| Revision as of 14:13, 10 January 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 464951362 of page Trimethylaluminium for the Chem/Drugbox validation project (updated: ''). |
Latest revision as of 13:36, 19 October 2024 edit Smokefoot (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers74,550 edits Undid revision 1252019882 by 185.205.224.91 (talk) seems in approp (a little long) and patents are unreliable sourcesTag: Undo |
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{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}} |
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{{chembox |
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{{chembox |
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| verifiedrevid = 449042573 |
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| verifiedrevid = 470615359 |
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| ImageFile = Trimethylaluminium-3D-balls.png |
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| ImageSize = |
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| Name = |
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| ImageFile = Trimethylaluminium-from-xtal-3D-bs-17-25.png |
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| IUPACName = trimethylalumane |
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| ImageFile1 = Trimethylaluminium-from-xtal-3D-sf.png |
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| OtherNames = Trimethylaluminium; aluminium trimethyl |
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| ImageSize = |
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| Section1 = {{Chembox Identifiers |
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| IUPACName = Trimethylalumane |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| OtherNames = Trimethylaluminum; aluminium trimethyl; aluminum trimethyl |
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| SystematicName = |
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| Section1 = {{Chembox Identifiers |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 10606585 |
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| ChemSpiderID = 10606585 |
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| InChI = 1/3CH3.Al/h3*1H3;/rC3H9Al/c1-4(2)3/h1-3H3 |
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| InChI = 1/3CH3.Al/h3*1H3;/rC3H9Al/c1-4(2)3/h1-3H3 |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo = 75-24-1 |
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| CASNo = 75-24-1 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| PubChem = 16682925 |
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| SMILES = C(C)C |
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| UNII = AV210LG46J |
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| PubChem = 16682925 |
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| SMILES = C(C)(1)1(C)C |
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| SMILES_Comment = ] |
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| SMILES1 = C(C)C |
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| SMILES1_Comment = ] |
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}} |
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}} |
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| Section2 = {{Chembox Properties |
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| Section2 = {{Chembox Properties |
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| Formula = C<sub>6</sub>H<sub>18</sub>Al<sub>2</sub> |
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| Formula = C<sub>6</sub>H<sub>18</sub>Al<sub>2</sub> |
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| MolarMass = 144.18 g/mol |
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| MolarMass = 144.17 g/mol<br> 72.09 g/mol (C<sub>3</sub>H<sub>9</sub>Al) |
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| Appearance = Colorless liquid |
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| Appearance = Colorless liquid |
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| Density = 0.752 g/mL |
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| Density = 0.752 g/cm<sup>3</sup> |
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| MeltingPt = 15 °C |
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| MeltingPtC = 15 |
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| BoilingPt = 125 °C |
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| BoilingPtC = 125-130 |
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| BoilingPt_ref = <ref name="sigma" /><ref name=chemister /> |
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| Solubility = |
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| VaporPressure = {{ubl |
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| 1.2{{nbsp}}kPa (20{{nbsp}}°C) |
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| 9.24{{nbsp}}kPa (60{{nbsp}}°C)<ref name="sigma" /> |
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}} |
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| Viscosity = {{ubl |
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| 1.12{{nbsp}}cP (20{{nbsp}}°C) |
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| 0.9{{nbsp}}cP (30{{nbsp}}°C) |
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}} |
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| Solubility = Reacts |
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}} |
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| Section3 = {{Chembox Thermochemistry |
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| HeatCapacity = 155.6{{nbsp}}J/mol·K<ref name=chemister>{{Cite web|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=3290|title = Trimethyl aluminum}}</ref> |
