Aluminum-promoted

Oxygen. Finely divided white phosphorus ignites in air. Contact with charcoal or amalgamated aluminum promotes ignition.25... 

Kawahara M, Muramoto K, Kobayashi K, Mori H, Kuroda Y (1994) Aluminum promotes the aggregation of Alzheimer s amyloid beta-protein in vitro. Biochem Biophys Res Commun 198 531-535... 

Diethyl(phenylthio)aluminum Promoted Claisen Rearrangement General Procedure341 ... 

Aluminum (Al). Along with nitrogen, aluminum promotes the formation of a refined grain structure. Most importantly, aluminum is added as a deoxidizer to produced killed steel. 

Yamamoto and Maruoka have reported the first aluminum-promoted asymmetric Claisen rearrangement [5]. They used a chiral 3,3 -bis(triarylsilyl)-substi-tuted binaphthol (BINOL) aluminum reagent 1 to promote the enantioselective coordination to one of the two enantiomeric oxygen lone pairs of 2. Enantioselective discrimination is based on two chair-hke transition states A and B to give two enantiomeric products 3, respectively (Scheme 2.2). 

Hybridizaton. The hybridization of the silicon and boron atoms is reviewed in Ch. 7, Sec. 2.2, and that of nitrogen in Ch. 10, Sec. 2.0. In the case of aluminum, promotion from its ground state to the hybrid... 

Figure 9-17. Schematic showing the corrosion of aluminum around an aluminum-copper intermetallic particle in an aluminum copper alloy with a copper content of 0.5-2%. The aluminum-copper particle, in the presence of pure aluminum, promotes the reduction of water (shown) or oxygen (not shown). Simultaneously, the reduction reaction causes the pure aluminum to oxidize and then dissolve. This localized corrosion (Al dissolution) results in the formation of pits.

Because tin and aluminum promote the formation of ordered TisAl (02) structures, Ti-5Al-2.5Sn is one of the titanium alloys most susceptible to stress-corrosion cracking. Like step-cooled TL-8A1-IMo-lV, the Ti-5Al-2.5Sn alloy is susceptible to corrosion cracking in distilled water. 

Oliveira, A. C., Valentini, A., Nobre, P. S. S., Fierro, J. L. G. Rangel, M. C. (2003). Non Toxic Fe-Based Catalysts for Styrene Synthesis. The Effect of Salt Precursor and Aluminum Promoter on the Catalytic Properties. Catal Today, 85, 49-57. 

Nonoshita K, Banno H, Maruoka K, Yamamoto H. Organo-aluminum-promoted Claisen rearrangement of allyl vinyl ethers. J. Am. Chem. Soc. 1990 112(l) 316-322. 

H. E. L. Bonfim, A. C. Oliveira, M. C. Rangel, 2003, The effect of zinc on the catalytic activity of hematite in ethylbenzene dehydrogenation. React.Kinet. Catal. Lett, 80,359-364. A. C. Oliveira, A. Valentini, P. S. S. Nobre, J. L. G. Fierro, M. C. Rangel, 2003, Non toxic Fe-based catalysts for styrene synthesis. The effect of salt precursor and aluminum promoter on the catalytic properties. Catal. Today, 85,49-573. 

Fries rearrangement (Section 24 9) Aluminum chlonde promoted rearrangement of an aryl ester to a ring acylated denvative of phenol... 

Tetrahydrofurfuryl alcohol reacts with ammonia to give a variety of nitrogen containing compounds depending on the conditions employed. Over a barium hydroxide-promoted skeletal nickel—aluminum catalyst, 2-tetrahydrofurfur5iarnine [4795-29-3] is produced (113—115). With paHadium on alumina catalyst in the vapor phase (250—300°C), pyridine [110-86-1] is the principal product (116—117) pyridine also is formed using Zn and Cr based catalysts (118,119). At low pressure and 200°C over a reduced nickel catalyst, piperidine is obtained in good yield (120,121). 

Most of the polymer s characteristics stem from its molecular stmcture, which like POE, promotes solubiUty in a variety of solvents in addition to water. It exhibits Newtonian rheology and is mechanically stable relative to other thermoplastics. It also forms miscible blends with a variety of other polymers. The water solubiUty and hot meltable characteristics promote adhesion in a number of appHcations. PEOX has been observed to promote adhesion comparable with PVP and PVA on aluminum foil, cellophane, nylon, poly(methyl methacrylate), and poly(ethylene terephthalate), and in composite systems improved tensile strength and Izod impact properties have been noted. 

Microstructurc. Crystal size, porosity, and impurity phases play a major role in fixing the fracture characteristics and toughness of an abrasive grain. As an example, rapidly cooled fused aluminum oxide has a microcrystalline stmcture promoting toughness for heavy-duty grinding appHcations, whereas the same composition cooled slowly has a macrocrystalline stmcture more suitable for medium-duty grinding. 

