Tetramethylethylenediamine

Chembox new
Name = Tetramethylethylenediamine
ImageFile = temed.png ImageName = Tetramethylethylenediamine
ImageFile1 = TMEDA-3D-balls.png ImageName1 = Ball-and-stick model of the TMEDA molecule
IUPACName =N,N,N',N'-tetramethyl-
ethane-1,2-diamine
OtherNames = TEMED
TMEDA
TMED
1,2-bis(dimethylamino)-
ethane
Section1 = Chembox Identifiers
SMILES = CN(C)CCN(C)C
CASNo = 110-18-9
RTECS = KV7175000
Section2 = Chembox Properties
Formula = C₆H₁₆N₂
MolarMass = 116.24 g/mol
Appearance = colorless liquid
Density = 0.78 g/cm³, liquid
Solubility = infinite
MeltingPt = -55 °C (218 K)
BoilingPt = 120-122 °C (393-395 K)
pKa = 8.97
pKb = 5.85
RefractIndex = 1.4179
Section3 = Chembox Structure
Coordination = sp³ throughout
Dipole = 0 D
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = flammable,
obnoxious odour
NFPA-H = 2 | Reactivity=1
NFPA-F = 4
NFPA-R =
FlashPt = 50 °F
RPhrases = 11-20/22-34
SPhrases = 16-26-36/37/39-45
Section8 = Chembox Related
Function = amines
OtherFunctn = ethylene diamine,
PMDTA,
trimethyltriazacyclononane

Tetramethylethylenediamine (TMEDA or TEMED) is a chemical compound with the formula (CH₃)₂NCH₂CH₂N(CH₃)₂. This species is derived from ethylenediamine 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 and copper(I) iodide, giving complexes that are soluble in organic solvents. In such complexes, 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 metallate many substrates including benzene, furan, thiophene, N-alkylpyrroles, and ferrocene. [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.] Many anionic organometallic complexes have been isolated as their [Li(TMEDA)₂] ⁺ complexes. [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] In such complexes [Li(TMEDA)₂] ⁺ behaves like a quaternary ammonium salt, such as [NEt₄] ⁺.

Other uses

Tetramethylethylenediamine is used with ammonium persulfate to catalyze the polymerization of acrylamide when making polyacrylamide gels, used in gel electrophoresis, for the separation of proteins or nucleic acids. 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