Raney alloy

Raney alloy was leached with 20% aq. NaOH at high temperature (80°C) RNi(H) 5 40... 

Radical initiators, 357 Raney alloys, 358 Reaction safety calorimetry, 358 Reaction simulation, 359 Reactive metals, 359 Redox compounds, 359 Redox reactions, 360 Reducants, 362 Refractory powders, 363 Refrigerators, 363 Repair and maintenance, 364 Rocket propellants, 364 Rosin, 365... 

Leaching by chemically dissolving the aluminum from Raney alloys (Ni, Co, Fe, and Cu) can be mentioned here (see this Handbook, Part A, chapter 2.1.2). Melt-... 

The process used for the preparation of Raney nickel was originally described in a patent issued to Murray Raney in 1927. The catalyst is prepared from Raney alloy which is commercially available and which consists of approximately equal weights of nickel and aluminum. 

Tishchenko (79), using a modified form of Raney nickel, obtained a 95.7 % yield of camphor from the dehydrogenation of borneol. Rutovskii, (80) received a 93.5% yield of camphor with Raney alloy. Reeves and Adkins (81), studying the dehydrogenation of primary alcohols, removed the hydrogen with ethylene. It was found that, though Raney nickel could be used for a catalyst for the reaction, the yields were low and, in general, the Raney nickel was inferior to a catalyst composed of copper, zinc, nickel, and barium chromite. 

Raney alloy has also been used (116) for the dehalogenation of 4-chloro-5-methylquinaldine and 4-chloro-7-methylquinaldine to form the 2,5- and 2,7-dimethylquinaldines. Zinc, in alkaline solution, in the presence of Raney nickel has been used to dehalogenate organic compounds (117). The halogen is then determined by a Volhard determination. 

Modest and Szmuszkovicz (145) applied the same reaction to make naphthalene and phenanthrene derivatives, and Papa, Schwenk, and Ginsberg (60e) used the reaction to cleavage thiophene derivatives utilizing, however, Raney alloy and aqueous alkali in the reaction mixture. 

Taira and Kuroda have shown that the addition of bayerite accelerates the reaction of Raney alloy with water and, by developing the alloy with addition of bayerite, prepared an active Raney Ni that was supported on bayerite and resistant to deactivation.57 The presence of bayerite probably promotes the crystallization of initially... 

Nishimura prepared a platinized T-4 Raney nickel by platinizing and simultaneously leaching Raney alloy specifically, chloroplatinic acid solution, made alkaline with a small amount of sodium hydroxide, was added to a suspension of Raney alloy in water.91 The partly leached and platinized Raney alloy was then developed in water, forming a large quantity of bayerite. Partial loss in activity of Raney nickel, which may result on treatment with chloroplatinic acid, could be avoided in this way, and the platinized Raney nickel thus obtained showed a better activity than that platinized by the method of Delepine and Horeau in hydrogenation of typical organic compounds including ketones such as cyclohexanone and acetophenone. 

Hart and Cassis, Jr. utilized the dechlorination with Raney alloy and alkali in the synthesis of 2,6-di-r-butylphenol from 4-bromo- or 4-chlorophenol as starting mate-... 

NICKEL SPONGE ONi 0901-S ONi 4303T ONP 2 O RANEY ALLOY RANEY NICKEL... 

Reduction of p-fluoroacetophenone with Raney alloys in 5% sodium hydroxide gives 1-phenylethanol in high yields (equation 35). ... 

Bromoanilines are reduced to anilines by hydrogenation over Raney nickel (equation 55), and p-bro-moacetophenone is converted to 1-phenylethanol on heating at 50 C with Raney alloys in 5% sodium hydroxide. The best yields are obtained using copper-aluminum alloy (89-91%). ... 

Another process for preparing Raney nickel particles of sufficient size for use in a flow reactor involves mixing a Raney alloy powder with a polymer and plasticizer. This mixture is extruded to an appropriate shape, the plasticizer is removed eind the extrudate calcined in air at high temperatures to form an a-alumina matrix to support the alloy. Reaction with base removes some of the surface aluminum to give an active surface of Raney nickel that has been shown to be active for vapor phase and trickle flow hydrogenations. ... 

A more direct approach is to use sodium deuteroxide in deuterium oxide to remove the aluminum from the Raney alloy. The activity of the resulting catalyst depends on the temperature and duration of the leaching process. Washing the catalyst with deuterium oxide and/or dioxane gives an effective catalyst for deuteration reactions. 

The Raney alloy... are leached in aqueous alkaline solutions to remove aluminum. The preferred solutions are dilute aqueous solution." of sodium or potassium hydroxide. Aluminum reacts with the aqueou. -caustic solution, resulting in the formation of hydrogen. If hot or concen trated solutions are used, reaction proceeds very rapidly with the immediate evolution of large quantities of hydrogen. This destroys the desired mechanical structure of the product. To prevent this occurrence, the leaching is instituted in relatively cool and dilute aqueous caustic solutions, i.e., initial room temperature leaching with solutions... 

Raney alloy in an alkaline medium reduces aromatic halides to hydrocarbons in good yielil. It has been used for reduction of the chlorinated polyene acid (4) to X phcnyl-/i-valcric acid (5). ... 

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