Sol—Gel Sintered Aluminum Oxide. A new and much more versatile sintered alumina abrasive is now produced from aluminum monohydrate, with or without small additions of modifiers such as magnesia, by the sol—gel process (see Sol-gel technology). The first modified sol—gel abrasive on the market, Cubitron, was patented (27) and produced by the 3M Corporation for products such as coated belts and disks. The success of this material promoted intensive research into sol—gel abrasives. 

Aluminum chloride [7446-70-0] is a useful catalyst in the reaction of aromatic amines with ethyleneknine (76). SoHd catalysts promote the reaction of ethyleneknine with ammonia in the gas phase to give ethylenediamine (77). Not only ammonia and amines, but also hydrazine [302-01-2] (78), hydrazoic acid [7782-79-8] (79—82), alkyl azidoformates (83), and acid amides, eg, sulfonamides (84) or 2,4-dioxopyrimidines (85), have been used as ring-opening reagents for ethyleneknine with nitrogen being the nucleophilic center (1). The 2-oxopiperazine skeleton has been synthesized from a-amino acid esters and ethyleneknine (86—89). 

Aluminum, the most common material used for contacts, is easy to use, has low resistivity, and reduces surface Si02 to form interfacial metal-oxide bonds that promote adhesion to the substrate. However, as designs reach submicrometer dimensions, aluminum, Al, has been found to be a poor choice for metallization of contacts and via holes. Al has relatively poor step coverage, which is nonuniform layer thickness when deposited over right-angled geometric features. This leads to keyhole void formation when spaces between features are smaller than 0.7 p.m. New collimated sputtering techniques can extend the lower limit of Al use to 0.5-p.m appHcations. 

Corrosion by Various Chemicals and Environments. In general, the rate of corrosion of magnesium ia aqueous solutions is strongly iafluenced by the hydrogen ion [12408-02-5] concentration or pH. In this respect, magnesium is considered to be opposite ia character to aluminum. Aluminum is resistant to weak acids but attacked by strong alkaUes, while magnesium is resistant to alkaUes but is attacked by acids that do not promote the formation of iasoluble films. 

The catalysts used in the industrial alkylation processes are strong Hquid acids, either sulfuric acid [7664-93-9] (H2SO or hydrofluoric acid [7664-39-3] (HE). Other strong acids have been shown to be capable of alkylation in the laboratory but have not been used commercially. Aluminum chloride [7446-70-0] (AlCl ) is suitable for the alkylation of isobutane with ethylene (12). Super acids, such as trifluoromethanesulfonic acid [1493-13-6] also produce alkylate (13). SoHd strong acid catalysts, such as Y-type zeoHte or BE -promoted acidic ion-exchange resin, have also been investigated (14—16). 

Al-Pb. Both lead [7439-92-17, Pb, and bismuth [7440-69-9] Bi, which form similar systems (Fig. 17), are added to aluminum ahoys to promote machinahility by providing particles to act as chip breakers. The Al—Pb system has a monotectic reaction in which Al-rich Hquid free2es partiahy to soHd aluminum plus a Pb-rich Hquid. This Pb-rich Hquid does not free2e until the temperature has fahen to the eutectic temperature of 327°C. SoHd solubiHty of lead in aluminum is negligible the products contain small spherical particles of lead which melt if they are heated above 327°C. 

Atmospheric corrosion is electrochemical ia nature and depends on the flow of current between anodic and cathodic areas. The resulting attack is generally localized to particular features of the metallurgical stmcture. Features that contribute to differences ia potential iaclude the iatermetaUic particles and the electrode potentials of the matrix. The electrode potentials of some soHd solutions and iatermetaUic particles are shown ia Table 26. Iron and sUicon impurities ia commercially pure aluminum form iatermetaUic coastitueat particles that are cathodic to alumiaum. Because the oxide film over these coastitueats may be weak, they can promote electrochemical attack of the surrounding aluminum matrix. The superior resistance to corrosion of high purity aluminum is attributed to the small number of these constituents. 

Aluminum chloride dissolves readily in chlorinated solvents such as chloroform, methylene chloride, and carbon tetrachloride. In polar aprotic solvents, such as acetonitrile, ethyl ether, anisole, nitromethane, and nitrobenzene, it dissolves forming a complex with the solvent. The catalytic activity of aluminum chloride is moderated by these complexes. Anhydrous aluminum chloride reacts vigorously with most protic solvents, such as water and alcohols. The ability to catalyze alkylation reactions is lost by complexing aluminum chloride with these protic solvents. However, small amounts of these "procatalysts" can promote the formation of catalyticaHy active aluminum chloride complexes. 

SP-100 Promoted Activated Alumina for Claus Catalysis, Product Data, Alcoa Chemicals Division, Aluminum Company of America, Pittsburgh, Pa., 1984. 

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