DE1518970C3

DE1518970C3 - Process for the preparation of saturated aliphatic dicarboxylic acids

Info

Publication number: DE1518970C3
Application number: DE19621518970
Authority: DE
Inventors: Charles N. Teaneck N.J. Winnick (V.St.A.)
Original assignee: Ausscheidung aus: 12 93 737 Halcon International, Inc., New York, N. Y. (V.StA.)
Priority date: 1961-04-27
Filing date: 1962-04-27
Publication date: 1976-09-02

Description

kleideies Reaktionsgefäß eingebracht, das mit einem Dampfabzug, einem Kühler und einem Wasserabscheider ausgestattet ist.Dressed the reaction vessel was introduced, which was equipped with a steam vent, a cooler and a water separator Is provided.

Ein Gemisch aus etwa 96% Stickstoff und 4% Sauerstoff wird mit einer Geschwindigkeit von 4,0 1 je Minute 5 Stunden lang durch das Gemisch geleitet. Die Temperatur wird hierbei auf etwa 165 bis 167°C und der Druck auf etwa 8,4 atü eingestellt.A mixture of about 96% nitrogen and 4% oxygen is produced at a rate of 4.0 liters per minute Passed through the mixture for 5 hours. The temperature is here to about 165 to 167 ° C and the Pressure adjusted to about 8.4 atmospheres.

Das während der Umsetzung kontinuierlich aus dem Reaktionsgefäß entweichende Abgas wird abgekühlt und nach Abtrennung des Wassers aus dem Kondensat wird das Cyclohexan in die Reaktion zurückgeführt.The exhaust gas continuously escaping from the reaction vessel during the reaction is cooled and after the water has been separated off from the condensate, the cyclohexane is returned to the reaction.

Das Reaktionsgemisch wird anschließend mit 200 g Wasser versetzt und eine Stunde zur Hydrolyse der Borsäureester unter Rückfluß bei etwa 70⁰C gerührt. Die gebildete Borsäure wird dann abfiltriert und das Filtrat in eine organische und in eine wäßrige Schicht zerlegt. Die wäßrige Schicht wird mit einer geringen Menge Cyclohexan extrahiert und der Extrakt mit der organischen Schicht vereinigt. Die organische Schicht wird dann durch Destillation bei einer Temperatur von 85°C und einem Druck von 1,12 at am Kolonnenkopf vom nicht umgesetzten Cyclohexan befreit und man erhält dann 360 g eines Gemisches aus etwa 82% Cyclohexanol, etwa 3% Cyclohexanon und andere Cyclohexanonoxydationsprodukte als Rest.The reaction mixture is then mixed with 200 g of water and stirred for one hour to hydrolyze the boric acid ester under reflux at about 70 ⁰ C. The boric acid formed is then filtered off and the filtrate is separated into an organic and an aqueous layer. The aqueous layer is extracted with a small amount of cyclohexane and the extract is combined with the organic layer. The organic layer is then freed from unreacted cyclohexane by distillation at a temperature of 85 ° C. and a pressure of 1.12 atm at the top of the column and 360 g of a mixture of about 82% cyclohexanol, about 3% cyclohexanone and other cyclohexanone oxidation products are then obtained as the rest.

Die so erhaltene Cyclohexanolfraktion wird destilliert, um als übergehenden Anteil Cyclohexanol und Cyclohexanon von den anderen, in der Cyclohexanolfraktion enthaltenen Stoffen abzutrennen. Der Destillationsrückstand kann für sich allein einer Oxydation und/oder Kristallisation unterworfen werden, um weitere Adipinsäure zu gewinnen.The cyclohexanol fraction obtained in this way is distilled in order to transfer cyclohexanol and Separate cyclohexanone from the other substances contained in the cyclohexanol fraction. The still residue can be subjected to oxidation and / or crystallization on its own, to further Obtain adipic acid.

