Trimethylaluminium

The mechanism of formation of Pt particles by the or-ganometallic reduction route, however, was found to proceed differently, for example in the reductive stabilization of Pt nanoparticles produced by reacting Pt-acetylacetonate with excess trimethylaluminium. Here, derivates of aluminium alkyls act as both reducing agents and colloidal stabilizers. As was shown by a combination... 

The effect of chloromethane on aluminium powder in the presence of aluminium chloride traces forms trimethylaluminium. Its spontaneous ignition has caused numerous accidents. The same is true for zinc. 

Bei Einwirkung einer elektrischen Entladung auf ein gasformiges Ge-misch von Wasserstoff und Trimethylaluminium AlMe3 resultiert unter schrittweisem Ersatz von Methylgruppen gegen Wasserstoffatome ein... 

In presence of catalytic amounts of aluminium chloride, powdered aluminium and chloromethane interact to form pyrophoric trimethylaluminium. Chloromethane may react explosively with magnesium, or potassium, sodium or their alloys. Zinc probably reacts similarly to magnesium. 

In preparation of di-//-mcthylcncbis(incthyl-pcntamcthylcyclopcntadicnvl)dirhod-ium complexes by aerobic oxidation of a solution of the halocomplex and methyl-lithium or trimethylaluminium in ether-benzene, the reaction mixture occasionally ignited and burned violently. Full precautions and a working scale below 1 mmol are recommended. 

Substituent effects on the endocyclic cleavage of glycosides by trimethylaluminium have been explained in terms of a cyclic C-H O hydrogen-bonded intermediate. ... 

One very important use of E and G numbers is the calculation of heats of interaction for systems which have not been examined experimentally. We are now in a position to predict almost 1000 enthalpies of adduct formation by combining the parameters in Tables 3 and 4 according to Eq. (13). The trimethylaluminium enthalpies are for the monomer... 

Triethylantimony, 2574 Triethylgallium, 2563 Triethylindium, 2564 Trimethylaluminium, 1291 Trimethylantimony, 1320 Trimethylbismuthine, 1298 Trimethylgallium, 1305... 

Dihydro-l,2,4-tetrazine 49 reacts with trimethylaluminium to produce mono 5 a and diketones 50b depending upon the reaction conditions. Borohydride reduction of 50a gives alcohol 50c. Aromatization of 50a-c by exposure to nitrous gases affords tetrazines 51a-c which have proved to be very good electron-defficient heteroatomic azadienes for inverse electron demand Diels-Alder chemistry. Numerous examples are described with symmetric and nonsymmetric electron rich dienophiies <98JOC10063>. 

In related work from the same group, dehydro-nucleoside 21 underwent stereospecific epoxidation with dimethyl-dioxirane (DMDO) to give epoxide 22. The ring opening of this compound with trimethylaluminium is presumably a predominantly S m1 process giving isomers 23 and 24 in a 5 1 ratio (Scheme 4) <2004JOC1831>. 

The ester 205 condensed with 206 when left overnight in the presence of trimethylaluminium at —78°C to yield 207 (Equation 22) <1996JOC3987>. 

When controlled nitridation of surface layers is required, as for example in the modification of the chemical properties of the surface of a support, the atomic layer deposition (ALD) technique can be applied." This technique is based upon repeated separate saturating reactions of at least two different reactants with the surface, which leads to the controlled build-up of thin films via reaction of the second component with the chemisorbed residues of the first reactant. Aluminium nitride surfaces have been prepared on both alumina and silica supports by this method wherein reaction cycles of trimethylaluminium and ammonia have been performed with the respective supports, retaining their high surface areas." This method has been applied to the modification of the support composition for chromium catalysts supported on alumina." ... 

A third method makes use of hydrides of group V elements together with volatile organometallic compounds of group III elements such as trimethylgallium and trimethylaluminium. 

A modified synthesis of vardenafil (2) on a multi-kilogram scale has recently been reported by a group from Bayer (Scheme 4). Benzamidine 12 was prepared in a different manner than described in Scheme 3, because it is difficult to use trimethylaluminium on a large scale. Thus, 2-ethoxybenzamide was dehydrated with thionyl chloride to give 2-ethoxybenzonitrile, which was treated with hydroxyl amine hydrochloride to afford the /V-hydroxybenzamidine 19. Catalytic hydrogenation of 19... 

Selective substitution may sometimes be achieved by indirect methods. Thus, treatment of 4,6-O-benzylidene acetals with cyanoborohydride and etheral hydrogen chloride converts than into the 6-O-benzyl ether, with a free hydroxyl group at the 4-position (see Chap. 3). Isopropylidene and benzylidene ketals are opened by trimethylaluminium to give good yields of a-hydroxy ten-butyl ethers, and a-hydroxy 1-phenylethyl ethers, respectively [5], The scope of the latter method has not yet been explored. 

S. Takano, T. Ohkawa, and K. Ogasawara, Regioselective formation of 3-r aIkoxy-1,2-glycols from 2,3-O-alkylidenetriols with trimethylaluminium, Tetrahedron Lett. 29 1823 (1988). 

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