Description
Diisobutylaluminium hydride (DIBALH, DIBAL, DIBAL-H or DIBAH) is a reducing agent with the formula (i-Bu2AlH)2, where i-Bu represents isobutyl (-CH2CH(CH3)2). It can be used for various homogeneous reductions such as alkynes to alkenes, esters or nitriles to aldehydes. It is available commercially as the neat reagent and as a solution in several different solvents (hexane, dichloromethane, tetrahydrofuran, etc.). The neat reagent is a liquid and is supplied in metal cylinders. It is pyrophoric and highly reactive and therefore must be handled with great care. The molar solutions in organic solvents are more stable and easier to handle provided that the normal precautions are taken for working with air-sensitive compounds. They must all be handled in an atmosphere free from oxygen and water. Commonly used solvents for diisobutylaluminium hydride are dichloromethane, diglyme, dioxane and tetrahydrofuran. Even when the substrate is not completely soluble in these solvents successful reductions can be accomplished.
Chemical Properties
Diisobutylaluminium hydride, also known as Dibal. colorless liquid. Viscosity 18.0mPa-s(25℃). Reacts violently with water to form hydrogen and isobutane. Tetrahydrofuran is not suitable as Dibal solvent, because the two react to produce coordination compounds. Diisobutylaluminium hydride is a useful reducing agent in organic synthesis. It can reduce ketones, carboxylic acids and esters to the corresponding alcohols. Dibal can also reduce lactones to o-hydroxy lactones.
Uses
Diisobutylaluminum hydride is used as reducing agent in pharmaceuticals. It is also used as raw material in organic synthesis, agrochemicals and dyestuffs.
Uses
Diisobutylaluminum hydride (DIBAL-H) is a common reducing agent to reduce aldehydes, ketones, esters, acids and acid chlorides to the corresponding alcohols. Some of the applications are:
Synthesis of α-acetoxy ethers by reduction and subsequent acetylation of esters.
Synthesis of coniferyl, sinapyl, and p-coumaryl alcohol by selective reduction of corresponding cinnamate esters.
Reduction of secondary phosphine oxides (SPOs) to the corresponding phosphines.
DIBAL-H can also be used in the hydroalumination of alkene and alkynes.
Uses
Diisobutylaluminum hydride is commonly used as a reducing agent in organic synthesis.
Diisobutylaluminum hydride can be used in the following protocols:
As a promotor of Tishchenko reaction of aldehydes.
Conversion of benzylidene acetals of 1,2-and 1,3-glycols to the corresponding monobenzyl ethers of the glycols.
To generate a novel chiral reducing agent based on (S)-proline for the asymmetric reduction of prochiral ketones.
Flammability and Explosibility
Spontaneously flammable in air (pyrophoric)
Safety Profile
Mddly toxic by
inhalation. Dangerous fire hazard; iptes
spontaneously in air. To fight fire, do not
use water, foam, or halogenated
extinguisking agents. See also HYDRIDES
and ALUMINUM COMPOUNDS.
