Nickel - , methanolate

Influence of the modifier structure on reaction time and chemoselectivity of the hydrogenation of l-chloro-2,4-dinitrobenzene (Raney nickel methanol 60°C 10 bar). 

Reaction time time and chemoselectivity for the hydrogenation of different substrates (formamidine acetate Raney nickel methanol 80°C 12 bar)... 

Fig. 2a-d Hydrogenation of 2-chloro-nitrobenzene in presence of different modifiers. Catalyst potential and concentration of reactants and products versus hydrogen uptake (conversion). (Raney nickel methanol 30°C 1.1 bar). 

A mixture of 3-methoxy-2-nitro-P-pyrrolidinostyrene (lOg, 40 mmol) and Raney nickel (25 g) in methanol-THF (40 ml of each) was heated to 60"C and,... 

Nickel Aluminum, aluminum(III) chloride, ethylene, 1,4-dioxan, hydrogen, methanol, nonmetals, oxidants, sulfur compounds... 

The reaction mechanism and rates of methyl acetate carbonylation are not fully understood. In the nickel-cataly2ed reaction, rate constants for formation of methyl acetate from methanol, formation of dimethyl ether, and carbonylation of dimethyl ether have been reported, as well as their sensitivity to partial pressure of the reactants (32). For the rhodium chloride [10049-07-7] cataly2ed reaction, methyl acetate carbonylation is considered to go through formation of ethyUdene diacetate (33) ... 

Methane. The largest use of methane is for synthesis gas, a mixture of hydrogen and carbon monoxide. Synthesis gas, in turn, is the primary feed for the production of ammonia (qv) and methanol (qv). Synthesis gas is produced by steam reforming of methane over a nickel catalyst. 

Steam Reformings of Natural Gas. This route accounts for at least 80% of the world s methanol capacity. A steam reformer is essentially a process furnace in which the endothermic heat of reaction is provided by firing across tubes filled with a nickel-based catalyst through which the reactants flow. Several mechanical variants are available (see Ammonia). 

Natural gas contains both organic and inorganic sulfur compounds that must be removed to protect both the reforming and downstream methanol synthesis catalysts. Hydrodesulfurization across a cobalt or nickel molybdenum—zinc oxide fixed-bed sequence is the basis for an effective purification system. For high levels of sulfur, bulk removal in a Hquid absorption—stripping system followed by fixed-bed residual clean-up is more practical (see Sulfur REMOVAL AND RECOVERY). Chlorides and mercury may also be found in natural gas, particularly from offshore reservoirs. These poisons can be removed by activated alumina or carbon beds. 

The nitro alcohols can be reduced to the corresponding alkan olamines (qv). Commercially, reduction is accompHshed by hydrogenation of the nitro alcohol in methanol in the presence of Raney nickel. Convenient operating conditions are 30°C and 6900 kPa (1000 psi). Production of alkan olamines constitutes the largest single use of nitro alcohols. 

A process based on a nickel catalyst, either supported or Raney type, is described ia Olin Mathieson patents (26,27). The reduction is carried out ia a continuous stirred tank reactor with a concentric filter element built iato the reactor so that the catalyst remains ia the reaction 2one. Methanol is used as a solvent. Reaction conditions are 2.4—3.5 MPa (350—500 psi), 120—140°C. Keeping the catalyst iaside the reactor iacreases catalyst lifetime by maintaining a hydrogen atmosphere on its surface at all times and minimises handling losses. Periodic cleaning of the filter element is required. 

Xylose is obtained from sulfite Hquors, particularly from hardwoods, such as birch, by methanol extraction of concentrates or dried sulfite lyes, ultrafiltration (qv) and reverse osmosis (qv), ion exchange, ion exclusion, or combinations of these treatments (201). Hydrogenation of xylose is carried out in aqueous solution, usually at basic pH. The Raney nickel catalyst has a loading of 2% at 125°C and 3.5 MPa (515 psi) (202,203). 

The reaction is carried out in the Hquid phase at 373—463 K and 3 MPa (30 atm) of carbon monoxide pressure using nickel salt catalyst, or at 313 K and 0.1 MPa (1 atm) using nickel carbonyl as both the catalyst and the source of carbon monoxide. Either acryHc acid or methyl acrylate may be produced directly, depending on whether water or methanol is used as solvent (41). New technology for acryHc acid production uses direct propjdene oxidation rather than acetylene carbonylation because of the high cost of acetjdene. This new process has completely replaced the old in the United States (see... 

Cyclopentadiene itself has been used as a feedstock for carbon fiber manufacture (76). Cyclopentadiene is also a component of supported metallocene—alumoxane polymerization catalysts in the preparation of syndiotactic polyolefins (77), as a nickel or iron complex in the production of methanol and ethanol from synthesis gas (78), and as Group VIII metal complexes for the production of acetaldehyde from methanol and synthesis gas (79). 

Esters can be obtained from halogenated olefins using a metal carbonyl catalyst (87), eg, /n j -l-bromo-2-phenylethylene is treated with nickel carbonyl in the presence of methanol to afford the corresponding methyl cinnamate (see Cinnamic acid). 

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. 

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