DE1282641B - Process for the preparation of carboxylic acid vinyl esters - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C 07c

BOIj

German class: 12 o-19/03
12 g-11/00

Number: 1282 641

File number: P 12 82 641.4-42 (F 49243)

Filing date: May 20, 1966

Opening day: November 14, 1968

The production of vinyl esters from ethylene, molecular oxygen and carboxylic acids in the presence of palladium oxide is known. Carrying out this process in the gas phase, however, falls short partly because of the slight tendency of the contact system to burn reactions to difficulties.

The invention now relates to a process for the preparation of carboxylic acid vinyl esters by reacting ethylene with molecular oxygen and aliphatic carboxylic acids in the gas phase in the presence of a catalyst which, in addition to an inert carrier material, contains palladium oxide, which is characterized in that the reaction is carried out in the presence of a catalyst , the at least one activator consisting of a salt of a strong inorganic base with an oxygen-containing acid, which is dissociated to less than 50% in normal aqueous solution, in an amount of 0.1 to 20 percent by weight, based on the total weight of ao support and catalyst, obtained is carried out at temperatures up to 25O ⁰ C above the boiling point of the carboxylic acid used.

The salts suitable as activators are compounds which are alkaline and neutral in aqueous solution or react slightly acidic. Their basic components are derived from strong inorganic bases, especially those of the alkali and alkaline earth hydroxide series. Their acidic components derive particularly from the Oxygen acids of boron, carbon, silicon, phosphorus, arsenic and antimony, the Molecules of these acids, apart from the elements mentioned, generally only contain oxygen and hydrogen atoms, on the other hand do not contain other atoms. Suitable salts are accordingly borates, carbonates, Silicates, ortho-, pyro- and metaphosphates, phosphites, arsenates or antimonates. Under oxo acids of the carbon are organic mono-, di- and tricarboxylic acids with preferably 1 to 10 carbon atoms such as acetic acid, propionic acid, n- and isobutyric acid, cyclohexanecarboxylic acid, oxalic acid, To understand succinic acid, citric acid and benzoic acid. If the acids are polybasic, so the acidic hydrogen atoms can wholly or only partially with the strong inorganic base have reacted with salt formation.

For example, the acetates and propionates are particularly suitable for use as activators of sodium, potassium and lithium, also calcium acetate, disodium phosphate, monopotassium phosphate, Sodium pyrophosphate, sodium metaborate, sodium bicarbonate.

Process for the production of
Carboxylic acid vinyl esters

Applicant:

Farbwerke Hoechst Aktiengesellschaft
formerly Master Lucius & Brüning,
6000 Frankfurt

Named as inventor:

Dr. Lothar Hörnig, 6000 Frankfurt-Schwanheim; Dr. Günter Mau,

Dr. Therese Quadflieg, 6230 Frankfurt-Höchst -

It is often particularly advantageous to use alkali or alkaline earth salts of the carboxylic acid which is to be reacted with ethylene to form the vinyl ester.

When using acetic acid as a reaction component, for example, the presence of Alkali acetates appropriate.

In many cases it is also preferred to use those salts which are used as the reaction component used carboxylic acid in the presence of water form a buffer system, which z. B. for the system Acetic acid-sodium acetate applies.

The precious metal-containing catalyst component consists almost exclusively or predominantly Part of palladium (II) oxide, PdO, but can optionally be admixed with oxide hydrates of PdO or other oxygen compounds of palladium.

The known porous materials with a large surface can be used as a catalyst carrier, z. B. coal, aluminum oxides or silicates, aluminum oxide-containing spinels, silicic acid, zeolites, Feldspars, pumice stones, clays or molecular sieves.

The salts can be applied to the PdO-containing catalyst in dissolved form, advantageously in aqueous solution are brought, after which the solvent is removed. But you can also first on the catalytic converter be formed by using decomposable salts of the metals mentioned, for example hydroxides or Carbonates, on the carrier or on the already PdO-containing catalyst and then with it the corresponding acids, e.g. phosphoric acid. The latter procedure is special then advantageous if the catalyst is extremely difficult in water »637/1297

3 4

or insoluble salts of the oxyacids of phosphorus filled with 30 mm inside diameter. Every hour

should contain phors. the at a pressure of 3 ata and a contact die The amount of activator added, depending on the temperature of 145 ° C, can contain 1.3 mol of vaporous vinegar

the type of salts used or after the other acid, 72 Nl ethylene and 10 Nl oxygen over the

Test conditions passed within wide limits 5 catalyst. The one leaving the reactor

vary. To activate and stabilize the gas mixture, it is depressurized and normalized

Sufficient amounts of catalyst are in the all-cooled. The vinyl acetate obtained in the condensate

common between 0.1 to 20, preferably 0.5 to is distillative of unreacted acetic acid and

10 percent by weight, calculated on the total weight of the water formed during the reaction,

of carrier and catalyst. io The raw materials not converted are

The reaction can be carried out under normal pressure, over- - after any purification - in the circuit

pressure or negative pressure in a temperature range reactor supplied again.

carry out the lower limit of the boiling temperature per liter of contact and per hour will be 38 g

the added carboxylic acid obtained from the applied vinyl acetate. The yield - based on

th pressure conditions and upwards by 15 used ethylene - is 93 percent by weight,

the decomposition temperature of the recovered vinyl. .

