Aluminum isopropoxide, catalyst

These reversible reactions are cataly2ed by bases or acids, such as 2iac chloride and aluminum isopropoxide, or by anion-exchange resias. Ultrasonic vibrations improve the reaction rate and yield. Reaction of aromatic aldehydes or ketones with nitroparaffins yields either the nitro alcohol or the nitro olefin, depending on the catalyst. Conjugated unsaturated aldehydes or ketones and nitroparaffins (Michael addition) yield nitro-substituted carbonyl compounds rather than nitro alcohols. Condensation with keto esters gives the substituted nitro alcohols (37) keto aldehydes react preferentially at the aldehyde function. 

AH (A)-menthol is made by synthetic methods. One method involves the cyclization of (+)-citroneIlal (68). Using a mild acid catalyst, (+)-citroneIlal [2385-77-5] undergoes an ene-reaction to produce a mixture of isopulegols (142). Catalytic hydrogenation of the isopulegol mixture gives a mixture of menthol and its isomers. The (A)-menthol is obtained after efficient fractional distillation and the remaining isomers can be equilibrated, usually with sodium menthol ate or aluminum isopropoxide. An equilibrium mixture is obtained, comprised of 62 wt % (A)-menthol, 23 wt % (+)-neomenthol, 12 wt % (+)-isomenthol, and 3 wt % (+)-neoisomenthol. The equilibrium mixture can be distilled to recover additional (+)-mentbol. 

In contrast to the situation with copper-based catalysis, most studies on ruthenium-based catalysts have made use of preformed metal complexes. The first reports of ruthenium-mediated polymerization by Sawamoto and coworkers appeared in I995.26 In the early work, the square pyramidal ruthenium (II) halide 146 was used in combination with a cocatalyst (usually aluminum isopropoxide). 

Catalysts A, prepared from aluminum isopropoxide and calcined at 700° for 4 hours A—Na, contained 1 % by weight of sodium by impregnation with sodium carbonate A—H, purchased from Harshaw Chemical Company it contained 0.35% of sodium. HLSV = hourly liquid space velocity, grams of alcohol per gram of catalyst per hour. 

Catalyst alumina from aluminum isopropoxide with piperidine. 2-B = 2-butanol 2-P = 2-pentanol 3-P = 3-pentanol. 

A refers to alumina prepared from aluminum isopropoxide. A(10% pip.) refers to reaction on catalyst A where the alcohol feed was mixed with 10% by weight of piperidine. B2 refers to alumina prepared from sodium aluminate and washed twice. 

Temperature, 275" catalyst, alumina from aluminum isopropoxide with piperidine. 

Pure alumina catalyst prepared either by hydrolysis of aluminum isopropoxide or by precipitation of aluminum nitrate with ammonia, and calcined at 600-800°, contains intrinsic acidic and basic sites, which participate in the dehydration of alcohols. The acidic sites are not of equal strength and the relatively strong sites can be neutralized by incorporating as little as 0.1 % by weight of sodium or potassium ions or by passing ammonia or organic bases, such as pyridine or piperidine, over the alumina. 

See Section 16-4E often useful for low-boiling aldehydes that can be distilled out of mixture as formed, thereby preventing condensation reactions aluminum isopropoxide or ferf-butoxide commonly are used as catalysts carbon-carbon double bonds are not attacked. 

Acrylic Esters, A procedure has been described for preparation of higher esters from methyl acrylate that illustrates the use of an acid catalyst together with the removal of one of the products by azeotropic distillation (112). Another procedure for the preparation of butyl acrylate, secondary alkyl acrylates, and hydroxyalkyl acrylates using/>-toluenesulfonic acid as a catalyst has been described (113). Aluminum isopropoxide catalyzes the reaction of amino alcohols with methyl acrylate and methyl methacrylate. A review of the synthesis of acrylic esters by transesterification is given in Reference 114 (see... 

Directions for the preparation of aluminum isopropoxide are given by Young, Hartung, and Crossley.2 This compound is also commercially available. Turbidity of the catalyst solution is to be expected and is not detrimental. 

Additionally, thin-film layers of the catalyst may be deposited on to the surface of the micro channels by sputtering [73] or CVD [63], In the latter case, aluminum isopropoxide, Al[(CH3)2CHO]3, was used as alumina precursor, which was passed through a ready-stacked reactor at 300 °C for 1 h in a flow containing nitrogen and oxygen in addition. The flow direction was subsequently changed and the procedure repeated. 

Since aluminum alkoxides function effectively as catalysts for alcohol exchange in esters,38 89 reduction of keto esters by aluminum isopropoxide frequently yields the isopropyl ester of the hydroxy acid. Thus the reduction of the cyclopropane derivative XLIV gave the isopropyl ester of the reduced acid (XLV).40 Similarly the substituted methyl /3-keto ester (XLYI)41 gave upon reduction the isopropyl esters of the stereoisomeric reduced acids (XLVII). 

Cu-MCM-41 and Cu-Al-MCM-41 samples have been obtained by ion exchange of the MCM-41 and Al-MCM-41 matrices prepared by hexadecyltrimethylammonium cloride, tetraethyl orthosilicate, aluminum isopropoxide and an ammonia solution. The aluminum concentration affects the MCM-41 textural properties and large amount of extra-framework aluminum species are supposed to be present in Al-MCM-41 with Si/Al = 30. Cu-MCM-41 and Cu-Al-MCM-41 catalysts have been tested for NO selective catalytic reduction by propane in the presence of oxygen, in comparison with microporous Cu-S-1 and Cu-ZSM-5 catalysts with similar copper loading and Si/Al atomic ratio. Cu-Al-MCM-41 catalysts are less active and selective with respect to the Cu-ZSM-5 catalysts indicating that they are not suitable for NO abatement reactions. 

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