Patent GB-797985-A (GB)
Title: A process for the preparation of ketoximes
IPC: B01J23/89
Filed: 1957-04-26
Abstract: Ketoximes are prepared by the catalytic hydrogenation of a nitro cycloalkane or secondary nitro alkane in the presence of a hydrogenation catalyst modified by treatment with a lead salt. Lead salts suitable for the preparation of modified hydrogenation catalysts are salts such as halides, chlorate, nitrate, acetate, formate, citrate and benzoate.  Suitable hydrogenation catalysts include metals of Group VIII of the Periodic Table.  These metals may be supported on carbon, calcium or barium carbonate or sulphate, alumina, chromic sesquioxide or magnesium oxide.  The following catalysts are preferred, an acetylene-black supported mixed platinum-palladium-ferric oxide catalyst, an acetylene-black supported mixed palladiumferric oxide catalyst, an acetylene black supported palladium catalyst, platinum on carbon, and palladium supported on carbon, calcium carbonate, calcium sulphate, alumina or chromium sesquixoide.  Usually sufficient salt is used so that about 1-3 per cent by weight of lead based on the weight of catalyst is retained on the catalyst.  It is preferable to employ a catalyst concentration of about 700 parts or more of a catalyst (based upon the weight of the metal) per million parts of nitro or cycloalkane. A diluent such as water, methanol, ethanol, isopropanol, water C1-C4 alkanol mixtures, cyclohexane, or cyclohexylamine may be present, and the process may be carried out at temperatures between 60 DEG  C. and the decomposition point of the nitro alkane or cycloalkane and at pressures from 1-1000 atmospheres.  Examples are given of the preparation of cyclohexanone oxime with cyclohexylamine as a by-product in some cases, cyclopentanone oxime and acetone oxime using various lead modified catalysts.  Cycloheptanone oxime and butanone oxime are also mentioned.  The process may be carried out batchwise or continuously and in the liquid or vapour-phase. Examples are also given for comparison purposes of the hydrogenation of nitrocyclohexane in the absence of lead salts, when the product is mostly cyclohexylhydroxylamine and cyclohexylamine.ALSO:Hydrogenation catalysts suitable for the hydrogenation of nitro cycloalkanes or secondary nitro alkanes to ketoximes are modified by treatment with a lead salt.  The lead modified catalyst may be prepared either by forming a slurry of the catalyst with an aqueous solution or suspension of the lead salt or by adding the lead salt to the catalyst containing hydrogenation mixture prior to the introduction of the hydrogen.  Suitable lead salts are halides, chlorate, nitrate, acetate, formate, citrate or benzoate. Usually about 1-3 per cent by weight of lead based on the weight of the catalyst is retained on the catalyst.  Suitable hydrogenation catalysts include metals of Group VIII of the Periodic Table, e.g. rhodium, ruthenium, palladium, platinum, osmium, indium, iron, cobalt and nickel.  The metals may be used in finely divided form or supported by e.g. carbon, calcium or barium carbonate or sulphate, alumina, chromic sesquioxide, and magnesium oxide.  Preferred catalysts are an acetylene-black supported mixed platinum-palladium-ferric oxide catalyst, an acetylene-black-supported mixed palladium-ferric oxide catalyst, an acetylene black supported palladium catalyst, platinum on carbon, and palladium supported on carbon, calcium carbonate, calcium sulphate, alumina or chromic sesquioxide.