Ethylenediaminetetraacetic acid

For other uses, see Ethylenediaminetetraacetic acid (disambiguation).

Ethylenediaminetetraacetic acid

Names
IUPAC name 2,2',2'',2'''-(ethane-1,2-diyldinitrilo)tetraacetic acid
Other names EDTA, Y, H4EDTA, Diaminoethanetetraacetic acid, Edetic acid, Edetate, Ethylenedinitrilotetraacetic acid, Versene, Ethylene diamine tetraacetic acid, ethylenediaminetetraacetate, 2-[2-(Bis(carboxymethyl)amino) ethyl-(carboxymethyl)amino]acetic acid
Identifiers
CAS Number	60-00-4 N
3D model (JSmol)	Interactive image
ChemSpider	5826
ECHA InfoCard	100.000.409
PubChem CID	6049
RTECS number	AH4025000
CompTox Dashboard (EPA)	DTXSID6022977
SMILES OC(CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O)=O
Properties
Chemical formula	C10H16N2O8
Molar mass	292.24
Density	0.86 g/cm3
Melting point	237–245 °C (dec.)
Acidity (pKa)	pK1=0.0 (CO2H) (µ=1.0) pK2=1.5 (CO2H) (µ=0.1) pK3=2.00 (CO2H) (µ=0.1) pK4=2.69 (CO2H) (µ=0.1) pK5=6.13 (NH+) (µ=0.1) pK6=10.37 (NH+) (µ=0.1)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	irritant
NFPA 704 (fire diamond)	1 0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

EDTA is a widely used initialism for the chemical compound ethylenediaminetetraacetic acid (which has many other names, see Table). EDTA is a polyamino carboxylic acid with the formula [CH₂N(CH₂CO₂H)₂]₂. This colourless, water-soluble solid is widely used to dissolve scale. Its usefulness arises because of its role as a chelating agent, i.e. its ability to "sequester" metal ions such as Ca²⁺ and Fe³⁺. After being bound by EDTA, metal ions remain in solution but exhibit diminished reactivity. EDTA is produced as several salts, notably disodium EDTA and calcium disodium EDTA.

No I did

No I did

Coordination chemistry principles

Metal-EDTA chelate

In coordination chemistry, EDTA^4- is a member of the polyamino carboxylic acid family of ligands. EDTA^4- usually binds to a metal cation through its two amines and four carboxylates. Many of the resulting coordination compounds adopt octahedral geometry. Although of little consequence for its applications, these octahedral complexes are chiral. The anion [Co(edta)]⁻ has been resolved into enantiomers. Many complexes of EDTA^4- adopt more complex structures due to (i) the formation of an additional bond to water, i.e. seven-coordinate complexes, or (ii) the displacement of one carboxylate arm by water. Early work on the development of EDTA was undertaken by Gerold Schwarzenbach in the 1940s. EDTA forms especially strong complexes with Mn(II), Cu(II), Fe(III), Pb (II) and Co(III).

Several features of EDTA's complexes are relevant to its applications. First, because of its high denticity, this ligand has a high affinity for metal cations:

[Fe(H₂O)₆]³⁺ + H₄EDTA ${\overrightarrow {\leftarrow }}$ [Fe(edta)]^- + 6 H₂O + 4 H⁺ (K_eq = 10^25.1)

Written in this way, the equilibrium quotient shows that metal ions compete with protons for binding to EDTA. Because metal ions are extensively enveloped by EDTA, their catalytic properties are often suppressed. Finally, since complexes of EDTA^4- are anionic, they tend to be highly soluble in water. For this reason, EDTA is able to dissolve deposits of metal oxides and carbonates.

Uses

NO I DID

GOT HERE FIRST

...

...

...

....

External links

• Lanigan RS, Yamarik TA (2002). "Final report on the safety assessment of EDTA, calcium disodium EDTA, diammonium EDTA, dipotassium EDTA, disodium EDTA, TEA-EDTA, tetrasodium EDTA, tripotassium EDTA, trisodium EDTA, HEDTA, and trisodium HEDTA". Int. J. Toxicol. 21 Suppl 2: 95–142. doi:10.1080/10915810290096522. PMID 12396676.
• pH-Spectrum of EDTA complexes
• EDTA: Molecule of the Month
• EDTA Determination of Total Water Hardness
• 507 references regarding oral EDTA
• EDTA: the chelating agent under environmental scrutiny, Química Nova, Nov.-Dec., 2003 (text version)
• EDTA: the chelating agent under environmental scrutiny, Química Nova, Nov.-Dec., 2003 (PDF version)