Preparation
In a 1L unsilver-plated hard glass Dewar flask, place approximately 400mL of anhydrous liquid ammonia. Stopper the flask with a bent capillary tube to prevent water vapor condensation on the surface of the liquid ammonia; the capillary tube acts as a condenser for the ammonia vapor. Crush dry ice (solid carbon dioxide) into small pieces and slowly add it to the liquid ammonia. Continue adding dry ice until the mixture resembles a semi-melted slush. Evaporate excess ammonia, leaving ammonium carbamate as a lumpy substance. Transfer this to a vacuum desiccator and store under slightly reduced pressure for 24 hours. After the residual ammonia dissipates and a small amount of ammonium carbamate decomposes, it will transform into a powdery solid. 200–300g of ammonium carbamate can be prepared from 400mL of liquid ammonia.
Chemical Properties
Ammonium carbamate is a colorless crystalline
powder or white powder. Ammonia-like odor. The
odor threshold is 5 ppm as NH3 (detection) and 46.8 ppm
as NH3 (recognition).
Uses
Ammonium carbamate is used in the preparation of fertilizers. It acts as an ammoniating agent. It plays an important role in the formation of carbamoyl phosphate, which is essential for urea cycle and pyrimidines production. In addition to this, it is used in the preparation of trimethylsilyl carbamate.
Air & Water Reactions
Water soluble.
Reactivity Profile
AMMONIUM CARBAMATE is a carbamate salt. Carbamates are chemically similar to, but more reactive than amides. Like amides they form polymers such as polyurethane resins. Carbamates are incompatible with strong acids and bases, and especially incompatible with strong reducing agents such as hydrides. Flammable gaseous hydrogen is produced by the combination of active metals or nitrides with carbamates. Strongly oxidizing acids, peroxides, and hydroperoxides are incompatible with carbamates. AMMONIUM CARBAMATE is unstable in an alkaline media . AMMONIUM CARBAMATE is incompatible with the following: Strong oxidizers, strongly alkaline pesticides . Moderate fire and explosion hazards when exposed to heat or flame [USCG, 1999].
Hazard
Evolves irritating fumes when heated.
Health Hazard
INHALATION: Irritating to mucous membranes of respiratory tract. EYES: Irritating.
Fire Hazard
Behavior in Fire: Moderate fire and explosion hazards when exposed to heat or flame
Safety Profile
Ammonium carbamate is Poison by intravenous route. See also CARBAMATES
Shipping
UN2757 Carbamate pesticides, solid, toxic,
Incompatibilities
Strong bases, strong oxidizers. Keep
away from heat (forms urea), moisture, and direct sunlight.
