Aluminum compounds chloride, supported

The supported chromium oxide catalysts can be prepared by impregnating a silica-alumina support with a solution of chromium ions or by coprecipitating the oxides. The preferred impregnating solutions contain dissolved Cr(N03)s.9H20 or CrOs in nitric acid because catalysts made from chromium chlorides or sulfates retain some of the anions after calcination. The solid mixture of chromium-silicon-aluminum compounds is calcined in dry air at 400-700° C or higher to obtain the desired oxide. This probably results in the reaction of surface hydroxy groups in the support material with CrOs to form chromate (IV) and dichromate (V) species ... 

The high-pressure process relied on large and complex plants that required careful process control. Therefore, the discovery in 1953 of the appropriate catalysts that allowed the process to be carried under low pressure ( 500 psi) was welcomed by the industry [7]. Three types of catalysts were developed about that time the Ziegler-type catalysts typically obtained by reacting alkyl aluminum compounds with titanium chloride metal oxide catalyst systems, developed by Phillips Petroleum in the United States, typically made of chromium oxide supported on a silicaceous carrier [8]) and a different type of oxide catalyst developed by Standard Oil Company. The first plants based on the Ziegler catalyst went on line in Germany by 1955 and a plant based on the Phillips catalyst in Texas opened in 1957. The third catalyst system developed much slower and was picked up by the Japanese plastics industry in a plant opened in 1961. 

Alkylation. Friedel-Crafts alkylation (qv) of benzene with ethylene or propylene to produce ethylbenzene [100-41 -4], CgH10, or isopropylbenzene [98-82-8], C9H12 (cumene) is readily accomplished in the liquid or vapor phase with various catalysts such as BF3 (22), aluminum chloride, or supported polyphosphoric acid. The oldest method of alkylation employs the liquid-phase reaction of benzene with anhydrous aluminum chloride and ethylene (23). Ethylbenzene is produced commercially almost entirely for styrene manufacture. Cumene [98-82-8] is catalytically oxidized to cumene hydroperoxide, which is used to manufacture phenol and acetone. Benzene is also alkylated with C1Q—C20 linear alkenes to produce linear alkyl aromatics. Sulfonation of these compounds produces linear alkane sulfonates (LAS) which are used as biodegradable deteigents. 

Other reagents that have been used to reduce support-bound aromatic nitro compounds include phenylhydrazine at high temperatures (Entry 5, Table 10.12), sodium borohydride in the presence of copper(II) acetylacetonate [100], chromium(II) chloride [196], Mn(0)/TMSCl/CrCl2 [197], lithium aluminum hydride (Entry 3, Table... 

Data from in vivo (intraperitoneal) exposures of mice to aluminum chloride also indicate that this compound is clastogenic. Mice were injected intraperitoneally with 0.01, 0.05, or 0.1 molar aluminum chloride, and bone marrow cells were examined for chromosomal aberrations. There was a significant increase in chromatid-type aberrations over the controls, and these occurred in a nonrandom distribution over the chromosome complement (Manna and Das 1972). No dose-response relationship could be demonstrated, although the highest dose of aluminum chloride did produce the greatest number of aberrations. These data are supported by in vitro studies that show that aluminum chloride causes cross-... 

Under acidic conditions, the alkylation and dealkylation of aromatic compounds are reversible reactions involving several steps in which n- and CT-complexes are formed. However, dealkylation proceeds only under more drastic conditions compared with alkylation. Nevertheless, this is not always the case. For example, if the aromatic compound is of the DPM type, the dealkylation may proceed under mild conditions since the cations formed (Fig. 6.6.5) are resonance-stabilized. This statement is supported by the fact that DPM derivatives may be degraded even at room temperature by aluminum chloride to yield benzene, alkylbenzene, and alkyldiphenylmethane, together with some resinous substances (Tsuge and Tashiro 1962, 1965). 

The earliest report of a reaction mediated by a chiral three coordinate aluminum species describes an asymmetric Meerwein-Poimdorf-Verley reduction of ketones with chiral aluminum alkoxides which resulted in low induction in the alcohol products [1]. Subsequent developments in the area were sparse until over a decade later when chiral aluminum Lewis acids began to be explored in polymerization reactions, with the first report describing the polymerization of benzofuran with catalysts prepared from and ethylaluminum dichloride and a variety of chiral compounds including /5-phenylalanine [2]. Curiously, these reports did not precipitate further studies at the time because the next development in the field did not occur until nearly two decades later when Hashimoto, Komeshima and Koga reported that a catalyst derived from ethylaluminum dichloride and menthol catalyzed the asymmetric Diels-Alder reaction shown in Sch. 1 [3,4]. This is especially curious because the discovery that a Diels-Alder reaction could be accelerated by aluminum chloride was known at the time the polymerization work appeared [5], Perhaps it was because of this long delay, that the report of this asymmetric catalytic Diels-Alder reaction was to become the inspiration for the dramatic increase in activity in this field that we have witnessed in the twenty years since its appearance. It is the intent of this review to present the development of the field of asymmetric catalytic synthesis with chiral aluminum Lewis acids that includes those reports that have appeared in the literature up to the end of 1998. This review will not cover polymerization reactions or supported reactions. The latter will appear in a separate chapter in this handbook. 

The first generation of alkene metathesis catalysts was based on ill-defined systems constituted of transition-metal oxides supported on alumina or sihca or transition metal chlorides activated by organometallic activators (alkyl aluminum or tin compounds). These systems are ill-defined in that the structure of then-active sites remains unknown, even today. It should be noted that, although... 

A novel hydrogenation technique has been introduced, in which both catalyst and hydrogen are prepared in situ These investigations have also yielded highly active carbon-supported catalysts. Preferential reduction of diaryl ketones can be achieved by using lithium N-dihydropyridylaluminum hydride . Base-sensitive 0X0 compounds can be reduced to hydroxy compounds by a 3-step sequence through diazo compounds Enamines can be hydro-genolyzed to alkenes with lithium aluminum hydride and aluminum chloride... 

Friedel-Crafts Reactions. Aluminum trifluoromethanesulfonate has been used for the Friedel-Crafts alkylation reaction of toluene with isopropyl and tert-butyl chlorides (eq 1), and for the acylation of benzene and toluene with acetyl and benzoyl chlorides in low to moderate yields. Intramolecular Friedel-Crafts acylation of an aromatic compound with Meldrum s acid has also been reported using catalytic amounts of Al(OTf)3. Acylation of 2-methoxynaphthalene with acetic anhydride has been reported using Al(OTf)3 and lithium perchlorate as an additive to afford the corresponding 6-acetylated adduct in 83% yield. Effective acylation of arenes with carboxylic acids has also been disclosed using polystyrene-supported Al(OTf)3. ... 

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