GB746385A - Improvements in or relating to catalytic hydrogenation - Google Patents

Abstract

Alkylated or arylated anthraquinhydrones or alkylated or arylated anthraquinols are produced from alkylated or arylated anthraquinones by hydrogenation in solvent medium in the presence of a catalyst comprising palladium deposited on a siliceous carrier which has been pretreated with an aqueous alkaline solution, e.g. of sodium hydroxide, carbonate or bicarbonate. Quinones specified are 2-ethyl anthraquinone and 2-tertiary butyl anthraquinone. The siliceous carrier may be silica gel, sodium aluminium silicate, or a silica-alumina catalyst. According to the examples, silica gel is pretreated with a boiling solution of sodium carbonate, hydroxide, or carbonate (examples 1, 2, and 5) and artificial sodium aluminium silicate is moistened with sodium bicarbonate solution and then dried (example 4). The treated carrier is palladized in the usual manner. The catalyst may be employed in suspension, a particle size corresponding to a screen aperture between 0.001 and 0.1 being suitable for this purpose, or as a fixed bed, the solution being passed either in co- or counter-current flow. The solvent may be a two-component mixture, the first component being e.g. cyclohexanyl acetate or propionate, or methyl cyclohexanyl acetate or propionate, and the second component being e.g. benzene, toluene or xylene. Specifications 465,070, 508,081, 580,897, 686,574, [all in Group III], 718,305 and 718,306 are referred to.ALSO:In the production of hydrogen peroxide by the successive hydrogenation and oxidation of alkylated or arylated anthraquinones in solvent medium, the hydrogenation is carried out in the presence of a catalyst comprising palladium deposited on a siliceous carrier which has been pre-treated with an aqueous alkaline solution e.g. of sodium hydroxide, carbonate, or bicarbonate. The siliceous carrier may be silica gel, sodium aluminium silicate or a silicaalumina catalyst. According to the examples, silica gel is pretreated with a boiling solution of sodium carbonate, hydroxide or bicarbonate, washed, and dried (Exs. 1, 2 and 5), and artificial sodium aluminium silicate is moistened with sodium bicarbonate solution and then dried (Ex. 4). The treated carrier is palladised in the usual way. The catalyst may be employed in suspension, a particle size corresponding to a screen aperture between 0.001 and 0.1 being suitable for this purpose, or as a fixed bed, the solution being passed either in co- or counter-current flow. Quinones specified are 2-ethyl anthraquinone and 2-tertiary butyl anthraquinone. The solvent may be a two-component mixture, the first component being e.g. cyclohexanyl acetate or propionate, or methyl cyclohexanyl acetate or propionate, and the second compound being e.g. benzene, toluene, or xylene. Specifications 465,070, 508,081, 624,353, 686,574, 718,305 and 718,306 are referred to.