The nucleophilic phosphine attacks the azide at the electrophilic terminal nitrogen. This acetate can be converted to the respective bromide, iodide, cyanate, cyanide, azide and thiocyanate. First phosphine imine-forming reaction is conducted involving treatment of the azide with the phosphine. Carbon monoxide, cyanide, hydrogen sulphide and azide effectively inhibit cytochrome oxidase. Heating the azide in ethanol yields the ethyl carbamate via the Curtius rearrangement. Reaction with other pseudohalides such as azide, cyanide, and thiocyanate are possible as well. Photochemical decomposition of the acyl azide is also possible. The overall conversion is a mild method of reducing an azide to an amine. With a stopper molecule such as phenyl azide, well-defined phenyl end-groups are obtained. The principal source of the azide moiety is sodium azide. Sodium azide is the propellant in automobile airbags. The acid is usually formed by acidification of an azide salt like sodium azide. Bacteriostats commonly used in laboratory work include sodium azide (which is acutely toxic) and thiomersal. Sodium azide is also used in airplane escape chutes. The initial nucleophilic attack on the azide is the rate-limiting step.