Description

N, N, N', N'-Tetramethylethylenediamine (TMEDA or TEMED), also known as Tetramethylethylenediamine, is a chemical compound with the formula (CH3)2NCH2CH2N(CH3)2. This species is derived from ethylenediamine by replacement of the four amine hydrogens with four methyl groups. It is a colorless liquid, although old samples often appear yellow. Its odor is similar to that of rotting fish. It is widely employed as a metal ions ligand and a catalyst in organic polymerisation.

Uses

TMEDA is widely employed as a ligand for metal ions. It forms stable complexes with metal halides, e.g., zinc chloride and copper(I) iodide, making complexes soluble in organic solvents. In such complexes, TMEDA serves as a bidentate ligand. TMEDA has an affinity for lithium ions.

TEMED consists of two tertiary amine groups linked by an ethyl-ene bridge. It can be used in cross-coupling or olefin polymerization reactions where, for example, a complex between di-methyl-nickel and TMEDA is used as a catalyst. However, TMEDA is most commonly used in the chemistry of organolithium compounds. The lithium–carbon bond is characterized by its high polarity, containing cationic lithium and carbanionic residues. These organolithium compounds form unreactive aggregates in non-polar solvents, which can be deaggregated by adding Lewis-basic ligands.

Precautions

TMEDA should be used directly after distilling. However, as required, it may be stored under nitrogen and transferred using a syringe and septum cap. For most applications, the amine is removed during aqueous workup simply by washing it with water, owing to its high solubility. Use in a fume hood. TMEDA is a skin and severe eye irritant: mildly toxic through skin contact and moderately toxic through ingestion. TMEDA is flammable when exposed to heat or flame and can react with oxidizing agents. Upon heating to decomposition, TMEDA will emit toxic fumes of NOx.