Diisobutylaluminium hydride

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Diisobutylaluminium hydride
IUPAC name
Diisobutylaluminum hydride
Other names
3D model (JSmol)
ECHA InfoCard 100.013.391
C16H38Al2 (dimer)
Molar mass 142.22 (monomer)
Appearance colorless liquid
Density 0.798 g/cm3
Melting point −80 °C (−112 °F; 193 K)
Boiling point 116 to 118 °C (241 to 244 °F; 389 to 391 K) at 1 mmHg
hydrocarbon solvents; violently reacts with water
Main hazards ignites in air
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Diisobutylaluminium hydride (DIBALH, DIBAL, DIBAL-H or DIBAH, /ˈdbæl/ DY-bal) 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.

DIBAL 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 DIBAL can be purchased commercially as a colorless liquid, it is more commonly purchased and dispensed as a solution in an organic solvent such as toluene or hexane.

Use in organic synthesis[edit]

DIBAL is useful in organic synthesis for a variety of reductions, including converting carboxylic acids, their derivatives, and nitriles to aldehydes. DIBAL 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]. DIBAL 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.


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


  1. ^ Ziegler, K.; Martin, H.; Krupp, F. (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. ^ Self, M. F.; Pennington, W. T.; Robinson, G. H. (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 (2): 151–153. doi:10.1016/S0020-1693(00)84819-7. 
  3. ^ Eisch, J. J. (1981). Organometallic Syntheses. 2. New York: Academic Press. ISBN 0-12-234950-4. 
  4. ^ Galatsis, P. (2001). "Diisobutylaluminum Hydride". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rd245. ISBN 0471936235. 

External links[edit]