Question

Why does\ceH3PO2\ceH3PO2not form pyroacids? All I know is pyroacids are derived oxyacids obtained by removing one\ceH2O\ceH2Omolecule from two molecules of oxyacids. Correct me if this is wrong. It’s essentially both reasons mentioned in the comments. "Pyro-" means "fire" or, more generally, "heat" ("pyrotechnics" = "fireworks"). Hypophosphorous acid, or more accurately phosphinic acid, is thermally not very stable decomposing at 110 °C. Thus there is no chance for condensation with water loss. SeeWikipedia — Hypophosphorous acid.Each monomer has one protic hydrogen. Condensing two of them with loss of water would mean both of the protic hydrogens area in the water instead of the dimer. So if a dimer were to form, it would not be a (Brønsted–Lowry) acid. Phosphorus(III): more successful With phosphorous/phosphonic acid, formation of the dimeric pyro acid can be accomplished by careful heating. Condensation to form the dimeric acid\ceH2(H2P2O5)\ceH2(H2P2O5)and possibly higher polymers were achieved at 120 °C, but disproportionation again to phosphine and phosphoric acid occurred at higher temperature. Several phosphite/phosphonate salts also gave generally impure dimeric pyro-salts upon heating.

Answer 1

Hypophosphorous acid (H3PO2) does not form pyroacids due to its lack of sufficient protic hydrogens for condensation and its thermal instability, decomposing before dimerization can take place.

Step-by-step explanation:

Pyroacids are typically formed by the condensation of two oxyacid molecules resulting in the loss of a water molecule, as seen with phosphoric acid (H3PO4). However, hypophosphorous acid, also known as phosphinic acid (H3PO2), does not form pyroacids. This is primarily because it only contains one protic hydrogen capable of condensation, and it thermally decomposes at 110 °C, making it difficult for a dimerization reaction to occur.

Additionally, the structural configuration of hypophosphorous acid limits the formation of such pyroacids. In the case of other acids, like phosphoric acid, pyroacids such as diphosphoric acid or pyrophosphoric acid, and triphosphoric acid are possible because phosphoric acid has three protic hydrogens and is structurally conducive to forming dimers or trimers by the loss of water molecules upon heating.