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| Entropy = 209.4{{nbsp}}J/mol·K<ref name=chemister /> |
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| DeltaHf = −136.4{{nbsp}}kJ/mol<ref name=chemister /> |
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| DeltaGf = −9.9{{nbsp}}kJ/mol<ref name=chemister /> |
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}} |
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| Section4 = {{Chembox Hazards |
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| GHSPictograms = {{GHS02}}{{GHS05}}<ref name="sigma">{{Sigma-Aldrich|id=597775|name=Trimethylaluminum|accessdate=2014-05-05}}</ref> |
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| GHSSignalWord = Danger |
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| HPhrases = {{H-phrases|250|260|314}}<ref name="sigma" /> |
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| PPhrases = {{P-phrases|222|223|231+232|280|370+378|422}}<ref name="sigma" /> |
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| MainHazards = Pyrophoric |
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| NFPA-H = 3 |
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| NFPA-F = 4 |
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| NFPA-R = 3 |
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| NFPA-S = W |
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| FlashPtC = -17.0 |
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| FlashPt_ref = <ref name="sigma" /> |
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| AutoignitionPt = |
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| Section3 = {{Chembox Hazards |
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| Section5 = {{Chembox Related |
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| OtherCompounds = ] |
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| MainHazards = Pyrophoric |
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| NFPA-H = 3 |
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| NFPA-F = 4 |
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| NFPA-R = 3 |
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| NFPA-O = W |
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| FlashPt = |
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| Section6 = |
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'''Trimethylaluminium''' is one of the simplest examples of an ] compound. Despite its name it has the ] ]<sub>2</sub>(])<sub>6</sub> (abbreviated as Al<sub>2</sub>Me<sub>6</sub> or TMA), as it exists as a ]. This colorless liquid is ]. It is an industrially important compound, closely related to ].<ref>{{Ullmann|doi=10.1002/14356007.a01_543|title=Aluminum Compounds, Organic|year=2000|last1=Krause|first1=Michael J.|last2=Orlandi|first2=Frank|last3=Saurage|first3=Alfred T.|last4=Zietz|first4=Joseph R.}}</ref><ref>{{cite book|title=Organometallics|author=C. Elschenbroich|publisher=VCH|year=2006|isbn= 978-3-527-29390-2}}</ref> |
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==Structure and bonding== |
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The structure and bonding in Al<sub>2</sub>R<sub>6</sub> and ] are analogous (R = alkyl). In Al<sub>2</sub>Me<sub>6</sub>, the Al-C(terminal) and Al-C(bridging) distances are 1.97 and 2.14 Å, respectively. The Al center is tetrahedral.<ref>{{cite book |author1=Holleman, A. F. |author2=Wiberg, E. | title = Inorganic Chemistry | publisher = Academic Press | location = San Diego | year = 2001 | isbn = 0-12-352651-5}}</ref> The carbon atoms of the bridging methyl groups are each surrounded by five neighbors: three hydrogen atoms and two aluminium atoms. The methyl groups interchange readily intramolecularly. At higher temperatures, the dimer ] into monomeric AlMe<sub>3</sub>.<ref>{{cite journal|doi=10.1021/om010994h|title=HeI Photoelectron Spectroscopy of Trialkylaluminium and Dialkylaluminium Hydride Compounds and Their Oligomers|year=2002|last1=Vass|first1=Gábor|last2=Tarczay|first2=György|last3=Magyarfalvi|first3=Gábor|last4=Bödi|first4=András|last5=Szepes|first5=László|journal=Organometallics|volume=21|issue=13|pages=2751–2757}}</ref>{{Clearleft}} |
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==Synthesis== |
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TMA is prepared via a two-step process that can be summarized as follows: |
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:2 Al + 6 ] + 6 Na → Al<sub>2</sub>(CH<sub>3</sub>)<sub>6</sub> + 6 NaCl |
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==Applications== |
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===Catalysis=== |
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Starting with the invention of ], ]s have a prominent role in the production of ]s, such as ] and ]. ], which is produced from TMA, is an activator for many transition metal catalysts. |
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===Semiconductor applications=== |
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TMA is also used in semiconductor fabrication to deposit thin film, high-k ]s such as Al<sub>2</sub>O<sub>3</sub> via the processes of ] or ]. TMA is the preferred precursor for ] (]) of aluminium-containing ]s, such as ], ], ], ], ], ], ], ], ], ], etc. Criteria for TMA quality focus on (a) elemental impurities, (b) oxygenated and organic impurities. |
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===Photovoltaic applications=== |
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In deposition processes very similar to semiconductor processing, TMA is used to deposit thin film, low-k (non-absorbing) dielectric layer stacks with Al<sub>2</sub>O<sub>3</sub> via the processes of ] or ]. The Al<sub>2</sub>O<sub>3</sub> provides excellent surface passivation of p-doped silicon surfaces. The Al<sub>2</sub>O<sub>3</sub> layer is typically the bottom layer with multiple silicon nitride (Si<sub>x</sub>N<sub>y</sub>) layers for capping. |
