Fosfiitit

Fosfiitit are salts or esters of phosphorous acid. Phosphorous acid itself is a diprotic acid with the chemical formula H3PO3. In aqueous solution, it exists in equilibrium with its tautomer, phosphonic acid (H3PO3). However, the term "fosfiitit" specifically refers to compounds derived from the H3PO3 structure where two hydrogen atoms are replaced by metal cations or organic groups.

Fosfiitit can be inorganic or organic. Inorganic fosfiitit typically involve a metal cation, such as sodium, potassium, or calcium, bonded to the phosphite anion. For example, sodium fosfiitit (Na2HPO3) and potassium fosfiitit (K2HPO3) are common examples. These compounds are often soluble in water. Organic fosfiitit, also known as phosphonates, have at least one carbon-phosphorus bond. They can be formed by esterification of phosphorous acid with alcohols. The general formula for organic fosfiitit is R-P(O)(OR')2, where R and R' are organic groups.

In industry, fosfiitit have various applications. Inorganic fosfiitit are used as reducing agents, as stabilizers in plastics, and in water treatment to prevent scale formation. Organic fosfiitit are widely employed as scale and corrosion inhibitors in industrial water systems, as chelating agents, and in detergents. Some fosfiitit derivatives also find use as flame retardants and in agriculture as fungicides. The reactivity of the P-H bond in phosphorous acid is key to many of its synthetic routes and applications.