Patent GB-401269-A (GB)
Title: Improvements in the manufacture of oxygenated organic compounds
IPC: C07C27/00
Filed: 1932-04-30
Abstract: Oxygenated organic compounds such as aldehydes, acids, anhydrides and esters, are produced by the catalytic oxidation or dehydrogenation of homologues of dimethyl ether, preferably symmetrical ethers corresponding with the primary alcohols.  The reaction is preferably effected in the vapour phase, and oxidizing gases and/or diluents may be present.  Suitable catalysts are platinum wire or foil, palladium black, gold, and silver; copper, cobalt, manganese aluminium, nickel, and their oxides; the sesquioxides of iron, chromium and uranium; and vanadium pentoxide; platinum black is not suitable except for the production of the acids and their anhydrides.  Carriers such as asbestos or pumice may be employed.  Copper gauze may be impregnated with a copper salt, copper hydroxide precipitated by treatment with an alkali, and the product reduced with hydrogen or other reducing gas.  Ethyl ether may be oxidized to acetaldehyde at 200--400 DEG C., using not more than one volume of oxygen to each volume of ether, a higher proportion of oxygen producing more highly oxidized products.  Alternatively the reaction may be effected by simple catalytic dehydrogenation; but a small addition of oxidizing gas is advantageous.  The dehydrogenation may be effected with the reduced copper catalyst described above, or with reduced nickel or cobalt or with iron, zinc, copper-zinc alloys, or oxides of uranium, molybdenum, zinc, vanadium, tin, and cadmium.  With reduced copper the temperature may be up to 300--350 DEG  C., considerably lower with reduced nickel, or up to 650 DEG  C. with iron, zinc and cobalt. An oxidation and a dehydrogenation catalyst may be used together or in succession.  Alternatively water vapour may be added to the gases, and a hydration catalyst such as titanium, thorium, aluminium, or zinc oxide may be used in advance of or mixed with the dehydrogenation or oxidation catalyst.  This is advantageous when it is desired to produce more acid and less anhydride or to hydrolyse an ester to alcohol and acid.  Aldehyde or the reaction products, containing it may be oxidized to acetic acid which may then be converted into anhydride by thermal treatment, if desired in presence of a catalyst such as phosphoric acid or phosphates alone or with a promoter such as copper, or tungstates may be employed.  Esters may be hydrolysed in the liquid or gaseous phase or may be decomposed to yield the corresponding ether and acid or anhydride as in Specification 284,582, [Class 2 (iii), Dyes &c.], or the esters may be treated with carbon monoxide to produce acids as in Specification 283,989, [Class 2 (iii), Dyes &c.].  In examples: (1) ethyl ether and air are passed over reduced copper on copper gauze at 300 DEG  C. and the product is oxidized to acetic acid by manganic acetate in the liquid phase; (2) diethyl ether with one-tenth of its volume of water vapour is passed over zinc oxide on asbestos at 450 DEG C.ALSO:Oxygenated organic compounds such as aldehydes, acids, anhydrides and esters, are produced by the catalytic oxidation or dehydrogenation of homologues of dimethyl ether, preferably symmetrical ethers corresponding with the primary alcohols.  The reaction is preferably effected in the vapour phase, and oxidizing gases and/or diluents may be present.  Suitable catalysts are platinum wire or foil, palladium black, gold, and silver; copper, cobalt, manganese aluminium, nickel and their oxides; the sesquioxides of iron, chromium and uranium; and vanadium pentoxide; platinum black is not suitable except for the production of the acids and their anhydrides.  Carriers such as asbestos or pumice may be employed.  Copper gauze may be impregnated with a copper salt, copper hydroxide precipitated by treatment with an alkali, and the product reduced with hydrogen or other reducing gas.  Ethyl ether may be oxidized to acetaldehyde at 200-400 DEG  C., using not more than one volume of oxygen to each volume of ether, a higher proportion of oxygen producing more highly oxidized products.  Alternatively the reaction may be effected by simple catalytic dehydrogenation, but a small addition of oxidizing gas is advantageous.  The dehydrogenation may be effected with the reduced copper catalyst described above, or with reduced nickel or cobalt or with iron, zinc, copper-zinc alloys, or oxides of uranium, molybdenum, zinc, vanadium, tin, and cadmium. With reduced copper the temperature may be up to 300-350 DEG  C., considerably lower with reduced nickel, or up to 650 DEG  C. with iron, zinc and cobalt.  An oxidation and a dehydrogenation catalyst may be used together or in succession, Alternatively water vapour may be added to the gases, and a hydration catalyst such as titanium, thorium, aluminium, or zinc oxide may be used in advance of or mixed with the dehydrogenation or oxidation catalyst.  This is advantageous when it is desired to produce more acid and less anhydride or to hydrolyse an ester to alcohol and acid.  Aldehyde or the reaction products, containing it may be oxidized to acetic acid which may then be converted into anhydride by thermal treatment, if desired in presence of a catalyst such as phosphoric acid or phosphates alone or with a promoter such as copper, or tungstates may be employed. Esters may be hydrolysed in the liquid or gaseous phase or may be decomposed to yield the corresponding ether and acid or anhydride as in Specification 284,582, [Class 2 (iii), Dyes &c.], or the esters may be treated with carbon monoxide to produce acids as in Specification 283,989, [Class 2 (iii), Dyes &c.].  In examples (1) ethyl ether and air are passed over reduced copper on copper gauze at 300 DEG  C. and the product is oxidized to acetic acid by manganic acetate in the liquid phase; (2) diethyl ether with one-tenth of its volume of water vapour, is passed over zinc oxide on asbestos at 450 DEG  C.