Urethane (NH2*COOCOC2H5) is an ester of carbamic acid in an arrangement created when an isocyanate reacts with a hydroxyl group. It is a white crystalline substance produced by the action of ammonia on ethyl carbonate or by heating urea nitrate and ethyl alcohol. It is used as a hypnotic, antipyretic, and antispasmodic. Hence, any ester of carbamic acid. When a polyisocyanate reacts with a polyol (a molecule with multiple hydroxyl groups), the result is polyurethane.