| 摘要 |
1,223,452. Electrochemical production of olefin oxides. FARBENFABRIKEN BAYER A.G. 18 April, 1968 [20 April, 1967], No. 8386/68. Heading C2C. [Also in Division C7] In the production of an olefin oxide by a process in which a halogen is formed by electrolysis of an aqueous solution of a metal halide in a cell having a diaphragm between anode and cathode, the resulting halogen or its hydrolysis products in solution being reacted with an optionally halogenated olefin to form the corresponding halohydrin and the halohydrin so obtained is dehydrohalogenated with the hydroxyl ions produced adjacent the cathode to form the olefin oxide, the electrolysis anode comprises a titanium core and a covering layer of an oxide of one or more of the noble metals platinum, palladium, iridium, ruthenium and rhodium. The olefin alone if naturally gaseous or in combination with a non-reacting gas, e.g. gaseous paraffins or their halogen derivatives, nitrogen, carbon dioxide under reaction conditions which render the olefin gaseous may be introduced into the anode compartment to form the halohydrin there. Alternatively, the halogen-containing anolyte may be withdrawn from the cell and reacted externally with olefin to form the halohydrin. In either case the halohydrin is then reacted with the catholyte, either by passage from the anode compartment through the diaphragm or externally of the cell, the resulting liquid after removal of the olefin oxide formed being returned to the anode compartment. If olefin oxide formation is effected in the cathode compartment, the hydrostatic pressure therein is kept below that of the anode compartment. Typically electrolysis is carried out using aqueous solutions containing 2 to 20%, by weight of NaCl or KCl at temperatures of 30‹ to 90‹ C. under pressures ranging from slightly sub-atmospheric to 5 atmospheres with an applied potential of 3 to 5 volts. Examples are given relating to producing oxides from propylene and ethylene and reference is also made to the use of butylene and allyl chloride. |
