Copper-chromite hydrogenation

Clemo, Ramage, and Raper (133), to quinolizidine by an electrolytic method and by hydrogenation over platinum oxide in acetic acid solution. Boekelheide and Rothchild (141) effected the same change by hydrogenation of XLVIII over copper chromite at high temperature and pressure, and also converted the Michael adduct of malonic ester and 2-vinyl-pyridine (XLIX) (142) to quinolizidine by copper chromite hydrogenation (141, 143). 

When Adkins tried to modify the Lazier recipe and make a copper chromite hydrogenation catalyst, he found that an active black cupric oxide was produced instead of the red oxide claimed by Lazier. Adkins and Folkers subsequently suggested modifications to the recipe, including the addition of barium, magnesium, or calcium oxides to stabilize the black oxide form, which was more active. Atypical recipe and catalyst composition is shown in Table 3.11. 

Reduction. Hydrogenation of dimethyl adipate over Raney-promoted copper chromite at 200°C and 10 MPa produces 1,6-hexanediol [629-11-8], an important chemical intermediate (32). Promoted cobalt catalysts (33) and nickel catalysts (34) are examples of other patented processes for this reaction. An eadier process, which is no longer in use, for the manufacture of the 1,6-hexanediamine from adipic acid involved hydrogenation of the acid (as its ester) to the diol, followed by ammonolysis to the diamine (35). 

Dicyclohexylarnine may be selectively generated by reductive alkylation of cyclohexylamine by cyclohexanone (15). Stated batch reaction conditions are specifically 0.05—2.0% Pd or Pt catalyst, which is reusable, pressures of 400—700 kPa (55—100 psi), and temperatures of 75—100°C to give complete reduction in 4 h. Continuous vapor-phase amination selective to dicyclohexylarnine is claimed for cyclohexanone (16) or mixed cyclohexanone plus cyclohexanol (17) feeds. Conditions are 5—15 s contact time of <1 1 ammonia ketone, - 3 1 hydrogen ketone at 260°C over nickel on kieselguhr. With mixed feed the preferred conditions over a mixed copper chromite plus nickel catalyst are 18-s contact time at 250 °C with ammonia alkyl = 0.6 1 and hydrogen alkyl = 1 1. 

Hydrogenation. Gas-phase catalytic hydrogenation of succinic anhydride yields y-butyrolactone [96-48-0] (GBL), tetrahydrofiiran [109-99-9] (THF), 1,4-butanediol (BDO), or a mixture of these products, depending on the experimental conditions. Catalysts mentioned in the Hterature include copper chromites with various additives (72), copper—zinc oxides with promoters (73—75), and mthenium (76). The same products are obtained by hquid-phase hydrogenation catalysts used include Pd with various modifiers on various carriers (77—80), Ru on C (81) or Ru complexes (82,83), Rh on C (79), Cu—Co—Mn oxides (84), Co—Ni—Re oxides (85), Cu—Ti oxides (86), Ca—Mo—Ni on diatomaceous earth (87), and Mo—Ba—Re oxides (88). Chemical reduction of succinic anhydride to GBL or THF can be performed with 2-propanol in the presence of Zr02 catalyst (89,90). 

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). 

For more selective hydrogenations, supported 5—10 wt % palladium on activated carbon is preferred for reductions in which ring hydrogenation is not wanted. Mild conditions, a neutral solvent, and a stoichiometric amount of hydrogen are used to avoid ring hydrogenation. There are also appHcations for 35—40 wt % cobalt on kieselguhr, copper chromite (nonpromoted or promoted with barium), 5—10 wt % platinum on activated carbon, platinum (IV) oxide (Adams catalyst), and rhenium heptasulfide. Alcohol yields can sometimes be increased by the use of nonpolar (nonacidic) solvents and small amounts of bases, such as tertiary amines, which act as catalyst inhibitors. 

Catalytic hydrogenation of furfural in the presence of copper chromite leads to furfuryl alcohol, the major intermediate of the furan resins Figure 28.1). 

I) of which one form (picrate, m.p. 116°) is identical with dl-dihydro-de-N-methylheliotridane and the other (picrate, m.p. 126°) is diastereoisomeric with, and convertible into, it by, dehydrogenation to the corresponding pyrrole and hydrogenation of the latter in presence of copper chromite as catalyst. 

