Lead(II) Nitrate - Applications

Applications

Due to the hazardous nature of lead(II) nitrate, there is a preference for using alternatives in industrial applications. In the formerly major application of lead paints, it has largely been replaced by titanium dioxide. Other historical applications of lead(II) nitrate, such as in matches and fireworks, have declined or ceased as well. Current applications of lead(II) nitrate include use as a heat stabiliser in nylon and polyesters, as a coating for photothermographic paper, and in rodenticides.

On a laboratory scale, lead(II) nitrate provides one of two convenient and reliable sources of dinitrogen tetroxide. By carefully drying lead(II) nitrate and then heating it in a steel vessel, nitrogen dioxide is produced along with dioxygen following the decripitation equation shown above. Alternatively, nitrogen dioxide is formed when concentrated nitric acid is added to copper turnings; in this case, substantial nitric oxide can also be produced. In either case, the resulting nitrogen dioxide exists in equilibrium with its dimer, dinitrogen tetroxide:

2 NO₂ ⇌ N₂O₄

In order to remove either impurity, the gas mixture is condensed and fractionally distilled to give a mixture of NO₂ and N₂O₄. As the dimerisation is exothermic, low temperatures favour N₂O₄ as the dominant form.

To improve the leaching process in the gold cyanidation, lead(II) nitrate solution is added. Although a bulk process, only limited amounts (10 to 100 milligrams lead(II) nitrate per kilogram gold) are required. Both the cyanidation itself, as well as the use of lead compounds in the process, are deemed controversial due to the compounds' toxic nature.

In organic chemistry, lead(II) nitrate has been used as an oxidant, for example as an alternative to the Sommelet reaction for oxidation of benzylic halides to aldehydes. It has also found use in the preparation of isothiocyanates from dithiocarbamates. Because of its toxicity it has largely fallen out of favour, but it still finds occasional use, for example as a bromide scavenger during S_N1 substitution.