Diisobutylaluminium hydride

Diisobutylaluminium hydride

Names
IUPAC name Diisobutylaluminum hydride
Other names DIBAH; DIBAL; DiBAlH; DIBAL-H; DIBALH
Identifiers
CAS Number	1191-15-7 Y
3D model (Jmol)	Interactive image
ChemSpider	10430352 Y
ECHA InfoCard	100.013.391
InChI InChI=1S/2C4H9.Al.H/c2*1-4(2)3;;/h2*4H,1H2,2-3H3;; Y Key: AZWXAPCAJCYGIA-UHFFFAOYSA-N Y InChI=1/2C4H9.Al.H/c2*1-4(2)3;;/h2*4H,1H2,2-3H3;;/rC8H19Al/c1-7(2)5-9-6-8(3)4/h7-9H,5-6H2,1-4H3 Key: AZWXAPCAJCYGIA-DFAADSFOAF
SMILES CC(C)C[AlH]CC(C)C
Properties
Chemical formula	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
Solubility in water	hydrocarbon solvents
Hazards
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).
Y  (what is YN ?)
Infobox references

Diisobutylaluminium hydride (DIBALH, DIBAL, DIBAL-H or DIBAH, DYE-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.

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. 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:

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.

DIBAL is useful in organic synthesis for a variety of reductions, including converting esters and nitriles to aldehydes. DIBAL efficiently reduces α-β unsaturated esters to the corresponding allylic alcohol. 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.