DE1269609B - Process and device for the production of saturated aliphatic or aromatic alpha, omega-dicarboxylic acids - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

German class:

Number:
File number:
Registration date:
Display day:

C07c

BOIk

12O-11

120-14

12h- 1

3rd October 1962

June 6, 1968

It is known to oxidize organic substances electrolytically. Serve as electrodes generally metal sheets, e.g. B. those made of nickel.

The invention relates to a process for the preparation of saturated aliphatic or aromatic α, ω-dicarboxylic acids, which is characterized is that an aliphatic or aromatic («-hydroxycarboxylic acid, which contains at least 3 carbon atoms, or its lactone on a hydrogen solution anode, compared to a calomel reference electrode at a potential that is 0.7 to 1.2 Volts more negative is held, is oxidized.

A hydrogen solution anode in the context of the invention is to be understood as an anode which is able to dehydrate the organic substance dissolved in the electrolyte and to store the hydrogen removed from the substance. The prerequisite for this is that the electrode is made of a material that has the property of a hydrogen activator. As soon as such an electrode has a sufficient potential with respect to the electrolyte, part of the accumulated hydrogen goes into solution ^{with the release of an electron as H + ion.} Suitable hydrogen solution anodes are, for example, those made of Raney nickel, platinum or palladium. It is expedient to use these materials to achieve a porous structure with carriers, e.g. B. coal, mixed use.

The potential of the hydrogen solution anode with respect to a calomel electrode must be between 0.7 and 1.2 volts, preferably at least 0.9 to 1.1 volts.

In principle, any metal cathode can be used as the cathode of the electrolytic cell according to the invention can be used. If a metal sheet cathode is used, it is necessary to use part of the To supply oxidation energy in the form of electrical energy from the outside.

It is particularly advantageous to use an oxygen solution electrode as the cathode in the method according to the invention to use. This is understood to mean an electrode that has the shape of a porous membrane and which is gaseous on the one hand Oxygen, e.g. B. in the form of air, while on the other side of the electrolyte is wetted. Suitable materials for the oxygen solution cathode are nickel oxide, charcoal, with special catalysts, e.g. B. spinels, is impregnated, or Raney metals, especially Raney silver.

According to the invention, -hydroxycarboxylic acids can process and apparatus for the production of saturated aliphatic or aromatic
α, ω-dicarboxylic acids

Applicant:

Farbwerke Hoechst Aktiengesellschaft
formerly Master Lucius & Brüning,
6000 Frankfurt

Named as inventor:

Dipl.-Phys. Dr. Otto Heuse, 6242 Kronberg;

Dipl.-Chem. Dr. Manfred Boldt, 6233 Kelkheim; Dipl.-Chem. Dr. Rudolf Wirtz,

6230 Frankfurt-Unterliederbach

with at least 3 carbon atoms are oxidized to the corresponding «, co-dicarboxylic acids. For example, eo-hydroxypropionic acid supplies malonic acid, ω-hydroxybutyric acid and succinic acid. According to the invention, forms from ω-hydroxycaproic acid Adipic acid. Likewise yields o-hydroxymethylbenzoic acid and p-hydroxymethylbenzoic acid Terephthalic acid. Instead of the co-hydroxycarboxylic acids their lactones, for example propiolactone or butyrolactone, can also be used which are converted into the corresponding hydroxycarboxylic acids in an alkaline electrolyte convert.

An aqueous, expediently an alkaline aqueous solution is used as the electrolyte. Particularly proven 1 to 6 n-alkali lye. Potash lye is preferred, however, caustic soda, lithium hydroxide solution or barium hydroxide solution is also suitable.

For economic reasons, the ω-hydroxycarboxylic acid in the electrolyte solution in as concentrated a form as possible. 12% to saturated Solutions are accordingly most suitable for the method of the invention. In principle, of course can also be used in lower concentrations.

Since the electrochemical processes during oxidation are independent of temperature, the process can can be carried out at any temperature at which the electrolyte is in liquid form is present. When producing malonic acid, the upper temperature limit of 100 ° C should not be exceeded otherwise decomposition of the reaction product is to be feared. For less sensitive ones Acids can raise the reaction temperature up to the boiling point of the electrolyte solution

809 558/381

Claims (4)

