Patent GB-719375-A (GB)
Title: Improvements in or relating to the production of aldehydes
IPC: C07C45/50
Filed: 1950-07-17
Abstract: In a process for improving the colour of an aldehyde produced by the reaction of carbon monoxide, hydrogen and a hydrocarbon containing olefinic unsaturation in the presence of an Oxo synthesis catalyst, the aldehyde is treated in the liquid phase with a member of the group consisting of solid organic acids, phosphorus pentoxide, acid salts of inorganic acids and acid salts of organic acids, which member is used in a substantially anhydrous condition, in the solid state or dissolved in or diluted by an organic solvent.  The term "substantially anhydrous condition" used with reference to organic acids, acid salts of inorganic acids and acid salts of organic acids includes the acids and salts in their normal crystalline form in which they may incorporate water of crystallization as well as the acids and salts in a truly anhydrous condition.  The treatment is preferably carried out at ordinary temperature and pressure but higher temperatures may be used provided the aldehyde is maintained in the liquid phase by means of an increase in pressure if necessary. Suitable solvents or diluents for the acids or salts include the lower alcohols, esters or other oxygen-containing organic compounds which are liquid at normal temperatures and the solvent is used in an anhydrous condition. Generally only a small amount of the lower alcohols, particularly methanol, is sufficient.  Other lower members of series may be used, preferably those containing not more than three carbon atoms in the molecule.  Suitable organic acids mentioned include oxalic acid, preferably used with simultaneous addition of a small amount of methanol, succinic acid or citric acid.  Acid sulphates are also suitable.  Metal compounds which separate during the treatment may be removed by filtration and the treated aldehydes may be further treated with active carbon or a similar adsorption medium simultaneously with or subsequent to filtration.  The filtered impurities may be used again in the production of the catalyst.  In examples: a crude C9 Oxo-aldehyde is shaken with oxalic acid and methanol and filtered after the addition of active carbon whilst oxygen is excluded (1); a further portion of the crude C9 aldehyde used in example (1) is shaken with methanol and succinic acid and filtered after addition of active carbon (2); a crude C10 Oxo aldehyde is shaken with phosphorus pentoxide and filtered (3); a crude C9 Oxo aldehyde is shaken with citric acid and filtered (4); and a crude C11 aldehyde is shaken with potassium bisulphate and filtered over active carbon (5).  The crude C9 aldehyde used in examples (1) and (2) is obtained by synthesis of an olefine-containing hydrocarbon mixture from a mixture of hydrogen and carbon monoxide using an iron catalyst and heating a fraction separated from the hydrocarbon mixture with water gas in the presence of a cobalt-magnesium-kieselguhr catalyst under pressure with water gas.  The crude C9, C10 and C11 aldehydes used in the remainder of the examples are obtained from C8, C9 and C10 olefines by the Oxo synthesis using cobalt catalysts.