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 hydrideligands.[2] Hydrides are small and, for aluminium derivatives, are highly basic, thus they bridge in preference to the alkyl groups.
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 synthesisedit
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]. 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.
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.[4]
DIBAL, like most alkylaluminium compounds, reacts violently with air and water, potentially leading to explosion.[6]
Referencesedit
^ abGalatsis, P. (2001). "Diisobutylaluminum Hydride". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rd245. ISBN0471936235.
^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.
^Eisch, J. J. (1981). Organometallic Syntheses. Vol. 2. New York: Academic Press. ISBN0-12-234950-4.
^Webb, Damien; Jamison, Timothy F. (2012-01-20). "Diisobutylaluminum Hydride Reductions Revitalized: A Fast, Robust, and Selective Continuous Flow System for Aldehyde Synthesis". Organic Letters. 14 (2): 568–571. doi:10.1021/ol2031872. hdl:1721.1/76286. ISSN 1523-7060. PMID 22206502.
^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.
^Thermo Fisher Scientific, Regulatory Affairs (January 3, 2005). "Safety Data Sheet Diisobutylaluminum hydride". Thermo Fisher Scientific. Retrieved October 9, 2023.
External linksedit
Stockman, R. (2001). "Dibal reduction of an amino acid derived methyl ester; Garner's Aldehyde". ChemSpider Synthetic Pages. doi:10.1039/SP161. SyntheticPage 161.[permanent dead link]
. University of Southern Maine, Department of Chemistry. Archived from the original on 2011-06-11.
(PDF). Akzo-Nobel. Archived from the original (PDF) on 2011-04-08. Retrieved 2011-02-23.
January 01, 1970
diisobutylaluminium, hydride, dibalh, dibal, dibal, dibah, reducing, agent, with, formula, bu2alh, where, represents, isobutyl, ch2ch, this, organoaluminium, compound, reagent, organic, synthesis, names, iupac, name, other, names, dibah, dibal, dibalh, dibal, . 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 Diisobutylaluminium hydride Names IUPAC name Diisobutylaluminium hydride Other names DIBAH DIBAL DiBAlH DIBAL H DIBALH Identifiers CAS Number 1191 15 7 Y 3D model JSmol Interactive image ChemSpider 10430352 Y ECHA InfoCard 100 013 391 EC Number 214 729 9 PubChem CID 16682954 monomer 131737379 dimer UNII H2EJ47H11A CompTox Dashboard EPA DTXSID4041866 InChI InChI 1S 2C4H9 Al H c2 1 4 2 3 h2 4H 1H2 2 3H3 YKey AZWXAPCAJCYGIA UHFFFAOYSA N YInChI 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 4H3Key AZWXAPCAJCYGIA DFAADSFOAF SMILES CC C C AlH CC C C Properties Chemical formula 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 Solubility in water Reacts with water Solubility Soluble in hydrocarbons THF and ether Hazards Occupational safety and health OHS OSH Main hazards ignites in air GHS labelling Pictograms Signal word Danger Hazard statements H220 H225 H250 H260 H314 Precautionary statements 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 Y verify what is Y N Infobox references Contents 1 Properties 2 Use in organic synthesis 3 Safety 4 References 5 External linksProperties editLike 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 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 editDIBAL is useful in organic synthesis for a variety of reductions including converting carboxylic acids their derivatives and nitriles to aldehydes DIBAL efficiently reduces a b 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 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 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 4 DIBALH was investigated originally as a cocatalyst for the polymerization of alkenes 5 Safety editDIBAL like most alkylaluminium compounds reacts violently with air and water potentially leading to explosion 6 References edit a b Galatsis P 2001 Diisobutylaluminum Hydride Encyclopedia of Reagents for Organic Synthesis New York John Wiley amp Sons doi 10 1002 047084289X rd245 ISBN 0471936235 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 Eisch J J 1981 Organometallic Syntheses Vol 2 New York Academic Press ISBN 0 12 234950 4 Webb Damien Jamison Timothy F 2012 01 20 Diisobutylaluminum Hydride Reductions Revitalized A Fast Robust and Selective Continuous Flow System for Aldehyde Synthesis Organic Letters 14 2 568 571 doi 10 1021 ol2031872 hdl 1721 1 76286 ISSN 1523 7060 PMID 22206502 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 Thermo Fisher Scientific Regulatory Affairs January 3 2005 Safety Data Sheet Diisobutylaluminum hydride Thermo Fisher Scientific Retrieved October 9 2023 External links editStockman R 2001 Dibal reduction of an amino acid derived methyl ester Garner s Aldehyde ChemSpider Synthetic Pages doi 10 1039 SP161 SyntheticPage 161 permanent dead link Oxidation And Reduction Reactions in Organic Chemistry University of Southern Maine Department of Chemistry Archived from the original on 2011 06 11 Diisobutyl Aluminum hydride DIBAL H and Other Isobutyl Aluminum Alkyls DIBAL BOT TIBAL as Specialty Organic Synthesis Reagents PDF Akzo Nobel Archived from the original PDF on 2011 04 08 Retrieved 2011 02 23 Retrieved from https en wikipedia org w index php title Diisobutylaluminium hydride amp oldid 1208997715, wikipedia, wiki, book, books, library,
