zum Directory-modus

Oxidation of Methylidene Groups to Carbonyl Groups

Oxidation of Methylidene Groups to Carbonyl Groups: Laboratory Applications

  • From gaseous olefins Excess gas is bubbled into a shaken solution of 100 mL palladium(II) chloride in a 250 mL flask equipped with a heating mantle . Reaction time varies from 5 min to over 2 h depending on reaction temperature and composition of the solution. Once the palladium(II) chloride is reduced to palladium or gas uptake is practically finished, the mixture is cooled with water followed by distillation of the carbonyl compound through a ca. 15 cm long packed column. Preparation of acetone. A solution of 1.64 g of potassium tetrachloropalladate (II) in 100 mL 0.3N perchloric acid under a propene atmosphere is shaken for 10 min at 70°C. Gas uptake is about 110 mL and the product ratio of propenal to acetone is 1:10.
  • From liquid olefins A mixture of a palladium(II) chloride solution and excess olefin is stirred in a three-neck flask equipped with stirrer, reflux condenser and thermometer until reduction of the palladium compound is finished. Reaction products are removed from the mixture by steam distillation, the distillate is extracted several times with ether, the combined extracts are dried, and the products are separated by gas chromatography. Preparation of heptanone. To a solution of 4.1 g potassium tetrachloropalladate (II) in 250 mL 1N perchloric acid is added 4 mL of 1-heptene. The mixture is stirred for 90 min at 70°C. Separation of the products from the reaction mixture by steam distillation is followed by the usual work-up. The product ratio of heptanal to heptan-2-one is 1:22
Page 4 of 7