Raney copper, hydrogenation catalyst

The preparation of methyl 12-ketostearate from methyl ricinoleate has been accompHshed using copper chromite catalyst. The ketostearate can also be prepared from methyl ricinoleate in a two-step process using Raney nickel. The first step is a rapid hydrogenation to methyl 12-hydroxystearate, the hydrogen coming from the catalyst, followed by a slower dehydrogenation to product (50,51). 

This type of catalyst is not limited to nickel other examples are Raney-cobalt, Raney-copper and Raney-ruthenium. When dry, these catalysts are pyrophoric upon contact with air. Usually they are stored under water, which enables their use without risk. The pyrophoric character is due to the fact that the metal is highly dispersed, so in contact with oxygen fast oxidation takes place. Moreover, the metal contains hydrogen atoms and this adds to the pyrophoric nature. Besides the combustion of the metal also ignition of organic vapours present in the atmosphere can occur. Before start of the reaction it is a standard procedure to replace the water by organic solvents but care should be taken to exclude oxygen. Often alcohol is used. The water is decanted and the wet catalyst is washed repeatedly with alcohol. After several washes with absolute alcohol the last traces of water are removed. 

An improved procedure for the laboratory preparation of 2,5-dimethylpyrazine has been reported.166 a-Amino alcohols are convenient precursors for the industrial preparation of alkylpyrazines. Thus when they are heated in the vapor phase with copper chromite catalysts, they are converted mainly into pyrazines [Eq. (8)] with hydrogenation catalysts such as Raney nickel, piperazines are the... 

The Reppe process is used to make 1,4-1 butanediol from acetylene. In this process, acetylene and formaldehyde are reacted in the presence of a copper-bismuth catalyst. The resulting intermediate, 2-butyne-l,4-diol is hydrogenated over a Raney nickel catalyst ... 

Many hydroxypyrazine A oxides have been A(-deoxygenated to pyrazines with a variety of reducing agents which include heating with hydrazine hydrate in alcohols hydriodic acid and red phosphorus in acetic or phosphoric acid iodine and red phosphorus in refluxing acetic acid phosphorus tribromide in ethyl acetate sodium dithionite catalytic reduction with hydrogen over Raney nickel dry distillation with copper-chromite catalyst and titanium trichloride in tetrahydrofuran at room temperature. 

Raney copper is another Raney type catalyst that is prepared from a copper-aluminum alloy. This catalyst has been used infrequently but does show some reaction selectivity not possible with other catalysts. Of particular interest is its use for the selective hydrogenation of substituted dinitrobenzenes (Eqn. 11.6).2 This catalyst, as well as Raney cobalt, generally promotes fewer side reactions than does Raney nickel. 25... 

The copper-chromium oxide ("copper chromite") catalyst, which was developed by Adkins, has been considered to be a complement of Raney nickel for hydrogenation reactions.26 This catalyst, which is, essentially, copper supported on chromium oxide or copper-chromium oxide,22-29 is useful for the hydrogenation of esters and amides but does not affect the saturation of... 

Raney copper is prepared from the commercially available copper aluminum alloy. It does not have much to offer the synthetic chemist as only a few reactions are reported to be affected by this catalyst. Raney copper, as well as Raney cobalt, generally produces fewer side reactions than Raney nickel even though they usually require higher reaction temperatures for the same reaction. Raney copper is, however, quite usefiil for the selective hydrogenation of substituted dinitro benzenes (Eqn. 8.6) with its activity apparently increasing with continued reuse. Raney copper can also be used for the catalytic hydrolysis of hindered nitriles to the amides (Eqn. 12.13). "2... 

The hydrogenation of isoprene, 75, however shows the reverse trend with the primary product from 1,2-addition being 2-methyl-l-butene (Eqn. 15.45), which is formed in about 75% yield over copper chromite catalysts. " The hydrogenation of isoprene over a sulfided Raney nickel catalyst "3 took place primarily by way of a 1,4-addition process to give 2-methyl-2-butene (Eqn. 15.45). 

We ultimately settled on a novel catalytic route for the production of DSIDA. The initial catalyst was a Raney copper composition that allowed us to convert diethanolamine, to DSIDA in a really interesting dehydrogenation reaction. This is an endothermic reaction that gives off hydrogen as a by-product. We were able to get the facility to work with this catalyst, but there were a lot of operational issues associated with this technology. Raney copper is a very malleable soft metal which resulted in catalyst stability issues. Ultimately we needed to go ahead and find something that was better. 

Raney metals are attractive because thermal treatment in a gas flow is not required to produce the catalytically active metal. Storage of the pyrophoric catalyst is, moreover, easy, because the catalyst can be stored in water. Another important advantage is that the catalyst particles are heavy, which enables separation of the catalyst by settling and decantation. A final attractive feature of Raney metals is that they can be exposed to alkaline liquids. Many other metal catalysts are not stable in alkaline liquids. Most well known is Raney nickel, which is an attractive hydrogenation catalyst [11-20]. Raney copper and Raney cobalt are also frequently employed. Raney metals are mostly used for hydrogenations in the fine-chemical industry. Raney nickel and Raney cobalt often have different selectivity the reason for the difference between nickel and cobalt is often obscure, though cobalt is more liable to poisoning and oxidation. 

Although palladium occupies the dominant position in semi-hydrogenation catalysts, it is by no means the only metal suitable for formulation into a viable catalyst. Mention has already been made of the nickel boride alternatives, with or without copper promotion, for example. Other examples include the skeletal catalyst Raney nickel [69], alumina-supported nickel [70], and aluminum phosphate-supported nickel [71] (Eqs 21 and 22) ... 

Alcan 756 C.l. 77775 Carbonyl nickel powder CCRIS 427 EINECS 231-111-4 EL12 Fibrex Fibrex P HSDB 1096 Ni 0901-S Ni 270 Ni 4303T Nichel Nickel 200 Nickel 201 Nickel 205 Nickel 207 Nickel 270 Nickel catalyst Nickel compounds Nickel, elemental Nickel, elemental/metal Nickel particles Nickel sponge NP 2 Raney alloy Raney nickel RCH 55/5. Metallic element, used in electroplating, as a hydrogenation catalyst and in iron- and copper-based alloys. Metal mp = 1453° bp (calc) = 2732° d= 8.908. Atomergic Chemetals Inco, Europe Lancaster Synthesis Co. Sigma-Aldrich Fine Chem. 

These reductive deaminations can be effected by hydrogenation over Raney nickel, palladium, or copper chromite catalysts, and also by means of sodium amalgam or zinc dust in aqueous-methanolic sodium hydroxide.344k... 

Hydrogenation of D-fructose over Raney-copper catalysts. 

By using sodium haiides or sodium borate the hydrogenation of D-fructose could be carried out almost to the completion. These results are shown in Table 3. In these experiments upon using Raney-copper catalysts the highest selectivity of D-mannitol, 82.7 %, was obsen/ed over a cobalt containing catalysts in the presence of sodium borate. Even higher D-mannitol selectivity, i.e. 88.2, was observed over CPG supported copper catalyst in the presence of sodium borate. 

---