Raney catalyst, applications

Most Raney nickel applications involve the use of fine catalyst particles in a batch type stirred reactor. Raney nickel can, however, be adapted for use in a fixed bed reactor by filling the reactor with the commercially available large granules of the alloy. A 10% solution of sodium hydroxide is passed through the reactor for a sufficient time to remove about 10-12% of the aluminum from the... 

Chattanooga, Tennessee. In his note to the editor, he referred to the catalyst as the Raney catalyst. This identification of the catalyst has been used almost universally thoughout the world ever since. In the years to follow. Professor Adkins and his students experimented on ways to prepare the catalyst and described a number of catalysts designated as the W-type Raney nickel. Numerous applications of the catalyst for the... 

Hydrogenation of the aminonitrile with a Raney catalyst leads to a family of branched diamines. Because of the branching, most of the aminonitriles and diamines are liquids at low temperature and have low freezing points. They have found markets as comonomers or curatives, since they lower polymer viscosity, crystallinity, and glass transition temperature. Catalytic hydrogenation of MGN with a Raney catalyst gives the branched-amine methylpentamethylenediamine, MPMD, and 3-methylpiperidine (3MP) shown in equation 3. The product is dependent on conditions and choice of catalyst. The MPMD was initially isolated from plant streams to develop the market. Many applications were found as a polymer additive in... 

Because of the hurdles in the synthesis and their structural complexity, intermetallic compovmds as catalysts may sound like an exotic application—perhaps with only academic interest. Intermetallic compounds do, however, offer a unique combination of valuable properties that outweighs by far the difficulties in their catalytic application—a picture which is corroborated by a careful literature search. Besides the well-known examples of the Raney-catalysts, there are about 1200 reports, where intermetallic compounds are involved in catalytic processes. On the one hand, they are used as precursors for high surface area catalysts, on the other hand they are commonly observed after catalytic processes where hydrogen is involved as a result of reactions between the supported noble metal and the partly reduced support. Also, very rarely, the catalytic properties of well-characterized intermetallic compounds have been investigated. 

In the practical applications of Raney nickel it is more convenient to measure the catalyst than to weigh it. The product, prepared as above, contains about 0-6 g. of the catalyst per millilitre of settled material a level teaspoonful is about 3 g. of nickel. 

An example of the application of the Raney nickel catalyst is given in Section IV,35 (p-phenylethylamine from benzyl cyanide). 

Probably the largest use of Ni is in the manuf of Monel metal, stainless steels, Ni-chrome resistance wire, in alloys for electronic and space applications, and as a catalyst (Raney Ni). It is also used as a fuel in pyrotechnics (Ref 2) and... 

The Raney nickel is a very efficient catalyst for the dehydrogenation of 2-butanol into butanone (Scheme 45) with a good selectivity (90%). But, for industrial applications selectivities as high as 99% are required. This can be achieved by poisoning some sites by reaction with Bu4Sn (the best results are obtained with a Sn/Ni ratio of 0.02), which probably occurs first on the sites responsible for the side reactions. The consequence is a slight decrease of the catalytic activity and an increase of the selectivity in 2-butanone which can reach 99%. This catalyst, developed by IFF, has been used commercially in Japan for several years [180]. 

Wainwright, Tomsett, Trimm, and coworkers/Mellor, Copperthwaite, and coworkers—Raney copper catalysts for WGS and methanol synthesis. In 1995, Wainwright and Trimm295 reviewed Raney178 copper catalysts for both water-gas shift and methanol synthesis applications and discussed the possibility of either a redox mechanism or a formate mechanism for Raney copper catalysts. Formates, they indicated, rapidly decompose to C02 and H2 over metallic copper surface. They... 

