DE1148990B - Process for the production of carboxylic acids from olefins, carbon oxide and water - Google Patents

Description

It has been known for a long time to produce carboxylic acids by reacting olefins with carbon monoxide and to produce water in the presence of various catalysts. As a suitable catalyst Phosphoric acid was also mentioned for this synthesis in various references (cf. e.g. UIlmanns "Encyclopedia of Industrial Chemistry", 3rd edition, Vol. 5 [1954], p. 121, last paragraph, and P. 137, para. 3 with table).

Twenty-six British and United States patents are listed in the table mentioned for the reaction of olefins with carbon monoxide and water, seven of which are named phosphoric acid as the catalyst, with one exception always on activated carbon. Incidentally, in this method should at very high pressure, practically at 200 to 1000, and temperatures are worked over 100 ° C, practically at 200 to 400 ⁰ C. This is also evident, for example, from the book by MJ As tie, "The Chemistry of Petrochemicals" [1956], p. 85, last paragraph.

Not only in “Ullmann's Encyclopedia”, but also in Houben-Weyl, “Methods of organic Chemistry ", 4th edition, Vol. IV / 2 [1955], p. 375/376, this process becomes technically meaningless marked.

A fundamentally different process is described in the journals "Fuel-Chemistry", Vol. 36 [1955], pp. 321 to 328, "Fette, Seifen, Anstrichmittel", Vol. 59 [1957], pp. 493 to 498, and in the German patent specification 942 987 described. In this process it is primarily important that the essential synthesis stage, namely the addition of the carbon oxide to the olefin, is carried out in the absence of free, ie chemically unbound, water. Accordingly, the theoretical catalysts used are those which contain less water than the compounds SO ₃ · 2H ₂ O and BF ₃ · 2H ₂ O, ie at least 90% sulfuric acid, anhydrous hydrogen fluoride alone or with the addition of boron trifluoride, and also monooxyfluoboric acid alone or their complex mixtures with phosphoric acid or sulfuric acid. Only after completion of the carbon oxide incorporation, with an intermediate product being formed, is water added, which enables the conversion product to be separated into the catalyst and an organic layer containing the carboxylic acid.

According to this method, relatively low temperatures of 0 to 70 ° C and a pressure from 1 to 100 at can be applied. As far as a higher pressure is applied, this is used for the Ver process for the production

of carboxylic acids from olefins,

Carbon dioxide and water

Applicant:

Study Society Coal mbH,
Mülheim / Ruhr, Kaiser-Wilhelm-Platz 1

Dr. Herbert Koch and Dr. Karl Erich Möller,

Mülheim / Ruhr,
have been named as inventors

preventing the migration of the methyl group and suppressing dimerization.

In German patent specification 972291, which carried out this synthesis with monooxyfluoboric acid or their complex compounds containing phosphoric acid or containing no free water Sulfuric acid, it says on page 3, lines 18 to 20: “Concentrated phosphoric acid alone applied, however, proves to be completely inactive «.

It has now surprisingly been found that

in contrast to this earlier statement, phosphoric acid alone also acts as a catalyst for certain olefins can be used if very specific conditions are met. These conditions are generally with respect to the reaction temperature above the conditions of in Germany developed processes with other catalysts, but essentially, also with regard to of pressure, below the practically used conditions of that developed in America Process that has remained technically insignificant.

For the successful implementation of the carboxylic acid synthesis with phosphoric acid alone as a catalyst, as in the case of the last-mentioned known processes, it is important that the addition of the carbon oxide to the olefin is carried out in the absence of free water, ie working with a phosphoric acid which contains less water than the compound P ₂ O ₅ -5 H ₂ O corresponds. Accordingly, at least 90%, preferably 95 to 100%, orthophosphoric acid or its even lower water derivatives, such as pyrophoric acid or higher polyphosphoric acids or mixtures thereof,

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be used. (For the composition of the condensed phosphoric acids, see »Chemical Reviews ", Vol. 58, p. 324 [1958].)

The temperatures required when working with phosphoric acid are generally higher than when using the catalysts preferred in the known processes mentioned last. Man operates at temperatures of about 50 to 150 ° C, but the higher range in terms of the corrosion phenomena that are already becoming significant are avoided as far as possible. The optimum with reference on synthesis conditions on the one hand and avoidance of corrosion phenomena on the other hand is at a temperature of 75 to 95 ° C is reached.

As far as the carbon oxide pressure is concerned, a pressure of 1 to 250 atmospheres can be used, preferably 10 to 100 at are applied.

