DE1443732A1 - Process for the preparation of carboxylic acid esters of unsaturated alcohols - Google Patents

Description

Applicant: The Distillers Company Limited, 12, Torphichen Street, Edinburgh 3, Scotland

"Process for the preparation of unsaturated carboxylic acid esters Alcohols "

The present invention relates to the preparation of esters of unsaturated alcohols.

The production of esters of unsaturated alcohols by the oxidation of an olefin in a carboxylate ion and carboxylic acid containing solution in the presence of a platinum group metal as a catalyst has already been proposed been. The oxidation can be carried out using oxygen as an oxidizing agent; also can the oxidation component of a redox system are used, and the reduced component can be recovered either in situ or outside the reaction environment by oxygen be oxidized and can be used again in the process. In either case, the oxygen is too Converted to water. Heretofore it has been taught that in order to obtain an economically acceptable yield of the ester it is necessary to carry out the process under almost anhydrous conditions and the necessity that arises therefrom the almost complete removal of water either from the reaction mixture or from the reoxidized one Redox system, to avoid the presence of water in the reaction mixture, increased the process costs

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DEUTSCHE BANK AO .. HARlURC 66/11852

POST CHECK HAMBURG 1173 30

In accordance with the present invention, it has now been found that acceptable yields can be obtained when in the presence water is used, provided that the process is carried out under increased pressure. Furthermore, it has been found that with certain reaction mixtures, the presence of water even increases the rate of the reaction and the effectiveness of the process, provided that increased pressure is applied.

According to the invention, a process for the preparation of esters of unsaturated alcohols is therefore disclosed, which therein consists that a Cp to Cg olefin of the general formula

R ₁ R ₃

C = C
R ^ H

in which R ₁ , R ₂ and R _{5 are} alkyl radicals or hydrogen atoms in a suspension or solution that contains carboxylate ions, a carboxylic acid, a metal or a metal compound of the platinum group as a catalyst and water in a concentration of up to about 25 vol .- ^, is oxidized at a pressure above atmospheric.

The olefin can be, for example, propylene or ethylene. Ethylene is preferred.

The carboxylic acid can be, for example, acetic acid or propionic acid.

The carboxylate ion preferably corresponds to the carboxylic acid and is added to the reaction mixture in the form of a salt of the carboxylic acid, e.g. an alkali or alkaline earth or copper salt added. The carboxylation ion can also be carried out in situ in the Reaction mixture can be formed from the carboxylic acid by adding a suitable base, e.g. an alkali metal or Brial alkali metal base or a strong organic base such as

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e.g. a tertiary amine.

The platinum group catalyst may, for example, be palladium metal as such or a palladium salt such as palladium-II chloride or palladium-II-acetate.

Oxidation can be achieved by introducing molecular oxygen be carried out in the reaction mixture, suitably in the form of air, and / or by introducing a redox system, e.g. a ferric / ferrous or copper-IIl / copper-II system, the latter being preferred.

The reaction can also be carried out in the presence of halogen ions which can be added in the form of metal salts. The copper-IIl / copper-II redox system is on best used in the presence of chloride ions, in which case the carboxylate and halogen ions of the reaction mixture in the form of various metal salts, one of which is a copper salt, for example as a mixture from sodium chloride and Rupfer III acetate.

The process is carried out in the presence of water, suitably in concentrations of from 0.5 to about 25 $ by volume and preferably in concentrations in the range of 1-10 vol. The water can be added to the reaction mixture as it is fed the starting materials are introduced, or the water of reaction can be allowed to accumulate in the system, whereby the addition of further amounts of water is not necessary. The water of reaction is formed in the reaction mixture, when the reaction is carried out in the presence of molecular oxygen and is also formed during the separation th oxidation of the redox system. In the latter case, can the water returned with the re-oxidized redox system will. When the reaction product is withdrawn and distilled to remove the unsaturated ester overhead, the residue containing the water of reaction can be recycled to the reaction in a sufficient amount Amount to keep the water concentration at the desired

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to maintain the highest level. In the 3PaIl where the unsaturated Ester continuously directly from the reaction mixture is distilled off, the water concentration can either be distilled together with the product or can be controlled by continuously withdrawing a calculated amount of the liquid reaction mixture.

The process is carried out under pressures above atmospheric, e.g., pressures up to about 200 atmospheres and preferably between 3 and 50 atmospheres.

Suitable reaction temperatures are those between 50 and 180 ⁰ O, wherein temperatures are preferably in the range 60-130 ⁰ C. The use of additional polar solvents, for example dimethylformamide or acetonitrile, is also within the scope of the invention.

