| 摘要 |
Alkenyl aromatic and heteroaromatic compounds are contacted with molecular oxygen in the presence of a catalyst comprising bromine and a metal oxidation catalyst at a temperature in the range of 50-115 DEG C. and at sufficient pressure to maintain a liquid phase to give the corresponding oxirane compounds. The alkenyl aromatic and heteroaromatic compounds used as starting materials are compounds having an aromatic nucleus, or a heterocyclic nucleus of aromatic character, to which is attached an alkenyl group. Suitable aromatic nuclei are, for example, benzene, naphthalene and phenanthrene nuclei and suitable heteroaromatic nuclei are, for example, pyridine, furane and thiophene nuclei. Among the starting materials which may be used are styrene, vinyl naphthalene, vinyl diphenyl, vinyl pyridine, vinyl phenol, chlorostyrene, bromostyrene, nitrostyrene, aminostyrene, propenyl benzene, butenylnaphthalene, butenyl diphenyl, vinyl diphenyl ether and propenyl pyridine. Preferred metals for use in the catalyst are manganese, cobalt, nickel, chromium, vanadium, molybdenum, tungsten, tin and cerium. The metal and the bromine may be present in the catalyst in elemental, combined or ionic form. Suitable bromine compounds which may be added are, for example, ammonium bromide, potassium bromate, tetrabromoethane and benzyl bromide. The metal may be supplied in the form of a salt or as an organic complex, e.g. an acetylacetonate, 8-hydroxyquinolate or an ethylene diamine tetraacetate. Preferably the catalysts are used in an amount of 0.1-10% based on the alkenyl compound. A solvent may be used, e.g. a non-acid organic compound, e.g. chlorinated polyphenyls, biphenyl, diphenyl ether or naphthalene or a monocarboxylic acid having 1-8 carbon atoms in the molecule. The oxygen may be used alone or in the form of gaseous mixtures.ALSO:Catalysts for use in the preparation of oxirane compounds comprise bromine and a metal oxidation catalyst. Both the bromine and the metal may be present in combined, elemental or ionic form. Preferred metals are manganese, cobalt, nickel, chromium, vanadium, molybdenum, tin and cerium and may be present in the form of a salt or of an organic complex, e.g. an acetylacetonate, 8-hydroxyquinolate or an ethylene diamine tetraacetate. Examples of suitable catalysts are manganese acetate and ammonium bromide; powdered manganese metal and ammonium bromide; cobalt acetate and ammonium bromide; manganese acetylacetonate and ammonium bromide; manganese 8-hydroxy quinolinate and ammonium bromide; a manganese complex of ethyl diamine tetraacetic acid and ammonium bromide; manganese borate and ammonium bromide; manganese chloride and ammonium bromide; manganese acetate and potassium bromate; manganese acetate and free bromine; manganese acid and tetrabromoethane; manganese acetate and benzyl bromide; the material obtained by evaporating a mixture of cerium hydroxide, ammonium bromide and hydrobromic acid to dryness; and similar mixtures obtained by using tungstic acid, ammonium molybdate or Raney nickel instead of cerium hydroxide. |
