Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Process for preparing a rhodium complex solution and process for producing an aldehyde
 A process for producing a rhodium complex solution, which comprises contacting an aqueous solution of a water-soluble rhodium compound and an organic solvent solution of a water-insoluble tertiary organic phosphorus compound, preferably in the presence of a C.sub.2-8 carboxylic acid, in a gas atmosphere containing carbon monoxide, followed by two phase separation, and recovering an organic solvent phase containing a rhodium-tertiary organic phosphorus compound complex. As the above aqueous solution of a rhodium compound, an aqueous solution having rhodium extracted into an aqueous phase from a waste catalyst liquid separated from a hydroformylation reaction step by oxidation treatment in the presence of a recovery accelerator such as a carboxylic acid, an amine, ammonia or an inorganic acid, is used, whereby recycling of rhodium represented by hydroformylation reaction/recovery of the catalyst/regeneration of the catalyst, is made possible, and a cumbersome step of preparing a complex catalyst from an inorganic salt or the like, or a step of preparing a soluble salt from a metal or oxide by combustion in water of the recovered catalyst, can be omitted. 
Mitsubishi Chemical Corporation
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Masaki Tomohiko Tomoyuki Kazuyuki
Takai Inoue Mori Yokoyama