DE2925336A1 - METHOD FOR PRODUCING OXAL SAEUREDIALKYLESTERS - Google Patents

Description

DR. STEPHAN G. BESZiDES PATENT ADVOCATE

AUTHORIZED REPRESENTATIVE AT THE EUROPEAN PATENT OFFICE

PROFESSIONAL REPRESENTATIVE ALSO BEFORE THE EUROPEAN PATENT OFFICE 8060 DACHAU NEAR MDNCHEN

BOX 1168

MDNCHENER STRASSE 8OA

Federal Republic of Germany

TELEPHONE: DACHAU 4371 Postal checking account Munich (BLZ 700 100 80)

Account no. 1 368 71

Bank account no. 906 370 at the Kreis- und Stadtsparkasse Dachau-Indersdorf ( bank code 700 515 AO) (VIA Bayerische Landesbank Girozentrale, Munich)

P 1 218

Description

for patent application

MOKTEDISON S.p.A.

Milano, Italy

concerning

Process for the production of oxalic acid dialkyl esters

The invention relates to a process for the preparation of oxalic acid esters. In particular, it concerns a catalytic process for the production of oxa! säuredialkyl-

909882/0860

292533S

esters by reacting carbon monoxide with alkyl nitrites in the presence of metals of group VIII respectively I of the periodic table.

If desired, the oxalic acid can be prepared from the oxalic acid esters by conventional methods, for example by hydrolysis.

The oxalic acid and the oxalic acid esters are important compounds with known wide application possibilities of considerable technical or industrial interest.

Oxalic acid can be used in the textile industry as a stripping aid when dyeing wool, as a bleaching agent for natural fibers or as a pickling agent for metal surfaces, especially copper surfaces. Their use as a dehydrating agent is also for example in condensation reactions, known.

Finally, the oxalate esters are well-known solvents, for example the Oxalsäux-ediethyl ester for cellulose.

It is known that oxalic acid esters are produced by oxidative reaction of carbon monoxide and monohydric alcohols with oxygen and also with quinones, preferably in one essentially anhydrous medium because of the presence of dehydrating substances caused by redox systems, in general consisting of a noble metal of the platinum group, such as palladium or osmium, in the form of finely divided Metal or soluble salts or complexes, such as citrates or chelates, one such and one

809882/0880 " ³ ~

ORlGfNAL INSPECTED

Salt and / or complex of one in several stages of oxidation existing compared to the former, more electropositive other metal, such as iron, cobalt, nickel, copper or manganese, for example a chloride or acetate those that are catalyzed to produce.

The above reaction is preferably carried out in the presence of cocatalysts and / or complexing agents, consisting of soluble Salts of alkali metals, for example lithium chloride or potassium chloride, carried out.

However, such processes are simultaneous because of les Occurrence of side reactions that lead to the formation of carbonates, carbon dioxide and esters such as acetates and formates, due to the associated low yields and proportionate laborious or annoying separation and cleaning operations and other operations from not to be regarded as entirely satisfactory from a technical point of view.

In addition, the use of gas mixtures of carbon dioxide and oxygen, with the resulting risk of explosions, represents a further serious obstacle to the technical or industrial implementation of d & r.

On the other hand, the other prior art processes also provide, such as the dehydration of sodium formate with subsequent conversion to calcium oxalate and acidification or the, for example, by iron or chromium, catalyzed oxidation of propylene with nitric acid, with considerable procedural engineering involved or technological difficulties and operational difficulties do not give better results, which they do

809882/0860

ORIGINAL INSPECTED

economical, especially for large-scale Manufacture, makes unattractive.

Finally, there is a process for the preparation of oxalic acid dialkyl esters by the liquid phase reaction of aliphatic alcohols with carbon oxide under pressure in the presence of a metal of the platinum group and a reaction accelerator consisting of nitric acid and / or Oxides of nitrogen, "known. Ultimately, the implementation to achieve acceptable yields preferably carried out in the presence of molecular oxygen. This The method is essentially aimed at eliminating the prior art described above discussed existing difficulty in finding the reaction medium, also by using dehydrating agents, under To keep anhydrous conditions from, since the formation of the oxalic acid ester through that formed during the reaction itself V7asser, even if it is in modest quantities, is prevented. The use of the accelerator (Nitric acid and / or oxides of nitrogen) seem to avoid the use of dehydrating agents allow. Nevertheless, this method also has disadvantages which call its technical application into question. the Reaction is carried out namely with the catalyst in dispersion in the liquid medium, which fact some procedural or technological problems, the recovery and recycling of the catalyst in the circuit concerning brings about. The practically necessary presence of molecular oxygen to achieve better Yields conjures up again those already in relation to the use of gas mixtures of carbon oxide and oxygen indicated dangers. Finally, the use of nitric acid and / or oxides of nitrogen brings about corrosion

