pyrophosphoric

Pyrophosphoric is an adjective relating to pyrophosphoric acid or to compounds containing its core pyrophosphate moiety, P2O7, as well as to derivatives such as pyrophosphate esters and salts. The term appears in inorganic and organic chemistry, biochemistry, and related fields, and is usually used to describe substances derived from pyrophosphoric acid or featuring the characteristic pyrophosphate linkage between two phosphate units.

Chemistry and structure. Pyrophosphoric acid is formed by the condensation of two orthophosphoric acid units with the loss of a water molecule. In solution, it can donate protons and form the pyrophosphate anion, P2O7^4−, upon deprotonation. Compounds described as pyrophosphoric include salts called pyrophosphates (for example, disodium pyrophosphate, tetrasodium pyrophosphate) and various pyrophosphate esters, where one or more alcohol or other groups are linked to the pyrophosphate moiety through ester bonds.

Occurrence and uses. Pyrophosphate salts are widely used in industry and food processing. In the food industry, pyrophosphates act as leavening agents, buffering agents, and stabilizers. In detergents and cleaning products, certain pyrophosphate salts serve as water-softening agents. In biochemistry, inorganic pyrophosphate (PPi) is a byproduct of nucleotide synthesis and other biosynthetic reactions; its hydrolysis to two phosphate ions, catalyzed by pyrophosphatases, helps drive otherwise unfavorable reactions forward.

Summary. Pyrophosphoric describes substances tied to the pyrophosphoric acid framework or the pyrophosphate linkage, encompassing a range of acids, salts, and esters with applications in chemistry, biology, nutrition, and industry. See also pyrophosphoric acid and pyrophosphate.