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Triisobutylaluminium

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Triisobutylaluminium

Monomeric form
Names
IUPAC name
Triisobutylaluminum
Other names
Aluminumtriisobutanide; TIBA
Identifiers
3D model (JSmol)
ECHA InfoCard 100.002.643 Edit this at Wikidata
UNII
  • CC(C)C[Al](CC(C)C)CC(C)C
Properties[1]
C12H27Al
Molar mass 198.330 g·mol−1
Appearance Colorless liquid
Density 0.786 g/mL at 25 °C
Melting point 4 to 6 °C (39 to 43 °F; 277 to 279 K)
Boiling point 86 °C (187 °F; 359 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Triisobutylaluminium (TiBA) is an organoaluminium compound with the formula Al(CH2CH(CH3)2)3. This colorless pyrophoric liquid is mainly used to make linear primary alcohols and αあるふぁ-olefins.[2]

Structure

Triisobutylaluminium exists in equilibrium with its dimer. The equilibrium constant, KD, is 3.810 at 20 °C.[3] In the dimer, the bridging carbon-aluminium bond is elongated and exhibits evidence of restricted rotation.

Synthesis

Trialkylaluminium compounds are available industrially through the reactions of aluminium powder, hydrogen gas, and the desired alkenes. The synthesis of TiBA requires two steps; the first step produces diisobutylaluminium hydride:

6 CH2=C(CH3)2 + 2 Al + 3 H2 → 6 HAl(CH2CH(CH3)2)2

In the second step isobutylene adds to the diisobutylaluminium to give TiBA:

CH2=C(CH3)2 + HAl(CH2CH(CH3)2)2 → Al(CH2CH(CH3)2)3

Reactions

αあるふぁ-olefins are readily eliminated from βべーた-branched trialkylaluminium compounds. Trialkylaluminium compounds are used in the industrial production of polymers. In the most common of these compounds, TIBA, a substantial level of Al – H bonds are present at equilibrium. The greater stability of unbranched trialkylaluminium compounds relative to branched trialkylaluminium compounds in TIBA forms the basis for a general synthesis of triethyl- and higher linear trialkylaluminium materials from triisobutylaluminium.

Al(CH2CH(CH3)2)3 + 3 RCH=CH2 → Al(CH2CH2R)3 + 3 CH2=C(CH3)2

Safety

Like most organoaluminium compounds, TiBA reacts violently with water and air.[1]

References

  1. ^ a b Sigma-Aldrich. "Triisobutylaluminum". MilliporeSigma. Merck Group. Retrieved 2021-03-15.
  2. ^ Michael J. Krause, Frank Orlandi, Alfred T. Saurage, Joseph R. Zietz Jr. "Aluminum Compounds, Organic" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_543
  3. ^ Smith, Martin B. (1970). "The Monomer-Dimer Equilibria of Liquid Ammonium Alkyls II Triisobutylaluminum". Journal of Organometallic Chemistry. 22 (2): 273–281. doi:10.1016/S0022-328X(00)86043-X.

Further reading

  • Keisuke Suzuki, Tetsuya Nagasaws, Encyclopedia of Reagents for Organic Synthesis, Triisobutylaluminum, 2009
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