809882/0860 " ⁵ "

Problems related to the device. The disadvantages indicated above lead, albeit partially must be technically remedied, in any case, in any case, to considerable burdens on the company and with regard to the economy, which this process for use in technical or industrial Make the scale unacceptable.

The invention is therefore based on the object of eliminating the disadvantages of the prior art, a simple one and economical process for the preparation of oxalic acid dialkyl esters, by means of which these in high yields and high purity under advantageous operating conditions and prevented the risk of explosion without laborious and annoying operations can be maintained to create

The above has surprisingly been achieved by the invention.

The invention relates to a fuel for production of oxalic acid dialkyl esters with alkyl groups with 1 to 10 carbon atoms by conversion of carbon oxide in the presence of a catalyst with a content of at least 1 of the metals palladium, Rhodium, iridium, platinum md / or gold and / or salts thereof or the same, which d. marked by is that the carbon monoxide with an alkyl nitrite of the general formula

EON = O j where R is an alkyl radical having 1 to 10 carbon atoms

909882/0880 -6-

- «er is implemented in the gas phase at temperatures of 50 to 500 ⁰ C and at least .under atmospheric pressure.

The implementation can be done schematically, by the following Eeactxons equation can be represented:

2 HONO ₀₈₃₊

Il

In this, R is defined as above.

As can be easily seen, the reaction does not involve the formation of water and so do not exist corresponding problems of preventing the response or the formation of by-products, such as carbonic acid diesters, in high! "close.

In other words, the reaction r-elbst takes care of Sufficiently anhydrous condition *: - i.

As mentioned above, implementation in the Gas phase carried out and so the most suitable alkyl nitrites are obviously those with a low carbon number of atoms, that is to say a number of carbon atoms from 1 to 3 · Therefore, preferred as the alkyl nitrite Methyl nitrite, ethyl nitrite or a propyl nitrite are used. The use of methyl nitrite is very particularly preferred,

Ö09882 / 0860 ~ ^? ~

2325336-

It is clear that, depending on the selected conditions of temperature and pressure, alkyl nitrites with a higher number of carbon atoms can be used within the stipulations of the invention.

The alkyl nitrites necessary for the reaction are "known, readily available or in any case compounds which can be easily prepared from nitrous acid and alcohols of the formula R - OH, in which R is defined as above. The alkyl nitrite can, for example, have been separated off by distillation.

As already warned, contain those used according to the invention PCatalysts at least 1 metal in elemental Form or in the form of its salt. This is because there are also catalysts formed by more than 1 of the metals mentioned effective in elemental form or as salt.

Are useful in the catalyst and / or cocatalyst as salts chlorides, sulfates, citrates, acetates respectively Acetyl ncetonate used.

According to an expedient embodiment of the erfindungsgeij-.äßcn Process is used as a catalyst which also contains at least 1 of the metals iron and / or copper and / or contains salts thereof or the same as cocatalysts. Using the This is because cocatalyst allows higher yields of and a better selectivity to be achieved the dialkyl oxalate (s).

The salts as well as complex salts such as alkoxy copper (II) halides are to be understood comprehensively.

909882/0880 " ⁸ "

The catalyst is advantageously used in a fixed layer Uni therefore preferably used on a carrier to which it can have been applied in a manner known per se.

Advantageously, silicon dioxide, Magnesium oxide, aluminum oxide, zinc oxide, chromium sesquioxide (C ^ Ox) or pumice stone or a mixture thereof is used will. In addition to these or instead of them, the cocatalyst can serve as a carrier. After an advantageous Embodiment of the process according to the invention is therefore the catalyst on a support, consisting of Silicon dioxide, magnesium oxide, aluminum oxide, zinc oxide, chromium sesquioxide or pumice stone or mixtures thereof and / or the cocatalyst used.

