Aluminum trialkyls

The olefins and aluminum alkyls are separated by distillation. The aluminum trialkyl obtained in the second transalkylation step contains predominantly C12-C18 alkyl groups and is subsequently treated in the same way as in the Alfol process. Table 10 shows the different alcohol mixtures of the Alfol and Epal process. A disadvantage of the Epal alcohols is their higher degree of branch-... 

Figure 19 Structures of (a) aluminum trialkyls (b) [AlH3(NMe3)] (c) [A1H3(DMEAA)].

Oxidative addition of the silyl species to nickel is followed by insertion of unsaturated substrates. Zero-valent nickel complexes, and complexes prepared by reducing nickel acetylacetonate with aluminum trialkyls or ethoxydialkyls, and in general Ziegler-Natta-type systems, are effective as catalysts (244, 260-262). Ni(CO)4 is specific for terminal attack of SiHCl3 on styrene (261). 

Air-reactive chemicals include aluminum hydride, aluminum alkyls, and yellow phosphorous. Other reactive chemicals include alkalis, aluminum trialkyls, anhydrides, charcoal, coal, hydrides, certain oxides, phosphorous, and sodium hydrosulfate. 

Indium reacts with Grignard reagent, forming indium trialkyls which are highly flammable and less stable than the corresponding aluminum trialkyls ... 

In the absence of monomers, trimethylaluminum (0.5 mol) reacts with t-butyl chloride (1.0 mol) at -78°C to give a quantitative yield of neopentane [22], Kennedy [23] found that aluminum trialkyls (AlMe3, AlEt3, A1Bu3) in the presence of certain alkyl halides are efficient initiators for the cationic polymerization of isobutylene, styrene, etc. 

Reduction reactions of nickel(If) compounds. The reduction of nickel(II) compounds to yield nickel(0) phosphine complexes has been carried out using a variety of reducing agents such as sodium amalgam, sodium sand, sodium borohydride, sodium naphthalenide and aluminum trialkyls. In some cases the phosphine ligand itself was found to act as the reducing agent. 

Bartocha, Reaction Compounds of Tetramethyl-tetrazene with Aluminum Trialkyls and Their Amine Complexes and the Preparation Thereof , USP 3321504 (1967) CA 67, 55831 (1967)... 

Aluminum trialkyls dissolve aluminum with hydrogen under pressure affording dialkylaluminum hydrides. The reaction products add to olefins in the next step (b) to give 50% more aluminum alkyl than the amount originally employed, a sequence which finally leads to any desired amount. 

Thus the aluminum trialkyls act as catalyst for the alkyl exchange and indeed it has been reported that small amounts of trialkylaluminum catalyze the exchange of alkyl groups in a mixture of BR3 and BR3 (140,141). 

B. Ethoxydiethylaluminum(III) was used and recommended by Reinsalu and Allen as a reducing agent instead of the more dangerous aluminum trialkyls. It is readily obtainable from the reaction of triethylalumi-num with ethanol. 

By polymerizing the trans isomer of 1,3-pentadiene two different types of crystalline cis-1,4 polymers have been obtained, one with an isotactic, the other with a syndiotactic structure. The isotactic polymer was obtained by homogeneous systems from an aluminum alkyl chloride and a cobalt compound, the syndiotactic one by homogeneous systems from an aluminum trialkyl and a titanium alkoxide. Some features of the polymerization by Ti and Co catalysts are examined. IR and x-ray spectra, and some physical properties of the crystalline cis-1,4 polymers are presented. The mode of coordination of the monomer to the catalyst, and possible mechanisms for the stereospecific polymerization of pentadiene to cis-1,4 stereoisomers are discussed. 

Shortly after the cis-1,4 syndiotactic polypentadiene was obtained and characterized, it was observed that the homogeneous systems prepared from an aluminum trialkyl and a titanium tetralkoxide can polymerize pentadiene to polymers predominantly cis-1,4. Both the cis and trans isomers of pentadiene are polymerized by these systems. However, while the crude polymers obtained from the cis isomer were found to be amorphous by x-ray examination, those obtained from the trans isomer were found to be crystalline. The type of crystallinity of these polymers appeared different from that of the polymers... 

Whereas, as mentioned above, aluminum trialkyls oligomerize ethene under pressure, cationic compounds of the type [ AlMe X- and [(L2AlMe)2(/r-Me)]+X [L = benzamidinate anion, X = MeB(C6F5)3] give high molecular weight polyethene under mild conditions.32... 

Insertions of carbon dioxide, sulfur dioxide, and sulfur trioxide yield aluminum carboxylates, sulfinates, and sulfonates, respectively. Treatment of the resulting complexes with aqueous acid yields the corresponding aUcylcarboxylic, alkylsulphinic, and aUcylsulphonic acids. High pressure and temperatures of 220-240 °C are required for multiple insertions of CO2 to yield more than one equivalent of carboxyhc acid per aluminum. Excess aluminum trialkyl must be avoided or the initially formed carboxylate is completely alkylated to a trialkylcarbinol. Reaction of Ets A1 with CO2, for example, gives a 90% yield of triethylcarbinol. 

In other recent developments, Sanchez, Arrington, and Arrington reported that Mc3Al binds CO to form OC- AlMe3 (15) in an argon matrix at 15 35K. Robinson reported the first neutral carbene complex (16) of an aluminum trialkyl in 1996. Complexes in which there is intramolecular base coordination have been reviewed. ... 

Scheme 2 Proposed reaction scheme for hydrolysis of aluminum trialkyls...

AIR3 (Aluminum trialkyls and their complexes with alkali metals or tetraalkyl-ammonium halides, especially fluorides in aromatics or as melts). 

Between 1953 and 1955, Ziegler and his coworkers developed a simple and direct synthetic route to aluminum trialkyls from aluminum, hydrogen, and the corresponding alkene [213,231]. Aluminum trialkyls, which are Lewis acids, show a strong tendency to react with alkali metal and tetraorganoammonium halides and pseudohalides to... 

Consequently, in early 1953, research on these complex compounds was initiated to determine whether they were suitable for electrolytic aluminum deposition. The first trials ended in disappointment, because the electrolytes, employed as melts, yielded useless aluminum coatings containing large portions of alkali metal. Besides, the electrolytes showed a very low conductivity compared to aqueous systems. Attempts to improve the quality of the aluminum deposits by adding excess triethylaluminum led to unexpected observations. Hence, a detailed investigation of alkali metal fluoride-aluminum trialkyl systems was necessary. 

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