Hydrogenation palladium hydroxide/carbon

The catalyst is previously prepared in an apparatus for catalytic hydrogenation, in which are placed 0.5 g. of palladous chloride, 3.0 g. of Norite, and 20 ml. of distilled water. The bottle is swept out with hydrogen and then shaken with hydrogen for 2-3 hours at 2-3 atmospheres (40 lb.) pressure. The palladium on carbon is collected on a Biichner funnel, washed with five 50-ml. portions of distilled water, then with five 50-ml. portions of 95% ethanol, and finally twice with ether. Upon drying, about 3 g. of the catalyst is obtained. It is stored in a vacuum desiccator over solid sodium hydroxide. If the reduction of the chloro-lepidine does not proceed normally, the used catalyst should be removed by suction filtration and a fresh 3-g. portion of catalyst added. Failure of the reduction step is usually due to an inactive catalyst or to impurities in the acetic acid or chlorolepidine. The palladium catalysts, prepared as described elsewhere in this volume, are presumably also satisfactory for the reduction of 2-chlorolepidine (p. 77). 

A surprising use of palladium hydroxide-on-carbon in the hydrogenation of (f )-a-phenylglycine to (R)-a-cyclohexylglycine was described by Tamura... 

For preparative purposes the cleavage of the ozonide is best carried out by catalytic hydrogenation over palladium hydroxide-on-calcium carbonate, a catalyst system which does not hydrogenate the aldehydic products the yield of the latter are usually fairly good. An alternative procedure for the decomposition of the ozonide is treatment with dimethylsulphide in methanol the use of the less obnoxious thiourea is a good alternative.107... 

Isoxazolo[4,5-c]pyridines have been converted into thiazolo[5,4-(>]pyridines by three methods. Catalytic hydrogenation of compound (616) using palladium on carbon (10%) in aqueous sodium hydroxide at 50 psi followed by neutralization with HC1 to selectively cleave the isoxazole ring afforded 6-chloro-3-(l-iminoethyl)-4-hydroxypyridine-2-thione (617) (57%) <90JCS(P1)1477>. Animation of the thione moiety of the imine (617) with hydroxyamine-Osulfonic acid and subsequent cyclization affords 6-chloro-4-hydroxy-3-methylisothiazolo[5,4-<5 pyridine (618) (57%) (Scheme 78). 

Hydrogenation of l,2-epoxy-2-methyloctane (8), carrying the epoxy group attached to a primary carbon and a tertiary carbon, gives selectively the primary alcohol over Raney Ni, while over palladium hydroxide catalyst, the tertiary alcohol is formed in 85% selectivity. In the presence of sodium hydroxide the tertiary alcohol was obtained quantitatively over the palladium catalyst by depressing the formation of other products such as hydrocarbons and carbonyl compounds (eq. 13.6).22... 

V- Sodium hydroxide, benzylchloroformate, palladium on carbon, hydrogen... 

Hydrogenation Copper chromite (Lazier catalyst). Copper chromium oxide (Adkins catalyst). Lindlar catalyst (see also Lithium ethoxyacetylide, Malealdehyde, Nickel boride). Nickel catalysts. Palladium catalysts. Palladium hydroxide on carbon. Perchloric acid (promoter). Platinum catalysts. Raney catalysts, Rhenium catalysts. Rhodium catalysts. Stannous chloride. Tributylborane. Trifluoroicetic acid, Tris (triphenylphosphine)chlororhodium. 

HYDROGENATION CATALYSTS Chloro-platinic acid-Triethyl silane. Lindlar catalyst. Nickel boride. Osmium-on-carbon. Palladium hydroxide. Tris(triphenylphos-phine)chlororhodium. 

---