DE537610C - Process for the preparation of monocarboxylic acids - Google Patents

Description

Process for the preparation of 1Konocarboxylic acids It is known that carbon dioxide with the aid of gaseous hydrochloric acid in the presence of copper chloride and other substances in hydrocarbons with the formation of the corresponding aldehydes can accumulate (see Gattermann-Koch, reports of the German Chemical Society, 30, 1612; 31, i149; L i eb i g s Annalen 347, 347).

It is also known (patent specification 403 489) that chlorinated hydrocarbons, such as B. can bring chlorobenzene into reaction with carbon dioxide, with preservation of the halogen, the corresponding aldehydes of the halogenated carbon, hydrogen are formed. One has already tried (British patent specification 254 8r9), carbon oxide or this containing gases in the presence of a catalyst, which is also a hydrating or this and a hydrogenating agent and optionally an alkali or Alkaline earth metal compound contains, at elevated temperatures and high pressures aliphatic alcohols or their esters, or mixtures of alcohols and their esters to act in vapor form, the alcohols etc. by aldehydes in the mixture can be replaced with carbon dioxide and hydrogen. As the end products of the process result in multi-body mixtures of varying composition from higher alcohols, higher fatty acids, esters, aldehydes, etc.

However, one has the catalytic effect of carbon monoxide on halogenated ones Starting materials for the direct substitution of the halogen by oxides of carbon not yet described. According to the current state of the art and due to the previous scientific knowledge of the properties of these compounds success in this direction was not to be expected.

Contrary to expectations, it has now been found that moist carbon monoxide can be found in Presence of metals or their compounds can use it at higher levels Store temperatures in chlorinated hydrocarbons, with elimination of the chlorine, the resulting compounds with the water vapor that is also present Immediately convert to carboxyl compounds that are known as such from the end product in Way can be easily isolated while the unreacted reaction components can be used again for the reaction in the cycle process.

In this way, with repeated throughput it is easy, almost quantitative yield based on the amount of halogenated hydrocarbons used, to represent the corresponding halogen-free carboxyl compounds.

If the reaction is carried out in the presence of ammonia, one obtains the ammonium salts of the carboxylic acids concerned; primary amines are formed at the same time. A wide variety of metals or metal compounds can be used as catalysts, especially z. B. those that already have a known affinity for carbon monoxide own, it was surprisingly found that a previous Reduction to metal is not absolutely necessary, but rather salts of these Elements, e.g. B. their halogen compounds to also catalyze the reaction capital. Mixtures of these elements or their salts can also be used and add activators to the catalyst whose activity-increasing effect z. B. on the physical properties of the carrier substances or, in interaction with these, is triggered chemically by the contact substances used.

The procedure leads to the goal with a smooth reaction even if one in place of carbon dioxide and water used substances known per se, which carbon oxide or split off carbon oxide and water under the chosen test conditions, that is z. B. aliphatic acids or esters thereof, acid amides, aldehydes, ketones o. like

With the exception of substances containing sulfur, there are, for example, carbon monoxide existing indifferent accompanying bodies almost without influence.

The use of increased pressures favors the course of the reaction.

Example i Via a catalyst support impregnated with nickel chloride and predried at 2oo °, e.g. B. pumice stone, pottery shards o. The like., Is passed at 300 to qoo ° carbon oxide, chlorobenzene and steam in a slow stream, with appropriate dosage of the reaction components, approximately in a ratio of 1 mol. Chlorobenzene to 2 mol. Carbon oxide, the resulting Benzoic acid precipitates in dense crystals on the cold wall behind the reaction zone. The hydrochloric acid or small amounts of carbonic acid formed by a side reaction are removed from the unconsumed carbon dioxide in a known manner, so that the latter and the chlorobenzene freed from dissolved benzoic acid in a known manner can be continuously returned to the cycle of the process. Since accompanying bodies only appear in extremely small quantities in the reaction, the benzoic acid obtained in this way is almost pure. Melting point: i2 °. After five to six times throughput there is a total yield of 96% of theory, based on chlorobenzene. Example e A catalyst support impregnated with a solution of nickel nitrate, copper nitrate and iron nitrate, e.g. B. pumice stone or pottery shards is treated in a stream of carbonic acid or nitrogen at about 300 ° until the decomposition of the salts is complete and then reduced to metal in a stream of hydrogen until the reduction is complete. At temperatures between 2.50 and q.00 ° a slow stream of p-chlorotoluene, carbon oxide and water vapor is passed over the catalyst. The resulting p-toluic acid is isolated in a known manner. After five throughputs there is a total yield of 1/3 of theory and above, based on the amount of p-chlorotoluene used. Example 3 Pumice stone or pottery shards are impregnated with a solution of nickel nitrate and copper nitrate and predried at 120 °. The catalyst support loaded in this way is treated with hydrogen at 300 to 330 ° until the reduction of the elements to metal is complete. After the hydrogen has been displaced by an inert medium, a mixture of carbon oxide, ammonia, chlorobenzene and water vapor at 375 to 10 ° C. is passed in a slow stream over the catalyst. Benzoic acid ammonium is formed. The yield of benzoic ammonium after four to five times the throughput is 87% of theory, based on the amount of chlorobenzene used. The by-products are: aniline, chlorammon and ammonium carbonate. Example q. If a mixture of copper formate and nickel formate is used analogously as the starting material for the preparation of the catalyst, acetic acid is obtained in a yield of 21% by the process from chloromethyl. Example s In an analogous manner, if a mixture of nickel oxalate and copper oxalate is used as the starting material for the catalyst, if chloroform is used in the reaction, acetic acid is obtained in a yield of 2.4%. EXAMPLE 6 A pressure-resistant, electrically heated reaction vessel with a manometer, inlet and outlet devices is filled about halfway with a catalyst consisting of a mixture of nickel and copper formate applied to pumice stone or the like, and the catalyst is filled at between 180 and 200.degree Hydrogen flow reduced.

The inner walls of the reaction vessel are expediently insulated in a known manner against chemical attack by the reactants. After the contact to metal has been reduced, the hydrogen is displaced by an inert gas, e.g. B. C02, and this appropriately before the addition of the reactants by carbon oxide. An approximately stoichiometric mixture of formainide, chlorobenzene and water is then continuously or periodically introduced into the reaction vessel at a reaction temperature of 20 ° and above while maintaining an operating pressure of about 25 atmospheres. The procedure is advantageously such that the addition of further amounts of reactants then takes place respectively when dropped due to the onset of reaction of the pressure to about 1 5 to 2o Atü.

After removing the residues of unchanged chlorobenzene and after separating off the chlorammone formed, the benzoic acid obtained is isolated in a yield of 88% of theory from the end product. EXAMPLE An approximately stoichiometric mixture of propionaldehyde, chlorobenzene and water is treated according to Example G at a reaction temperature of 235 to 25o ° and an operating pressure of 25 A.tii. In this embodiment, the rear end of the reaction vessel not filled with catalyst is advantageously brought to a temperature of about z25 °, whereby the benzoic acid formed can be drained off periodically or continuously in liquid form. The yield is 90 % of theory and above.

Claims (1)

PATENT CLAIM: Process for the treatment of chlorinated hydrocarbons with carbon oxide at elevated temperature in the presence of catalysts, characterized in that for the purpose of representing monocarboxylic acids, the carbon oxide is simultaneously with Water vapor or ammonia-containing water vapor, expediently at temperatures of 2oo ° and above, optionally with the application of pressure in the cycle to monochlorohydrocarbons can act.