Phosphitecontaining

Phosphitecontaining refers to chemical compounds that incorporate the phosphite anion, which has the chemical formula PO3^3-. This anion is a derivative of phosphorous acid, H3PO3. Phosphites are distinct from phosphates, which contain the phosphate anion (PO4^3-) derived from phosphoric acid. The central phosphorus atom in phosphite has an oxidation state of +3, whereas in phosphate it has an oxidation state of +5. This difference in oxidation state leads to different chemical properties and reactivity.

Phosphites can exist as salts or as part of organic molecules. Inorganic phosphites are often found as salts with alkali metals, alkaline earth metals, or other cations. For example, potassium phosphite (K2PO3) and calcium phosphite (Ca3(PO3)2) are known compounds. Organic phosphites, also known as phosphonites, feature a direct phosphorus-carbon bond. In these compounds, the phosphorus atom is bonded to at least one organic group and typically to two oxygen atoms.

In agriculture, phosphite-containing compounds, particularly potassium phosphite, are widely used as fungicides. They are effective against a range of oomycete pathogens, such as Phytophthora and Plasmopara species. The mechanism of action is believed to involve direct inhibition of pathogen growth and stimulation of the plant's defense mechanisms. They are applied either as foliar sprays or soil drenches. Beyond agriculture, phosphites find applications in areas such as flame retardants, plasticizers, and as antioxidants.