Das Cyclohexanol-Cyclohexanon-Gemisch wird dann zur Einstellung des Gewichtsverhältnisses von Cyclohexanol zu Cyclohexanon auf etwa 1 : 1 dehydriert. Die Fraktion wird verdampft und bei 375°C unter Verwendung eines Zinkoxydkatalysators bei einem auf das Volumen bezogenen stündlichen Flüssigkeitsdurchsatz von 2 (Verhältnis des Volumens der flüssigen Beschickung zum Volumen des Katalysators pro Std.) dehydriert. Die erhaltenen Produkte werden kondensiert, wobei ein Gemisch erhalten wird, das etwa 50 Gewichtsprozent Cyclohexanon und 50 Gewichtsprozent Cyclohexanol enthält.The cyclohexanol-cyclohexanone mixture is then used to adjust the weight ratio of Cyclohexanol dehydrated to cyclohexanone at about 1: 1. The fraction is evaporated and stored at 375 ° C Use of a zinc oxide catalyst with an hourly liquid flow per volume of 2 (ratio of the volume of liquid feed to the volume of catalyst per hour) dehydrated. The products obtained are condensed to give a mixture that is about 50% Contains percent by weight cyclohexanone and 50 percent by weight cyclohexanol.

Dieses Dehydrierungsgemisch wird mit etwa dem Dreifachen seines Gewichts an Essigsäure sowie mit 0,35 Teilen Manganacetattetrahydrat pro 100 Teilen des bei der Dehydrierung gebildeten Gemischs vermischt. This dehydration mixture is with about three times its weight in acetic acid as well as with 0.35 parts of manganese acetate tetrahydrate per 100 parts of the mixture formed in the dehydration.

Die so erhaltene Lösung wird etwa 6 Stunden bis 85 bis 90⁰C gehalten und während dieser Zeit wird ein 8% Sauerstoff in Stickstoff enthaltendes Gasgemisch mit einer Geschwindigkeit von 28 bis 56 Nl je Minute und bei einem Druck von etwa 6 atü durch 2400 g der Lösung geleitet. Das Reaktionsgemisch wird dann auf etwa 20⁰C abgekühlt, um die gebildete Adipinsäure zur Kristallisation zu bringen.The solution obtained in this way is held for about 6 hours at 85 to 90 ^° C. and during this time a gas mixture containing 8% oxygen in nitrogen is passed through 2400 g of the at a rate of 28 to 56 Nl per minute and at a pressure of about 6 atmospheres Solution headed. The reaction mixture is then ^{cooled to about 20 °} C. in order to cause the adipic acid formed to crystallize.

Durch Abzentrifugieren werden etwa 310 g Adipinsäure erhalten.About 310 g of adipic acid are obtained by centrifugation.

Bezogen auf umgesetztes Cyclohexan beträgt die Ausbeute an Adipinsäure etwa 60 Molprozent.Based on converted cyclohexane, the yield of adipic acid is about 60 mol percent.

B e i s ρ i e 1 2B e i s ρ i e 1 2

Verwendet man an Stelle von Cyclohexan Cyclooctan, so erhält man nach der in Beispiel 1 beschriebenen Arbeitsweise Korksäure in praktisch gleicher Ausbeute. If cyclooctane is used instead of cyclohexane, the one described in Example 1 is obtained Working method Succic acid in practically the same yield.

Claims

Claim:

Process for the production of saturated aliphatic dicarboxylic acids by 2-stage oxidation of Cycloparaffins at elevated temperature with oxygen or an oxygen-containing gas, wherein the first oxidation in the presence of a cycloalkane peroxide initially formed and resp. or cycloalkanol esterifiable inorganic or organic boron compounds carried out, then released the cycloalkanol in any order from the boric acid esters formed, unreacted cycloalkane removed and the organic fraction of the boron compound formed separated and finally the boron-free organic fraction in the presence of a catalyst is further oxidized, characterized in that that the boron-free organic fraction before further oxidation to form a mixture dehydrated, the cycloalkanol and cycloalkanone in a weight ratio of at least contains about 0.25 parts of cycloalkanone per part of cycloalkanol.

