VAPOUR PHASE OXIDATION OF DIOLS

1,234,766. Vapcur phase oxidation of 1,2- diols. LAPORTE CHEMICALS Ltd. 12 Dec., 1968 [15 Sept., 1967], No. 42180/67. Heading C2C. A hydroxycarbonyl compound is obtained by contacting a gaseous mixture containing a 1,2- diol of the general formula RCH(OH)CH 2 OH, wherein R is H, methyl, ethyl, n-propyl or isopropyl group with molecular oxygen, the molar ratio of oxygen to the diol in the gaseous mixture being less than 4: 1 in the presence of a metallic copper, silver or gold catalyst having a surface area of less than 50 square metres per gram. The gaseous mixture preferably contains a diluent gas, e.g. nitrogen, CO 2 , argon or helium and water vapour should also desirably be present. The reaction temperature may be between the b.pt. of the diol and about 500‹ C., e.g. between 250‹ and 350‹ C. Examples are given for the oxidation of ethylene glycol to form glycollic aldehyde together with some glyoxal and a small amount of glycollic acid, the catalyst being either pure copper gauze spirals of surface area of less than 5 m.2/g. or a metallic silver catalyst in the form of spirals of surface area less than 5 m.2/g. When R is methyl the products are acetol and 2-hydroxy propionaldehyde.