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Names | |
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IUPAC name Diisobutylaluminium hydride | |
Other names DIBAH; DIBAL; DiBAlH; DIBAL-H; DIBALH | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.013.391 |
EC Number |
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PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C8H19Al (monomer) C16H38Al2 (dimer) | |
Molar mass | 142.22 g/mol (monomer) 284.44 g/mol (dimer) |
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 |
Reacts with water | |
Solubility | Soluble in hydrocarbons, THF, and ether |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards | ignites in air |
GHS labelling: | |
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Danger | |
H220, H225, H250, H260, H314 | |
P210, P222, P223, P231+P232, P233, P240, P241, P242, P243, P260, P264, P280, P301+P330+P331, P302+P334, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P335+P334, P363, P370+P378, P377, P381, P402+P404, P403, P403+P235, P405, P422, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
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). This organoaluminium compound is a reagent in organic synthesis. [1]
Like most organoaluminum compounds, the compound's structure is most 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 β-hydride elimination: [3]
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 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 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. [1] By contrast, LiAlH4 reduces esters and acyl chlorides to primary alcohols, and nitriles to primary amines [using Fieser work-up procedure]. Similarly, DIBAL reduces lactones to hemiacetals (the equivalent of an aldehyde). [4]
Although DIBAL reliably reduces nitriles to aldehydes, the reduction of esters to aldehydes is infamous for often producing large quantities of alcohols. Nevertheless, it is possible to avoid these unwanted byproducts through careful control of the reaction conditions using continuous flow chemistry. [5]
DIBALH was investigated originally as a cocatalyst for the polymerization of alkenes. [6]
DIBAL, like most alkylaluminium compounds, reacts violently with air and water, potentially leading to explosion. [7]
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to an organyl group, or hydrogen, or other groups. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.
In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.
In organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.
Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[AlH4] or LiAlH4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage.
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