Tetramethylethylenediamine
Tetramethylethylenediamine, commonly known as TMEDA (or TEMED) is the chemical compound with the formula (CH3)2NCH2CH2N(CH3)2. This species is derived from ethylene diamine by replacement of the four N-H groups with four N-methyl groups. It has a disagreeable fishy odour.
As a reagent in organic and inorganic synthesis
TMEDA is widely employed as a ligand for metal ions. It forms stable complexes with many metal halides, e.g. zinc chloride, copper(I) iodide, giving complexes that are soluble in organic solvents. In such complexes, the TMEDA serves as a bidentate ligand.
Perhaps TMEDA is most renowned for its affinity for lithium ions. It converts butyl lithium into a cluster of higher reactivity than the hexamer. BuLi/TMEDA is able to metallate or even doubly metalate many substrates including benzene, furan, thiophene, N-alkylpyrroles, and ferrocene.[1] Many anionic organometallic complexes have been isolated as their [Li(TMEDA)2]+ complexes.[2] In such complexes [Li(TMEDA)2]+ behaves like a quaternary ammonium salt, such as [NEt4]+, except that it is more resistant to deprotonation.
Other uses
Tetramethylethylenediamine is used with ammonium persulfate to catalyze the polymerization of acrylamide in making a polyacrylamide gel, used in gel electrophoresis and Western blotting. Although the amounts used in this technique may vary from method to method, 0.1-0.2% v/v TMEDA is a “traditional” range.
References
- ↑ Haynes, R. K.; Vonwiller, S. C. “N,N,N’,N’-Tetramethylethylenediamine” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi: 10.1002/047084289.
- ↑ Morse, P. M.; Girolami, G. S. “Are d0 ML6 Complexes Always Octahedral? The X-ray Structure of Trigonal Prismatic [Li(tmed)]2[ZrMe6],” Journal of the American Chemical Society 1989, volume 111, 4114-5.doi:10.1021/ja00193a061
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