The aforementioned deuterated derivatives were prepared by way of reduction of a ketone, aldehyde, or ester with sodium borodeu-teride, or by deuteroboration of an alkene. An interesting reaction, perhaps eventually applicable to direct deuteration of polysaccharides, was reported by Koch and Stuart413 and by them and their coworkers,41b who found that treatment of methyl a-D-glucopyranoside with Raney nickel catalyst in deuterium oxide results in exchange of protons attached to C-2, C-3, C-4, and C-6. In other compounds, some protons of CHOH groups are not replaced, but the spectra may nevertheless be interpreted with the aid of a- and /3-deuterium effects. 

The reduction is usually made in a multi-compartment electrochemical cell, where the reference electrode is isolated from the reaction solution. The solvent can be water, alcohol or their mixture. As organic solvent A,A-dimethyl form amide or acetonitrile is used. Mercury is often used as a cathode, but graphite or low hydrogen overpotential electrically conducting catalysts (e.g. Raney nickel, platinum and palladium black on carbon rod, and Devarda copper) are also applicable. 

Triple bonds in side chains of aromatics can be reduced to double bonds or completely saturated. The outcome of such reductions depends on the structure of the acetylene and on the method of reduction. If the triple bond is not conjugated with the benzene ring it can be handled in the same way as in aliphatic acetylenes. In addition, electrochemical reduction in a solution of lithium chloride in methylamine has been used for partial reduction to alkenes trans isomers, where applicable) in 40-51% yields (with 2,5-dihydroaromatic alkenes as by-products) [379]. Aromatic acetylenes with triple bonds conjugated with benzene rings can be hydrogenated over Raney nickel to cis olefins [356], or to alkyl aromatics over rhenium sulfide catalyst [54]. Electroreduction in methylamine containing lithium chloride gives 80% yields of alkyl aromatics [379]. 

Naphthol has been reduced to 1-decalol using platinum,5 Raney nickel,6 and Raney copper.7 The reactions catalyzed by nickel and copper required elevated temperatures and pressure. The present procedure allows the preparation of substantial quantities of 1-decalol under much more convenient conditions and shorter reaction times. Previous methods5-7 require costly catalysts or high-pressure equipment and frequently result in a high degree of hydrogenolysis. The submitters have found that the present method is applicable to a wide variety of aromatic nuclei, some of which are listed in Table I. 

Heterogeneous hydrogenation of the C=N bond is a very widely used synthetic process with application to small and large-scale reactions. Many of the catalysts described in other sections may also be employed, for example those based on supported rhodium, palladium etc, and Raney Nickel. This area has been reviewed extensively recently192. Hydrogenation of oximes and hydrazones results in formation of amines. Milder conditions can be used for oxime reduction if the ethylaminocarbonyl derivative is prepared in situ prior to reduction276. 

Active Raney nickel induces desulfurization of thiazoles. The reaction apparently occurs by two competing mechanisms (57JCS1652). In the first, under alkaline conditions, ring cleavage occurs before desulfurization, whereas in the second, using a neutral catalyst, the initial desulfurization is followed by fission of the C—N bond and formation of carbonyl derivatives (Scheme 18). Because of the easy and versatile syntheses of thiazoles, this reaction could have interesting synthetic applications. 

Subsequently Raney produced a nickel catalyst by leaching a 50wt% Ni-Al alloy in aqueous sodium hydroxide and that catalyst was even more active and a patent application was filed in 1926 [3], This class of... 

Following the development of sponge-metal nickel catalysts by alkali leaching of Ni-Al alloys by Raney, other alloy systems were considered. These include iron [4], cobalt [5], copper [6], platinum [7], ruthenium [8], and palladium [9]. Small amounts of a third metal such as chromium [10], molybdenum [11], or zinc [12] have been added to the binary alloy to promote catalyst activity. The two most common skeletal metal catalysts currently in use are nickel and copper in unpromoted or promoted forms. Skeletal copper is less active and more selective than skeletal nickel in hydrogenation reactions. It also finds use in the selective hydrolysis of nitriles [13]. This chapter is therefore mainly concerned with the preparation, properties and applications of promoted and unpromoted skeletal nickel and skeletal copper catalysts which are produced by the selective leaching of aluminum from binary or ternary alloys. 

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