DD156529A5 - PROCESS FOR THE PREPARATION OF CARBON ACIDS BY CARBONYLATION - Google Patents

Abstract

1. Process for the preparation of acetic acid by reaction of carbon monoxide with methanol in the presence of an effective amount of nickel, an alkyl or acyl halide and a carboxylic acid initially introduced, in the liquid phase, at a temperature above 120 degrees C and under a total pressure of less than 200 bars, characterized in that the reaction is carried out in the presence of at least one alkali metal salt.

Description

Process for the preparation of carboxylic acids by means of carbonylation

Field of application of the invention

The invention relates to a process for the preparation of carboxylic acids, in particular of acetic acid, by means of carbonylation of an alcohol.

Characteristic of the known technical solutions

It is well known that especially acetic acid can be prepared by carbonylating methanol under relatively severe pressure conditions in the presence of nickel and a free or bound halogen.

For example, US Pat. No. 2,729,651 describes, in particular, that the carbonylation of methanol is carried out in the presence of nickel complexes obtained by reacting nickel halides with quaternary ammonium or phosphonium halides; these complexes correspond to the general formula I ₁ in which X is a bromine or iodine atom, M is a phosphorus or nitrogen atom and A is, for example, a lower alkyl group.

These complexes can be used in this form in the reaction in question or they can be formed in situ. However, the efficiency of the catalyst system, expressed as hourly productivity or performance, despite the high pressure of about 700 atmospheres or carbonylation reaction used in the carbonylation reaction. bar very low.

The productivity, which is given either based on the reaction volume or based on the mass (amount) of nickel used, could be significantly improved by the reaction on the one hand a nickel halide and on the other hand, a quaternary ammonium or phosphonium halide is used in a greater amount than the Stoichiometric ratio for the formation of complexes of general formula I corresponds (see, DE-PS 933 148). However, even in this latter case, the pressure conditions remain very strict

Catalyst systems have recently become known which can be used to carbonylate methanol under less severe pressure conditions. Thus, FR-AS 2 370 023 describes the carbonylation of methanol in the presence of at least 10 mol of methyl iodide per 100 mol of methanol, of nickel and of a free and / or nickel-complexed phosphine under a pressure of less than 70 bar. Nevertheless, the effectiveness of such a system, expressed as hourly output or productivity, remains low.

It has also been pointed out in a low pressure carbonylation process

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- Ti - £ &

(see FR-AS 2 404 618) that the presence of Lösungsraitteln as. Carboxylic acids or their esters, has a beneficial effect on the course of the carbonylation reaction. However, the use of such solvents is not essential and the alcohol that is expected to act as a solvent can be used «

However, the technical significance of these more recently developed operations is hampered by the instability and cost of the phosphine or amines necessary to carry out these processes.

Object of the invention

It has now been found that it is possible to produce carboxylic acids, in particular lower alkanoic acids and above all acetic acid, by means of carbonylation of alcohols in the presence of nickel and at least one halogenated promoter with a remarkable productivity under relatively moderate pressure conditions and avoiding the aforementioned disadvantages.

The invention thus relates to an improved process for the carbonylation of alcohols in the liquid phase under a total pressure of less than 200 bar in the presence of an effective amount of nickel, an alkyl halide or acyl halide, at least one alkali salt and an originally charged carboxylic acid.

Surprisingly, it has been found, in particular in the context of the carbonylation of methanol to acetic acid,

that the results are not satisfactory when the partial pressure of carbon monoxide is too high _e This is all the more surprising as many frühre work stressed the need to work under very high pressures and have demonstrated.

The investigations that have led to the present invention have the surprising behavior of the alkali metal salts as catalysts for the carbonylation

of alcohols in the liquid phase

and under a total pressure of less than 200 bar * It has surprisingly been found that the salts and derivatives of

other

However, many metals, including metal carbonyls, do not allow to react carbon monoxide with an alcohol in a carboxylic acid in the presence of nickel and a halogenated promoter under the conditions mentioned above.

Explanation of the "essence of the invention

According to the invention, carbon monoxide is allowed to act on an alcohol to obtain the corresponding carboxylic acid according to Reaction Scheme II, in which

R is a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms or the group C ^ H, - C "Ho -.-, in which η is an integer from 1 to 6 (1 5 η 5 6). The group R ¹ may have one or more substituents inerted under the reaction conditions. Preferably R is a lower linear or branched alkyl group having 1 to 4 carbon atoms and especially for the methyl group.

