DE879988C - Process for the production of carboxylic acids or their esters - Google Patents

Description

Process for the preparation of carboxylic acids or their esters It is already known by the action of carbon monoxide under increased pressure and at higher temperature. to the addition compounds of boron fluoride to ether, the boron fluoride compounds of carboxylic acids, from which, by decomposition with water, the free Can win carboxylic acids.

It has now been found that carboxylic acids or their esters can be reduced to simpler ones Way can be obtained, if one carbohydrate: oxide on ether, which the ether oxygen atom not contained in a ring-shaped bond, at elevated temperatures and under elevated temperatures Pressure in the presence of metals which form metal carbonyls or their compounds can act.

The ethers of methanol may be mentioned as starting materials, for example and its homologues as well as the ethers of polyhydric alcohols, e.g. B. of glycols.

Of the metals forming metal carbonyls suitable as catalysts and metal compounds are above all nickel and its compounds, for example Salts of nickel, in particular the halides and oxyhalides, cyanides and sulphides, also carboxylic acid salts and nickel carbonyl and complexes of the Nickel or the nickel salts with nitrogen bases and other organic substances. Even Iron and cobalt or their compounds are suitable. The implementation can through the addition of other metal salts with an activating effect, in particular of Iodides, for example des, copper, beryllium, zinc, aluminum, tin, zirconium, Arsenic, antimony, sulfur, chromium or manganese, or of other iodine compounds, z. B. alkyl or aryl iodides or free halides, especially iodine, accelerate. The addition of vanadium, tantalum or niobic acid also has beneficial effects. Even an additive, other acids and acidic compounds, e.g. B. Halogene Hydrogen Acids, Boron fluoride and its addition compounds, in particular that with the starting materials, sometimes has a beneficial effect. -The catalysts can stand alone or on the usual carriers, such as active charcoal, silica gel or aluminum oxide, are used will.

The implementation is best effected at over 10o ', advantageously between 150 and 300 °. If you @aiuch at moderately increased pressures, e.g. B. at I o; at, can work ,, so, eats @it is advisable to use pressures above ioo; at. The carbon dioxide can be used pure or diluted with inert gases such as nitrogen, carbon dioxide or methane. It is also advantageous to work in the presence of solvents or diluents, such as water, aliphatic and aromatic hydrocarbons, H, allogeneic hydrocarbons. You can also use the starting materials in excess so that they themselves serve as solvents.

The implementation can be interrupted moderately continuously, e.g. B. after the Trickle method, are carried out, with one the carbon oxide and possibly not converted starting material leads in a cycle.

In comparison to the method mentioned at the beginning, the present the addition of carbon monoxide to the ether takes place immediately, so that the additional Use and dismantling that require labor and always involve losses the boron fluoride compounds is avoided.

The parts given in the example below are parts by weight. EXAMPLE 100 parts of dimethyl ether are pressed in the presence of 10 parts of nickel powder and I part iodine in a shake bomb made of chromium-nickel steel carbon oxide under iooat on, heated to 19o ° and lasts 45 hours with repeated injection of carbon dioxide of 2ooat at this temperature. The conversion mixture contains in addition to unchanged Dimethyl ether 3i, 6% acetic acid, of which 1.6% as. free acetic acid, the rest in the form of methyl acetate are present, corresponding to an ester content in the conversion mixture of 37%.

If you work in a V 4A shake bomb under otherwise identical conditions, the reaction mixture contains, in addition to unchanged dimethyl ether, 2o.5% acetic acid, 7.7% thereof as free acetic acid, the remainder in the form of methyl acetate an ester content in the reaction mixture of 16011o.

Claims (1)

PATENT claims I: Process for the production of carboxylic acids or their esters by the action of carbon monoxide on ethers, in which the oxygen atom is not bound in a ring, at elevated temperature and under elevated pressure, characterized in that the reaction is formed in the presence of metal carbonyls Metals or their compounds, optionally in the presence of activators, undertakes.