Thus, the catalyst used is preferably a v / elcher of at least 1 of the metals palladium, rhodium, iridium, platinum and / or gold in elemental form or as salt and of at least 1 cocatalyst, which consists of at least 1 of the metals iron and / or copper in elementary form or as Salt is formed, the latter can also act as a carrier or the catalyst on itinem as above specified conventional carrier can be used.

The content or total content of the catalytically active element or the catalytically active elements on the conventional carrier, consisting of silicon dioxide, magnesium oxide, aluminum oxide, zinc oxide, chromosesquioxide or pumice stone or a mixture thereof, is preferably based on 0.1 to 50% by weight ₃ on the carrier. However, these values are in no way mandatory for a correct implementation of the method according to the invention.

809882/0880 ~ ⁹ ~

It is also preferred that the catalytically active Element or the catalytically active elements in an amount or total amount of 0.1 to 10 g, in particular 0.5 to 5 g »de mol of alkyl nitrite used is or will be used.

Is d _a s Weight ratio of the amount or the sum of the amounts of the element or the elements palladium, rhodium, iridium, platinum and / or gold to the amount or sum of the amounts of the element or the elements iron and / or copper (co-catalyst ', respectively to be advantageous In terms of metal, 1: 100 to 25 _: 100 '.nsbesondc.re 1: 100 to 5: 100 is selected, these values also not being mandatory for carrying out the method according to the invention.

Examples of catalysts which can advantageously be used in the process according to the invention are the following: From 2% by weight of palladium and 1% by weight of gold on zinc (II) oxide and chronsesquioxide mixed with methoxyhupfer (II) chloride LCu (OCH ₅ ) Cl] or from 5 wt .-% palladium on copper (I) - chloride [CuCl] or from 5 wt .-% palladium on iron (II) chloride [FeCl ^ j or from 5 wt. -% rhodium on aluminum oxide or from 5% by weight rhodium and 5% by weight palladium on aluminum oxide or from 5% by weight palladium on metallic iron.

For example, the one used in the present invention Catalyst on a carrier prepared as follows:

The predetermined amount of the substance (s) which is the carrier for the catalyst is placed in a small flask

Ö09882 / 0880 -10-

forms or forms, introduced. This substance or substance mixture is then combined with a Salt of the precious metal to be deposited on the carrier containing solution covered. The concentration of the salt in the solution depends on the total amount of precious metal to be deposited on the carrier. After achieving the Suspension by stirring, the solvent is distilled off to dryness under vacuum. Venn the addition of a vom first precious metal various other precious metal than If a catalyst is desired, the procedure described is repeated up to this point. The same applies to the cocatalyst. After making the solid material, consisting from the carrier with the metal salt or salts, the carrier becomes in a hydrogen stream for about 2 hours heated to 200 C for a long time. At the end of this operation is The catalyst is ready to use and comes naturally in one Nitrogen held binosphere.

The parameters of the conditions of temperature, pressure and contact times can be set within further Areas can be varied depending on the mutual choice.

Preferably are called temperature. around 150 to 55 ° C used as this will give the most beneficial results.

It is also preferred to increase the contact times of the gaseous reactants with the catalyst 0.1 to 10 seconds, in particular 0.1 to 1 second, to choose ^

The reactant gases are advantageous as partial pressures about atmospheric pressure up to about 200 atm,

- 11 -

909882/0860

especially atmospheric pressure up to 50 atm.

According to one embodiment of the method according to the invention, the carbon dioxide is mixed with among the Reaction conditions inert gases, especially those used in the industrial production of carbon monoxide and hydrogen The use of the carbon dioxide with such is namely compatible.

The separation of the oxalic acid dialkyl ester can easily can expediently be accomplished by known procedures, for example by conventional distillation. From the Oxalic acid dialkyleate can easily be obtained, for example, by hydrolysis according to customary procedures will.

The nitrogen mist evolving from the reaction (l.'O) can come from and after its oxidation Production of the alkyl nitrite can be reused.

! Tech of an advantageous embodiment of the inventor-äßc-n The procedure is as follows:

In one with feed organs for the reactants provided and equipped with a flow regulator and a temperature regulator system introduced the catalyst layer produced. Thereafter, the gas stream of the reactants becomes the desired Ratio, passed through the reaction device in the desired amount and for the desired contact time. Condensed at the outlet of the reaction device

909882/0860 -12-

INSPECTED

a liquid from which the dialkyl oxalate is obtained by distillation.