The inventive method is carried out in the liquid phase in the presence of a urnnrünglich discontinued -.

"2 2

Carboxylic acid of the general formula R COOH, in the R

1 2 1

has the meaning given to R, where R and R may be the same or different, "in other words; The carboxylic acid, which in some instances serves as a solvent, is not necessarily the carboxylic acid produced by the carbonylation reaction. However, it may prove to be advantageous that the solvent used as the carboxylic acid is the same as that produced by the reaction. However, the use of a heavier carboxylic acid, as it is produced in the reaction, may also facilitate, as a solvent, the operations of separation. ,

The carboxylic acid RCOOH constitutes at least 10% by volume and preferably at least 20% by volume of the reaction medium. It can make up a considerable proportion of the reaction medium, especially in the continuous mode of operation, in which the alcohol R OH is injected or introduced into the carbonylation reactor.

In the process of the invention, an effective amount of nickel must be present. Any nickel source can be used. It can be worked with metallic nickel, such as Raney nickel or nickel in any other convenient form. Examples of nickel compounds which can be used according to the invention are nickel carbonate, nickel oxide, nickel hydroxide, nickel halides, in particular nickel iodide, carboxylic acid nickel salts, in particular Nic.kelac.e1a. Nickel carbonyl is also good. "Preference is given to using Raney nickel, nickel iodide, nickel acetate and nickel carbonyl."

* original

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The amount of nickel used is not critical. The nickel content, which exerts an influence on the reaction rate, is determined as a function of the reaction rate, which is considered suitable. In general, from 5 to 2,000 mg of atom of nickel per liter of solution give satisfactory results. It is preferable to use an amount of 20 to 1,000 mg of atomic nickel per liter of _c

The process of the invention also requires the presence of at least one alkyl halide or acyl halide. These halides correspond to the general formulas R? X or "R? -C (O) -X, in which X is a chlorine atom, bromine atom or, preferably, iodine atom

• z 12

and R - has the meaning given above for R and R,

Where R and R or R and R may be identical or different to one another. The halide, which may initially participate in the reaction medium, may also be generated in situ starting from halogen compounds such as Cl ₂ , Br ₂ , J _{3 2} , HCl, HBr, HJ, NiBr ₂ and NiJ ₂ and alcohol (starting material) are formed. In other words, some or all of the alkyl halide necessary for carrying out the process can be generated from its just-defined precursor compounds. "

Furthermore, it will be noted that when the halogen compound is chosen from among the nickel compounds, it may be considered not only as a precursor compound for the alkyl halide but also as a precursor compound for the metallic catalyst. In this particular case, it proves to be advantageous to at the beginning additionally aufzuseben an alkyl halide or an acyl halide and / or a precursor compound different from the in question stinging nickel halides.

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In the context of the invention, the lower alkyl-quodides having 1 to 4 carbon atoms in the alkyl group represent a preferred group of alkyl halides. In particular, methyl iodide is suitable for carrying out the inventive process.

For a good implementation of the process according to the invention, the concentration of alkyl halide should generally be at least 0.5 mol per liter of reaction medium. The increase in the concentration of alkyl halide or acyl halide has an advantageous effect on the reaction rate; but it proves advantageous not to go beyond a concentration of 8 moles per liter. Very satisfactory results are obtained with a concentration of alkyl or acyl halide of from 0.8 to 6 moles per liter, preferably from 1.5 to 5 moles per liter. "

One of the essential features of the invention is that at least one alkali metal salt is used, d.ho at least one compound of the general formula Ml X ¹¹¹ "in which m is 1 or 2, M is a lithium, sodium, potassium, cesium or rubidium atom and X ³¹¹ "" is an anion from the following group * .OH "", Cl ", Br", J "", R 1 -COO ", R ⁴ -O-, SOT ₉ NO", CO ² where R ^{4 is} the

1 HJ?J h A

has the meaning given above for R and R and R may be the same or different from each other; , the alkali metal salts may be in hydrated form. The lithium, sodium or potassium salts are particularly suitable.

The nature of the anion XT is not fundamental to the process.

