Bismuth oxynitrate

Bismuth oxynitrate is an inorganic compound with the chemical formula BiONO₃. It is a white or pale yellow chemical compound that is insoluble in water but soluble in concentrated nitric acid. Bismuth oxynitrate is used in various applications, including cosmetics, pharmaceuticals, and as a precursor for the synthesis of other bismuth compounds.

Properties

Bismuth oxynitrate appears as a white or pale yellow powder. It is insoluble in water, which makes it useful in applications where moisture resistance is required. The compound is, however, soluble in concentrated nitric acid, allowing it to be processed and purified through acid-base reactions. Bismuth oxynitrate has a relatively high molecular weight and exhibits low toxicity, making it suitable for use in a variety of consumer products.

Synthesis

Bismuth oxynitrate is typically synthesized through the reaction of bismuth metal with nitric acid. The reaction involves the dissolution of bismuth in concentrated nitric acid, followed by precipitation of the bismuth oxynitrate upon dilution or cooling:

\[ \text{Bi} + 4\text{HNO}_3 \rightarrow \text{BiONO}_3 + 2\text{H}_2\text{O} + 2\text{NO}_2 \]

The precipitated bismuth oxynitrate is then filtered, washed, and dried to obtain the final product.

Applications

Cosmetics

Bismuth oxynitrate is widely used in cosmetics, particularly in products like face powders, where it serves as a white pigment and a skin protectant. Its low toxicity and good adherence to the skin make it a preferred ingredient over other more toxic pigments.

Pharmaceuticals

In the pharmaceutical industry, bismuch oxynitrate is used as an astringent and protective agent. It has been incorporated into wound dressings and gastrointestinal medications due to its antibacterial properties and its ability to form a protective barrier on the skin or mucous membranes.

Catalysis

Bismuth oxynitrate serves as a catalyst in organic synthesis, facilitating various chemical reactions due to its acidic properties. It is particularly useful in the synthesis of fine chemicals and pharmaceutical intermediates.

Safety

Bismuth oxynitrate is considered to have low toxicity, but it should be handled with care to avoid inhalation or prolonged skin contact, which can lead to irritation. In the environment, bismuth compounds are regarded as relatively inert due to their low solubility in water.

See Also

• Bismuth
• Nitric acid
• Inorganic compounds
• Catalysis
• Cosmetics