Nitrilotriacetic acid

Chemical compound From Wikipedia, the free encyclopedia

Nitrilotriacetic acid (NTA) is the aminopolycarboxylic acid with the formula N(CH2CO2H)3. It is a colourless solid. Its conjugate base nitrilotriacetate is used as a chelating agent for Ca2+, Co2+, Cu2+, and Fe3+.[5]

Quick facts Names, Identifiers ...
Nitrilotriacetic acid
Skeletal formula of nitrilotriacetic acid
Skeletal formula of nitrilotriacetic acid
Names
Preferred IUPAC name
2,2′,2′′-Nitrilotriacetic acid[1]
Other names
N,N-Bis(carboxymethyl)glycine
2-[Bis(carboxymethyl)amino]acetic acid[2]
Triglycine[3] Trilon
Identifiers
3D model (JSmol)
1710776
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.004.869 Edit this at Wikidata
EC Number
  • 205-355-7
3726
KEGG
MeSH Nitrilotriacetic+Acid
RTECS number
  • AJ0175000
UNII
UN number 2811
  • 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) checkY
    Key: MGFYIUFZLHCRTH-UHFFFAOYSA-N checkY
  • O=C(O)CN(CC(=O)O)CC(=O)O
Properties
C6H9NO6
Molar mass 191.14 [4]
Appearance White crystals
Melting point 246[4] °C (475 °F; 519 K)
Insoluble. <0.01 g/100 mL at 23°C [4]
Thermochemistry
−1.3130–−1.3108 MJ mol−1
Hazards
GHS labelling:
GHS07: Exclamation mark GHS08: Health hazard
Warning
H302, H319, H351
P281, P305+P351+P338
Flash point 100 °C (212 °F; 373 K)
Lethal dose or concentration (LD, LC):
1.1 g kg−1 (oral, rat)
Related compounds
Related alkanoic acids
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[6] NTA is also cogenerated as an impurity in the synthesis of EDTA, arising from reactions of the ammonia coproduct.[7] Older routes to NTA included alkylation of ammonia with chloroacetic acid and oxidation of triethanolamine.

Coordination chemistry and applications

The conjugate base of NTA is a tripodal tetradentate trianionic ligand, forming coordination compounds with a variety of metal ions.[8]

Like EDTA, its sodium salt is used for water softening to remove Ca2+. For this purpose, NTA is a replacement for triphosphate, which once was widely used in detergents, and cleansers, but can cause eutrophication of lakes.

In one application, sodium NTA removes Cr, Cu, and As from wood that had been treated with chromated copper arsenate.[9]

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.[10] 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.[11]

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.[12]

For laboratory uses, Ernst Hochuli et al. (1987) coupled the NTA ligand and nickel ions to agarose beads.[13] 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]−.
    Three views of the structure of [Ni(NTA)(H2O)2]−.
  • Structure of the nitrilotriacetate anion [Ca(NTA)(H2O)3]−.
    Structure of the nitrilotriacetate anion [Ca(NTA)(H2O)3]−.

Toxicity and environment

In contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment.[6] 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.[14]

Related compounds

  • N-Methyliminodiacetic acid (MIDA), the N-methyl derivative of IDA
  • Imidodiacetic acid, the amino diacetic acid
  • N-(2-Carboxyethyl)iminodiacetic acid, a more biodegradable analogue of NTA
  • N-hydroxyiminodiacetic acid (HIDA), HON(CH2CO2H)2 (registry number = 87339-38-6)[15] See HIDA scan.

References

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