GB745946A - Improvements in the production of saturated ketones - Google Patents

Abstract

A process for the production of saturated ketones comprises hydrogenating a ketol, preferably one with a tertiary hydroxyl group, in the presence of a hydrogenation catalyst and a free acid which remains a free acid in the presence of hydrogen at elevated temperature. Suitable catalysts are metals of the first or eighth sub group of the periodic system which may be activated by chromium, alkali metals, magnesium, boron or alumina and may be deposited on a carrier such as pumice, silica gel, kieselguhr, charcoal, coke, chamotte or porcelain. Non-volatile acids derived from phosphorus or boron, such as phosphoric, boric, phosphomolybdic, phosphotungstic and borotungstic acids or borylphosphate are preferred, but volatile organic acids such as formic, acetic and propionic acids and aromatic acids such as benzoic, phenylacetic and phthalic acids are also suitable. The carrier-free hydrogenation catalyst may be added to the ketol in which at least 5 per cent of an organic acid is dissolved, or the catalyst or the inorganic acid may be suspended on a carrier. Hydrogenation at high pressure, e.g. 100 to 300 atmospheres, is preferred. The process may be effected intermittently or batchwise. Temperatures of about 150 DEG to 300 DEG C. are suitable. Ketols obtainable by condensation with aqueous alkali hydroxides such as pentanolone-2,4, diacetone alcohol), 3-methyl-pentanolone-2,4, heptanolone-2,4, undecanolone-2,4, benzoylisopropanol and (1-hydroxypropyl)-cyclohexanone can be hydrogenated. In examples diacetone alcohol is hydrogenated (1) in an autoclave with acetic acid and a chromium-activated to give acetone, isopropanol, hexone, methylpentanol and components of higher boiling-point; (2) as in (1), in the presence of added water, to give hexone and cleavage products; (3) by passage with hydrogen under pressure through a heated tube containing a catalyst comprising copper and chromium with phosphoric acid on silica gel, to give acetone, isopropanol, hexone and mesityl oxide; (4) by passage with hydrogen through a heated tube containing boric acid, phosphoric acid, copper, nickel and chromium (obtained by mixing borylphosphate and a CuNi-hydrogenation catalyst, activated with chromium) to give acetone, isopropanol, methyl pentanone and hexone; (5) by passage under pressure with hydrogen through a heated tube charged with a mixture of coke, phosphoric acid, Na2H2P2O7, trimetaphosphate and Madrell salt and a hydrogenation catalyst containing cooper, nickel, chromium and kieselguhr to give hexone and higher-boiling materials.ALSO:As hydrogenation catalysts for use in a process of preparing a saturated ketone by hydrogenation of a ketol in the presence of a free acid which remains a free acid in the presence of hydrogen at elevated temperature (see Group IV(b)), there are specified metals of the first or eighth group of the periodic system which may be activated by chromium, alkali metals, magnesium, boron or alumina and may be deposited on a carrier such as pumice, silica gel, kieselguhr, charcoal, coke, chamotte or porcelain. In examples there are employed (1) and (2) a carrier-free copper catalyst activated by chromium, (3) a catalyst containing copper, phosphoric acid, chromium and silica gel, (4) a mixture of boric acid, phosphoric acid, copper, nickel, chromium and kieselguhr obtained by mixing boryl phosphate and a Cu-Ni-hydrogenation catalyst activated with chromium (5) a mixture of coke phosphoric acid Na2H2P2O7, trimetaphosphate and Madrell salt and a hydrogenation catalyst containing copper, nickel, chromium and kieselguhr.