Hydrogenation with nickel

The general population is also exposed to nickel in nickel alloys and nickel-plated materials including steel, coins, and jewelry. Residual nickel may be present in soaps, fats, and oils hydrogenated with nickel catalysts (Sunderman 1986). 

A high trans-mixture can be prepared starting from /3-cyclocitral which is hydrogenated to 2,2,6-trimethylcyclohexane carboxaldehyde. Condensation with 2-penta-none in the presence of sodium ethoxide yields the corresponding 3-hexenone. Hydrogenation with nickel copper chromite as a catalyst gives a mixture with up to 95% of the trans-isomer [114]. 

Dowden and Reynolds (49,50) in further experimental work on the hydrogenation of benzene and styrene with nickel-copper alloys as catalysts, found a similar dependence. The specific activities of the nickel-copper alloy catalysts decreased with increasing copper content to a negligible value at 60% copper and 30-40% copper for benzene and styrene, respectively. Low-temperature specific heat data indicated a sharp fall (1) in the energy density of electron levels N(E) at the Fermi surface, where the d-band of nickel becomes filled at 60 % copper, and (2) from nickel to the binary alloy 80 nickel -)- 20 iron. Further work by these authors (50) on styrene hydrogenation with nickel-iron alloy... 

Hydrogenations in methanol tend to be poisoned by ammonia. It is noteworthy that, in contrast to the hydrogenation with nickel and cobalt catalysts, the yields of secondary and tertiary amines even increased in the presence of ammonia over these platinum metal catalysts. 

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). 

Nitronaphthalene is reduced with iron or hydrogen with nickel catalysts it is purified by distillation. In modem processes, the 2-naphthylamine content can be reduced to below 10 ppm. 

Sorbitol is manufactured by the reduction of glucose in aqueous solution using hydrogen with a nickel catalyst. It is used in the manufacture of ascorbic acid (vitamin C), various surface active agents, foodstuffs, pharmaceuticals, cosmetics, dentifrices, adhesives, polyurethane foams, etc. 

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... 

Another significant use of 3-methylphenol is in the production of herbicides and insecticides. 2-/ f2 -Butyl-5-methylphenol is converted to the dinitro acetate derivative, 2-/ f2 -butyl-5-methyl-4,6-dinitrophenyl acetate [2487-01 -6] which is used as both a pre- and postemergent herbicide to control broad leaf weeds (42). Carbamate derivatives of 3-methylphenol based compounds are used as insecticides. The condensation of 3-methylphenol with formaldehyde yields a curable phenoHc resin. Since 3-methylphenol is trifunctional with respect to its reaction with formaldehyde, it is possible to form a thermosetting resin by the reaction of a prepolymer with paraformaldehyde or other suitable formaldehyde sources. 3-Methylphenol is also used in the production of fragrances and flavors. It is reduced with hydrogen under nickel catalysis and the corresponding esters are used as synthetic musk (see Table 3). 

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. 

Alkylthio groups are oxidized to sulfoxides by H2O2 and readily by various oxidizing reagents to sulfones, e.g. in the imidazole series. The SR group is replaced by hydrogen with Raney nickel, and dealkylation is possible, e.g. of 3-alkylthio-l,2-dithiolyliums to give... 

Hydrogenation with Adams catalyst took place only with the 6-alkyl derivatives. Dioxohexahydrotriazine itself acted as a catalyst poison (in common with 1,3,5-triazine and cyanuric acid ). Dioxo-tetrahydrotriazine as well as its A-alkyl and 6-alkyl derivatives can be readily hydrogenated by using Raney nickel. ... 

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