Pentetic acid

Pentetic acid

Names
IUPAC name 2-[Bis[2-[bis(carboxymethyl)amino]ethyl]amino]acetic acid
Other names DTPA; H5dtpa; Diethylenetriaminepentaacetic acid; Penta(carboxymethyl)diethylenetriamine
Identifiers
CAS Number	67-43-6 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:35739 Y
ChemSpider	2945 Y
ECHA InfoCard	100.000.593
KEGG	D05422 Y
PubChem CID	3053 6441444 (Zinc-DTPA)
RTECS number	MB8205000
UNII	7A314HQM0I N
InChI InChI=1S/C14H23N3O10/c18-10(19)5-15(1-3-16(6-11(20)21)7-12(22)23)2-4-17(8-13(24)25)9-14(26)27/h1-9H2,(H,18,19)(H,20,21)(H,22,23)(H,24,25)(H,26,27) Y Key: QPCDCPDFJACHGM-UHFFFAOYSA-N Y
SMILES C(CN(CC(=O)O)CC(=O)O)N(CCN(CC(=O)O)CC(=O)O)CC(=O)O
Properties
Chemical formula	C14H23N3O10
Molar mass	393.35 g·mol−1
Appearance	White crystalline solid
Melting point	220 °C (428 °F; 493 K)
Boiling point	decomposes at a higher temp.
Solubility in water	<0.5 g/100 mL
Acidity (pKa)	~1.80 (20 °C)
Hazards
Flash point	Non-flammable
Related compounds
Related compounds	EDTA, NTA
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Pentetic acid or diethylenetriaminepentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an expanded version of EDTA and is used similarly. It is a white, water-soluble solid.

The conjugate base of DTPA has a high affinity for metal cations. Thus, the penta-anion DTPA⁵⁻ is potentially an octadentate ligand assuming that each nitrogen centre and each COO⁻-group counts as a centre for coordination. The formation constants for its complexes are about 100 greater than those for EDTA. As a chelating agent, DTPA wraps around a metal ion by forming up to eight bonds. Transition metals, however, usually form less than eight coordination bonds. So, after forming a complex with a metal, DTPA still has the ability to bind to other reagents, as is shown by its derivative pendetide. For example, in its complex with copper(II), DTPA binds in a hexadentate manner utilizing the three amine centres and three of the five carboxylates.

Like the more common EDTA, DTPA is mainly used for sequestering metal ions that otherwise decompose hydrogen peroxide, which is used to bleach pulp in paper making. Several million kilograms are produced for this purpose annually.

Its chelating properties are useful in deactivating calcium and magnesium ions in hair products. DTPA is used in over 150 cosmetic products. Additionally, DTPA is used in MRI contrasting agents. DTPA improves MRI images by forming a complex with a gadolinium ion, which alters the properties of nearby water molecules.

DTPA has been considered for treatment of radioactive materials such as plutonium, americium, and other actinides. In theory, these complexes are more apt to be eliminated in urine. It is normally administered as the calcium or zinc salt, since these ions are readily displaced by more highly charged cations. DTPA forms complexes with thorium(IV), uranium(IV), neptunium(IV), and cerium(III/IV).