Patent / 1973
Gently and selectively acting palladium on carbon supports as hydrogenation catalysts
PdCl2 soln. is stirred at 40-60.degree. with active charcoal while passing in coal gas, optionally dild. with up to 99 parts of H, until all the Pd is deposited as metal on the charcoal, which is then filtered, washed and dried. The product is a selective hydrogenation and (or) dehalogenation catalyst. In an example, 5 g of PdCl2 was dissolved in the min. amt. of H2O and the soln. poured into a stirred suspension of 54 g of active charcoal in 100 ml of H2O at 50.degree.. The mixt. was stirred for 2 hr at 50.degree. while passing in a rapid stream of a mixt. of H 96 and coal gas 4% until gas absorption ceased. The cooled mixt. was filtered, washed and dried to give a catalyst contg. 5% Pd. 6-Chloro-16-methylene-17.alpha.-hydroxypregna-1,4,9(11)-triene-3,20-dione, 85 g, dissolved in 900 ml of AcOH was hydrogenated in presence of 12 g of Pd supported on charcoal, at 20-30.degree. and a pressure of 1,000 mm of H2O until 2 equivs. of H were consumed. The catalyst is filtered off and 16.beta.-methyl-17.alpha.-hydroxypregna-1,4,-9(11)-triene-3,20-dione is pptd. in 96% yield by addn. of 5 l. of H2O to the filtrate. Similar treatment of 9.alpha.-bromo-11.beta.,17.alpha.-dihydroxy-16-methylene-1,-4-pregnadiene-3,20-dione gives a 93.4% yield of a new compd., 11.beta.,17.alpha.-dihydroxy-16.beta.-methyl-1,4-pregnadiene-3,20-dione.