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 similar to that of rotting fish.[4]

Tetramethylethylenediamine
Skeletal formula of tetramethylethylenediamine with some implicit hydrogens shown
Ball and stick model of tetramethylethylenediamine
Names
Preferred IUPAC name
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
  • InChI=1S/C6H16N2/c1-7(2)5-6-8(3)4/h5-6H2,1-4H3 ☒N
    Key: KWYHDKDOAIKMQN-UHFFFAOYSA-N ☒N
  • CN(C)CCN(C)C
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 (20 °C)[2]
Hazards
GHS labelling:
GHS02: Flammable GHS05: Corrosive GHS07: Exclamation mark
Danger
H225, H302, H314, H332
P210, P280, P305+P351+P338, P310
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
2
4
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)
[3]
Related compounds
Related amines
 Triethylenetetramine
Related compounds
Supplementary data page
Tetramethylethylenediamine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

As a reagent in 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.[4] 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.[4] Many anionic organometallic complexes have been isolated as their [Li(tmeda)2]+ complexes.[5] 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.[6]

sec-Butyllithium/TMEDA is a useful combination in organic synthesis where the n-butyl analogue adds to substrate. TMEDA is still capable of forming a metal complex with Li in this case as mentioned above.

Other uses

The complexes (TMEDA)Ni(CH3)2 and [(TMEDA)Ni(o-tolyl)Cl] illustrate the use of tmeda to stabilize homogeneous catalysts.[7] [8]

Synthesis of [(TMEDA)Ni(o-tolyl)Cl]

Isomers

Tetramethylethylenediamine can also refer to 2,3-dimethyl-2,3-diaminobutane, H2NCMe2−CMe2NH2.[9]

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. Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
  3. "MSDS" (PDF).
  4. 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.
  5. Morse, P. M.; Girolami, G. S. (1989). "Are d0 ML6 Complexes Always Octahedral? The X-ray Structure of Trigonal Prismatic [Li(tmed)]2[ZrMe6]". Journal of the American Chemical Society. 111 (11): 4114–4116. doi:10.1021/ja00193a061.
  6. 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 (49): 11855. doi:10.1021/ja971920t.
  7. Shields, Jason D.; Gray, Erin E.; Doyle, Abigail G. (2015-05-01). "A Modular, Air-Stable Nickel Precatalyst". Organic Letters. 17 (9): 2166–2169. doi:10.1021/acs.orglett.5b00766. PMC 4719147. PMID 25886092.
  8. Magano, Javier; Monfette, Sebastien (2015-04-17). "Development of an Air-Stable, Broadly Applicable Nickel Source for Nickel-Catalyzed Cross-Coupling". ACS Catalysis. 5 (5): 3120–3123. doi:10.1021/acscatal.5b00498.
  9. Jackson, W.Gregory; Rahman, A.F.M.Mokhlesur; Wong, M.Anthony (2004). "Solvent Exchange, Solvent Interchange, Aquation and Isomerisation Reactions of cis- and trans-[Co(tmen)2(NCMe)2]3+ in Water, Me2SO and MeCN: Kinetics and Stereochemistry". Inorganica Chimica Acta. 357 (3): 665–676. doi:10.1016/j.ica.2003.05.010.
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