Raney nickel catalytic hydrogenation

Adipic acid (1,4-butanedicarboxylic acid) is used for the production of nylon-6,6 and may be produced from the oxidation of cyclohexane as shown in structure 17.1. Cyclohexane is obtained by the Raney nickel catalytic hydrogenation of benzene. Both the cyclohexanol and cyclohexanone are oxidized to adipic acid by heating with nitric acid. 

Cyclododecene may be prepared from 1,5,9-cyclododecatriene by the catalytic reduction with Raney nickel and hydrogen diluted with nitrogen, with nickel sulfide on alumina, with cobalt, iron, or nickel in the presence of thiophene, with palladium on charcoal, with palladimn chloride in the presence of water, with palladium on barium sulfate, with cobalt acetate in the presence of cobalt carbonyl, and with cobalt carbonyl and tri- -butyl phosphine. It may also be obtained from the triene by reduction with lithium and ethylamine, by disproportionation, - by epoxidation followed by isomerization to a ketone and WoliT-Kishner reduction, and from cyclododecanone by the reaction of its hydrazone with sodium hydride. ... 

Catalytic reduction of pyrroles gives successively A3-pyrroles and pyrrolidines. Tetrahydrofurans are formed by the catalytic reduction of furans with Raney nickel and hydrogen ring cleavage products... 

Catalytic hydrogenation of the nitro group of 21 with Raney nickel under hydrogen atmosphere followed by catalyst removal and recrystallization from methanol-water then furnished aniline 22 and set the stage for the ultimate installation of costly biphenyl-2-carbonyl chloride. Selective acylation of the aniline moiety of 22 was readily achieved by treatment with biphenyl-2-carbonyl chloride in a refluxing mixture of pyridine and acetonitrile. Subsequent addition of a solution of hydrogen chloride in ethyl acetate to the cooled reaction mixture resulted in the precipitation of conivaptan HCl (1), which was isolated in 74% yield. 

Hilditch and Pathak (58) studying the catalytic reduction of methyl eleostearate, found that the reaction at 110° and at 170° was extremely selective in the presence of Raney nickel. No methyl stearate was formed until 90% of the linoleate had been transformed into octadeceno-ates. Ehrhart (59) used Raney nickel to hydrogenate compounds of the type RCH(CN)NHCOR The nitrile was reduced to the amine, but the amide was untouched. 

The condensation of tryptamine (XXVI) with the glutaric ester XCIX in the presence of Raney nickel and hydrogen yields a pair of isomeric lactams (Ca and Cb) of which the former on cyclization with phosphorus oxychloride followed by catalytic reduction gave the... 

Several derivatives of phenols have been found to be especially suited for hydrogenolysis by catalytic hydrogenation. Phenol ethers prepared by the reaction of phenols with l-phenyl-5-chlorotetrazole or with 2-chlorobenzoxazole are hydrogenolyzed over 5% palladium on carbon or over platinum oxide, but not over Raney nickel. The hydrogenations are run at 35 °C in benzene, ethanol or tetrahydrofuran, and give 35-89% yields of the corresponding hydrocarbons. The reaction sequence is exemplified by conversion of phenylphenols to biphenyls (equation 77). 

Another example illustrates that catalytic hydrogenation for reduction of a nitrile can tolerate labile functional groups. Raney nickel catalyzed hydrogenation of 1.54 gave methyl 5-amino-2-methoxypentanoate (/.55).3i No elimination of the labile a-methoxy group occurred, despite the reaction temperature of 265°C. Methyl 6-amino-3-methoxyhexanoate was prepared in an identical manner from methyl 5-cyano-2-methoxypentanoate. 

The products of catalytic reduction of chromone-2-carboxylic acids or esters depend partly on the catalyst used, the amount of hydrogen present and the conditions of reaction. Ethyl chromone-2-carboxylate is reduced (in 86 per cent yield) to the corresponding chromanone in the presence of Raney nickel and hydrogen at a pressure of 50 Ib/in [184]. The 5-hydroxy analogue is similarly reduced at 80°C and 30 Ib/in in 44 per cent yield [8]. A nitro group on the benzene ring is more readily hydrogenated than the pyrone double bond (10 atmospheres, platinum-charcoal or palladium-charcoal catalyst) [24,40]. 

Catalytic hydrogenation is mostly used to convert C—C triple bonds into C C double bonds and alkenes into alkanes or to replace allylic or benzylic hetero atoms by hydrogen (H. Kropf, 1980). Simple theory postulates cis- or syn-addition of hydrogen to the C—C triple or double bond with heterogeneous (R. L. Augustine, 1965, 1968, 1976 P. N. Rylander, 1979) and homogeneous (A. J. Birch, 1976) catalysts. Sulfur functions can be removed with reducing metals, e. g. with Raney nickel (G. R. Pettit, 1962 A). Heteroaromatic systems may be reduced with the aid of ruthenium on carbon. 

