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Diisobutylaluminium hydride
CAS number 1191-15-7 Yes check.svgY
Molecular formula C16H38Al2 (dimer)
Molar mass 142.22 (monomer)
Appearance colorless liquid
Density 0.798 g/cm3
Melting point

–18 °C

Boiling point

116–118 °C/1 mmHg

Solubility in water hydrocarbon solvents
Main hazards ignites in air
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Diisobutylaluminium hydride, DIBAL, DIBAL-H or DIBAH, is a reducing agent with the formula (i-Bu2AlH)2, where i-Bu represents isobutyl (-CH2CH(CH3)2). This organoaluminium compound was investigated originally as a co-catalyst for the polymerization of alkenes.[1]



Like most organoaluminum compounds, the compound’s structure is probably more than that suggested by its empirical formula. A variety of techniques, not including X-ray crystallography, suggest that the compound exists as a dimer and a trimer, consisting of tetrahedral aluminium centers sharing bridging hydride ligands.[2] Hydrides are small and, for aluminium derivatives, are highly basic, thus they bridge in preference to the alkyl groups.

DIBAH can be prepared by heating triisobutylaluminium (itself a dimer) to induce beta-hydride elimination:[3]

(i-Bu3Al)2 → (i-Bu2AlH)2 + 2 (CH3)2C=CH2

Although DIBAH can be purchased commercially as a colorless liquid, it is more commonly purchased and dispensed as a solution in organic solvents such as toluene.

Use in organic synthesis

DIBAH is useful in organic synthesis for a variety of reductions, including converting esters and nitriles to aldehydes. DIBAH efficiently reduces α-β unsaturated esters to the corresponding allylic alcohol.[4] By contrast, LiAlH4 reduces esters and acyl chlorides to primary alcohols, and nitriles to primary amines [use Feiser work-up procedure]. DIBAH reacts slowly with electron-poor compounds, and more quickly with electron-rich compounds. Thus, it is an electrophilic reducing agent whereas LiAlH4 can be thought of as a nucleophilic reducing agent.


DIBAH, like most alkylaluminium compounds, reacts violently with air and water, potentially leading to fires.


  1. ^ K. Ziegler, H. Martin and F. Krupp (1960). "Metallorganische Verbindungen, XXVII Aluminiumtrialkyle und Dialkyl-Aluminiumhydride Aus Aluminiumisobutyl-Verbindungen". Justus Liebigs Annalen der Chemie 629 (1): 14–19. doi:10.1002/jlac.19606290103. 
  2. ^ Mark F. Self, William T. Pennington and Gregory H. Robinson (1990). "Reaction of diisobutylaluminum hydride with a macrocyclic tetradentate secondary amine. Synthesis and molecular structure of [Al(iso-Bu)]2[C10H20N4][Al(iso-Bu)3]2: evidence of an unusual disproportionation of (iso-Bu)2AlH". Inorganica Chimica Acta 175: 151–3. doi:10.1016/S0020-1693(00)84819-7. 
  3. ^ Eisch, J. J. Organometallic Syntheses Volume 2, Academic Press: New York, 1981. ISBN 0-12-234950-4.
  4. ^ Galatsis, P. “Diisobutylaluminum Hydride” in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons: New York, 2001. doi:10.1002/047084289X.rd245

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