Patent GB-345253-A (GB)
Title: Improvements in the manufacture and production of unsaturated ethers
Filed: 1929-12-12
Abstract: Catalysts for the production of unsaturated ethers from metals consist of precious metals, (ie. silver, gold, and the platinum and palladium metals) with or without metals (other than alkali metals) of groups 1-4 and 6-8 of the periodic system or their heat-resisting compounds, such as rapidly or difficulty reducible oxides, phosphates, or silicates.  Such additional metals may be copper, magnesium, calcium, and other alkali earth metals, zinc, cadmium, titanium, aluminium, tin, lead, thorium, zirconium, chromium, molybdenum, tungsten, uranium, manganese, and metals of the iron group.  Carriers may be employed such as the usual mineral, ceramic, or metallic substances, alumina, silica and other gels, active carbon, &c.  Examples include the use of asbestos or kieselguhr treated with ammoniacal silver carbonate, the material in the latter case being heated in air at 100 DEG  C. and reduced in hydrogen at 250 DEG  C.; and clay sherds treated with uranyl nitrate heated to 400 DEG  C., soaked in ammoniacal silver carbonate solution, dried, and reduced in hydrogen at 270 DEG  C.ALSO:Vinyl and other unsaturated ethers are produced by passing the vapour of an aliphatic or aromatic acetal with or without a diluent, over precious metals (i.e. silver, gold, and the platinum and palladium metals) with or without metals (other than alkali metals) of groups 1-4 and 6-8 of the periodic system or their heat-resisting compounds, such as readily or difficulty reducible oxides, phosphates or silicates. Such additional metals may be copper, magnesium, calcium and other alkaline-earth metals, zinc, cadmium, titanium, aluminium, tin, lead, thorium, zirconium, chromium, molybdenum, tungsten, uranium, manganese, and metals of the iron group.  Carriers may be employed such as the usual mineral, ceramic or metallic substances alumina, silica and other gels, active carbon, &c.  The diluent may be nitrogen, carbon dioxide, methane, or the vapour of water, alcohols, ethers or hydrocarbons such as benzene or benzine.  In the examples (1) diethyl acetal is passed over palladium asbestos at 270 DEG  C., yielding vinyl ethyl ether; (2) vinyl butyl ether is produced similarly from dibutyl acetal at 300 DEG  C.; (3) isopropenyl ethyl ether is produced from acetone diethyl acetal at 230 DEG  C., using a catalyst prepared from asbestos and ammoniacal solution of silver carbonate; (4) n-propenyl ethyl ether is produced similarly from propionaldehyde diethyl acetal; (5) n-butenyl methyl ether is produced from butyl aldehyde dimethyl acetal at 250 DEG  C. using a catalyst prepared by dissolving silver carbonate in aqueous ammonia with cooling, stirring in kieselguhr, evaporating to dryness, moulding into small cylinders and heating in air at 100 DEG  C. and reducing in hydrogen at 250 DEG  C.; (6) a-phenylvinyl ethyl ether is produced from acetophenone diethyl acetal mixed with nitrogen at 220 DEG  C., using a catalyst prepared by treating clay sherds with uranyl nitrate solution, heating to 400 DEG  C., soaking in ammoniacal silver carbonate solution, drying, and reducing with hydrogen at 270 DEG  C.; (7) vinyl (2 ethoxy ethyl) ethyl ether (a -vinyl-b -ethyl ethylene diether), is produced from acetaldehyde(2-hydroxy-ethyl ethyl) acetal at 260 DEG  C., using platinized asbestos.  This acetal is produced by condensing acetaldehyde with ethylene glycol monoethyl ether in presence of hydrochloric acid, at temperatures below 35 DEG  C. and in absence of oxygen.