/8th

Examples of alkali metal salts which are suitable for carrying out the process are: LiOH, NaCl, KBr, RbJ, -. CsJ, Li ₂ SO 4, NaNO ₃ , K ₂ CO ₅ , Rb ₂ SO 4, CsNO, lithium acetate, sodium acetate, potassium acetate, sodium metylate, potassium methoxide and sodium ethylate, potassium ethylate or lithium ethylate The carboxylic acid alkali metal salts (R-COOM) and in particular the acetates are convenient to handle and therefore highly recommended for carrying out the process. Well suited are lithium acetate, sodium acetate and potassium acetate. According to a preferred embodiment, a lithium salt and in particular lithium acetate is used. ,

Good results are achieved when the atomic ratio M / Ni is 0.1 to 20; but lower or higher ratios can also be selected. Advantageously, this ratio is set to a value of 0.5 to 5.

Generally, a reaction temperature of at least 120 is required to achieve a satisfactory reaction rate. A temperature range of I60 proves advantageous to 200 ⁰ C. It has been found that the activity of the above defined catalyst system, in particular for temperatures below 16O ° C can be increased if two alkali metal salts used with varying cation v / ground. In this case, the combination of a lithium salt with a sodium salt or a potassium salt proves very useful. The common use of lithium acetate and potassium iodide proves to be particularly advantageous.

It is not necessary for the process according to the invention that the alcohol and the carboxylic acid which belong to

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Beginning are used, cleaned or dried for ₆ may be used technically pure alcohols and carboxylic acids, optionally up to 20 VoI · - contain% water "On the other hand, in the reaction, the total quantity or a part quantity of the alcohol ROH in the form of an ester R ² Use COOR,

12 wherein R and R have the meaning given above

and R and R may be the same or different. In this case, some water must be added at the beginning in an amount which corresponds at least to the theoretical amount required for the hydrolysis of the discontinued ester.

The carbonylation process according to the invention is carried out in the liquid phase under a pressure above atmospheric pressure but below 200 bar. It is especially recommended to work under a CO partial pressure of 25 to 100 bar. Substantially pure carbon monoxide is preferably used, as is commercially available. However, the presence of impurities such as carbon dioxide, oxygen, methane and nitrogen is not harmful. The presence of hydrogen is also not harmful, even in relatively large quantities. "

After completion of the reaction, the reaction mixture is separated into its various constituents, by means of any suitable means, for example by distillation.

The inventive method is particularly suitable for the production of acetic acid by means of carbonylation of methanol, especially in acetic acid. The following examples serve to illustrate the invention.

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Exemplary embodiments

In the following examples, the following abbreviations are used

• AcOH means acetic acid,

AcOMe means methyl acetate,

RR denotes the molar ratio

(AcOH + AcOMe) titrated - (AcOH) originally present (CH _x OH + CH _x J). originally present,

d "h. the molar ratio between the resulting "potential acetic acid" and the original (CH _x OH + CH _x J) present,

- ν is the initial carbonylation rate

in moles of CO absorbed per hour and per atom of nickel,

- t is the effective duration of CO absorption

at the test temperature,

T is the total duration of the experiment

- θ is the temperature in ⁰ C,

- Pr refers to productivity, based on

the time t (given in hours) _s given in grams of "potential acetic acid" which per liter of originally existing reaction mixture has arisen _o

Example 1

The following were placed in a 125 ml Hastelloy B alloy autoclave:

- 362 egg moles (15 ml) of methanol,

340 mmol (20 ml) of acetic acid,

- ,. 200 mmol (28 _S 4 g) of methyl iodide,

100 mmol (2.4 g) of lithium hydroxide,

20 mmol (2.6 ml) of nickel tetracarbonyl *

The autoclave was closed and a CO pressure of 40 bar was set. Then, the shaker was turned on and the autoclave brought to 180 ⁰ C in about 20 minutes, using a ring furnace. The pressure in the autoclave was then 60 bar; he was then held by recharging pure CO at 70 bar.

The pressure drop of the high-pressure reservoir, from which the autoclave (expander) was continuously fed, was recorded.

The absorption of CO was terminated after 30 minutes of reaction at 180 ° C; Subsequently, it was heated for a further hour to this temperature.

Then we switched off the shaker and the heater, the autoclave cooled and degassed.

The erhalia reaction mixture was diluted and analyzed by gas chromatography »It contained 48.7 g of acetic acid (RR = 84 %) * methyl acetate was not detected. ,

The productivity (Pr) of the reaction with respect to acetic acid was thus 1,130 g per hour and per liter (g / h χ 1).

