DE1292651B - Process for the production of acrylic or methacrylic acid by the oxidation of propylene or isobutylene in a liquid solvent - Google Patents

Description

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The invention relates to a process for the production of solvents, according to the invention, acetic acid is used, of acrylic or methacrylic acid by oxidation of ■ which can also be replaced by other 1-alkanoic acids Is propylene or isobutylene in a liquid solution. You can z. B. Use propionic acid to the medium with molecular oxygen at a temperature caused by volatilization losses from 100 to 250 ° C and at least normal pressure 5 ring, or η-butter, isobutter, valerian, in the presence of a catalyst; it is therefore caproic, caprylic and capric acid. characterized in that the oxidation is carried out in a. As a catalyst, the process is used liquid alkanoic acid as a solvent in an invention manganese acetate.

Pressure of 1 to 200 at, advantageously 5 to 100 at, and it is advisable to use easily oxidizable starting materials,

in the presence of manganese acetate as a catalyst, the io such as acrolein, cyclohexanone, hexaphenylethane or can also contain an accelerator, acetone, or reactive oxidizing agents, such as and the resulting acid "in the usual ozone,. Peroxides, bromine or iodine, hydrogen bromide or Way. .... · to use hydrogen iodide as an accelerator.

Numerous processes are already known, according to which molecular oxygen can be used as air, also under to which olefins are fed by oxidation to the appropriate pressure, unsaturated acids are converted. The pressure should be sufficient for the reaction

In U.S. Pat. No. 2,369,182, there is a method of keeping the mixture liquid; it is 1 to 200 at; Press for the oxidation of unsaturated organic compounds - from about 5 to 100 at are preferably used, genes such as propylene or isobutylene with oxygen at The oxidation takes place at temperatures below

normal or elevated pressure in the presence of 20 about 100 ° C relatively slowly. With tempera hydrogen bromide As a catalyst to the corresponding doors above 300 ° C, the yields are proportionally unsaturated Carboxylic acids described. moderately bad; therefore, the oxidation in one

In contrast, in accordance with the procedure of the temperature SRON 100, particularly, the oxidation with manganese acetate as carried out at 125 to 25O ⁰ C invention.

Catalyst instead of hydrogen bromide, producing 25 Da at any required temperature of the percent Formation of unsaturated bromides, such as allyl bromide, tual degree of conversion from the amount of catalyst avoided and satisfactory yields can be achieved. depends, this should be chosen so that one Obtains the necessary rate of oxidation according to the process of the USA patent specification. the

2,373,240 is also hydrogen bromide as a catalyst suitable amount of catalyst, is 1 part, based on sator, but as starting materials are unsaturated 30 to the weight of the manganese, per 1 million parts Halides are used, but this makes halogenated solvents up to about 10 parts per 100 parts

. unsaturated acids are formed .... solvents; about 0.5 to 5 parts per 100 parts

According to the method of the German patent specification, solvents are preferred. 871147 are also unsaturated hydrocarbons The amount of propylene or isobutylene im

substances oxidized. This. The process differs but both solvents can vary in a wide range the starting materials as well as in the choice of the ken and can be used in implementation forms in which the Catalyst from that of the invention, since the simultaneous supply of oxygen and propylene or total oxidation in the presence of an isobutylene catalyst at rates approximately equal to that from free selenium and a fixed rate of oxidation conversion takes place, be almost zero, catalyst takes place. The other implementation 4 ° The process is batchwise or continuously conditions are not carried out with those of the invention, with various forms of contingent being comparable. detailed implementation are possible. If that

The older German patents 1118 183, 1123 312, solvents higher than those in "der Oxydation gebil-1132111,1145 602,1166174 and 1181193 relate to the acid boiling, the resulting acid is Proposals according to which olefins are distilled off continuously to give the corresponding 45. Used as a solvent Aldehydes, ketones and / or the aldehydes acetic acid are used, the reaction mixture is corresponding acids are oxidized. With all of them for the extraction of acetic acid and the resulting In this process, however, the reaction is carried out in unsaturated carboxylic acid by distilling off the catalyst in the presence a liquid catalyst mixture that liert. The recovered solvent and the unlike that of the invention, from a 50 catalyst residue can be returned to the cycle redox catalyst and a noble metal compound.