Thanks to the simple operating conditions, the method according to the invention has proven to be particularly advantageous.

Other advantages consist in the selectivity in relation to the achievement of the oxalic acid dialkyl esters among themselves anhydrous conditions of the reaction and in the exclusion of the risk of explosion in operation because of the absence of Mixtures of carbon dioxide and oxygen.

The procedure of the "solid layer" allows the stationary presence of the catalyst, which is not in the Reaction mass is dispersed, and provides a much simpler and more economical performance respectively Effectiveness of the operation of the replacement, extraction and reclamation operations assured.

Finally, there is the possibility of using mixtures of carbon monoxide and hydrogen, as suggested by the Production of synthesis gas come from without affecting the efficiency or effectiveness of the process would be of particular interest.

The invention is illustrated by the following examples explained.

909882/0860 ~ ¹³ "

example 1

The heterogeneous catalysis 1.5.6 of a catalyst consisting of 5% by weight of palladium on copper (I) chloride was introduced into a reaction device made of glass door and provided with a porous diaphragm. The Eeaktionsvorrichtung was placed in a muffle furnace with a known heat diagram and maintained at a temperature of 200 ⁰ C.

Then, over the catalyst, a gas of the following became Composition headed:

4- Nl / hour carbon dioxide and 3 Nl / hour methyl nitrite

Under these conditions was the residence time of the reaction mixture and the duration of contact with the catalyst 0.5 second.

At the outlet of the reaction device, a ^{collecting trap kept at 0 0} G was placed. After 2 hours from the start of the experiment, the liquid separated out in the trap was collected and dialysed. The analysis was carried out both by gas chromatography and directly by titrating the precipitated calcium oxalate. Thus 100 mg of dimethyl oxalate were determined in the collected liquid.

909882/0860

Example 2

The procedure of Example 1 was * repeated in the same device with the difference that a catalyst consisting of 2 wt .-% palladium and 1 wt .-% gold on a framework of 70 wt .-% zinc (II) oxide and 10 wt .-% chromium sesquioxide with 10 wt .-% admixed methoxy copper (II) chloride j ^ Cu (OCH ^) GlJ, and 180 ⁰ C were used as the reaction temperature. The experiment was thus carried out for J hours.

At the end of the experiment, a liquid containing 20 mg of dimethyl oxalate was at the outlet of the reaction device contained, collected.

Thereafter, the feed of the reactants was under resumed the same conditions for another 6 hours. At the end, 40 mg of dimethyl oxalate were obtained.

Then the introduction of the indicated reactants was in the direction of the reaction for a further 16 hours. At the end, 230 mg of Cxalsä'iiredimethylester were still collected.

Example 3

The procedure of Example 1 was repeated in the same device with the difference that a catalyst consisting of 5% by weight of palladium on iron (II) chloride was used and the reaction temperature was 200 ° C. The experiment was carried out for M hours.

At the end of this experiment, a 500 mg oxalic acid

totm / oiia -15-

liquid containing dimethyl ester obtained

The feed of the reactants was then resumed for a further 1 hour
50 mg of dimethyl oxalate collected.

Example 4

The procedure of Example 1 was carried out with the
The difference is that a catalyst consisting of 5% by weight of rhodium on aluminum was used, a stream of carbon oxide of 2 Nl / hour was passed over the catalyst and 200 ^° C. was used as the reaction temperature. The experiment was carried out for 4 hours.

At the end of the experiment, an amount of dimethyl oxalate determined by gas chromatography was obtained Liquid obtained.

Example 5

The procedure of Example 1 was carried out with the
Difference repeats that a catalyst consisting of 5% by weight of rhodium and 5% by weight of palladium on aluminum oxide was used. Thus the same results were obtained.

- 16 -

909882/0880

Example 6

The procedure of Example 1 was repeated with the difference that a catalyst consisting of 5% by weight palladium on iron, used and as the reaction temperature 200 ° C were applied. This experiment was carried out for 4 hours.

At the end of the experiment, 460 mg of dimethyl oxalate was obtained containing liquid obtained.

Example 7

The procedure of Example 1 was repeated with the difference that a catalyst consisting of 5 wt .-% palladium on iron (II) chloride, used in the Reaction device 3 Nl / hour ethyl nitrite and 4 Nl / hour Carbon oxide was introduced and the temperature applied was 200 ° C. This experiment was carried out for 5 hours.

