Aluminum family

Based on overall initiator efficiencies, coinitiator efficiencies seem to decrease as Et2AlI > Et2 AlBr > Et2 A1C1. The coinitiator efficiency sequence for the alkyl-aluminum families is EtAlCl2 > Et2AlX > Me3 Al. 

Boron is the first element in Group 13 (IIIA) of the periodic table. The periodic table is a chart that shows how the chemical elements are related to each other. The elements in this group are usually referred to as the aluminum family. 

Heterogeneous Catalysis. The main discovery of the 1980s was the use of titanium sihcaUte (TS-1) a synthetic zeoHte from the ZSM family containing no aluminum and where some titanium atoms replace siUcon atoms in the crystalline system (Ti/Si = 5%) (33). This zeoHte can be obtained by the hydrolysis of a siUcate and an alkyl titanate in the presence of quaternary ammonium hydroxide followed by heating to 170°C. Mainly studies have been devoted to the stmcture of TS-1 and its behavior toward H2O2 (34). The oxidation properties of the couple H2O2/TS-I have been extensively developed in... 

ARALL laminates, a family of hybrid composites consisting of aramid fibers bonded with epoxy between 0.3 mm thick aircraft ahoy sheets, were introduced in the 1980s (53). The laminates have lower density than even the new Al—Li ahoys and are greatly superior to monolithic aluminum sheet in resisting the growth of fatigue cracks. ARALL laminates have been specified for aircraft stmcture which is subjected to cycHc tension loads (see Laminates). 

The aluminum halides and aluminum nitrates have similar properties with the exception of the family of aluminum fluoride compounds which are discussed elsewhere (see Fluorine compounds, inorganic). Of the remaining members ia this aluminum haUde family, chloride derivatives are the most commercially important alurniaum brornide /7727-/3 -JJ AlBr, alumiaum iodide [7784-23-8] and alumiaum nitrate [13473-90-0] are of... 

Commercially, aluminum chloride is available as the anhydrous AIQ, as the hexahydrate, AICI36 H2O, or as a 28% aqueous solution designated 32°Be. Polyalumiaum chloride, or poly(alumiaum hydroxy) chloride [1327-41 -9] is a member of the family of basic aluminum chlorides. These are partially neutralized hydrates having the formula Al2Clg (0H) 6 H2O where x = 1-5. 

Aluminum hydroxides are technically the most widely used members of the alurnina chemicals family. The most important source of aluminum hydroxides is the bauxite refining plant for alurnina production. A small amount of somewhat purer aluminum hydroxide is produced by the Sinter process. 

Future brakes must satisfy health standards and most vehicle manufacturers have moved toward removing all asbestos from brakes. Lighter weight rotors and caUpers based on aluminum-based metal-matrix materials are also on the horizon for lighter vehicles requiring a whole new family of compatible friction materials. 

Catalysts developed in the titanium-aluminum alkyl family are highly reactive and stereoselective. Very small amounts of the catalyst are needed to achieve polymerization (one gram catalyst/300,000 grams polymer). Consequently, the catalyst entrained in the polymer is very small, and the catalyst removal step is eliminated in many new processes. Amoco has introduced a new gas-phase process called absolute gas-phase in which polymerization of olefins (ethylene, propylene) occurs in the total absence of inert solvents such as liquefied propylene in the reactor. Titanium residues resulting from the catalyst are less than 1 ppm, and aluminum residues are less than those from previous catalysts used in this application. 

Lithium aluminum hydride is an exceptionally powerful reducing agent, whereas sodium borohydride is a mild one. We undertook to develop a family of reducing agents with capabilities between these extremes (27-30). 

The most studied catalyst family of this type are lithium alkyls. With relatively non-bulky substituents, for example nBuLi, the polymerization of MMA is complicated by side reactions.4 0 These may be suppressed if bulkier initiators such as 1,1-diphenylhexyllithium are used,431 especially at low temperature (typically —78 °C), allowing the synthesis of block copolymers.432,433 The addition of bulky lithium alkoxides to alkyllithium initiators also retards the rate of intramolecular cyclization, thus allowing the polymerization temperature to be raised.427 LiCl has been used to similar effect, allowing monodisperse PMMA (Mw/Mn = 1.2) to be prepared at —20 °C.434 Sterically hindered lithium aluminum alkyls have been used at ambient (or higher) temperature to polymerize MMA in a controlled way.435 This process has been termed screened anionic polymerization since the bulky alkyl substituents screen the propagating terminus from side reactions. 

The (TPP)A1X family of initiators has been used to initiate the polymerization of a range of other monomer classes including epoxides, episulfides, and methacrylates.776 In the latter case the propagating species is an aluminum enolate and this too may initiate the ROP of lactones, such as 6-VL, albeit slowly. In this way a block copolymer P(6-VL)-b-PM M A of narrow molecular weight distribution (Mw/Mn= 1.11) has been prepared.787... 

The Lewis acidity and reactivity of these alkyl aluminum cocatalysts and activators with Lewis basic polar monomers such as acrylates make them impractical components in the copolymerization of ethylene with acrylates. To address this shortcoming, Brookhart et al. developed well-defined cationic species such as that shown in Fig. 2, in which the counterion (not illustrated) was the now-ubiquitous fluorinated arylborate family [34] such as tetrakis(pentaflurophenyl)borate. At very low methyl acrylate levels the nickel catalysts gave linear copolymers but with near-zero levels of acrylate incorporation. 

Dimersol A family of processes for dimerizing single or mixed olefines, catalyzed by mixtures of trialkyl aluminum compounds and nickel salts. Developed by IFP and first commercialized in 1977 by 1997 it was used in 26 plants. 

Hichlor A family of processes for making aluminum trichloride and other volatile metal chlorides by chlorinating fly ash and other coal wastes in fixed and fluidized beds. Developed by Ames Laboratory and Iowa State University from the mid-1970s to the mid-1980s. Not commercialized. 

Selexsorb A five-stage process for purifying ethylene before converting it to polyethylene. Developed by the Industrial Chemicals Division of the Aluminum Company of America. More than 50 installations were operating in 1996. The name is now used for a family of selective adsorbents based on alumina produced by Alcoa. The range includes Selexsorb CD, CDO, CDX, COS, SPC1, HC1. 

The discovery of the new class of high-silica zeolites "pentasil" during the last decade has attracted considerable interest due to the important applications of these zeolites in catalysis. The best known member of this family of zeolites is ZSM-5, developed in the Mobil laboratories. The unusual properties of pentasil zeolites have rekindled the interest in other high-silica zeolites, prepared by dea-lumination of low-silica zeolites. In this paper we shall review the preparation methods of aluminum-deficient zeolites, and shall discuss the properties of these materials, with emphasis on recent advances in their characterization. 

Ford planned to produce a fuel cell family car based on the aluminum and composite P2000 which is like the Ford Contour but weighs a thousand pounds less. In 1997, Ford announced that its fuel cell car would carry compressed hydrogen, but the fuel storage question may be still open. 

The reactions of gibbsite (y-Al(OH)3) with liX salts (X = e.g. Cl, Br, I, NO3, 5CO3, ISO4) in aqueous media to yield the LDHs [IiAl2(OH)6]X-mH20 (liAl-X) are rare examples of reactions in which both cations and anions are similarly intercalated into the host lattice. Although other routes are available to synthesise this family of LDHs, including hydrolysis of aluminum... 

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