Ruthenium is excellent for hydrogenation of aliphatic carbonyl compounds (92), and it, as well as nickel, is used industrially for conversion of glucose to sorbitol (14,15,29,75,100). Nickel usually requires vigorous conditions unless large amounts of catalyst are used (11,20,27,37,60), or the catalyst is very active, such as W-6 Raney nickel (6). Copper chromite is always used at elevated temperatures and pressures and may be useful if aromatic-ring saturation is to be avoided. Rhodium has given excellent results under mild conditions when other catalysts have failed (4,5,66). It is useful in reduction of aliphatic carbonyls in molecules susceptible to hydrogenolysis. 

Ruthenium dioxide or ruthenium-on-carbon are effective catalysts for hydrogenation of mono- and dicarboxylic acids to the alcohol or glycol. High pressures (5,000-10,000 psig) and elevated temperatures (130-225 C) have been used in these hydrogenations 8,12,24). Yields of alcohol tend to be less than perfect because of esterification of the alcohol. Near quantitative yields of alcohol can be obtained by mixing ruthenium and copper chromite catalysts so as to reduce the ester as formed. 

Alcohols are the most frequently formed products of ester hydrogenolysis. The hydrogenation of esters to alcohols is a reversible reaction with alcohol formation favored at high pressure, ester at low pressure (/). Copper chromite is usually the catalyst of choice. Details for the preparation of this catalyst (/7) and a detailed procedure for hydrogenation of ethyl adipate to hexamethylene glycol (/[Pg.80]

The presence of catalysts markedly changes the deflagration rate. The greatest rate increase is produced by copper chromite, a well-known hydrogenation catalyst. Some additives which catalyze the process at higher pressures may inhibit it strongly at lower pressures. The catalyst effect is related to catalyst particle-size and concentration, but these factors have not been studied extensively. 

The phthalide used by the submitters and by the checkers was a commercial product, obtained from E. I. du Pont de Nemours and Company, Wilmington, Delaware. This product is no longer available. Phthalide may be prepared in 82.5 per cent yields by hydrogenation of phthalic anhydride in benzene at 270° under 3000 lb. pressure in the presence of copper chromite 1 or, in yields of 61-71 per cent, from phthalimide according to the procedure given in Org. Syn. 16, 71 Coll. Vol. 2, 1943, 526. 

The hydrogenation of HMF in the presence of metal catalysts (Raney nickel, supported platinum metals, copper chromite) leads to quantitative amounts of 2,5-bis(hydroxymethyl)furan used in the manufacture of polyurethanes, or 2,5-bis(hydroxymethyl)tetrahydrofuran that can be used in the preparation of polyesters [30]. The oxidation of HMF is used to prepare 5-formylfuran-2-carboxylic acid, and furan-2,5-dicarboxylic acid (a potential substitute of terephthalic acid). Oxidation by air on platinum catalysts leads quantitatively to the diacid. [32], The oxidation of HMF to dialdehyde was achieved at 90 °C with air as oxidizing in the presence of V205/Ti02 catalysts with a selectivity up to 95% at 90% conversion [33]. 

Copper chromite catalyst, after use in high-pressure hydrogenation of fatty acids to alcohols, is pyrophoric, possibly owing to presence of some metallic copper and/or chromium. Separation of the catalyst from the product alcohols at 130°C in a non-inerted centrifuge led to a rapid exotherm and autoignition at 263°C. 

The hydrogenation step talces place in the conventional way in vessel packed with catalyst where the aldehydes and hydrogen are admixed at 200-300°F and 600-1200 psi. The catalyst is usually nickel or copper chromite on an inert carrier such as kieselguhr, silica gel, or alumina. The crude butyl alcohols are finally separated and purified by distillation. 

Methoxy-delta-6-Dehydro-10,16-Dioxoisomorphinan. One g of the above phenanthrene and 200 mg of copper chromite are suspended in 30 cc of absolute aleohol and redueed in an autoclave at 144-150° with 25 atmospheres hydrogen pressure (cold, before heating, thats where pressure was set) for 4 hours. The cooled reaction mixture is decolorized with Norit, filtered, and concentrated. Pale, yellow prismatic needles (585 mg) are separated. This step can be accomplished in larger scale at the expense of the yield. 

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