The invention relates to a process for the preparation of saturated aliphatic dicarboxylic acids by means of 2-stage Oxidation of cycloparaffins at elevated temperature with oxygen or an oxygen-containing gas, the first oxidation in the presence of a cycloalkane peroxide initially formed and / or Cycloalkanol esterifiable inorganic or organic boron compound carried out, then in The cycloalkanol is released in any order from the boric acid esters formed, unreacted Cycloalkane removed and the organic fraction separated from the boron compound formed and finally the boron-free organic fraction is further oxidized in the presence of a catalyst.

The implementation of the above two oxidation stages is described in detail in DT-AS 12 93 737.

The known processes for the production of saturated aliphatic dicarboxylic acids, such as adipic acid, from cycloparaffins are not completely satisfactory with regard to the achievable yields and the way they are carried out, there either a considerable proportion of the converted cycloparaffin into undesired by-products is transferred or a complex work-up of intermediates for the further implementation must be made.

Thus, from US-PS 25 57 282 a process is known in which cyclohexane is first oxidized with air and that Oxidation product is further oxidized with nitric acid to adipic acid. The use of nitric acid makes the procedure costly. According to the method of US Pat. No. 2,831,024, in the second oxidation step although part of the nitric acid is replaced by atmospheric oxygen, the cost savings are insignificant, whereas the yield of adipic acid compared with that of the first-mentioned process is clear is decreased.

It is also known that oxygen or air oxidation of paraffin hydrocarbons in the presence of catalysts containing boric acid (DT-PS 5 02 433 and 5 70 732). These are boric acid salts or complex boric acid compounds of Metals which are unsuitable in the quantities used, the oxidative selectivity to cycloalkanol and cycloalkanone, especially the former one.

The object of the invention is therefore to provide a process for the preparation of saturated aliphatic dicarboxylic acids in which cycloparaffins are inexpensive are oxidized and the product is obtained in high yield and purity.

This object is achieved in the method according to the invention of the type mentioned at the outset by that the boron-free organic fraction is dehydrated prior to further oxidation to form a mixture, the cycloalkanol and cycloalkanone in a weight ratio of at least about 0.25 parts Contains cycloalkanone per part of cycloalkanol.

The boron-free organic fraction contains cycloalkanol and cycloalkanone in a ratio which can be in the range from 1.5: 1 to 1000: 1 parts of cycloalkanol to cycloalkanone. The mixture also contains about 5 to 25 percent by weight of cycloalkane oxidation products other than cycloalkanol and cycloalkanone.
In most cases, however, the ratio of cycloalkanol to cycloalkanone in this fraction is above 4: 1. The use of such fractions as starting material for the second oxidation stage leads to unsatisfactory yields of the desired dicarboxylic acids. By using the process according to the invention, part of the cycloalkanol in these fractions is dehydrated to the alkanone and the ratio of the two is reduced to 4: 1 or below. This measure has the effect that the yields of saturated aliphatic dicarboxylic acid which can be achieved in the subsequent second oxidation stage are increased considerably.

In the practical implementation of the method according to the invention, it has proven to be useful the dehydrogenation of the cycloalkanol containing fraction at temperatures and pressures in the range from 200 to 550 ° C and 0.21 to 3.5 atmospheres, preferably 300 to 500 ° C and 0.84 to 1.4 atmospheres, and in particular 360 to 450 ° C and 0.98 to 1.12 atmospheres, to form a mixture, the cycloalkanone and cycloalkanol in a weight ratio of at least about 0.5 parts, preferably at least about 0.65 parts and especially at least about 1 part cycloalkanone / part cycloalkanol contains.

The fraction is dehydrated at a liquid throughput per volume based on the volume Hour from about 0.1 to 20, suitably about 0.5 to 5, and preferably 1 to 3. According to a preferred one In the embodiment, a zinc oxydehydrogenation catalyst is used, but others can also be used suitable catalysts, such as copper or brass, are used.

The course of dehydration can be easily seen through regular Sampling and analysis can be followed, producing a reaction mixture of the above desired composition can be obtained.

The following examples illustrate the invention. Parts are by weight unless otherwise is specified.

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Example. 1

• 2711 g of cyclohexane are mixed with about 450 g of boric acid mixed. This mixture is poured into a glass