![]() ^ a b c d e f Sigma-Aldrich Co., Trimethylaluminum.Trimethylaluminium is pyrophoric, reacting violently with air and water. It reacts with ketones to give, after a hydrolytic workup, tertiary alcohols. TMA is a source of methyl nucleophiles, akin to methyl lithium, but less reactive. The NASA ATREX mission ( Anomalous Transport Rocket Experiment) employed the white smoke that TMA forms on air contact to study the high altitude jet stream. the complex with the tertiary amine DABCO, are safer to handle than TMA itself. The enthalpy data show that AlMe 3 is a hard acid and its acid parameters in the ECW model are E A =8.66 and C A = 3.68. The Lewis acid properties of AlMe 3 have been quantified. Adducts Īs for other "electron-deficient" compounds, trimethylaluminium gives adducts R 3N. In combination with 20 to 100 mol % Cp 2ZrCl 2 ( zirconocene dichloride), the (CH 3) 2Al-CH 3 adds "across" alkynes to give vinyl aluminium species that are useful in organic synthesis in a reaction known as carboalumination. Tebbe's reagent, which is used for the methylenation of esters and ketones, is prepared from TMA and titanocene dichloride. TMA/metal halide reactions have emerged as reagents in organic synthesis. Al 2Me 6 reacts with aluminium trichloride to give (AlMe 2Cl) 2. ![]() When combined with gallium trichloride, it gives trimethylgallium. ![]() TMA reacts with many metal halides to install alkyl groups. For example, dimethylamine gives the dialuminium diamide dimer: 2 AlMe 3 + 2 HNMe 2 → 2 + 2 CH 4 Reactions with metal chlorides Under controlled conditions, the reaction can be stopped to give methylaluminoxane:Īlcoholysis and aminolysis reactions proceed comparably. Trimethylaluminium is hydrolyzed readily, even dangerously: Reactions Hydrolysis and related protonolysis reactions The Al 2O 3 layer is typically the bottom layer with multiple silicon nitride (Si xN y) layers for capping. The Al 2O 3 provides excellent surface passivation of p-doped silicon surfaces. In deposition processes very similar to semiconductor processing, TMA is used to deposit thin film, low-k (non-absorbing) dielectric layer stacks with Al 2O 3 via the processes of chemical vapor deposition or atomic layer deposition. Criteria for TMA quality focus on (a) elemental impurities, (b) oxygenated and organic impurities. TMA is the preferred precursor for metalorganic vapour phase epitaxy ( MOVPE) of aluminium-containing compound semiconductors, such as AlAs, AlN, AlP, AlSb, AlGaAs, AlInGaAs, AlInGaP, AlGaN, AlInGaN, AlInGaNP, etc. TMA is also used in semiconductor fabrication to deposit thin film, high-k dielectrics such as Al 2O 3 via the processes of chemical vapor deposition or atomic layer deposition. Methylaluminoxane, which is produced from TMA, is an activator for many transition metal catalysts. Starting with the invention of Ziegler-Natta catalysis, organoaluminium compounds have a prominent role in the production of polyolefins, such as polyethylene and polypropylene. TMA is prepared via a two-step process that can be summarized as follows:Ģ Al + 6 CH 3Cl + 6 Na → Al 2(CH 3) 6 + 6 NaCl Applications Catalysis
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