Palladium on active charcoal

The slurry was prepared by adding ice-cold methanol to 10% palladium on activated charcoal. The slurry was transferred to the reaction flask with a pipet. 

Palladium, 26 107, 30 18-19, 32 73-74,37 45-47 see also Supported palladium Unsupported palladium on active charcoal, 20 128-131... 

Alternative methods for removing 1-propenyl groups under non-acidic conditions have been reported these include reaction with alkaline potassium permanganate solution,204,205 ozonolysis followed by alkaline hydrolysis,204 205 treatment with a mercuric chloride-mercuric oxide reagent,206,207 and treatment with palladium on activated charcoal in a hydroxylic solvent containing a trace of an acid.2070 The last procedure is a combined isomerization-hydrolysis, but the isomerization step may be independently achieved by omission of the acid.2070,2076... 

Deprotection of allyl aryl ethers is accomplished by protonolysis with palladium on activated charcoal in methanol solution in the presence of toluene-p-sulphonic acid,42 or by reduction with sodium bis(2-methoxy-ethoxy)aluminium hydride in toluene solution43 (Aldrich). This latter reagent also cleaves aryl benzyl ethers. 

The azido functionality is finally hydrogenated by means of hydrogen in presence of catalytic amounts of palladium on activated charcoal to furnish 8. 

Benzyl 4,6-di-0-benzoyl-2-0-benzyl-3-deoxy-3,3-difluoro-a-D-gluco-pyranoside (220 mg, 0.44 mmol) was dissolved in methanol in the presence of 200 mg of palladium on activated charcoal (10% Pd content). The suspension was stirred at room temperature under hydrogen pressure (10 bar) for 16 h. The suspension was then filtered through a thin silica gel pad, and evaporated. The residue was purified by CC to give 105 mg (59%) of 4,6-di-0-benzoyl-3-deoxy-3,3-difluoro-a/p-D-gluco-pyranoside as an inseparable anomeric mixture (ratio a/ 3 = 5 1). 

The corresponding hydrogenation with palladium-on-active charcoal (5% strength) gives a quantitative yield of a pure 6-benzyl-5,7-dioxo-octahydropyrrolo[3,4-b]pyridine of melting point 67°-69°C. 

Catalytic hydrogenation of benzylic lactones 71 and 72 over 10% palladium on activated charcoal gave diacids 73 and 74 which were isolated as their corresponding dibenzhydryl esters 75 and 76 after treatment of the crude hydrogenolysis product with diphenyldia-... 

Scheme 3.11 Microwave-assisted transfer-hydrogenation of cinnamaldehyde with palladium on activated charcoal...

Of the heterogeneous catalysts employed in conjunction with ionic liquids, palladium on activated charcoal is most frequently used.[60,75,86,88]... 

Catalytic reduction of 2-acetyl-3-methyl(or 3-phenyl)quinoxaline with 5% palladium on activated charcoal in ethanol gives 2-acetyl-3-methyl(or 3-phenyl)-l,4-dihydroquinoxaline. °... 

An example of a catalyst used frequently in the laboratory is palladium on activated charcoal (Fig. 4.1)... 

The aqueous solution is sent to the hydrogenation reactor, operating in the same conditions in the presence of a catalyst bed of palladium on activated charcoal, and fed with a slight stream of hydrogen. The hydrogenated product is centrifuged, washed with water, and dried with air. 

Aromatic sulfinic acids can be synthesized from aryldiazonium tetrafluorobo-rates by hydrogenative sulfination in the presence of palladium on activated charcoal [118], As depicted in Scheme 7.20, the catalytic cycle consists of oxidative addition of the substrates to Pd(0) to form cationic arylpalladium(II) intermediate, SO2 insertion into palladium-carbon a-bond, and the following hydrogenolysis of sulfinylpalladium intermediate. The key to success is the formation of the cationic... 

The thermochemical liquefaction of wood in water to produce fuel or chemical intermediates has been studied intensively over the last decade ( l). The earlier works used either sodium carbonate as soluble catalyst and carbon monoxide as reducing gas ( ) ( ), or nickel catalyst ( U) or palladium on activated charcoal ( 5) in the presence of hydrogen. Then it has been shown that the presence of a reducing gas was not necessary if iron powder was used as additive, with moderate heating rates ( ). When the wood suspended in water was rapidly heated to 350°C, and then quenched, no catalyst was necessary and a yield in acetone solubles as high as 50 wt was obtained (T ) ( ). 

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