- 12 examples 2 to 7

In the apparatus according to Example 1 and according to the procedure described there, a series of experiments was carried out, starting from a batch consisting of 15 ml of methanol, 20 ml of acetic acid, 20 RigAtom nickel in the form of nickel tetracarbonyl and methyl iodides The temperature was 180 ⁰ C; the pressure was maintained at 70 bar unless otherwise specified. The individual conditions and the results obtained are listed in Table 1 below.

The comparison test a listed in the table was carried out in the absence of alkali metal salt. The comparative test b listed in the table was carried out at 200 bar.

Comparative tests c to η

In the apparatus of Example 1 and according to the procedure described there, a series of experiments was carried out, starting from a batch consisting of 15 ml of methanol, 20 ml of acetic acid and methyl iodide, at 18O ⁰ C and below 70 bar in the presence of various metal compounds. No reaction was observed after 2 hours at the indicated temperature.

The individual conditions for these comparative experiments are summarized in the following Table 2

Examples 8 to 10

In the manner described in Example 1 and the autoclave described there, a number of

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Search performed starting from a batch consisting of 15 ml of methanol, 20 ml of acetic acid, methyl iodide and _(nickel in the form of Ni (CO) ^, unless otherwise stated, "The total pressure" bar was maintained at the temperature indicated in the 70th The total duration of Experiment (T) was 2 hours. The individual conditions and results are summarized in the following Table 3.

Example 11

In a 250 ml stainless steel autoclave Z8-CNDT 17-12 (standard AFNOR) were submitted:

322 mmol (13 ml) of methanol,

689 mmol (40 ml) of acetic acid,

285 mmol (40.48 g) of methyl iodide,

100 mmol (6.6 g) of lithium acetate,

50 mmol (8.3 g) of potassium iodide,

21 mmol (2.7 ml) of nickel tetracarbonyl.

The autoclave was closed and a CO pressure of 30 bar was set. The shaker was turned on and the autoclave brought to 150 ⁰ C in about 20 minutes, using a ring furnace »The Duck in the autoclave was 50 bar and then was maintained by recharging pure CO at 40 bar»

The pressure drop of the high-pressure reservoir, from which the autoclave (expander) was continuously fed, was recorded.

The CO absorption was terminated after 4.5 hours of reaction at 150 ⁰ C. It was then heated for a further 13 hours to this temperature.

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ιδ 7 7 7 'H / 4

Then the shaking device and the heater were turned off, the autoclave cooled and degassed

The reaction mixture was analyzed by gas chromatography after dilution. It contained 68.7 g of acetic acid, (RR = 78 %) and 0.37 g of methyl acetate *

The productivity of the reaction with respect to acetic acid was thus 85 g / h χ 1.

Example 12

The experiment described in Example 11 was repeated with the omission of potassium iodide The total duration of the test was 9 hours at 150 ⁰ C. After completion of the test 69.5 g of acetic acid (RR = 80%) and 0.4 g .Methylacetat were observed (Pr = 40 g / h χ l).

Example 13

The procedure was as in Example 11, but without lithium acetate. -

The total duration of the experiment was 18.5 hours at

The analysis after completion of the experiment revealed 53.5 g of acetic acid (RR = 42 %) and 4.51 g of methyl acetate (Pr = 11 g / h χ 1).

B._e_ i._s__p ± _e__l 14

In a 225 ml autoclave made of titanium were submitted:.

r-

522 mmol (13 nil) of methanol,

- 688 mmol (40 ml) of acetic acid,

290 mmol (41.21 g) of methyl iodide,

50 mmol (3.30 g) of lithium acetate,

21 mmol (2.7 ml) of nickel tetracarbonyl.

After closing the autoclave, a pressure of 40 bar CO was set, the shaking turned on and brought the autoclave in about 25 minutes by means of a ring furnace at 175 ° C. The pressure in the autoclave was then 65 bar; it was kept at 60 bar by recharging pure CO.

The pressure drop of the high pressure reservoir, which continuously fed the autoclave (expander), was recorded.

The CO absorption was complete after about 1 hour of reaction at 175 ⁰ C and it was heated for a further 4 hours at this temperature.

Then the shaking device and heating were switched off, the autoclave cooled and degassed.