At the end of the experiment, 50 mg of diethyl oxalate was obtained containing liquid obtained.

Example 8

The procedure of Example 7 was repeated with the difference that the temperature used was 300 ° C) became. 20 mg of diethyl oxalate were obtained in this way.

- 17 909882/0860

Example 9

The procedure of Example 1 was repeated in the same device with the difference that a catalyst consisting of 5% by weight of platinum on iron (II) chloride was used as the catalyst and 210 ^° C. as the reaction temperature. This experiment was carried out for 3 hours.

At the end of the experiment, a 130 mg oxalic acid dimethyl ester was placed in the outlet of the reaction device Liquid collected.

Example 10

The procedure of Example 9 was followed with the difference repeats that as a catalyst 5 wt .-% rhodium on iron (II) - chloride was used. The trial was 3 hours long carried out.

4-50 mg of dimethyl oxalate were obtained in this way.

Example 11

The procedure of Example 9 was carried out with the Difference repeats that as a catalyst 5 wt .-% Iridium on ferrous chloride was used. This Experiment was carried out for 3 hours · So were 100 mg of dimethyl oxalate were obtained.

Claims 909882/0860

INSPECTED

Claims (12)

2325336 Claims Y: rfahren for producing Oxalsäuredialkylestern by alkyl groups having 1 to 10 carbon atoms by reacting carbon monoxide i ⁿ the presence of a catalyst with a content of at least 1 of the same of the metals palladium, rhodium, iridium, platinum and / or gold and / or salts thereof "or the same , characterized in that the carbon oxide with an alkyl nitrite of the aUgeif-a formula R-O-N = O, where R is an alkyl radical having 1 to 10 carbon atoms., in the gas phase at {temperatures from 50 to 50O ⁰ C and -at least xin atmospheric pressure. 2.) Verfahi'ön according to claim 1, characterized ^ _s that one is alkyl nitrite ₄ methyl nitrite as Alkylnrtrlt. or a propyl nitrite is used. 3.) Method according to claim T or 2, characterized in that that the catalyst is one which also contains at least 1 of the metals iron and / or copper and / or salts thereof or the same as cocatalyst is used. 4-.) Process according to claim 1 to 3, characterized in that one in the catalyst and / or Cocatalyst as salts chlorides, sulfates, Nitrates, acetates or acetylacetonates are used. 5.) Process according to claim 1 to 4, characterized in that the catalyst is on a Carrier consisting of silicon dioxide, magnesium oxide, aluminum oxide, zinc oxide, chromium sesquioxide or pumice stone or mixtures thereof and / or the cocatalyst. 6.) Method according to claim 1 to 5 »characterized in that that one is the catalytically active element or the catalytically active elements that are not the carrier forms or forms, on the Tx-a- ~ n an amount or total amount "of 0.1 to 10% by weight, based on the carrier, used, 7.) Method according to claim 1 to 6, characterized in that that the catalytically active element or the catalytically active elements in an amount or total amount of 0.1 to 10 g, in particular 0.5 "to 5 g» O'e mol used alkyl nitrite used. 8.) Method according to claim 1 to 7, dnoir-ch & ■ "■■" - BATH ORIGINAL draws that one is the weight ratio of the amount or sum of the amounts of the element or the elements palladium, rhodium, iridium, platinum and / or gold to the amount respectively Sum of the quantities of the element respectively of the elements iron and / or copper, each expressed as metal, at 1: 100 to 25: 100, in particular 1: 100 to 5: 100, selects. 9 ») Method according to claim 1 to 8, characterized in that the temperature is about 15Ο to 35O ° C applies. 10.) Process according to claims 1 to 9 _T , characterized in that the contact times of the gaseous reactants with the catalyst are selected to be 0.1 to 10 seconds, in particular 0.1 to 1 second. 11.) The method according to claim 1 to 10, characterized in that that as partial pressures of the reactant gases from about atmospheric pressure to about 200 atm, especially atmospheric pressure up to 50 atm, applies. 12.) Process according to claim 1 to 11, characterized in that the carbon monoxide is mixed with gases which are inert under the reaction conditions, especially those used in industrial production hydrogen derived from synthesis gas. 809882/0860