Raney hydrogenations with

Single-bond cleavage with molecular hydrogen is termed hydrogenolysis. Palladium is the best catalyst for this purpose, platinum is not useful. Desulfurizations are most efficiently per-formed with Raney nickel (with or without hydrogen G.R. Pettit, 1962 A or with alkali metals in liquid ammonia or amines. The scheme below summarizes some classes of compounds most susceptible to hydrogenolysis. 

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. 

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... 

This acetal is stable to hydrogenation with W4-Raney Ni, which was used to cleave a benzyl group in 99% yield. ... 

The third and fourth isomerides, viz., the two aZZosolanidanols, were prepared from solanidone (A Solatubenone of Roehelmeyer A -solaniden-3-one), already deseribed (p. 663), by hydrogenation with platinised Raney niekel in an alkaline medium. The reaetion produet yielded aZZosolanidan-3(a)-ol and aZZosolanidan-3(jS)-ol. R probably also ineluded the two solanidanols sinee the unerystallisable residue on epimerisation by sodium in boiling xylene followed by preeipitation with digitonin, yielded some solanidan - 3( j8 )-ol. 

The hydrogenation of equilenin (64) occurs predominantly by attack at ring A over both platinum and Raney nickel. With platinum extensive cleavage of the 3-hydroxyl group takes place. 

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. ... 

The perhydroisoindole system can be prepared by high-pressure hydrogenation of the isoindole over nickel on alumina at elevated temperatures. The use of Raney nickel with dioxane in the reduction of l,3-diphenyl-2-methylisoindole (47) gives the perhydro product (96), accompanied by the isoindoline (97). An alternative route to partially hydrogenated isoindoles has been described in Section III, D. 

Nickel(II) chlorophyll derivatives undergo catalytic hydrogenation with Raney nickel as catalyst to yield stereoisomeric isobacteriochlorins in which ring A of the chlorophyll derivatives is reduced.16... 

Among the earlier studies of reaction kinetics in mechanically stirred slurry reactors may be noted the papers of Davis et al. (D3), Price and Schiewitz (P5), and Littman and Bliss (L6). The latter investigated the hydrogenation of toluene catalyzed by Raney-nickel with a view to establishing the mechanism of the reaction and reaction orders, the study being a typical example of the application of mechanically stirred reactors for investigations of chemical kinetics in the absence of mass-transfer effects. 

ADN, 19.4% CL, 1.3% ACAM, 2.2% CVAM and 30.9% others and was hydrogenated with Raney Co 2724 under identical conditions to the above. The reaction showed an initial hydrogen uptake rate of 7.8 psi (53.8 kPa)/minute. After 240 minutes, the reaction had consumed 525 psig (3.72 MPa) a sample was removed from the reactor for analysis. It comprised 39% HMD, 18% CL, and by-products. The reaction showed no evidence of catalyst deactivation. While the rate of hydrogen consumption was detectably larger in this experiment than in the Raney Co experiment with C02 and NH3, the differences are not sufficiently large to infer a mechanistic difference. 

Add with stirring, in small portions over Vi hour, 40 g 50% Raney-Ni to 600 ml 10% NaOH in a 1 L three-neck flask and continue stirring one hour. Let the Ni settle and decant the solution. Wash residue with 5X200 ml water, 5X50 ml ethanol, always keeping the Ni covered with liquid. Store under ethanol in refrigerator. Hydrogenation with this catalyst can be carried out in a low pressure Parr bottle (e.g., 30-80 ml ethanol, 5-10 g Ni suspension, 1-2 ml 20% NaOH, 40° - 50° and 40-60 PSI H ). 

These are converted into chiral a-amino acids (5) on hydrogenation with Raney nickel. 

One of the important conclusions of the early attempts was that it is fruitful to place the functionality near an optically active support. Already in 1958, Isoda and coworkers reported for the first time the enantioselective hydrogenation with a Raney nickel catalyst modified with optically pure amino acids. Optical yields reported at that time were from low (2.5%) to moderate (36%) values (for references see [12]). Subsequently, in 1963, Izumi and coworkers [100] initiated an extended study of the modified Raney nickel system with TA. As a result of their initial researches, this system was the first heterogeneous chiral catalyst to give high enantioselectivities in the hydrogenation of / -ketoesters (95%) [101,102],... 

The hydroxybutyraldehyde is subsequently hydrogenated with a Raney nickel catalyst to give EDO. 

Another Hydrogenation with Platinum Oxide. JACS, 55, 2694. This method is used to reduce those hydrox-mandelonitriles in the amphetamine section. It uses low pressure and can be used on about any reducible compound. It can also use palladium oxide as the catalyst. A solution of 35.8 g of phenyl-2-propanol in 250 ml of 80% ethanol containing 7.3 g of HCl is hydrogenated for 3 hours in a Parr hydrogenation bottle at 3,5kg/cm or 50 p.s.i, over 0,5 g of platinum oxide (or palladium oxide Raney nickel may also work) or an equimolar ratio of analog catalyst for about 3 hours. Filter off the catalyst and rinse with a little water to wash all the product from the catalyst. Dilute the filtrate to 1 liter of volume with water and extract twice with ether to remove any acid insoluble material. The ether extracts do not contain product. The aqueous layer is made alkaline with solid NaHCOs to a pH of 8-9 and the basic oil which separates is extracted with two 300 ml portions of ether. This ether solution is dried over MgS04, and filtered, then evaporated to remove the ether. To convert to the oxalate, add ether to the crude product and add to a solution of 9.6 g of oxalic acid dihydrate in a small volume of methanol. Give ample... 

Buspirone Buspirone, 8-[4-[4-(2-pyrimidyl)-l-piperazinyl]butyl]-8-azaspiro [4,5] decan-7,9-dione (5.2.6), is synthesized by the reaction of l-(2-pyrimidyl)-4-(4-aminobutyl)piperazine (5.2.4) with 8-oxaspiro[4,5]decan-7,9-dione (5.2.5). In turn, 1-(2-pyrimidyl)-4-(4-aminobutyl)piperazine (5.2.4) is synthesized by the reaction of l-(2-pyrimidyl)piperazine with 4-chlorobutyronitrile, giving 4-(2-pyrimidyl)-l-(3-cyanopropyl)piperazine (5.2.3), which is hydrogenated with Raney nickel into buspirone (5.2.4) [51-55]. 

The first manufacturing route of the GEM side-chain relied on a-cyanoketone 125 however, the number of chemical steps from 125 to the final side-chain was reduced by one step (Noh et ah, 2004a). The sequence began with a selective hydrogenation with Raney nickel followed by double bond migration to enamine 131 (Scheme 4.25). The amino functionality of 131 was then monoprotected, and the double bond was reduced under hydrogenation conditions to afford pyrrolidine-3-one 133. Treatment of 133 with methoxylamine yielded methoxyoxime 129. Deprotection of the carbamate functionality was achieved with methanesulfonic acid to afford the C7-side-chain as the bis-methansulfonate salt. 

Selective catalytic hydrogenation with chromium-promoted Raney nickel is reported (e.g. citral and citronellal to citronellol) NaHCr2(CO)io and KHFe(CO)4 reduction of a/3-unsaturated ketones (e.g. citral to citronellal) has been described (cf. Vol. 7, p. 7). The full paper on selective carbonyl reductions on alumina (Vol. 7, p. 7) has been published." Dehydrogenation of monoterpenoid alcohols over liquid-metal catalysts gives aldehydes and ketones in useful yields. ... 

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