Palladium calcium hydroxid

Preparation of palladium - calcium carbonate catalyst. Prepare 60 g. of precipitated calcium carbonate by mixing hot solutions of the appropriate quantities of A.R. calcium chloride and A.R. sodium carbonate. Suspend the calcium carbonate in water and add a solution containing 1 g. of palladium chloride. Warm the suspension until all the palladium is precipitated as the hydroxide upon the calcium carbonate, i.e., until the supernatant liquid is colourless. Wash several times with... 

In this special field, earlier work had been done in other laboratories, such as by the Schering Company, Berlin (36), and by Ipatieff (37) in connection with his work on the hydrogenation of camphor and of other organic compounds. At both places, the favorable effect of alkali oxides and earth alkali oxides on nickel, cobalt and copper has been investigated. Similarly, Paal and his coworkers (38) have used a palladium-aluminum hydroxide catalyst in 1913 for the hydrogenation of double bonds. Bedford and Erdman (39) had reported that the catalytic action of nickel oxide is enhanced by the oxides of aluminum, zirconium, titanium, calcium, lanthanum, and magnesium. 

Palladium-calcium carbonate/sodium hydroxide Dehalogenative aromatization... 

Palladium-calcium carbonate/calcium hydroxide Replacement of chlorine by hydrogen s. 11, 495... 

The palladium on carbon catalysts should be dried at room temperature or the carbon may ignite. These catalysts are first dried in air and then over potassium hydroxide (or calcium chloride) in a desiccator. 

To prepare palladium on charcoal (5% Pd), heat a solution of 1.7 g of palladium chloride (1) in 1.7 ml of concentrated hydrochloric acid and 20 ml of water on a water bath for 2 hours or until solution is complete, and add this to a solution of 30 g of sodium acetate trihydrate in 200 ml of water contained in a 500-ml hydrogenation flask. Add 20 g of acid-washed activated charcoal (2) and hydrogenate in an atmospheric hydrogenation apparatus (Fig. 2.63(a)) until absorption ceases. Collect the catalyst on a Buchner funnel and wash it with five 100 ml portions of water and suck as dry as possbile. Dry the catalyst at room temperature (3) over potassium hydroxide pellets or anhydrous calcium chloride in a vacuum desiccator. Powder the catalyst (about 20 g) and store in a tightly stoppered bottle. 

For palladium hydroxide on calcium carbonate mix hot solutions of 55 g of anhydrous calcium chloride and 53 g of anhydrous sodium carbonate each dissolved in 150 ml of distilled water. Filter the resulting precipitate of calcium... 

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... 

Lead-Poisoned Pd-CaCQs (Lindlar Catalyst))82 Palladium chloride (1.48 g, 0.0083 mol) is placed in a 10-ml Erlenmeyer flask, and 3.6 ml (0.043 mol) of 37% hydrochloric acid is added. The flask is shaken at about 30°C until the palladium chloride is dissolved. The chloropalladic acid solution is transferred to a 150-ml beaker with 45 ml of distilled water. The pH of the solution is brought to 4.0-4.5 by slow addition of aqueous 3M sodium hydroxide. The solution is diluted to approximately 100 ml and placed in a 200- or 250-ml three-necked, round-bottomed flask equipped with a mechanical stirrer and a thermometer. Precipitated calcium carbonate (18 g) is added. The well-stirred suspension is heated to 75-85°C and held... 

Reduction of 2-carboxypyrazine in aqueous potassium hydroxide over palladium-charcoal at 50° and atmospheric pressure gave 2-carboxypiperazine and 2,3-dicarboxy-, 2,5-dicarboxy-, 2,6-dicarboxy-, and 2-carbamoyl-3-carboxy-piperazines were prepared in an analogous manner (1269). Similar results were obtained on reduction of the calcium salts (1352). Reduction of 2-chlorocarbonylpyrazine with lithium tri-r-butoxyaluminohydride in tetrahydrofuran gave 2-(pyrazin-2 -ylmethoxycarbonyOpyrazine (1077). 

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