Nickel chromite catalyst

Bis(trirnethylsiloxy)spiro[2.3]hex-4-ene (70 g. 0.27 mol) in anhyd cyclohexane (250 mL) was hydrogenated over a modified nickel chromite catalyst at 25 "C and under 100 atm pressure. After the absorption of hydrogen had ceased, the catalyst was filtered off and the solution was evaporated to remove cyclohexane. The residue was distilled under vacuum to give the product as a colorless liquid yield 55 g (78%) bp 92-94°C/12 Torr. 

Uses ndReactions. Nerol (47) and geraniol (48) can be converted to citroneUol (27) by hydrogenation over a copper chromite catalyst (121). In the absence of hydrogen and under reduced pressure, citroneUal is produced (122). If a nickel catalyst is used, a mixture of nerol, geraniol, and citroneUol is obtained and such a mixture is also useful in perfumery. Hydrogenation of both double bonds gives dimethyl octanol, another useful product. 

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). 

Palladium catalysts, mostly palladium on carbon and Pearlman s catalyst, are used for the hydrogenolysis of the benzyl—nitrogen bond. However, in some cases, platinum, nickel, and copper chromite catalysts have also been used. 

Reduction of unsaturated ketones to saturated alcohols is achieved by catalytic hydrogenation using a nickel catalyst [49], a copper chromite catalyst [50, 887] or by treatment with a nickel-aluminum alloy in sodium hydroxide [555]. If the double bond is conjugated, complete reduction can also be obtained with some hydrides. 2-Cyclopentenone was reduced to cyclopentanol in 83.5% yield with lithium aluminum hydride in tetrahydrofuran [764], with lithium tris tert-butoxy)aluminium hydride (88.8% yield) [764], and with sodium borohydride in ethanol at 78° (yield 100%) [764], Most frequently, however, only the carbonyl is reduced, especially with application of the inverse technique (p. 21). 

With Raney nickel-copper chromite catalysts, methylionones are converted into tetrahydromethylionols, which are also used as fragrance materials [91]. 

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... 

Many amino alcohols have been made from esters of amino acids by catalytic reductions over Raney nickel and copper chromite catalysts. The yields are generally better than those obtained by reduction with sodium and alcohol." The action of ammonia or amines on /8-keto... 

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. 

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... 

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). 

The concentration theory completely fails to explain the selective nature of catalysis. Why, for example, does formic acid decompose into hydrogen and carbon dioxide with a zinc oxide catalyst, whereas with titanium oxide, it breaks down to carbon monoxide and water Or, to quote another example, why do carbon monoxide and hydrogen form methane in the presence of nickel, whereas quantitative yields of methanol are produced with a zinc chromite catalyst.6... 

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... 

Somewhat milder conditions — a temperature region of 100-250° and pressures up to 25 atm (rarely 100-150 atm) — suffice for alkylation of ammonia or primary or secondary amines by primary or secondary alcohols in the presence of hydrogenation catalysts such as platinum, palladium, nickel, and copper chromite. In these cases the temperature required for reaction depends largely on the catalyst. Noble-metal catalysts can be effective from about 100°, nickel catalysts usually have a working temperature in the region 150-200°, but copper chromite catalysts need 190-250°. Frequently the reaction is carried out in an atmosphere of hydrogen. 

In general, nickel in its various forms requires elevated temperature and pressure conditions for the catalytic reduction of pyridines. Hydrogenations with nickel on keiselguhr (4) or nickel chromite (5), for example, employ similar rigorous conditions. Copper chromite (6) (copper chromium oxide) has also been investigated. With this catalyst temperature conditions are usually higher than with nickel catalysts. There is a report of the use of a palladium catalyst in the reduction of some 2-(/3-hydroxyalkyl) pyridines at 130° and 200 atmospheres pressure (7). 

In the pre-World War II days there was little work done at Princeton on synthesis of catalysts. Copper catalysts were made by reduction of Kahlbaum copper oxide, the iron ammonia catalysts were obtained from the Fixed Nitrogen Laboratory through the courtesy of Dr. Paul Emmett, the nickel on kleselguhr catalyst was obtained from DuPont. Platinum on asbestos was made in the laboratory by soaking asbestos with chloroplatinic acid and then igniting it, mixed chromite catalysts were precipitated and calcined and a study was made. 

The effect, for this reaction, is apparently peculiar to catalysts of the nickel chromite type, since the addition of thiophene to a system containing Raney nickel, or of either thiophene or biphenyl sulfide to a similar system containing either platinum or palladium, did not lead to similar results. It may be noted that this reaction is not one involving the isolation of an intermediate product and the action of the sulfur compound seems difficult to explain. In another paper, by Adkins and Billica (44), it was also shown that the hydrogenation of ethyl lactate to 1,2-propanediol with Raney nickel is accelerated by adding small quantities of triethylamine. 

The examples of the hydrogenation of glucose to sorbitol and of esters to alcohols demonstrate the dilemma of reactor choice. Formerly, suspension reactors with Raney nickel or copper chromite catalysts were used, but today trickle-bed reactors with novel noble metal catalysts are preferred. The following advantages are claimed for the trickle-bed reactors ... 

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