The resulting reaction mixture was diluted and analyzed by gas chromatography. It contained 62.2 g of acetic acid (RR = 57 %); no methyl acetate was detected »

The productivity of the reaction with respect to acetic acid was thus 230 g / h χ 1 "

2 * 1 1 ^p l Ö "Ί ρ% ' JF / β Π ψ W

Be i S ρ i el 15,

The above experiment (Example 14) was used with repeated reverse amounts of methanol and acetic acid _s d * h ", there were added 40 ml of methanol and 13 nil acetic acid"

The CO absorption was completed after 4.5 hours of reaction at 175 ⁰ C; the reaction mixture was held at this temperature for a further 30 minutes.

After the experiment was obtained 71 g of acetic acid and 1.55 g of methyl acetate (RR = 79%).

The productivity of the reaction with respect to acetic acid was thus 175 g / h χ l _e

Example 14 was repeated with potassium iodide (50 mg atom) instead of lithium acetate.

The CO absorption was completed after 2.5 hours of reaction at 175 ° C; Subsequently, the reaction mixture was kept for 2 hours 40 minutes at this temperature.

At the end of the experiment, 58 g of acetic acid were detected and no traces of methyl acetate were detected (RR = 45 %, Pr = 90 g / h x 1).

In the apparatus and manner described in Example % , an experiment was carried out with the following batch

13 ml of methanol,

- 40 ml of acetic acid,

'"- 21 mg atom nickel in the form of ^

- 100 mmol of lithium iodide.

The temperature was 175 ° C; the total pressure was kept at 60 bar «

After 5 hours of reaction at the indicated temperature, 39.5 g of acetic acid and 8β 1 g of methyl acetate were detected analytically (RR = 27 % _f Pr = 20 g / hχI).

Comparative experiment ρ.

In the apparatus described in Example 14 and with the procedure there, an experiment was carried out with the following batch:

53 ml of methanol,

- 21 mg atom nickel in the form of Ni (CO) ^,

288 mmol of methyl iodide,

- 50 mmol of lithium acetate.

After 5 hours of reaction at 178 ° C under a pressure of 70 bar 9 * 4 g of acetic acid and 15.3 g of methyl acetate (RR = 23 %, Pr = 50 g / h χ l) were detected.

TABLE

- at- * , CH ₃ I Cocatalyst ato r milligram-atom    t T ν AcOH mcbgp-. AcOMe: (g) RR% AcOH Pr: g / hxl: : game • mmol _: Art 100 injjri) 2h (G) : 1 200 LiOH 50 30 2h 35 48.7 0 84 1130: : 2 209 AcOLi. 50 60 lh 30min 15 44.9 1.48 75 520: : 3 208 KJ 100 60 lh 30 min 17.5 34.6 5.18 ' 53. 370: : 4 210 AcOLi 100 90 4h 45 49.3 .2,66 94 410: : 5x 203 LiCl 100 ND: 2h ND 31.4 6.29 48 ND ': : 6 209 AcOK: 50) 50 y 120. 2h 10 25.6 ! 15.3 52 • 175: : 7: VergL. % r- _: sucn 204 [AcOLi 0 75 2h 45 47.3 1.48 83 450: : a 249 100 120 2h 0 10.5 10.6 0   0: : b. 207 ¹ AcOLi. 120 <5 16.1 - 15.9 26 90:

"In the course of the experiment, the pressure dropped from 100 to 38 bar (autogenous pressure) ND = not determined

TABLE 2 Comparative Experiments

• -Verge .Ver * r · nickel compound: mgAtoni CH ₃ J: Metal compound: milligram-atom: search kind • • 20: a mmol: Type: a 50: : c Ni (CO) ₄ 4 20: 201: Cr (CO) ₆ : a 100: : d Ni (CO) ₄ 20: 206 Zn (OAc) ₂ , 2H ₂ O: 50: : e Ni (CO) ₄ • 20: 203 Zn ·: 100: : f Ni (CO) ₄ : 20: 209 Mn (OAc) ₂ , AH ₂ O: 50: - 9 • : Ni (CO) ₄ : 20: 10 '. 2OA : Al J ₃ • 100: • 30: • : Hi • : Ni (CO) _4- Ni (OAc) ₂ , 4H ₂ O : 8th 203 205 : Co (OAc) ₂ , AH ₂ O: MoBr ₃ • 100: " Ni (OAc) ₂ , AH ₂ O : 20 202 *: Fe (OAc) ₂ : 10: •: k Ni (CO) ₄ : 10 205 : MoJ ₃ : 10: • : 1 : Ni (CO) ₄ : 20 209 : 100: •: m : Ni (CO) ₄ : 8th : 211 : Mg (OAc) ₂₅ AH ₂ O : AO: : η : Ni (CO) ₄ : 200 : Bi J ₃