The process is preferably carried out continuously by adding the olefin under pressure to the reaction mixture is conducted, together with new carboxylic acid, Carboxylate ions, the platinum catalyst, the redox system and additional water, if necessary, and the ester formed is continuously removed. The ester can can be obtained from the reaction product e.g. by fractional distillation. In one embodiment, a Portion of the liquid reaction mixture continuously withdrawn and subjected to a fractional distillation, to remove the unsaturated ester as the top fraction, while part of the residue from the column to the Reaction is returned. Otherwise, the unsaturated ester formed can continuously flow out of the reaction mixture be distilled off, e.g. by gin excess of the gaseous olefin or the mixture of olefin with oxygen and / or an inert gas is passed through the reaction mixture; in this case, it is preferable that the unreacted Olefin circulated.

If a redox system is present, this can be caused by oxidation regenerated with molecular oxygen in a separate stage. Otherwise the redox system can partially or fully regenerated in situ by introducing molecular oxygen with the reaction mixture. Air or other oxygen-containing gases can be used for the supply of oxygen in any case will.

The process according to the invention is further illustrated below by the following examples. In the examples are all parts given as parts by weight.

example 1

For comparison, a mixture of 60 parts was copper acetate monohydrate III, 25 parts of sodium chloride and one part of palladium-II-chloride (PDE ₂₎ in 500 parts glacial acetic acid, to which 20 parts of water were added at 60 ⁰ G in the presence of ethylene at stirred at one atmosphere pressure. 4.3 parts of ethylene were absorbed over 197 minutes. The reaction product contained 1.1 parts of vinyl acetate and 4.2 parts of acetaldehyde. The yields of vinyl acetate and acetaldehyde, based on the absorbed ethylene, were 8 and 61 $, respectively.

Example 2

The reaction described in Example 1 was repeated by stirring at 60 ⁰ C a mixture of 60 parts of copper acetate III, 18 parts of sodium chloride and a portion palladium _Ί dium-II-chloride in 500 parts of glacial acetic acid, to which 20 parts of water were added , in the presence of ethylene at a pressure of 3.2 atmospheres. In the course of 103 minutes, 4 _{tons of} 4 parts of ethylene were absorbed. The reaction product was fractionally distilled and contained 4.1 parts of vinyl acetate and 3.3 parts of acetaldehyde. The yields of vinyl acetate and acetaldehyde, based on the amount of ethylene absorbed, were therefore

80 980 9/1 141 ~ ⁶ ~

30 and 48%, respectively. This example shows how to use an increased pressure in the presence of water in accordance with the present invention leads to an improved yield leads to vinyl acetate.

Example 3

■ A mixture of 60 parts of copper (III) acetate monohydrate, 18 parts of sodium chloride and one part of palladium-11-chloride in 500 parts of glacial acetic acid and 20 parts of water was ^{toe at 60 °} C. in the presence of ethylene at a pressure. Stirred for 10 atmospheres. After 73 minutes the sealing mixture was cooled. The reaction product contained 5.6 parts of vinyl acetate and 2.5 parts of acetaldehyde »

Example 4

The reaction described in Example 3 was repeated at different temperatures. Table 1 shows the temperature the reaction time and the yield of vinyl acetate, based on the amount of ethylene absorbed *

temperature ⁰ G time (min.) Yield ^a ß> 80 100 53 Tab. 1 96 60 59 110 20th 62 124 20th 63 Example 5

A mixture of 60 parts of copper (III) acetate monohydrate, 18 parts of sodium chloride and 1 part. Palladium-II-chloride in 520 parts of a mixture of glacial acetic acid and water was at 96 - 10 atmospheres stirred 10O ⁰ C in the presence of ethylene at a Druck.von. Table 2 shows the yield of vinyl acetate as a function of the water concentration

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tration in the water-acetic acid mixture. Table 2

water
Volume $ yield
* 0 37 4th 59 9 40 20th 15th

Example 6

The reaction described in Example 3 was repeated at 100 ⁰ G with 4 parts of palladium-II-chloride instead of one part. 4.9 parts of ethylene were absorbed over the course of 60 minutes. The reaction product contained 9.5 parts of vinyl acetate. The yield based on ethylene absorbed was

Example 7

The reaction described in Example 3 was repeated in the presence of 12 parts of sodium acetate. In the course of 3.2 parts of ethylene were absorbed in 60 minutes. The reaction mixture contained 5.3 parts vinyl acetate. The yield based on the amount of ethylene absorbed was $ 54.

Example 8

A mixture of 110 g of anhydrous copper (III) acetate, 40 g of sodium chloride, 2 g of palladium (II) chloride, 1000 g of acetic acid and 10 g of water was introduced into a stirred reaction vessel with a capacity of 1 liter per hour. The reaction vessel was maintained at 100 ⁰ C and ethylene was fed with the proviso that a pressure was maintained lbs./sq.inch of 100th The reaction mixture was continuously flowing out of the reaction vessel

44 "3-732

deducted at a rate of about 1 liter per hour.

