Palladium carbonate/sodium

Palladium-carbon sodium tetrahydridoborate Amines from nitro compounds... 

Palladium-carbon sodium hydroxide Carboxylic acids... 

Palladium-carbon sodium tetrahydridoborate Methyl from aldehyde groups... 

Palladium-carbon sodium tetrahydridoborate Cyclic hydroxamic acids from nitrocarboxylic acid esters... 

Palladium-carbon/sodium hydroxide Partial hydrogenation of N-heterocyclics... 

Palladium-carbon sodium acetate Aldehydes from carboxylic acid chlorides Modified Rosenmund-Zetzscfae reduction... 

Palladium-carbon/sodium hydroxide air Replacement of bromine by hydroxyl... 

Palladium carbon-sodium hydroxide Pyridazine ring s. 13, 343... 

Palladium-carbon/sodium hydroxide Mercaptans from disulfides... 

Diacetone-L-sorbose (DAS) is oxidized at elevated temperatures in dilute sodium hydroxide in the presence of a catalyst (nickel chloride for bleach or palladium on carbon for air) or by electrolytic methods. After completion of the reaction, the mixture is worked up by acidification to 2,3 4,6-bis-0-isoptopyhdene-2-oxo-L-gulonic acid (2,3 4,6-diacetone-2-keto-L-gulonic acid) (DAG), which is isolated through filtration, washing, and drying. With sodium hypochlorite/nickel chloride, the reported DAG yields ate >90% (65). The oxidation with air has been reported, and a practical process was developed with palladium—carbon or platinum—carbon as catalyst (66,67). The electrolytic oxidation with nickel salts as the catalyst has also... 

A mixture of 2.0 g (0.064 mol) of 2-fluoromethyl-3-(o-tolyl)-6-nitro-4(3H)-qulnazolinone, Oi g of 5% palladium-carbon and 100 ml of acetic acid is shaken for 30 minutes in hydrogen gas. The initial pressure of hydrogen gas is adjusted to 46 lb and the mixture is heated with an infrared lamp during the reaction. After 30 minutes of this reaction, the pressure of hydrogen gas decreases to 6 lb. After the mixture is cooled, the mixture is filtered to remove the catalyst. The filtrate is evaporated to remove acetic acid, and the residue is dissolved in chloroform. The chloroform solution is washed with 5% aqueous sodium hydroxide and water, successively. Then, the solution is dried and evaporated to remove solvent. The oily residue thus obtained is dissolved in 2 ml of chloroform, and the chloroform solution is passed through a column of 200 g of silica gel. The silica gel column is eluted with ethyl acetate-benzene (1 1). Then, the eluate is evaporated to remove solvent. The crude crystal obtained is washed with isopropylether and recrystallized from isopropanol. 0.95 g of 2-fluoromethyl-3-(o-tolyl)-6-amino-4(3H)-quinazolinone Is obtained. Yield 52.5% MP 195°-196°C. 

Palladium. Palladium catalysts are much like platinum, but a little more versatile. Palladium oxide is made by heating palladium chloride with sodium nitrate to fusion at 575-600°. Use palladium oxide (an equimolar amount) in the formulas already given for reducing with platinum oxide. Below is a reduction with palladium-carbon. 

The use of soluble metal catalysts makes it possible to react 8 and its substituted derivatives with aryl bromides and triflates at 100 °C. The catalyst systems that have been used are Pd2(dba>3 and ( )BINAP with calcium carbonate as base (dba = dibenz[ ,. ]anthracene, BINAP = 2,2-bis(diphenyl-phosphanyl)-l,l-binaphthyl)<2000JA2178>, and 2-(di-r-butylphosphino)biphenyltris(dibenzylideneacetone)palladium with sodium yt-butoxide as base <2003T3109>. 