The reaction vessel consists of inert substances

Redox catalyst can form. According to the procedure or is lined with such, the Ausder Invention, however, only manganese acetate as clothing fabrics will have a high impact on the process Catalyst used; in addition, for these 55 the implementation is exercising. Stainless steel is used in known method an increased pressure is not generally used, while platinum in the absolutely necessary. The best wall material in terms of yield

Furthermore, 869 950 are likely to be in German patent specification. Vessels lined with silver are and U.S. Patent Nos. 2153 406, 2212 900, also useful. Other precious metals can 2,341,339 and 2,397,891, in which the uses 60 are also used, likewise titanium and formation of low molecular weight aliphatic carboxylic acids, aluminum, and ceramics, including glass like acetic acid, mentioned as solvent, oxy- and quartz.

dations described. After this procedure, the conversion time is set so that the however, the easily accessible 1-alkenes are not retained as the main part as unsaturated acids. Therefore Starting materials used, but aldehydes. 65 can be several hours or just a short one

The oxidation of propylene or isobutylene will take time such as 1 hour or less according to the process of the invention in a liquid The following examples serve to illustrate the Alkanoic acid carried out as a solvent. As the best invention.

example 1

a) In a pressure vessel, which is lined with platinum metal and has a capacity of 320 cm ^s , 1 g of manganese acetate tetrahydrate, which corresponds to 0.2 g of manganese, 1 cm ^{3 of} 48% aqueous hydrobromic acid, 100 cm ^{3 of} glacial acetic acid and 10 g of propylene introduced. 21 atm of air are forced into the vessel, and this is then ^{heated to 200 °} C. for 4 hours, ensuring that the reaction mixture is agitated. Working up the solution after the reaction has ended shows that 3.1 g of acrylic acid have been formed from the propylene. The rest of the propylene is largely unchanged. There is no smell of acrola in the solution.

b) The procedure is as in test a), but presses 14 at air, then increasing the pressure on at 56 and heated to 200 ⁰ C. After 2 hours of heating, the reaction mixture contains 3.2 g of acrylic acid. Distillation of below 200 ⁰ C boiling the reaction mixture shows that it (as determined chromatographically) from 3 ° / ₀ water, 2-bromopropane and there may be an acetone compound. The acetic acid is recovered almost quantitatively. The acrylic acid is obtained as the fraction boiling at 138 to 142 ° C. as the main oxidation product.

c) Experiment a) is repeated with the exception that the reaction is carried out in a stainless steel tube Steel carries out. Only 1% of the Propylene converted into acrylic acid, which is due to the inhibiting effect of stainless steel. By Doubling the amount of catalyst, 5% of the propylene is converted into acrylic acid.

d) Experiment a) is repeated, but the amount of manganese acetate and hydrogen bromine substance is doubled. This converts 22% of the propylene into acrylic acid; the rest of the propylene remains unchanged.

e) repetition of the experiment a) at different temperatures is as follows: The order conversion of propylene to acrylic acid is at 100 ⁰ C is less than 2% at 150 ° C 9%, at 25O ⁰ C at 8 ° / ₀ and at 300 ⁰ C less than 1%.

f) Experiment e) is repeated in the absence of hydrogen bromide. The reaction proceeds at the beginning somewhat slower, but the yield of acrylic acid is not adversely affected; it corresponds that of experiment e).

Example 2

Example 1 is repeated using 13.3 g of isobutylene in place of the propylene. It a mixture of acrylic acid and methacrylic acid resulted, as can be detected by gas chromatography could.

The recovery of the acids formed from the reaction mixture can, for. B. by azeotropic distillation take place.

Claims (4)

Patent claims: 1. A process for the preparation of acrylic or methacrylic acid by oxidation of propylene or isobutylene in a liquid solvent with molecular oxygen at a temperature of 100 to 250 ⁰ C and at least normal pressure in the presence of a catalyst, characterized in that the oxidation is carried out in a liquid Alkanoic acid as a solvent at a pressure of 1 to 200 at, advantageously 5 to 100 at, and in the presence of manganese acetate as a catalyst, which may also contain an accelerator, and the acid formed is separated off in the usual way. 2. The method according to claim 1, characterized in that the oxidation in vinegar or Propionic acid performs as a solvent. 3. The method according to claim 1 or 2, characterized in that the oxidation is carried out in the presence from 1 part to 10 parts of catalyst based on the weight of the manganese per 1 million parts carries out up to 100 parts of the solvent. G 4. The method according to any one of claims 1 to 3, characterized in that the oxidation in Presence of hydrogen bromide, bromine, hydrogen iodide, iodine, ozone or a peroxide as Accelerator performs.