Tetramethylethylenediamine

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 amine hydrogens with four methyl groups. It is a colorless liquid, although old samples often appear yellow. Its odor is remarkably similar to that of rotting fish.[3]

Tetramethylethylenediamine
Names
Other names
N,N,N′,N′-Tetramethylethane-1,2-diamine[1]
Identifiers
3D model (JSmol)
Abbreviations TMEDA, TEMED
1732991
ChEBI
ChemSpider
ECHA InfoCard 100.003.405
EC Number
  • 203-744-6
2707
MeSH N,N,N',N'-tetramethylethylenediamine
RTECS number
  • KV7175000
UNII
UN number 2372
Properties
C6H16N2
Molar mass 116.208 g·mol−1
Appearance Colorless liquid
Odor Fishy, ammoniacal
Density 0.7765 g mL−1 (at 20 °C)
Melting point −58.6 °C; −73.6 °F; 214.5 K
Boiling point 121.1 °C; 249.9 °F; 394.2 K
Miscible
Acidity (pKa) 8.97
Basicity (pKb) 5.85
1.4179
Hazards
Safety data sheet See: data page
GHS pictograms
GHS Signal word Danger
GHS hazard statements
 H225, H302, H314, H332
P210, P280, P305+351+338, P310
NFPA 704 (fire diamond)
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
4
2
1
Flash point 20 °C (68 °F; 293 K)
Explosive limits 0.98–9.08%
Lethal dose or concentration (LD, LC):
  • 5.39 g kg−1 (dermal, rabbit)
  • 268 mg kg−1 (oral, rat)
[2]
Related compounds
Related amines
 Triethylenetetramine
Related compounds
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

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.

TMEDA has an affinity for lithium ions.[3] When mixed with n-butyllithium, TMEDA's nitrogen atoms coordinate to the lithium, forming a cluster of higher reactivity than the tetramer or hexamer that n-butyllithium normally adopts. BuLi/TMEDA is able to metallate or even doubly metallate many substrates including benzene, furan, thiophene, N-alkylpyrroles, and ferrocene.[3] Many anionic organometallic complexes have been isolated as their [Li(tmeda)2]+ complexes.[4] In such complexes [Li(tmeda)2]+ behaves like a quaternary ammonium salt, such as [NEt4]+.

TMEDA adduct of lithium bis(trimethylsilyl)amide. Notice that the diamine is a bidentate ligand.[5]

It is also worth noting that s-BuLi/TMEDA is also a useful combination in organic synthesis. Utilization of this is useful in cases where the n-butyl anion is able to add into the starting material due to its weak nucleophilic nature. TMEDA is still capable of forming a metal complex with Li in this case as mentioned above.

Other uses

TEMED 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 TEMED is a "traditional" range. TEMED can also be a component of hypergolic propellants.

References
  1. "N,N,N′,N′-tetramethylethylenediamine – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Retrieved 30 June 2012.
  2. "MSDS" (PDF).
  3. Haynes, R. K.; Vonwiller, S. C.; Luderer, M. R. (2006). "N,N,N′,N′-Tetramethylethylenediamine". In Paquette, L. (ed.). N,N,N′,N′-Tetramethylethylenediamine. Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289X.rt064.pub2. ISBN 0471936235.
  4. Morse, P. M.; Girolami, G. S. (1989). "Are d0 ML6 Complexes Always Octahedral? The X-ray Structure of Trigonal Prismatic [Li(tmed)]2[ZrMe6]". J. Am. Chem. Soc. 111 (11): 4114–4116. doi:10.1021/ja00193a061.
  5. Henderson, K. W.; Dorigo, A. E.; Liu, Q.-L.; Williard, P. G. (1997). "Effect of Polydentate Donor Molecules on Lithium Hexamethyldisilazide Aggregation: An X-ray Crystallographic and a Combination Semiempirical PM3/Single Point ab Initio Theoretical Study". J. Am. Chem. Soc. 119: 11855. doi:10.1021/ja971920t.
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