EDTA is a widely-used acronym for the chemical compound ethylenediamine tetraacetic acid. EDTA refers to the chelating agent with the formula (HO2CCH2)2NCH2CH2N(CH2CO2H)2. This amino acid is widely used to sequester di- and trivalent metal ions. EDTA binds to metals via four carboxylate and two amine groups. EDTA forms specially strong complexes with Mn(II), Cu(II), Fe(III), and Co(III).[1]
Synthesis
EDTA is mostly synthesised from
1,2-diaminoethane (ethylenediamine), formaldehyde (methanal), water and
sodium cyanide.[2] This yields the tetra sodium salt, which can be
converted into the acidic forms by acidification.
Popular vs. chemical nomenclature
To describe EDTA and its various
protonated forms, chemists use a more cumbersome but more precise
acronym that distinguishes between EDTA4−, the conjugate base that is
the ligand, and H4EDTA, the precursor to that ligand.
Coordination chemistry principles
In coordination chemistry, H4EDTA is a member of
the aminocarboxylate family of ligands that includes imidodiacetic acid
("H2IDA") and nitrilotriacetic acid ("H3NTA"). More specialized
relatives include N,N'-ethylenediaminediacetic acid ("H2EDDA") and
1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid ("H4CyDTA"). These
ligands are all formally derived from the amino acid glycine.
H4EDTA forms highly stable coordination compounds that are soluble in water. In these complexes, the ligand is usually either hexa- or pentadentate, EDTA4− or HEDTA3−, respectively. Such complexes are chiral, and [Co(EDTA)]− has been resolved into enantiomers.[3]
Uses in Medicine:
References