The molar yields of vinyl acetate and acetaldehyde obtainable by this method were $ 40 and $ 4, respectively the theory, based on the converted ethylene. The yield in terms of space and time of vinyl acetate was 12 g per liter per hour.

Acetaldehyde and vinyl acetate were separated from the reaction product by fractional distillation and the remaining used catalyst ^{mixture was treated in air at 80 0} O under a pressure of 100 lbs / sq. Inch to reduce the copper (II) ions to the copper (III) oxidation stage to oxidize.

Example 9

The procedure of the previous example was repeated, but the amount of water fed in per hour was reduced to 50 g increased.

The molar yields of vinyl acetate and acetaldehyde obtainable under these conditions were 60 and 60, respectively. 15 $ of the theory, based on the converted ethylene and the yield per space and time of vinyl acetate was 16.0 g per liter per hour.

The yield per unit of space and time can be increased by increasing the feed rate of the reaction mixture into the reaction vessel.

For comparison, it should be noted that if the procedure of this example carried out under atmospheric pressure is * the Hätiptreaktionsprodukt is acetaldehyde and the yield on vinyl acetate less than $ 10 of theory on the implemented

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Claims (22)

Claims 1.) Process for the preparation of esters of unsaturated alcohols by oxidizing an olefin of the general formula R ₂ H wherein IL, Rp and R, alkyl radicals or hydrogen atoms represent in a suspension or solution containing carboxylate ions, a carboxylic acid and a A catalyst from the platinum group, characterized in that the reaction mixture contains water in one concentration contains up to about 25 vol .- # and the reaction is carried out at pressures above atmospheric pressure will. 2.) Process according to claim 1, characterized in that the catalyst is palladium or a palladium-II salt iet. 3.) Process according to claim 2, characterized in that the catalyst is palladium-II chloride or acetate. 4.) Process according to one of the preceding claims, characterized in that the olefin is propylene or ethylene. 5.) Method according to one of the preceding claims, characterized in that the carboxylic acid is acetic acid. 6.) Method according to one of the preceding claims, characterized characterized in that the carboxylate ion gives the reaction mixture in the form of a salt of the corresponding carboxylic acid is added. 7 ·) Method according to claim 6, characterized in that the carboxylate ion is an acetate and to the reaction mixture 80 990 9/1141 -2- Schung added as alkali or alkaline earth or copper acetate will. 8.) Method according to one of claims 1-5, characterized in that that the carboxylate ion is formed in situ in the reaction mixture from the carboxylic acid by adding a base will. 9 ·) Process according to claim 8, characterized in that the base is an alkali or alkaline earth base · 10.) Method according to one of the preceding claims, characterized in that that the reaction is carried out in the presence of oxygen 11) Method according to one of the preceding claims, characterized in that that the reaction takes place in the presence of a redox system is carried out· 12.) The method according to claim 11, characterized in that the Redox system is a copper-IIl / copper-II system. 13.) Method according to one of the preceding claims, characterized in that that the reaction is carried out in the presence of halogen ions 14 · -) Method according to claim 13, characterized in that the Halogen ion and carboxyl atradical to the reaction mixture in the form of a mixture of sodium chloride and cupric acetate be added 15.) Method according to one of the preceding claims, characterized in that that it is carried out in the presence of water in a concentration in the range of 1-10 vol .-? 6. 16.) Method according to one of the preceding claims, characterized in that that it is carried out at a pressure between 3 and 50 atmospheres. 17.) Method according to one of the preceding claims, characterized in that -3-8 0 9809/1141 U43732 indicates that it is carried out within the temperature range of 50-180 ^° C. 18.) Method according to one of the preceding claims, characterized characterized in that it is carried out in the presence of an additional polar solvent. 19 ·) Method according to claim. 18, characterized in that that the additional polar solvent is dimethylformamide or acetonitrile. 20.) Method according to one of the preceding claims, characterized in that the method is carried out continuously will. 21.) Method according to claim 20, characterized in that part of the liquid reaction mixture is continuous withdrawn and subjected to a fractional distillation to remove the unsaturated ester and the residue is recycled to the reaction. 22.) Method according to claim 20, characterized in that the unsaturated ester formed is continuously distilled off from the reaction mixture by passing it through an excess amount of ethylene, ethylene-oxygen mixture or an inert gas through the reaction mixture. 23 ·) Process according to one of the preceding claims, characterized in that the redox system is at least partially regenerated by oxidation in a separate stage »