Palladinized Charcoal Catalyst

PdCl2 + HCHO + 3KOH Pd -f 2KC1 + HCOOK -f 2HaO 

A sample of activated carbon having high adsorptive capacity is warmed with dilute aqueous nitric acid. The resulting mixture is filtered, washed with water until free of acid, and dried at 200°. Twelve grams of the treated carbon, 8 g. of palladium chloride, and 24 ml. of commercial formalin are mixed thoroughly and treated with 48 ml. of 50% aqueous potassium hydroxide solution. The reaction mixture is held below room temperature during this operation. The solid obtained is removed by filtration, washed with water until free of alkali, and then dried at 120°. The resulting catalyst contains about 30% palladium. 

Calcium carbonate is prepared by precipitation with sodium carbonate from a hot aqueous calcium chloride solution. Fifty grams of the washed calcium carbonate is suspended in water, and an aqueous solution containing 1 g. of palladous chloride is added. The mixture is warmed gently until the color of the palladous chloride is gone from the aqueous solution, indicating conversion of the palladous chloride to the insoluble hydroxide. The solid material is washed by decantation a few times with distilled water, followed by suction filtration, and then washed until the wash water is free of chloride ion. No more wash water than necessary should be used since some of the palladous hydroxide may be lost by washing with large volumes of water. 

The resulting dried powder is used for catalytic removal of halogen atoms by hydrogen. 

Eleven milliliters of water is added to 12.5 ml. of a 2% aqueous solution of polyvinyl alcohol followed by 1 ml. of an aqueous solution of palladium chloride containing 1% palladium. To the resulting solution is added dropwise 0.5 ml. of a 4% aqueous solution of sodium carbonate. The mixture is diluted with water or ethanol, depending on whether the catalyst is to be used in water or water-ethanol medium. The catalyst is used by agitating it with hydrogen until the hydroxide is reduced to palladium metal, after which the compound to be reduced is added. 

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The resulting solution was filtered through animal charcoal and, after addition of 2 liters of methanol, it was debenzylated by hydrogenation at 60°C over palladinized charcoal as a catalyst. After removal of the catalyst by filtration, the filtrate was concentrated by evaporation, whereupon the hydrochloride of 1-p-methoxyphenyl-2-((3-3, 5 -dihydroxyphenyl-(3-oxo)-ethylamino-propane (MP 244°C) crystaiiized out. For the purpose of demethyiation. 

Other olefinic ketones have been reduced selectively at room temperature and atmospheric pressure over a platinum or palladium catalyst to give good yields of the ketones, namely, 5-methyl->heptanone (94%), diisobutyl ketone (100%), and a-benzylacetophenone (81-95%). Selective hydrogenations of some 3-alkyl-2-cyclohexenones have been carried out over palladinized charcoal in essentially quantitative yields. Preparation of platinum catalyst has been described. Many olefinic ketones prepared by the aldol condensation or by acylation of olefins have been hydrogenated however, the yields are not always stated. Benzalacetone, CgHsCHasCHCOCHj, is selectively reduced to benzyl-acetone in a 63% yield by the action of sodium amalgam in acetic acid-alcohol solution. ... 

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