Patent GB-879652-A (GB)
Title: Oxidation of polyoxyalkylene compounds
IPC: C07C51/235
Filed: 1957-09-05
Abstract: Ether acids are obtained by the oxidation of polyoxyalkylene compounds containing at least one terminal -CH2OH group with molecular oxygen in the presence of a catalyst comprising in conjoint presence bromine and a metal oxidation catalyst at an elevated temperature and at a pressure such that a liquid phase is maintained. The reaction is preferably carried out in the presence as solvent or diluent of a mono-carboxylic acid having 1-8 carbon atoms in the molecule, e.g. acetic, propionic, butyric, valeric, iso-butyric, caproic, phenylacetic, beta-ethoxyacetic or benzoic acid. Particularly suitable metal oxidation catalysts are those in which the metal is manganese, cobalt, nickel, chromium, vanadium, molybdenum, tungsten, tin and cerium and a combination of metals may be used.  Other metals specified are Be, Al, Bi, Cd, Fe, Pd, Pb, Nd and Cu.  The metal and the bromine may be added in elemental, combined, or ionic form and as a source of bromine ammonium bromide or a metal compound soluble in the reaction medium may be used and satisfactory results are obtained with potassium bromate, tetrabromethane and benzyl bromide.  The metal is suitably used in the form of a salt; e.g. a manganese salt of a C1-C8 aliphatic carboxylic acid, manganese acetylacetonate, manganese 8-hydroxy quinolate, or manganese ethylene diamine tetra-acetate; or manganese borate, halide or nitrate may be used.  Suitable reaction temperatures are from 50 DEG -150 DEG C. and suitable reaction pressures are from 100-1,500 p.s.i.g.  The oxygen may be substantially pure or may be provided by a gaseous mixture containing oxygen, e.g. air.  Specified polyoxy-alkylene compounds are solid or liquid polyethylene glycols, polyoxyethylated phenols and condensation products of other organic compounds containing an active hydrogen atom, e.g. amines, with an alkylene oxide.  The products are monobasic or dibasic ether acids.  Other specified polyoxyalkylene compounds are mono-alkoxypolyethylene glycols, and fatty acid mono-esters of polyalkylene glycols.  Examples are given for the oxidation of polyethylene glycols (molecular weight 200-700) to form a mixture p  of the corresponding mono- and di-carboxylic acids which are recovered by treating the oxidation residue dissolved in water with barium hydroxide to form the barium salts which are then acidified with aqueous sulphuric acid.  The oxidation is effected with air in the presence of cobalt acetate and manganese bromide using acetic, caproic or benzoic acid as diluent.  Several other catalysts are specified including nickel bromide, manganese acetate and either free bromine, tetrabromoethane or benzyl bromide, and a catalyst obtained by mixing either cerium hydroxide, tungstic acid, ammonium molybdate, or Raney nickel alloy, with ammonium bromide and 20% hydrobromic acid and evaporating to dryness.ALSO:Ether acids are obtained by the oxidation of polyoxyalkylene compounds containing at least one terminal -CH2OH group with molecular oxygen in the presence of a catalyst comprising in conjoint presence bromine and a metal oxidation catalyst at an elevated temperature and at a pressure such that a liquid phase is maintained.  The reaction is preferably carried out in the presence as solvent or diluent of a mono-carboxylic acid having 1 to 8 carbon atoms in the molecule, e.g. acetic, propionic, butyric, valeric, isobutyric, caproic, phenylacetic, beta-ethoxyacetic or benzoic acid.  Particularly suitable metal oxidation catalysts are those in which the metal is manganese, cobalt, nickel, chromium, vanadium, molybdenum, tungsten, tin and cerium and a combination of metals may be used.  Other metals specified are Be, Al, Bi, Cd, Fe, Pd, Pb, Nd and Cu.  The metal and the bromine may be added in elemental, combined, or ionic form and as a source of bromine ammonium bromide or a metal compound soluble in the reactions medium may be used and satisfactory results are obtained with potassium bromate, tetrabromethane and benzyl bromide. The metal is suitably used in the form of a salt; e.g. a manganese salt of a C1-C8 aliphatic carboxylic acid, manganese acetylacetonate, manganese 8-hydroxy quinolate, or manganese ethylene diamine tetra-acetate; or manganese borate, halide or nitrate may be used. Suitable reaction temperatures are from 50 to 150 DEG C. and suitable reaction pressures are from 100 to 1500 p.s.i.g.  The oxygen may be substantially pure or may be provided by a gaseous mixture containing oxygen, e.g. air. Specified polyoxyalkylene compounds are solid or liquid polyethylene glycols, polyoxyethylated phenols and condensation products of other organic compounds containing an active hydrogen atom, e.g. amines, with an alkylene oxide.  The products are monobasic or dibasic ether acids.  Other specified polyoxyalkylene compounds are monoalkoxypolyethylene glycols, and fatty acid mono-esters of polyalkylene glycols.  Examples are given for the oxidation of polyethylene glycols (molecular weight 200 to 700) to form a mixture of the corresponding mono- and di-carboxylic acids which are recovered by treating the oxidation residue, dissolved in water, with barium hydroxide to form the barium salts which are then acidified with aqueous sulphuric acid.  The oxidation is effected with air in the presence of cobalt acetate and manganese bromide using acetic, caproic or benzoic acid as diluent. Several other catalysts are specified including nickel bromide, manganese acetate and either free bromine, tetrabromoethane or benzyl bromide, and a catalyst obtained by mixing either cerium hydroxide, tungstic acid, ammonium molybdate, or Raney nickel alloy, with ammonium bromide and 20% hydrobromic acid and evaporating to dryness.