GB1054119A - - Google Patents

Abstract

1,054,119. Electrolytically converting metal to metal ions. FARBWERKE HOECHST A.G. May 21, 1964 [May 21, 1963], No. 21092/64. Heading C7B. A process for the oxidation of an olefinically unsaturated compound comprises reacting the compound with an acid or neutral solution containing the ions of at least one metal selected from the group consisting of Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au and Hg to form the oxidation product and free metal. The metal ions are regenerated electrolytically from the free metal for further action by applying the free metal to the surface of an inert porous anode in an electrolytic cell. Regenerated metal ions are prevented from being reduced to the free metal at the cathode by separating the anode space from the cathode space by means of a membrane permeable to hydrogen ions but substantially impermeable to the metal ions and/or by using an oxygen solvent electrode as the cathode, i. e. an electrode in the form of a porous membrane to one side of which an oxidizing agent such as gaseous oxygen is fed. As illustrated in Fig. 1 (and Fig. 2 not shown), the oxidation of an olefinically unsaturated compound is in a reaction vessel 15 and the electrolysis in a separate vessel 1. As shown in Fig. 3, both reactions take place in the vessel 1. Figs. 1 and 3 show a porous anode 2 and a cathode 3 separated by a membrane 7 permeable to hydrogen ions and substantially impermeable to metal ions (the membrane being omitted and an oxygen solvent cathode being used instead in Fig. 2 (not shown) ). As shown in Fig.1, olefine is supplied at 17, olefine oxidation product removed at 18, Pd from a Pd SO 4 catalyst in the vessel 15 is pumped to the anode 2 through tube 13, and regenerated Pd SO 4 solution is pumped through the porous anode 2 and tubes 11 and 12 to the reaction vessel 15. Nascent hydrogen produced at the cathode, e. g. of Pt or Pd, can be used to hydrogenate liquid at 16. H 2 escapes at 19. As shown in Fig. 3, olefine is forced through an inlet 25 and the porous anode 2 and the olefine oxidation product removed at 27. The membrane 7 may be a cation exchange membrane based on polystyrene or a copolymer of styrene. Oxygen solvent electrodes may be of nickel oxide, C impregnated with a spinel or a noble metal or "Raney" (Trade Mark) Ag. Other cathodes may be of porous carbon, porous sintered metal, or be a metal grid. The electrolyte may be aq. H 2 SO 4 , aq. H 3 PO 4 , aq. (NH 4 )2 SO 4 and may contain a solution promoter such as a low aliphatic alcohol, ketone or ether or a surfactant such as ataurine. Olefinically unsaturated compounds which can be oxidized by the process include olefines and substituted olefines, e.g. unsaturated carboxylic acids, aldehydes, esters, ethers and ketones, and olefinic compounds substituted e. g. by halogen atoms, amino, nitrile, nitro or amide groups. The process may be used for converting olefines into aldehydes, ketones or the acids corresponding to the aldehydes by the process of oxidation described in Specification 898,790.