Urushibara catalysts

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Heterogeneous catalysts of the Urushibara type are mostly used for the hydrogenation of chemical compounds. The catalysts always consist of two different metals, the less noble one serving as the carrier material.

history

The Urushibara catalysts were invented by Yoshiyuki Urushibara (1901-1972) in the early 1950s in order to circumvent patents for the reductive production of estradiol from estrone using new methods.

Manufacturing

Redox reaction

The catalysts are produced by reacting an aqueous transition metal salt solution, usually chlorides and acetates of iron , cobalt , nickel and copper , with a less noble elemental metal (such as zinc or aluminum ) in powder form at elevated temperature. The less noble metal is used in excess and at the same time serves as a reducing agent and carrier substance.

Formula: Urushibara catalysts: production of finely divided metals by reduction with zinc.

activation

The reactivity of the catalysts that can be generated in this way can be influenced by subsequent treatment with alkalis (mostly sodium hydroxide ) and acids (mostly acetic acid ).

properties

The catalysts can in many cases serve as a substitute for the pyrophoric Raney nickel and are easy to manufacture. The magnetization of the particles depends on the manufacturing process.

Applications

Urushibara catalysts have a similarly broad field of application as Raney nickel . They can be used for the reduction of ketones, double bonds, nitriles and nitro compounds, for reductive desulphurisation and for nitrile hydrolysis.

Individual evidence

  1. ↑ a b J. Chem. Soc., Faraday Trans. 1, 1980, 76, 998-1007; doi : 10.1039 / F19807600998 .
  2. ↑ a b c d e f Review: Yoshiyuki Urushibara, THE URUSHIBARA CATALYSTS, Annals of the New York Academy of Sciences , Volume 145, Catalytic Hydrogenation and Analogous Pressure Reactions pp. 52-57, October 1967; doi : 10.1111 / j.1749-6632.1967.tb52998.x .
  3. ↑ a b J. Chem. Soc., Perkin Trans. 1, 2002, 2586-2597; doi : 10.1039 / b009711j .
  4. ↑ AIP Conf. Proc., April 1975, Volume 24, pp. 391-393 doi : 10.1063 / 1.30150 .
  5. ↑ Russian Chemical Reviews (1984), 53 (9): 900; doi : 10.1070 / RC1984v053n09ABEH003130 .

See also