Patent GB-815162-A (GB)
Title: Improvements in the production of alcohols and ketones by the oxidation of cycloaliphatic or araliphatic hydrocarbons
Filed: 1956-06-14
Abstract: Alcohols and ketones are produced by oxidizing in the liquid phase at elevated temperatures cycloaliphatic or araliphatic hydrocarbons having at least 2 carbon atoms in the side chain with gases containing oxygen, the process comprising leading the initial materials with the addition of oxygen-containing gas through a plurality of successive reaction vessels, washing the oxidation mixture with water after the mixture has passed through one or more of the reaction vessels, preferably after the last reaction vessel, the oxidation mixture being treated after one or more stages with an aqueous solution of alkali hydroxide or alkali carbonate, after the mixture has been washed at least once with water, this alkali washing being carried out preferably after the oxidation mixture has been, at least partly, freed from unreacted initial hydrocarbon, and distilling off the unreacted hydrocarbon from the oxidation mixture, unless distillation has been carried out prior to the alkali washing step.  Suitable hydrocarbons for use as starting materials are, for example, cyclohexane, cyclo-octane, ethyl benzene and other alkylbenzenes having 2 or more carbon atoms in the side chain.  The oxidation is carried out, for example, at temperatures in the range 120-170 DEG  C.  The preferred type of reaction vessels are those having a tubular insertion, the inner tube having a cross-sectional area equal to 20-70 per cent of the overall cross-sectional area of the vessel. The starting materials are introduced into the inner tube; part of the liquid reaction product is withdrawn at the opposite end of the reaction vessel the other part flowing back into the intermediate space between the tube and vessel wall and again entering the interior of the tube.  To prevent the reaction temperature rising too high cooling of the circulating material may be necessary, for example by providing cooling aggregates in the circulation system or by withdrawing part of the circulating material, cooling it and returning it to the reaction vessel. Suitable catalysts are conventional oxidation catalysts, e.g. cobalt, cerium, nickel, iron, lead, titanium, vanadium, chromium, molybdenum, uranium, manganese, platinum, silver, tin, calcium or magnesium; oil-soluble salts of these metals, such as naphthenic acid or mono- or dicarboxylic acid salts; and inorganic compounds such as oxides, halides, sulphates, phosphates, vanadates, molybdates, tungstates and chromates.  The catalysts may be applied to carriers such as bleaching earths, synthetic silicates, active aluminas, magnesia or zinc oxide.  Substances which accelerate oxidation, such as peroxides, may be used with the catalysts.  In a typical example preheated cyclohexane, air and cobalt acetate solution are fed into a series of reaction vessels maintained at 140 DEG  C.; after passage through each reaction vessel the reaction mixture is washed with water; it is also treated with caustic soda solution after passage through the second reaction vessel and again after distillation of the mixture to remove the bulk of unchanged cyclohexane after passage through the last reaction vessel; the mixture is then redistilled to remove the remaining cyclohexane and the residue containing cyclohexanol and cyclohexanone is subjected to fractional distillation; from the wash liquors adipic acid is separated. Cyclo-octane may be oxidized in an analogous manner to give cyclo-octanone and cyclo-octanol with some suberic acid as by-product.