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TABLE

; examples Ni : CH ₃ JR Cokatalysäor milligram-atom 180 t ND AcOH AcOMe. % Pr: ^: play mgAton rn.Mol kind 50 180 ' min 53 vdesen (g) Cg) · AcOH g / hxl ;: : 8th 10 208: KJ 100 190 120 45 28.9 '7,1 36% , 140: : 9x 15 203 AcOLi 100 · 60 55.1 , 0.5 100% : 700: : 10 20 110 · AcOLi 45 50.4 1.18 100% .850:

χ experiment carried out with Ni (OAc), 4H ₂ O and in the presence of hydrogen (30 bar)

7249

-15

For m e 1 b la t t

M7 ₂ Ni

R ¹ OH -f CO-

-> R '- C ~ OH

Il

II

7249

Claims (7)

invention claim 1 · Process for the preparation of a carboxylic acid of 1 1 general formula R COOH, wherein R is a linear, branched or cyclic C -, - C ^ alkyl group, or a group ^C 6 ^H 5 ~ _^CnH2n ~ "means ^m ^ 1 · 5η ^ 6, by the action of carbon monoxide to the corresponding alcohol R -OH in the presence of an effective amount of nickel and an alkyl halide or acyl halide, in the liquid phase at a temperature of 120 ° C or above and under a total pressure below 20D bar, marked aaaurch net /, that the reaction is listed in an initial 2 give carboxylic acid of the general formula R-COOH, 2 11 in which R has the same meaning as R and R and R may be the same or different, and is carried out in the presence of at least one alkali metal salt * 2. The method according to item 1, characterized in that the alkyl halide or acyl halide is an iodide. 3o method according to item 2 _t, characterized in that the alkyl halide is a C ^ -C ^ alkyl iodide. -32 - 4c Process according to item 3 », characterized in that the alkyl iodide is the methyl iodide. 5 * Method according to one of the preceding points, -j characterized in that R is a 2
.Cl-C ^ alkyl group and R is a linear, branched or cyclic C 1 -C 6 -alkyl group _f or a group - with 1 5n ^ 6. 6. Procedure according to point 5, net in that R is the methyl group. 7ο Method according to one of the preceding points, characterized in that the carboxylic acid R COOH at least 10 VoI .-% of the original reaction medium. 8. The method according to any one of the preceding points, characterized in that the nickel concentration is 5 to 2,000 mgAtom per liter of reaction medium » Method according to item 8, characterized in that the nickel concentration is 20 to I 000 mg of atom per liter of reaction medium 10. The method according to any one of the preceding points, characterized in that the concentration of Alky! Halide or Acylnalogenid made up 0.5 to 8 moles per liter of reaction medium II o method according to item 10, characterized in that * the concentration of alkyl halide or acyl halide from 0.8 to 6, in particular 1.5 to 5 moles per liter of reaction medium made / 3 system. -13 - 12. Method according to one of the preceding points, g β ke η η:
are the same 1 2 characterized in that R and R 13 * Process according to one of the preceding points, characterized in that the alkali metal salts of the general formula M ^ X ⁰¹ "" correspond, in the m = 1 or 2, M is a lithium, sodium, potassium, cesium or rubidium atom and X * ¹¹ "an anion from the group OH", Cl ", Br ~, J"% R ⁴ -C00 ~, R ⁴ -O ~, SO ?, N0 ~, - 4 1 CO ^, where R has the meaning given for R and R and R may be the same or different. 14 »Method according to item 13, characterized in that M represents a lithium, sodium or potassium atom» 15 "method according to item 13 *, characterized in that M represents a lithium atom, 16, Method according to one of the points 1.3 to 15, characterized in that the anion) a carboxylic acid anion of the general formula R-COO "" in which R has the meaning given to R, 4 1
where R and R may be the same or different « 17 · Method according to item 16, characterized in that the anion (X ¹¹¹ "") is the acetate anion. 18. The method according to any one of the points 13 to 17, characterized in that the atomic ratio M / Ni is 0.1 to 20, preferably 0.5 to 5. 19e method according to one of the preceding points, characterized in that the reaction * is -2A ~ temperature is 16O to 200 ⁰ C. 20 © Method according to one of the preceding points, characterized in that the partial pressure of the carbon monoxide is 25 to 100 bar. HteraitSiie formulas