Ethylene-diamine-tetraacetic acid

Ethylene-diamine-tetraacetic acid (often abbreviated as EDTA) is a chelating agent that is widely used in various industries and scientific research. It is a polyamino carboxylic acid and a colorless, water-soluble solid. Its conjugate base is ethylenediaminetetraacetate.

Chemical Structure

EDTA is a hexadentate ligand, which means it creates six bonds with a central metal ion. When it reacts with a metal ion in a solution, it results in a chelate, EDTA4−, which is a complex anion.

Synthesis

EDTA is produced as a mixture of four isomers. Its synthesis involves the reaction of ethylene diamine, formaldehyde, and sodium cyanide, which produces a nitrile that is hydrolyzed to give the target compound.

Uses

EDTA has a wide range of uses across various industries.

• Industrial Uses: In industry, EDTA is mainly used to sequester metal ions in aqueous solution. In the textile industry, it prevents metal ion impurities from modifying colors of dyed products. In the pulp and paper industry, EDTA inhibits the ability of metal ions, especially Mn2+, from catalyzing the disproportionation of hydrogen peroxide.

• Scientific Research: In the laboratory, EDTA is widely used for both inorganic and biochemistry applications. In biochemistry and molecular biology, ion depletion is commonly used to deactivate metal-dependent enzymes, either as an assay for their reactivity or to suppress damage they may cause.

• Medicine: In medicine, it is used in chelation therapy to treat mercury and lead poisoning. It works by binding to the metal ion and causing its elimination from the body.

Safety

EDTA has a low acute toxicity, but in long-term, it can cause adverse effects including reproductive and developmental effects.

Environmental Impact

EDTA is a persistent organic pollutant. It resists degradation in the environment and can cause negative effects on wildlife, particularly aquatic life.