ester is limited. It is expedient to work with the comparative example

That the manufactured temperatures up to 250 ° C, advantageously to 150 ⁰ C, 325 ml according to Example 1, nitrate-free

in particular up to 100 ° C, above the boiling point of the contact substance, without the addition of phosphate in the

used carboxylic acid under the applied 30 same reactor and under the same reaction

Printing conditions. conditions as in Example 1 with 1.3 mol of steam

As the carboxylic acid, aliphatic carboxylic acids in the form of acetic acid, 72 Nl ethylene and 10 Nl acid are used. These include acetic acid and propionic acid. The space-time performance is only and n- and iso-butyric acid are particularly preferred. 5 g of vinyl acetate per liter of contact per hour, but also higher carboxylic acids, for example 25 yield 88 percent by weight. Valeric acid, can be used. . . ₁

Ethylene can be used in pure form or mixed with Example 2 Inert gases such as nitrogen, ethane or carbon oxides, 300 ml of the nitrate-free produced according to Example 1 can be used. The molecular oxygen can be concentrated with a contact substance in pure form or expediently in the form of air, an aqueous solution of 5.4 g of sodium propionate is used will. soaked and then soaked for 15 hours at 150 ° C

The residence time of the gas mixture on the catalyst dries. In a heatable steel reactor (30 mm

is generally not more than 100 seconds, internal diameter) the dried contact is at

preferably between 1 and 50 seconds. 2 ata and 160 ° C hourly with 1 mol of vapor

The process can be carried out batchwise, with especially propionic acid, 69 Nl ethylene and 10 Nl oxygen

whose success is also carried out continuously. The hot product mixture is treated on

will. The reactor outlet is relaxed and at room temperature

Reactants who cooled down in the course of the reaction. The condensate is converted into 6.3 g per hour

vinyl propionate can be isolated. The yield is> 90%

advantageous after separation of the reaction products, 40 based on the ethylene used, the space-time

be returned in the circuit to the contact zone. Output 21 g / l / h

This current can not be converted off. .

course products before introducing the reaction example

zone a stream of fresh starting material beige- 325 ml of the nitrate-free prepared according to Example 1

be mixed. 45 contact substance are concentrated with a

The inventive use of Aktiva- solution of monopotassium dihydrogen phosphate in gates in the PdO-containing catalysts draws water treated, so that the contact after the is particularly characterized by the fact that the performance of this drying 3.5 percent by weight of the potassium salt decatalysts significantly increases and the formation of holds. The catalyst is among those in Example 1 By-products, for example carbon oxides, equal to 5 ° listed reaction conditions with acetic acid, is reduced early. The catalyst shows practically ethylene and oxygen brought into contact. the end table has no tendency to form what is known as the condensate that accumulates, 12 g per hour hot zones obtained by burning carbon vinyl acetate. The yield is> 92% Hydrogen compounds are formed. the space-time output 36.9 g / l / hour.

Example 1 Example4

On 700 ml of a lithium-aluminum spinel in a heatable steel reactor with an inner

Spherical shape (mean diameter 4 mm) are 25 mm in diameter every hour at 140 ° C

24.2 g of palladium dissolved in dilute nitric acid and normal pressure over 300 ml of a contact that

nitrate applied. Within about 10 hours 60 of 2.5 percent by weight of palladium (II) oxide and

the nitrate-containing substance is subjected to a supply of air to 4 percent by weight sodium acetate for sinter-resistant

Heated about 500 ° C, then 2 hours with ger silica in spherical form (mean diameter

Treated pure oxygen at 500 ° C and about 3.5 mm) as a carrier, 0.9 mol vapor

Heated for 12 hours at 700 ^° C. with admission of oxygen. Acetic acid, 60 Nl ethylene and 12 Nl oxygen

325 ml of the nitrate-free contact is passed with a 65. From the product-concentrated solution of 10.6 g of Na ₂ HPO ₄ .12 H ₂ O mixture leaving the reactor, 8 g of vinyl acetate are obtained per hour, soaked in water and ^{dried at 150 °} C. for 15 hours. The yield is 92%, the space-time Output and in a U-shaped, heatable steel reactor 26.6 g / l / hour.

Claims (2)

Patent claims: 1. Process for the preparation of carboxylic acid vinyl esters by reacting ethylene with molecular oxygen and aliphatic carboxylic acids in the gas phase in the presence of a Catalyst which contains palladium oxide in addition to an inert carrier material, characterized in that that the reaction in the presence of a catalyst, the at least one activator consisting of a salt of a strong inorganic base with an oxygen-containing acid, which is in normal aqueous solution less than 50% dissociated, in an amount IO contains from 0.1 to 20 weight percent, based on the total weight of carrier and catalyst, at temperatures up to 25O ⁰ C above the boiling point of the carboxylic acid employed, is carried out. 2. The method according to claim 1, characterized in that that the reaction is carried out in the presence of a catalyst containing the alkali or alkaline earth metal salts contains the carboxylic acid as activator that is reacted with ethylene to form the vinyl ester, performs. Considered publications:
German publication No. 1196 644. 809 637/1297 11.68 0 Bundesdruckerei Berlin