Adiponitrile undergoes the typical nitrile reactions, eg, hydrolysis to adipamide and adipic acid and alcoholysis to substituted amides and esters. The most important industrial reaction is the catalytic hydrogenation to hexamethylenediarnine. A variety of catalysts are used for this reduction including cobalt—nickel (46), cobalt manganese (47), cobalt boride (48), copper cobalt (49), and iron oxide (50), and Raney nickel (51). An extensive review on the hydrogenation of nitriles has been recendy pubUshed (10). 

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... 

Reduction. Just as aromatic amine oxides are resistant to the foregoing decomposition reactions, they are more resistant than ahphatic amine oxides to reduction. Ahphatic amine oxides are readily reduced to tertiary amines by sulfurous acid at room temperature in contrast, few aromatic amine oxides can be reduced under these conditions. The ahphatic amine oxides can also be reduced by catalytic hydrogenation (27), with 2inc in acid, or with staimous chloride (28). For the aromatic amine oxides, catalytic hydrogenation with Raney nickel is a fairly general means of deoxygenation (29). Iron in acetic acid (30), phosphoms trichloride (31), and titanium trichloride (32) are also widely used systems for deoxygenation of aromatic amine oxides. 

Dinitrotoluenes can be catalytically hydrogenated to toluenediamines under a wide variety of temperatures, pressures, and solvents the catalyst can be supported noble metal, eg, Pd/C or nickel, either supported or Raney type. The reduction requires six moles of hydrogen per mole of DNT and produces four moles of water. 

Succinic anhydride is manufactured by catalytic hydrogenation of maleic anhydride [108-31-6]. In the most widely used commercial process this reaction is performed in the Hquid phase, at temperatures of 120—180°C and at moderate pressures, in the range of 500—4000 kPa (72—580 psi). Catalysts mentioned in the patent Hterature include nickel (124), Raney nickel (125,126), palladium on different carriers (127,128), and palladium complexes (129). The hydrogenation of the double bond is exothermic Ai/ = —133.89 kJ/mol (—32 kcal/mol) (130). 

Succinic acid can also be produced by catalytic hydrogenation of aqueous solutions of maleic or fumaric acid in the presence of noble metal catalysts, ie, palladium, rhodium, mthenium, or their mixtures, on different carriers (135—139) or on Raney nickel (140). 

CatalyticaHy Active Species. The most common catalyticaHy active materials are metals, metal oxides, and metal sulfides. OccasionaHy, these are used in pure form examples are Raney nickel, used for fat hydrogenation, and y-Al O, used for ethanol dehydration. More often the catalyticaHy active component is highly dispersed on the surface of a support and may constitute no more than about 1% of the total catalyst. The main reason for dispersing the catalytic species is the expense. The expensive material must be accessible to reactants, and this requires that most of the catalytic material be present at a surface. This is possible only if the material is dispersed as minute particles, as smaH as 1 nm in diameter and even less. It is not practical to use minute... 

Ethylamines. Mono-, di-, and triethylamines, produced by catalytic reaction of ethanol with ammonia (330), are a significant outlet for ethanol. The vapor-phase continuous process takes place at 1.38 MPa (13.6 atm) and 150—220°C over a nickel catalyst supported on alumina, siUca, or sihca—alumina. In this reductive amination under a hydrogen atmosphere, the ratio of the mono-, di-, and triethylamine product can be controlled by recycling the unwanted products. Other catalysts used include phosphoric acid and derivatives, copper and iron chlorides, sulfates, and oxides in the presence of acids or alkaline salts (331). Piperidine can be ethylated with ethanol in the presence of Raney nickel catalyst at 200°C and 10.3 MPa (102 atm), to give W-ethylpiperidine [766-09-6] (332). 

Nitropyridazines are reduced catalytically either over platinum, Raney nickel or palladium-charcoal catalyst. When an N-oxide function is present, palladium-charcoal in neutral solution is used in order to obtain the corresponding amino N-oxide. On the other hand, when hydrogenation is carried out in aqueous or alcoholic hydrochloric acid and palladium-charcoal or Raney nickel are used for the reduction of the nitro group, deoxygenation of the N- oxide takes place simultaneously. Halonitropyridazines and their N- oxides are reduced, dehalogenated and deoxygenated to aminopyridazines or to aminopyridazine N- oxides under analogous conditions. 

Reduction of the halogen substituent has been carried out by different procedures such as catalytic hydrogenation using palladium-carbon or Raney nickel, red phosphorus and hydroiodic acid, and zinc and sulfuric acid (66AHQ6)347). 3-Deuteropyrazole has been... 

Diethyl isonitrosomalonate has been reduced catalytically, over palladium on charcoal, Raney nickel, and chemically by aluminum amalgam or hydrogen sulfide. ... 

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