-, ethyl ester (615-53-2)
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