Pyrofosfater

Pyrofosfater is a term used in several languages for pyrophosphates, a class of inorganic compounds consisting of two phosphate units connected by a phosphoanhydride bond. The two phosphate groups condense with the loss of one water molecule, yielding the pyrophosphate anion P2O7^4−. In salts, this anion is balanced by metal cations such as sodium, potassium, or calcium.

Chemically, pyrophosphates are highly hydrated and exhibit a strong tendency to hydrolyze to orthophosphate (PO4^3−) in aqueous solutions. The P–O–P bridge is cleaved by hydrolysis, a reaction that can be accelerated enzymatically or by acid or base catalysis. This lability makes pyrophosphates useful in various buffering, chelating, and sequestering contexts, and their salts differ in solubility and hydration state.

Natural occurrence of pyrophosphates is limited; they appear as intermediates in metabolic processes and as transient species in the condensation of phosphate groups. Industrially, they are prepared by dehydration of phosphoric acid derivatives or via reactions of phosphate-containing reagents. Several salts are commercially available, including sodium and potassium pyrophosphates.

Applications of pyrofosfater compounds include use as leavening agents and emulsifying salts in the food industry (often referred to as diphosphates, E450), and as water-softening, buffering, and chelating agents in detergents and other formulations. In biochemistry, pyrophosphate participates in energy- and phosphate-transfer reactions and can be used to drive reactions when hydrolyzed by specific enzymes such as pyrophosphatases.

Safety and regulation vary by context, but pyrophosphates are generally regarded as safe at approved levels in foods and consumer products. See also orthophosphate, pyrophosphatase, and diphosphate.