The quantitative ratio between olefin and phosphoric acid must be chosen in the process that at least 1 mole of phosphoric acid is applied to 1 mole of olefin. Generally will one uses more than 2 mol, preferably 4 to 8 mol of phosphoric acid per 1 mol of olefin. It can but in certain cases it may be advantageous to use even more phosphoric acid.

Under these conditions certain olefins can be produced with satisfactory to very favorable results hi carboxylic acids are converted. These are olefins with 5 to 12 carbon atoms, it doesn't really matter whether they are straight, branched or cyclic. Good up Very good results are obtained with normal olefins with 5 to 10 carbon atoms, branched olefins this carbon number range, e.g. B. 2-methylpentene-1 and trimerpropene, and with cyclic olefins, e.g. B. octaline or cyclododecatriene achieved.

The inventive method offers the particular advantage that the reaction mixture after the end of the carbon dioxide deposition, it separates itself into two layers, the upper one of which is the desired one Contains carboxylic acids. The lower layer is the catalyst, which is fed back into the process will.

By using concentric phosphoric acid as a catalyst after the carbon dioxide has been incorporated delamination which occurs naturally without the addition of water differs Working method very much from working with the previously claimed catalysts that result from only allow the reaction product to separate out again after adding water.

The concentrated phosphoric acid is under the conditions according to the invention of the carboxylic acid synthesis capable of releasing the chemically bound water in it to form the carboxylic acids that are then no longer bound to the phosphoric acid in the reaction product.

The release of chemically bound water is with the concentrated phosphoric acid catalyst made possible by the partial transition from orthophosphoric acid to pyrophosphoric acid, which is less watery or even higher molecular weight polyphosphoric acids.

Of course, the reaction system must also be used in the new procedure according to the invention Formation of the carboxylic acids Add stoichiometrically required amount of water. This can be broken down into various Realize in a manner and at different times, e.g. B. can add the water advantageously take place after the completion of the incorporation of the carbon monoxide, because this still separates the layers is favored.

Another particular advantage of the method according to the invention is that because of this easy separation of layers can also work in one stage, which is important with regard to a fully continuous implementation of the process is. In this case, the procedure is to use a catalyst for the synthesis which is one of the the amount of olefin to be converted has a corresponding higher phosphorus pentoxide content. One then leads that amount of water during the reaction together with the olefin or also separately therefrom a, which is stoichiometrically required for the formation of the carboxylic acid.

The separation of the layers can also be achieved by adding low-boiling hydrocarbons, e.g. B. from technical hexane, are favored as a diluent.

Besides this easy separability of phosphoric acid, its comparatively low price is one of the reasons another advantage of the new process. However, its advantages only come into their own when if the material of the reaction vessels and the temperature are coordinated in such a way that none significant corrosion occurs.

example 1

In a 5 l V4A autoclave with magnetic stirring, which was charged with 985 cm ³ (= 19 mol) of 100% phosphoric acid and was under a CO pressure of 100 atm, were at a temperature of 85 to 90 ° C 336 g (4 mol) of 1-hexene, diluted with 750 cm ^{3 of} technical η-hexane, were injected within IV2 hours. After a total of 8 hours, the reaction mixture was admixed with a further 500 cm ^{3 of} η-hexane and the amount of water stoichiometrically required to form the carboxylic acid (3 mol at 75% yield), the catalyst being completely separated off.

371 g of carboxylic acids were isolated from the organic layer via their alkali salts. As a fine fractionation showed, these were 87 _{% C 7} acids (b.p. _2O 110 to 112 ° C.) and 13% C ₁₃ acids ( _{b.p. 20} 170 to 180 ° C.) _3, corresponding to a total yield of 74 ° / », based on the olefin used. The separated catalyst was used for three further experiments with equal success.

Example 2

a) Under the experimental conditions described in Example 1, 392 g (4MoI) of 1-heptane were reacted ^{using 985 cm 3 of 100% phosphoric acid.} The reaction mixture was ^{diluted with 500 cm 3 of} technical grade hexane in order to promote the separation of the layers. After the catalyst had been separated off, 437 g of carboxylic acids were obtained in the work-up via the alkali metal salts. Due to the acid number (AN = 363), more than 90% of these consisted of C ₈ acids (calculated AN = 389), corresponding to a total yield of 77%, based on the olefin used. The separated catalyst, from which the water removed for the formation of carboxylic acid was fed back, was used under the same conditions for four further batches without its activity being reduced.

b) The reaction of 1 mole of heptane-1 with 1104 g of a catalyst of the composition 4 H ₃ PO ₄ · 4 H ₄ P ₂ O ₇ (corresponding to a P ₂ O ₃ content of 77.2%) under the same conditions as under a) led to a yield of carboxylic acids of 52 ⁰ Zo, based on the amount of olefin used.

