H4EDTA

H4EDTA refers to the fully protonated form of ethylenediaminetetraacetic acid (EDTA), a widely used chelating agent. In this neutral form, all four carboxyl groups are protonated, making H4EDTA the acid form of the compound. EDTA itself is a hexadentate ligand that can bind metal ions through its two amine nitrogens and four carboxylate oxygens when deprotonated.

In solution, EDTA exists in multiple protonation states that depend on pH. H4EDTA is the predominant species at very low pH, while progressively deprotonated forms (mono-, di-, tri-, and tetra-anionic) dominate as the pH increases. The capacity to form stable metal complexes increases with deprotonation, and the hexadentate coordination geometry typically involves two nitrogens and four oxygens from the ligand.

Uses and applications of EDTA derivatives are widespread. H4EDTA itself is primarily of theoretical or specialized interest, as deprotonation is required for effective metal binding. In practice, EDTA is employed as a chelating agent in water treatment, detergents, cosmetics, foods, and analytical chemistry to sequester metal ions and stabilize formulations. In medicine, salts of EDTA (such as calcium disodium EDTA) are used therapeutically to treat certain metal poisonings and to prevent metal-induced crystallization in some conditions.

Safety and handling follow standard chemical hygiene practices. EDTA and its salts are generally considered low in acute toxicity but can chelate essential minerals; proper labeling and handling are advised. See also EDTA, chelation therapy, and metal chelation terminology.