Aluminum, triethyl

Aluminum triethyl (triethyl aluminum) [97-93-8] M 114.2, b 69°/1.5mm, 76°/2.5mm, 129-131°/55mm, d 0.695, n 1.394. Purified by fractionation in an inert atmosphere under vacuum in a 50cm column containing a heated nichrome spiral, taking the fraction 112-114°/27mm. It is very sensitive to H2O and should be stored under N2. It should not contain chloride which can be shown by hydrolysis and testing with AgN03. [J Am Chem Soc 75 4828 51937953 NMR J Am Chem Soc 81 3826 7959.]... 

Chemical Designations - Synonyms ATE Aluminum triethyl TEA Chemical Formula (C2H3)3A1. Observable Characteristics - Physical State (as shipped)-.Liquid Color Colorless Odor Not pertinent. 

A1(C2H5)3 + CH7 = CH2 Trialkyl aluminum Triethyl aluminum Ethylene (A polymer chain)... 

Aluminum Stearate. See under Stearates Aluminum Stearate Gels. See under Stearates Aluminum Triethyl. Same as Triethyl Aluminum Aluminum Tripropyl. Same as Tripropyl Aluminum... 

When polymerizing 1.3-pentadiene, the optical activity of the isotactic cis-1.4-polymer obtained in the presence of catalysts prepared from (—)-titanium tetramenthoxide and aluminum triethyl, is far higher than that of the analogous polymers obtained with catalysts prepared from titanium tetrabutylate and (+)-tris-[(S)-2-methyl-butyl]-aIumin-um (05). 

Fundamental work on organoaluminum chemistry by Prof. Karl Ziegler and co-workers at the Max Planck Institute provided the basis for a commercial synthesis of even-carbon-numbered straight chain primary alcohols. These alcohols are identical with products derived from naturally occurring fats. In this process, ethylene is reacted with aluminum triethyl to form a higher aikylaluminum which then is oxidized and hydrolyzed to give the corresponding alcohols. 

The aluminium alkyls and alkoxides were found to be effective also in the polymerization of ethylene oxide and phenyl glycidyl ether the latter gave considerable amounts of low molecular weight, crystalline polymer. Aluminum triethyl was examined by Kambaka and Hatano (38) in the polymerization of several cyclic ethers and found to be fairly effective for propylene oxide and 2-methyl-oxacyclobutane but not for oxacyclobutane and tetrahydrofuran. The combination of zinc diethyl and alumina gave a high rate of polymerization with ethylene or propylene oxide (39). 

Just about the same time Japanese workers (107) polymerized this dialdehyde with boron trifluoride etherate, p-toluene sulfonic acid, and titanium tetrachloride as well as with aluminum triethyl-water catalyst systems. Completely insoluble products were obtained with the cationic catalysts, whereas partially soluble materials were isolated with the latter initiator. On the basis of infrared evidence, the above structure was assigned to the soluble product. In spite of the fact that ether linkages were found by infrared analysis in the cationic product, the authors concluded that its structure was different from that of the soluble polymer obtained with organometallic catalyst. The structure of the soluble fraction was assumed to be ... 

High-Density Polyethylene (HDPE). Polymerization of ethylene to polyethylenes is most often carried out at low temperature and pressure, using either the Ziegler aluminum triethyl plus titanium tetrachloride catalyst system, the Phillips chromic oxide plus silica plus alumina system, or more recently the newer metallocene single-site catalyst systems. 

Table III. Optical Activity of the cis-1,4 Isotactic Polypentadiene Obtained by the Aluminum Triethyl-Titanium Tetramenthoxide"Catalyst System...

TRIETHOXYSILANE TRIETHYL ALUMINUM TRIETHYL PHOSPHITE TRIETHYLAMINE TRIETHYLENE TETRAHIHE... 

Fig. 29. The instantaneous rate of polymerization during a 3 h experiment at different concentrations of aluminum triethyl. (1) 5 mmol...

Several brief preliminary reports in the literature indicate the formation of products from nitric oxide containing nitrogen-nitrogen bonds. Lithium aluminum hydride plus nitric oxide is reported to give rise to hyponitrite ion (17), Grignard reagents (27) and aluminum triethyl (3), when reacted with NO, give rise to intermediates which upon hydrolysis produce nitrosated alkyl-substituted hydroxyl-amines. These materials are reported to be unstable and evidence for their existence is indirect. If these products are indeed formed, the reactions can be easily incorporated into the BNO scheme. 

In contrast to the structure-catalyst ratio dependence shown in the AIBU3-TiCl4 system, the polymerization of butadiene with a catalyst prepared by reaction of aluminum triethyl or diethylaluminum chloride with vanadium tetrachloride or oxychloride reportedly yields a polymer whose structure is relatively unaffected by the Al/V ratio—i.e., the polybutadiene obtained in heptane at 15° C. contains 95 to 99% tram-1,4-, 0 to 1% cis-1,4-, and 1 to 5% 1,2- structures at Al/V ratios ranging from 0.5 to 10. After extraction with diethyl ether, diisopropyl ether, and benzene, the residual polymer, constituting 55 to 75% of the total polymer, has 99 to 100% tram- 1,4- structure (15). 

As in the case of butadiene polymerization, the microstructure of polyisoprene is dependent upon the ratio of catalyst components, the reaction temperature, and the reaction medium. As shown in Table V, using an aluminum triethyl-titanium tetrachloride catalyst system, an Al/Ti ratio of 1.0 or higher yields a polyisoprene containing 96% cis-1,4-, 4% 3,4-, and essentially no trans-, A- or 1,2- units. Below this ratio, the trans-, A- structure is produced apparently at the expense of the cis-1,4- structure (I). An AlBua-TiCLt catalyst system is reported (7) to yield an essentially all- rarw-l,4-polyisoprene at an Al/Ti ratio of 0.67 and below. 

At the present time, the most likely concept of the mechanism of a heterogeneous polymerization catalyzed by a Ziegler-Natta catalyst involves a complex in which the organometallic component and the transition metal component—i.e., the A1 and Ti atoms—are joined by electron-deficient bonds. Natta, Corradini, and Bassi (13) have reported such a structure for the active catalyst prepared from bis (cyclopentadienyl) titanium dichloride and aluminum triethyl. Natta and Pasquon (14), Patat and Sinn (18), and Furukawa and Tsuruta (2) have proposed mechanisms for the stereospecific polymerization of a-olefins in terms of such electron-deficient complexes. 

Anhydrous nickel chloride in chlorobenzene suspension is reduced in the presence of excess butadiene with aluminum triethyl. The product is the previously mentioned intermediate, I, of the cyclododecatriene synthesis. 

While the exact nature of the active material present is still poorly understood, it is thought that the catalytic material produced from aluminum triethyl and titanium trichloride has a bridged structure as shown (first structure. Fig. 22.5). A bimetallic mechanism, originally proposed by Natta, illustrates a probable mode of progression of a substituted vinylic monomer to stereoregular polymer. 

They also found that mixtures of bis-(cyclopentadienyl)-titanium dichloride and aluminum triphenyl or bis-(cyclopentadienyl)-titanium diphenyl and aluminum triethyl were active catalysts, and presumably formed similar, bridged complexes. Interestingly, the hydrocarbon substituent attached to aluminum became an end group in the polymer. 

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