Example 3

The procedure was as in Example 1, but the starting material used was a C _c -C ₈ fraction of an olefin-rich cleavage product which predominantly contained unbranched olefins. During the conversion of 400 g of this fraction, after adding 500 cm ^{3 of} technical-grade η-hexane to the reaction mixture and separating off the catalyst, 390 g of carboxylic acids were isolated via their alkali metal salts. They consisted of 95 ⁰ Zo of C ₇ , C ₈ and C ₉ acids, corresponding to a total yield of 68 ⁰ Zo, based on the amount of olefin used.

The separated catalyst, to which the water removed for the formation of carboxylic acid is fed back was, under completely constant conditions for five further approaches with partially even better Success (batch 6: 76% yield) use again. The catalyst could be separated off speed up short centrifugation considerably.

Example 4

^{500 cm 3} (= 936 g) of 100 ° C phosphoric acid were introduced into a V4A magnetic stirrer autoclave with a capacity of 21 and, at a CO pressure of 100 at and a temperature of 140 to 145 ° C, 2 mol (= 224 g) octene 1 injected. The reaction mixture obtained after a test period of 3 hours was Za ¹ cm ³ mineral spirits and the stoichiometrically required amount of water for the formation of carboxylic acids (2 mol) was added with 500, wherein the catalyst is completely separated.

The carboxylic acids formed were isolated from the organic layer by fractional distillation in vacuo. The total amount was 226 g, of which 95 <> / o to C ₉ acids (bp. 139 to 141 ° C _2O) and 5% on C ₁₇ acids. The overall yield, based on the olefin used, was 72 ⁰ Za.

With the catalyst originating from the first batch were in a further experiment under the same conditions again 2MoI oct-1 with Carbon dioxide implemented. Carboxylic acids could again be isolated in a yield of 73% will.

The series of tests was carried out with constant reuse of the catalyst for a total of five tests extended, with equally good yields being achieved up to the end.

Example 5

a) In a 2-liter V4A magnetic stirrer ^{autoclave charged with 620 cm 3 of} 100 ° C phosphoric acid, 168 g (2 Mol) 2-methylpentene-1, diluted with 250 cm ³ η-hexane, injected. After a total of 5 hours, the reaction mixture was ^{treated with 500 cm 3 of} η-hexane and, after the catalyst had been separated off, worked up as usual.

200 g of carboxylic acids were isolated. They consisted of 77 ⁰ Zo of approximately equal proportions of the two tertiary C ₇ acids α, α-dimethylvaleric acid and a-methyl-a-ethyl-butyric acid and 23 ⁰ Zo of C ₁₃ acids. The overall yield, based on the olefin used, was 81 ⁰ Zo.
The series of tests was extended to a total of four tests, each time reusing the catalyst without losing any of its activity. The water withdrawn for the formation of carboxylic acid was repeatedly fed to the catalyst.

ίο b) In another approach were 85 cm ^{3 fl} Zoiger phosphoric acid at a temperature of 90 to 100 ⁰ C and a CO pressure of 100 atm reacted 2MoI 2-methyl-pentene-l with the 500th After a total of 6 hours' reaction time, only 53 g of C ₇ acids = 20 ⁰ Zo, based on the olefin used, were isolated in the usual work-up using the alkali metal salts.

Example 6

In a 2-1 magnetic stirrer ^{autoclave which was charged with 620 cm 3 of} 100 ^{0 zoiger phosphoric acid, 0.5 mol of octalin, diluted with 75 cm 3} η, were at a temperature of 75 to 85 ° C. and a CO pressure of 50 at -Hexane, implemented. After the catalyst had been separated off, 67 g of decalincarboxylic acid-9 = 74 ⁰ Zo, based on the olefin used, were isolated in the work-up via the alkali metal salts.

In a second approach reusing the separated from the first approach catalyst, to which the extracted carboxylic acid to form water was supplied again, the yield was 93 even Zo ⁰ C _g-acids, based on 0.5 mol of Oktalin.

Example 7

The procedure was as in Example 6, but at a temperature of 80 to 90 ° C. and a CO pressure of 100 atm, the olefin was 2 mol of cyclododecatriene-1,5,9, diluted with 300 cm ^{3 of} technical grade n-heptane. The reaction mixture obtained after a total of 5 hours was admixed with IV2MOI of water to completely separate off the catalyst, and the carboxylic acids were separated off from the organic layer via their alkali metal salts. 256 g = 62 ⁰ zo of monocarbons solid at room temperature

4S organic acids with the empirical formula C ₁₃ H ₂₀ O ₂ can be isolated. It is a mixture of isomeric perhydroacenaphthenecarboxylic acids.