The residue was subjected to azeotropic operation with toluene two times, and ether was added to the residue. The precipitate derived from trioxane was removed by filtration and washed with ether, and the combined ethereal solutions were concentrated under reduced pressure. The residue was dissolved in ethyl acetate, and the solution was washed with water and aqueous saturated solution of sodium chloride, was dried, and was concentrated to give 4 g of an oily material. The oily material was dissolved in 20 ml of methanol and to the solution was added 20 ml of aqueous 1 N solution of sodium hydroxide, and the mixture was stirred for 14 hours at room temperature. After removal of methanol under reduced pressure, water was added to the mixture, and this solution was acidified to pH 3 with aqueous 2 N hydrochloric acid. The mixture was extracted five times with ethyl acetate, and the ethyl acetate extract was dried and concentrated to give 3.5 g of crude crystals. After addition of ethanol to the crude crystals, the crude crystals were filtered. The filtrate was concentrated, and to the residue was added ethanol and ethyl acetate, and precipitate was collected by filtration. The combined amount of the crude crystals was 1.6 g. After the combined crude crystals were methylated with diazomethane, the reaction product was dissolved in 20 ml of ethyl acetate. To this solution was added 1.5 g of sodium acetate and 300 mg of 10% palladium-carbon, and the mixture was stirred for 2 hours under hydrogen. Then, the reaction product was filtered, and after addition of aqueous saturated solution of sodium hydrogen carbonate to the filtrate, the mixture was extracted two times with ethyl acetate. The extract was washed with an aqueous saturated solution of sodium chloride, dried, and concentrated to give 1.3 g of crude crystals. The crude crystals were recrystallized from ethyl acetate to yield 765 mg of the title compound (melting point 134-135°C, yield 43%). 

Ammonia Hydrochloric acid Palladium on carbon Sodium hydroxide... 

Dimethyl malonate Palladium on carbon Sodium nitrite Polyphosphoric acid... 

In 0.5 N aqueous sodium hydroxide solution (0.8 ml) was dissolved 2-(3-carboxymethyl-4-nitrophenyl)propionic acid (50 mg, 0.2 mmol). The solution was stirred for 18 hours at room temperature in a hydrogen gas atmosphere, after addition of 10% palladium/carbon (10 mg). Insolubles were removed by filtration, and the filtrate was concentrated under reduced pressure to give 55 mg (yield quantitative amount) of the desired compound as a colorless oil. 

Sodium hydride Hydrochloric acid Aluminum chloride o-Phosphoric acid Sodium hydroxide Palladium on carbon Sodium borohydride l,3-Dihydro-l-benzyl-2H-benzimidazol-2-one... 

A suspension of 4.0 g of the 6-oxime of 4,5-dihydroimidazo[4,5,l-j-k][l]benzazepin-2,6,7[lH]-trione 2.0 g of 10% palladium carbon and 150 ml of methanol was stirred under hydrogen for 2,5 h and was then filtered. The filtrate was cooled in an ice bath while slowly adding with mild stirring 0.66 g of sodium borohydride and the mixture was stirred at 5°C for 90 min. The mixture was evaporated to dryness under reduced pressure at 30°C and the residue was dissolved in 15 ml of methanol. The solution was acidified to a pH of 1-2 by addition of hydrogen chloride in ethyl acetate and the mixture was vacuum filtered to obtain 3.6 g of (6RS, trans)-6-amino-7-hydroxy-4,5,6,7-tetrahydro-imidazo[4,5,l-j-k][l]benzazepin-2[lH]-one hydrochloride melting at >260°C (crystallization from methanol and then from ethanol). The base (6RS, trans)-6-amino-7-hydroxy-4,5,6,7-tetrahydro-imidazo[4,5,l-j-k][l]benzazepin-2[lH]-one may be produced from (6RS,trans)-6-amino-7-hydroxy-4,5,6,7-tetrahydro-imidazo[4,5,l-j-k][l]benzazepin-2[lH]-one hydrochloride by treatment of salt with sodium hydroxide. 

When the required 1,2-diaminoarencs are not readily available it is often possible to utilize o-nitroanilines as substitutes. They can be successively reduced or hydrogenated and then cyclized [82, 91, 133], or the cyclization and reduction processes can be combined. Suitable reducing agents are triethyl phosphite, iron pentacarbonyl, titanium(III) chloride, Raney nickel-hydrazine, palladium-carbon, bisulfite or dithionitc, and metal-acid [54, 134,135]. Thus, 4,5-dimethyl 2-nitroaniline heated at 90"C (1 h) with formic acid and sodium dithionitc gives 5,6-dimethyIbenzimidazolc in 92% yield [136]. 

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