Nickel catalyst, Raney, in preparation

Nickel catalyst, Raney, in preparation of 2,2 bipvndine, 46, 5 VV7 J, preparation of, 46, 5 Nickel ion, as catalyst for decomposition of diazomum xanthates, 47,... 

Raney-type nickel catalysts are typically prepared by leaching aluminium from a Ni-Al alloy using a concentrated sodium hydroxide solution [1-3], This process of activation critically affects the structure and properties of Raney-type nickel catalysts. The initial structure and composition of the starting alloy also influence the performance of the final catalyst [4-7], In this paper, numerical modelling is compared to experimental measurements in an attempt to simulate both the 3D morphology of as-leached Raney-Ni catalyst material and investigate the nature of the exposed catalyst surfaces. 

Raney nickel A special form of nickel prepared by treating an Al-Ni alloy with NaOH solution. The nickel is left in a spongy mass which is pyrophoric when dry. This form of nickel is a most powerful catalyst, especially for hydrogenations. 

P-Phenylethylamine is conveniently prepared by the hydrogenation under pressure of benzyl cyanide with Raney nickel catalyst (see Section VI,5) in the presence of either a saturated solution of dry ammonia in anhydrous methyl alcohol or of liquid ammonia the latter are added to suppress the formation of the secondary amine, di- P phenylethylamine ... 

H-acid, l-hydroxy-3,6,8-ttisulfonic acid, which is one of the most important letter acids, is prepared as naphthalene is sulfonated with sulfuric acid to ttisulfonic acid. The product is then nitrated and neutralized with lime to produce the calcium salt of l-nitronaphthalene-3,6,8-ttisulfonic acid, which is then reduced to T-acid (Koch acid) with Fe and HCl modem processes use continuous catalytical hydrogenation with Ni catalyst. Hydrogenation has been performed in aqueous medium in the presence of Raney nickel or Raney Ni—Fe catalyst with a low catalyst consumption and better yield (51). Fusion of the T-acid with sodium hydroxide and neutralization with sulfuric acid yields H-acid. Azo dyes such as Direct Blue 15 [2429-74-5] (17) and Acid... 

This procedure is based on the method of Lindsay and Hauser as modified slightly by Osgerby and Pauson. N,N-dimethyl-aminomethylferrocene methiodide has also been prepared by heating formylferrocene with dimethylamine and hydrogen in the presence of Raney nickel catalyst to give dimethylamino-methylferrocene, which was quaternized with methyl iodide. ... 

Clean sodium (0.19 g), free of paraffin or petroleum residues, is dissolved in deuterium oxide (1.2 ml) and Raney nickel alloy (0.25 g) is added in small portions over 8 min while maintaining the temperature at about 50°. When the addition is complete, the supernatant is poured off and the catalyst is washed by decantation with deuterium oxide (3x2 ml) followed by methanol-OD (2x1 ml). The catalyst should be prepared fresh as needed and the preparation carried out as rapidly as possible. 

Two different sets of experimental conditions have been used. Buu-Hoi et al. and Hansen have employed the method introduced by Papa et using Raney nickel alloy directly for the desulfurization in an alkaline medium. Under these conditions most functional groups are removed and this method is most convenient for the preparation of aliphatic acids. The other method uses Raney nickel catalysts of different reactivity in various solvents such as aqueous ammonia, alcohol, ether, or acetone. The solvent and activity of the catalyst can have an appreciable influence on yields and types of compounds formed, but have not yet been investigated in detail. In acetic anhydride, for instance, desulfurization of thiophenes does not occur and these reaction conditions have been employed for reductive acetylation of nitrothiophenes. Even under the mildest conditions, all double bonds are hydrogenated and all halogens removed. Nitro and oxime groups are reduced to amines. 

In 1956 it was found that when pyridine is refluxed with a modified Raney-nickel catalyst, 2,2 -bipyridine (1) is formed in satisfactory yield. The isomeric bipyridines could not be detected, and the product was readily purified. Similar heterocyclic biaryls have been formed in the same way from substituted pyridines and from some related compounds, the yield being dependent on the nature of the compound. The reaction has become the method of choice for the preparation of 2,2 -bipyridine, and it is now used on an industrial scale. Bipyridyls are of particular importance as chelating agents. 

A solution of 151 grams of 1-(3, 4 -dimethoxyphenyl)-2-propanone oxime in 200 cc of absolute ethanol is treated with 5 grams of Raney nickel catalyst and ammonia in an autoclave at about 25 atm of pressure and at 75 -100°C. The reduction is complete in about one-half hour and the reaction mixture is filtered and fractionated under reduced pressure to recover the a-methylhomoveratrylamine formed by the reduction. a-Methylhomoveratryl-amine thus prepared boiled at 163°-165°C at 18 mm pressure. 

Raney nickel has long been known as a hydrogenation catalyst. Other forms of active nickel can be easily prepared by reducing nickel salts in situ with NaBH4, Fe, Grignard reagents, etc. (199-202). 

Raney predicted that many other metal catalysts could be prepared with this technique, but he did not investigate them [8], Copper and cobalt catalysts were soon reported by others [4,5], These catalysts were not nearly as active as Raney s nickel catalyst and therefore have not been as popular industrially however they offer some advantages such as improved selectivity for some reactions. Skeletal iron, ruthenium and others have also been prepared [9-13], Wainwright [14,15] provides two brief overviews of skeletal catalysts, in particular skeletal copper, for heterogeneous reactions. Table 5.1 presents a list of different skeletal metal catalysts and some of the reactions that are catalyzed by them. 

R. Schroter, Reductions with Raney nickel catalysts, in Newer Methods of Preparative Organic Chemistry, Interscience Publishers Inc., New York, 1965, pp. 61-101. 

---