The test series was extended to a total of six tests with reuse in each case of the catalyst without losing any of its activity.

Example 8

a) In a 2-1-Magnetrührautoklav, ³ 100 ⁰ Zoiger phosphoric acid was charged with 500 cm, were at at a CO pressure of 100 and injected at a temperature of 100 ° C over 40 minutes 252 g (2 mol) of trimeric . After a total of 9 hours, the reaction mixture was admixed with 500 cm ^{3 of} technical grade hexane and, in order to separate off the catalyst completely, with 1 mol of water. When the organic layer was worked up via its alkali metal salts, 176 g of C ₁₀ acids = 51 ⁰ Zo, based on the olefin used, were isolated. b) In a second batch, a further 2 moles of trimerpropene were reacted at a temperature of 126 ° C. in the presence of 500 cm ^{3 of} 85 ° C. phosphoric acid at a CO pressure of 100 atm. After ins-

The reaction mixture was worked up as usual for a total of 8 hours. Only 21 g of C ₁₀ acids = 6.1 * / <>, based on the olefin used, could be isolated. The separated catalyst was green. The experiment was extended to 100 hours without the catalyst losing any of its activity. During this test period, a total of 21kg (corresponding to 250MoI) were converted into 2-methylpentene-1

colored, a phenomenon which suggests strong corrosion 5 19.5 kg of C ₇ acids and 2.5 kg of C ₁₃ acids.

Example 9

In another attempt, 2-methylpentene-1 was used as the olefin in a continuous single-stage Working method implemented. The cylindrical reaction vessel, made of V4A steel and equipped with an effective magnetic stirrer, had a capacity of 51 and had holes in the bottom with valves for feeding the catalyst and for injecting olefin and water. In the upper Half of the electrically heated pressure vessel was fitted with another valve from which the Reaction mixture could be continuously withdrawn during the experiment, with one in the autoclave Fluid amount of about 3.51 was maintained.

The experiment was carried out with the carbon dioxide pressure kept constant at 80 atm and a temperature of 85 to 90.degree. The catalyst circulating in the system had a phosphorus pentoxide content of 74% and had a composition of 6H ₃ PO ₄ - IH ₄ P ₂ O ₇ . The amount of catalyst fed hourly to the reaction vessel by means of a pressure feed pump was about 11, corresponding to about 20 mol of catalyst of the specified composition. At the same time, 210 g (corresponding to 2.5 mol) of 2-methylpentene-1, diluted with 400 cm ^{3 of} technical-grade η-hexane, were injected per hour. The amount of water supplied at the same time was 36 g (2 moles).

The reaction mixture corresponding to the added amounts of the reactants was removed from the pressure vessel and transferred to a sedimentation vessel, where the layers were separated. The catalyst obtained as the lower layer was fed back into the process, while the upper organic layer was worked up to the carboxylic acids. This work-up was carried out in the usual way using the alkali metal salts. The yield of carboxylic acids, based on the olefin used, was on average 80% greater than theory. On the basis of the result of the fine fractionation, the carboxylic acid _{mixture obtained consisted of 75% tertiary C 7} acids and 25% of C ₁₃ acids.

Claims (7)

PATENT CLAIMS: 1. A process for the preparation of carboxylic acids from straight-chain, branched or cyclic olefins having 5 to 12 carbon atoms, carbon oxide and water at temperatures below 150 ° C and elevated pressure in the presence of phosphoric acid as a catalyst, characterized in that the catalyst is at least 9O ° / o, preferably 95 to 100 ⁰ / o orthophosphoric acid or its water poorer derivatives, such as pyrophosphoric acid or higher polyphosphoric acids, or mixtures thereof be used. 2. The method according to claim 1, characterized in that one at a temperature of 50 to 150 ° C, preferably from 75 to 95 ° C, works. 3. The method according to claim 1 and 2, characterized in that at a pressure of 1 to 250 at, preferably from 10 to 100 at, works. 4. The method according to claim 1 to 3, characterized in that more than 2 mol Phosphoric acid, preferably 4 to 8 moles of phosphoric acid, used per 1 mole of olefin. 5. The method according to claim 1 to 4, characterized in that after completion of the carbon oxide deposition adding as much water as necessary for the stoichiometric formation of carboxylic acid is, whereupon the organic, the carboxylic acid containing from the inorganic, separating the catalyst-containing layer. 6. The method according to claim 5, characterized in that the layer separation by adding a diluent, e.g. B. a low-boiling hydrocarbon, favored. 7. The method according to claim 1 to 4, characterized in that one with continuous Working together the stoichiometric amount of water required to form the carboxylic acid with or separately from the olefin. ι 309 597/333 5.63