Nitrilotriacetic acid

Nitrilotriacetic acid

Names
Preferred IUPAC name 2,2′,2′′-Nitrilotriacetic acid
Other names N,N-Bis(carboxymethyl)glycine 2-[Bis(carboxymethyl)amino]acetic acid Triglycine
Identifiers
CAS Number	139-13-9 (free acid) Y 5064-31-3 (trisodium salt) Y
3D model (JSmol)	Interactive image
Beilstein Reference	1710776
ChEBI	CHEBI:44557 Y
ChemSpider	8428 Y
DrugBank	DB03040 Y
ECHA InfoCard	100.004.869
EC Number	205-355-7
Gmelin Reference	3726
KEGG	C14695 N
MeSH	Nitrilotriacetic+Acid
PubChem CID	8758
RTECS number	AJ0175000
UNII	KA90006V9D Y E3C8R2M0XD (trisodium salt) Y
UN number	2811
CompTox Dashboard (EPA)	DTXSID6020939
InChI InChI=1S/C6H9NO6/c8-4(9)1-7(2-5(10)11)3-6(12)13/h1-3H2,(H,8,9)(H,10,11)(H,12,13) Y Key: MGFYIUFZLHCRTH-UHFFFAOYSA-N Y
SMILES O=C(O)CN(CC(=O)O)CC(=O)O
Properties
Chemical formula	C6H9NO6
Molar mass	191.14
Appearance	White crystals
Melting point	246 °C (475 °F; 519 K)
Solubility in water	Insoluble. <0.01 g/100 mL at 23°C
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−1.3130–−1.3108 MJ mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H319, H351
Precautionary statements	P281, P305+P351+P338
Flash point	100 °C (212 °F; 373 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1.1 g kg−1(oral, rat)
Related compounds
Related alkanoic acids	EDTA Iminodiacetic acid EDDS
Related compounds	Triethanolamine Tris(2-aminoethyl)amine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Nitrilotriacetic acid (NTA) is the aminopolycarboxylic acid with the formula N(CH₂CO₂H)₃. It is a colourless solid that is used as a chelating agent, which forms coordination compounds with metal ions (chelates) such as Ca²⁺, Co²⁺, Cu²⁺, and Fe³⁺.

Production and use

Nitrilotriacetic acid is commercially available as the free acid and as the sodium salt. It is produced from ammonia, formaldehyde, and sodium cyanide or hydrogen cyanide. Worldwide capacity is estimated at 100 thousand tonnes per year. NTA is also cogenerated as an impurity in the synthesis of EDTA, arising from reactions of the ammonia coproduct. Older routes to NTA included alkylation of ammonia with chloroacetic acid and oxidation of triethanolamine.

Coordination chemistry and applications

NTA is a tripodal tetradentate trianionic ligand.

The uses of NTA are similar to those of EDTA, both being chelating agents. It is used for water softening and as a replacement to sodium and potassium triphosphate in detergents, and cleansers.

In one application, NTA as a chelating agent removes Cr, Cu, and As from wood that had been treated with chromated copper arsenate.

Laboratory uses

In the laboratory, this compound is used in complexometric titrations. A variant of NTA is used for protein isolation and purification in the His-tag method. The modified NTA is used to immobilize nickel on a solid support. This allows purification of proteins containing a tag consisting of six histidine residues at either terminus.

The his-tag binds the metal of metal chelator complexes. Previously, iminodiacetic acid was used for that purpose. Now, nitrilotriacetic acid is more commonly used.

For laboratory uses Ernst Hochuli et al. 1987 coupled the NTA ligand and Nickel-ions to agarose beads. This Ni-NTA Agarose is the most used tool to purify his tagged proteins via affinity chromatography.

• NTA complexes
• 

  Three views of the structure of [Ni(NTA)(H₂O)₂]⁻.

• 

  Structure of the nitrilotriacetate anion [Ca(NTA)(H₂O)₃]⁻.

Toxicity and environment

Nitriloacetic acid can cause eye, skin, and respiratory tract irritation; and can cause kidney and bladder damage. The compound is anticipated to have the potential to cause human cancers.

In contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment. The environmental impacts of NTA are minimal. Despite widespread use in cleaning products, the concentration in the water supply is too low to have a sizeable impact on human health or environmental quality.