Aluminum trimethyl

The first is a pyrolytic approach in which the heat dehvered by the laser breaks chemical bonds in vapor-phase reactants above the surface, allowing deposition of the reaction products only in the small heated area. The second is a direct photolytic breakup of a vapor-phase reactant. This approach requires a laser with proper wavelength to initiate the photochemical reaction. Often ultraviolet excimer lasers have been used. One example is the breakup of trimethyl aluminum [75-24-1] gas using an ultraviolet laser to produce free aluminum [7429-90-5], which deposits on the surface. Again, the deposition is only on the localized area which the beam strikes. 

MAO is a relatively expensive chemical its price in 1994 was about 450/kg of 30 wt % MAO solution, but projected to decrease to about 200/kg (28). Continuous efforts to replace MAO have resulted in the development of co-catalysts containing mixtures of MAO and trimethyl aluminum (29) as well as new co-catalyst types (30,31). Another approach is to prepare MAO directiy in a polymeriza tion reactor by co-feeding into it trimethyl aluminum and water (32). 

Trimethyl aluminum and propylene oxide form a mixture of 2-methyl-1-propanol and 2-butanol (105). Triethyl aluminum yields products of 2-methyl-1-butanol and 2-pentanol (106). The ratio of products is determined by the ratio of reactants. Hydrolysis of the products of methyl aluminum dichloride and propylene oxide results ia 2-methylpropeae and 2-butene, with elimination of methane (105). Numerous other nucleophilic (107) and electrophilic (108) reactions of propylene oxide have been described ia the Hterature. 

Most metallo-organic compounds are monomers with some important exceptions, such as trimethyl aluminum which is a dimer. Their vapor pressures are usually directly related to the molecular weight, with the lower molecular weight compounds having the higher volatility. 

AIN is now often produced by MOCVD by reacting ammonia with trimethyl aluminum at low pressure (< 1 Torr), in the temperature range 900-1400°C raP]... 

Barron et al. report the synthesis of several adducts of tertiary phosphanes with trimethyl aluminum, Eq. (2) [34]. 

A systematic NMR spectroscopic study of these adducts suggests that the steric repulsion between the trimethyl aluminum Lewis acid and the phosphane Lewis base rather than the electronic factors account for the detected changes in the P-NMR spectroscopic chemical shifts (Table 1). The change in the chemical shift (A) of the phosphanes on coordination to AlMe3 has been correlated to the... 

Equation (3) shows that when tri(2-pyridyl)phosphane 9 [44] is treated directly with trimethyl aluminum in diethyl ether the adduct complex Me3Al(/r-Py)PPy2 10 is obtained which has structurally been characterised,... 

Compound 13a can been obtained via two different routes firstly in the reaction of 11 with dimethyl aluminum chloride where LiCl is eliminated and secondly by the reaction of di(pyridyl) phosphane 12 (Py2PH) with trimethyl aluminum where methane is formed, (Scheme 5). The X-ray structure determination of [Me2AlPy2P] 13a, (Fig. 3) elucidates the aluminum atom to be coordinated by the two nitrogen atoms of the pyridyl rings in addition to the two remaining methyl groups leaving the aluminum four... 

Cyclodiphosphazanes(III) 27 shown in Scheme 16 undergo oxidation reactions to give the cyclodiphosphazanes(V) of type 28. These are prospective ligands in catalysis since these ligands due to lack of phosphorus lone-pairs are less susceptible to the destructive cycloreversion of the ligands. Hence they could prevent catalyst deactivation in the process. When treated with trimethyl aluminum the cyclodiphosphazanes form symmetrically substituted bimetallic species of type 29 [90]. Characterization by single-crystal X-ray studies show... 

Lactones can be protected as dithiolane derivatives using a method that is analogous to ketone protection. The required reagent is readily prepared from trimethyl-aluminum and ethanedithiol. 

Wipf and coworkers used a Claisen rearrangement of allyl phenyl ethers 4-309 followed by an enantioselective carboalumination using the chiral Zr-complex 4-310 and trimethyl aluminum (Scheme 4.67) [104]. After an oxidative work-up of the intermediate trialkylalane, the corresponding alcohols 4-311 were obtained with up to 80% ee and 78% yield. One can also transfer an ethyl group using triethyl aluminum with even better ee-values (up to 92%), but the yields were rather low (42%) due to a more sluggish oxidative cleavage of the Al-C bond. 

Lithium alkylamides react with dimethyltin dichloride to give the cyclotristannazane, which is methylated by trimethyl-aluminum, -gallium, or -indium, giving the metal stannylamides, which are coordinatively dimerized (Equation (167)).503... 

Alternatively, bromo trienyne 66, prepared by the Wittig reaction of TMS-capped propargyl ylide with , -5-bromo-2,4-pentadienal, could be coupled with dienyl zinc reagent 67, as illustrated in equation 3657. Subsequent desilylation followed by treatment with trimethyl aluminum in the presence of catalytic Cp2ZrCl2 afforded the alane of tetraenyne 68 which, on exposure to chloroformate, gave essentially all- polyene ester 69. 

Much the same activity is retained when the nitrogen atoms in the heterocyclic nucleus are shifted around. The convergent scheme to this related compound starts with the acylation of alanine (35-1) with butyryl chloride (35-2). The thus-produced amide (35-3) is then again acylated, this time with the half-acid chloride from ethyl oxalate in the presence of DMAP and pyridine to afford the intermediate (35-4). In the second arm of the scheme, the benzonitrile (35-5) is reacted with the aluminate (35-6), itself prepared from trimethyl aluminum and ammonium chloride, to form the imidate (35-7). Treatment of this intermediate with hydrazine leads to the replacement of one of the imidate nitrogen atoms by the reagent by an addition-elimination sequence to form (35-8). Condensation of this product with (35-4) leads to the formation of the triazine (35-9). Phosphorus oxychloride then closes the second ring... 

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