will. Higher temperatures are also basic, which is initially 480mAmp. After expiration of time also possible, but then it is necessary to use 440 mAmp. fraud. Between anode and cathode To avoid the evaporation of the solution, a voltage of 650 mVolt was initially applied Pressure to work, which measured the procedure, which slowly dropped to 60OmVoIt. That complicated in terms of equipment. 5 Anode potential was about 900 mVolt more negative The particular advantages of the method of the invention as the calomel reference electrode. tion consist in the fact that it was after the specified time in «,« - dicarboxylic acids found in good yield with ratio electrolytes 204 g of adipic acid, moderately low temperature allowed and that secondary. . reactions practically do not take place. This advantage io example / is particularly important in the production of malonic acid in a cell corresponding to that in example 1 to advantage, since this acid has been described in other ways, 104 g were dissolved in 6 η-potassium hydroxide solution difficult to manufacture. Another benefit of co-hydroxybutyric acid is electrolyzed. The current invention lies in the fact that the energy of the exothermic carried an average of 450 mAmp. with a moderate clamping oxidation reaction to a large extent in the form of a voltage of 600 mVolt. The anode potential was obtained from electrical energy. about 900 mVolt more negative than the calomial reference To carry out the process one can use an electrode. After 8 days of electrolysis for example the one in A b b. 1 above, 79 g of succinic acid isolated from the electrolyte serve direction. This consists of a vessel 1, be. One wall 2 of which is used as an oxygen solution cathode 20, Example 3 is designed as it is from the technology of the fuel " elements is known. In the vessel there is a power generating cell according to A b b. 1 became a perforated container 3 that comes with a kata- like this: lytically active electrode material 4 (hydrogen by impregnating a carbon membrane with a solution anode) is filled. The hollow space of the palladium chloride solution and reduction in the water vessel is filled by the electrolyte 5. The material stream was using a porous palladium electrode Calomel electrode 6 serves together with the Po an atomic ratio of palladium to carbon tentiometer7 to establish the potential between that of 1:50. It serves as an oxygen solution electrolyte 5 and the electrode 4 to control. cathode. One served as the hydrogen solution anode The electrical energy released during the reaction is made of Raney nickel gie leads to a current flow between the elec- tric nickel network. trode, which is controlled by the ammeter 8 The cell was filled with a solution of 28 g propionate and benefits the consumer. ketone charged in 200 g of 4 η potassium hydroxide solution. She delivers A b b. 2 shows a further device for a current of 110 mAmp. at 0.5 volts. That implementation of the method according to the invention. Instead of 35 the anode potential was about 850 mVolt more negative of or in addition to those previously discussed as the calomel reference electrode. After 14 days components, this device receives a nickel sheet - 13.8 g of malonic acid had formed, cathode 10 and a power source 11, from which the for. this process variant required electrical energy Example 4 energy for the oxidation is taken. The open 40 25.9 g of propiolactone were in 190 g of 4N potassium hydroxide solution tion 12 serves to dissolve the resulting from the reaction and put it in a cell according to A b b. 2 during remove the hydrogen from the cell. 8 days at 25 * C of the action of a current of Of course, the 200 mAmp. exposed. The potential of water travel also be carried out continuously, the broth electrode was about 85OmVoIt, that of the by placing the electrolyte 45 hydrogen separation electrode in a known manner about 1400 mVolt passes through a cell that has the above described more negative than that of the calomel reference electrode. To Contains electrodes and pumping around the electrode this time were 17.4 g of malonic acid in the solution lytlösung and a continuous separation of the found. Reaction products permitted. Example 5 Example 1 4.5 g of 4-hydroxymethylbenzoic acid were added in 190 g A cell according to Fig. 1 was dissolved in the following 4η potassium hydroxide solution and at 25 ⁰ C for 7 days Way produced: exposure to a current of 100 mAmp. in a The pores of a porous carbon membrane (middle cell exposed according to A b b. 2. The potential of the Pore size about 0.5 mm) were measured with a Raney 55 hydrogen solution electrode was about 900 mVolt, Silver alloy made of silver and aluminum in combination with the hydrogen separation electrode, for example ratio 1: 1 filled out. Then the Alu- 140OmVoIt became more negative than that of the calomeal reference minium dissolved in a known manner in an alkaline way. electrode. The solution was then acidified. This mechanically strong membrane served as an acidic The precipitate formed was used for removal solute cathode. The electrode had an upper surface of the remaining 4-hydroxymethylbenzoe- area of about 20 square centimeters. acid extracted with alcohol. There remained 2.07 g Raney nickel, crystalline terephthalic acid, served as the hydrogen solution anode, which was in the Nickemetz. The surface " the anode was also 20 square centimeters. Patent claims: In this cell were 264 g of co-hydroxycaproone 65 l. Process for the production of saturated acid, dissolved in 6 η-potassium hydroxide solution, introduced. The aliphatic or aromatic α, ω-dicarbon Electrodes were closed over a resistor, characterized in that sen. A current flowed for about 18 days, an ali- phatic or aromatic (o-hydroxycarboxylic acid containing at least 3 carbon atoms, or its lactone on a hydrogen solution anode, the opposite of a calomel reference electrode is held at a potential more negative by 0.7 to 1.2 Volts, is oxidized. 2. The method according to claim 1, characterized in that the conversion takes place in a cell, whose cathode is an oxygen solution electrode flushed with oxygen. 3. Process according to Claims 1 and 2, characterized in that ω-hydroxypropionic acid is oxidized to malonic acid. 4. Device for the electrochemical oxidation of -hydroxycarboxylic acids to α, ω-dicarboxylic acids, Consists of a cell that has a hydrogen solution anode and one with oxygen contains rinsed oxygen solution cathode that are electrically conductive with one another outside the cell are connected. Considered publications: Robert Müller, "General and technical electrochemistry of non-metallic substances" [Vienna 1937], Pp. 337 to 357. 1 sheet of drawings 809 558/381 5.68 0 Bundesdruckerei Berlin