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==Reactions== |
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===Hydrolysis and related protonolysis reactions=== |
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Trimethylaluminium is hydrolyzed readily, even dangerously: |
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:Al<sub>2</sub>Me<sub>6</sub> + 3 H<sub>2</sub>O → Al<sub>2</sub>O<sub>3</sub> + 6 CH<sub>4</sub> |
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Under controlled conditions, the reaction can be stopped to give ]: |
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:AlMe<sub>3</sub> + H<sub>2</sub>O → 1/n <sub>n</sub> + 2 CH<sub>4</sub> |
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Alcoholysis and aminolysis reactions proceed comparably. For example, ] gives the dialuminium diamide dimer:<ref>{{cite journal |doi=10.15227/orgsyn.059.0049|title=Conversion of Esters to Amides with Dimethylaluminium Amides: N,N-Dimethylcyclohexanecarboxamide|journal=Organic Syntheses|year=1979|volume=59|page=49|first1=Michael F.|last1=Lipton|first2=Anwer|last2=Basha|first3=Steven M.|last3=Weinreb}}</ref> |
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:2 AlMe<sub>3</sub> + 2 HNMe<sub>2</sub> → <sub>2</sub> + 2 CH<sub>4</sub> |
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===Reactions with metal chlorides=== |
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TMA reacts with many metal halides to install alkyl groups. When combined with gallium trichloride, it gives ].<ref>{{cite book |doi=10.1002/9780470132463.ch45|chapter=Trimethylgallium|last1=Gaines|first1=D. F.|last2=Borlin|first2=Jorjan|last3=Fody|first3=E. P.|title=Inorganic Syntheses|pages=203–207|volume=15|year =1974|isbn=978-0-470-13246-3}}</ref> Al<sub>2</sub>Me<sub>6</sub> reacts with ] to give (AlMe<sub>2</sub>Cl)<sub>2</sub>. |
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TMA/metal halide reactions have emerged as reagents in ]. ], which is used for the methylenation of ]s and ]s, is prepared from TMA and ].<ref>{{cite journal | last1 = Pine|first1=S. H.| last2=Kim|first2=V.| last3=Lee| first3=V. | title = Enol ethers by methylenation of esters: 1-Phenoxy-1-phenylethene and 3,4-dihydro-2-methylene-2''H''-1-benzopyran | journal=Org. Synth.|volume = 69 | page = 72 | doi = 10.15227/orgsyn.069.0072 | year = 1990}}</ref> In combination with 20 to 100 mol % Cp<sub>2</sub>ZrCl<sub>2</sub> (]), the (CH<sub>3</sub>)<sub>2</sub>Al-CH<sub>3</sub> adds "across" alkynes to give vinyl aluminium species that are useful in ] in a reaction known as carboalumination.<ref>{{cite journal | author1 = Negishi, E. |author2=Matsushita, H. | title = Palladium-Catalyzed Synthesis of 1,4-Dienes by Allylation of Alkenyalane: α-Farnesene <nowiki></nowiki> | journal=Organic Syntheses|year = 1984 | volume = 62 | pages = 31 | doi=10.15227/orgsyn.062.0031}}</ref> |
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===Adducts=== |
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As for other "electron-deficient" compounds, trimethylaluminium gives ]s R<sub>3</sub>N<big>.</big>AlMe<sub>3</sub>. The Lewis acid properties of AlMe<sub>3</sub> have been quantified.<ref>{{cite journal|author1=Henrickson, C. H. |author2= Duffy, D. |author3= Eyman, D. P. |year= 1968|title= Lewis acidity of Alanes. Interactions of Trimethylalane with Amines, Ethers, and Phosphines|journal=Inorganic Chemistry|volume=7|issue= 6 |pages=1047–1051|doi=10.1021/ic50064a001}}</ref> The enthalpy data show that AlMe<sub>3</sub> is a ] acid and its acid parameters in the ] are E<sub>A</sub> =8.66 and C<sub>A</sub> = 3.68. |
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These adducts, e.g. the complex with the ] ], are safer to handle than TMA itself.<ref>{{cite journal |last1=Vinogradov|first1=Andrej |last2=Woodward|first2=S.|title=Palladium-Catalyzed Cross-Coupling Using an Air-Stable Trimethylaluminium Source. Preparation of Ethyl 4-Methylbenzoate| journal = Organic Syntheses | year = 2010 | volume = 87 | page = 104 | doi = 10.15227/orgsyn.087.0104|doi-access=free}}</ref> |
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The ] ATREX mission (]) employed the white smoke that TMA forms on air contact to study the high altitude jet stream. |
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===Synthetic reagent=== |
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TMA is a source of methyl nucleophiles, akin to ], but less reactive. It reacts with ketones to give, after a hydrolytic workup, tertiary alcohols. |
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==Safety== |
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Trimethylaluminium is pyrophoric, reacting violently with air and water. |
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== References == |
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{{reflist}} |
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==External links== |
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{{Commons category|Trimethylaluminium}} |
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*. |
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{{Aluminium compounds}} |
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{{Authority control}} |
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] |
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] |
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] |
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] |