RU2218325C2 - Amine production process - Google Patents

Abstract

FIELD: industrial organic synthesis. SUBSTANCE: invention relates to producing amines useful in obtaining therapeutic preparations, anticorrosion coatings, and surfactants. Method is accomplished via electrocatalytic hydrogenation of pyridines, nitriles, oximes, and azomethynes in aqueous solution in electrolyzer provided with cathode activated by skeletal nickel catalyst and anode from magnetite or platinum. Aqueous solution contains nonoxidable alkali metal salts or combination of these salts with alkali. When single-cell electrolyzer is used, concentration of nonoxidable salts ranges between 1 and 15% and that of alkali between 0 and 5%; with double-cell electrolyzer with ion-exchange diaphragm 1-15 and 0-5%, respectively. EFFECT: increased lifetime of catalyst without decrease of yield based on current and substance. 6 cl, 5 tbl, 5 ex

Description

 The present invention relates to a method for producing primary and secondary amines used to obtain drugs, anti-corrosion coatings, surfactants (I.V. Kirilus. Electrocatalytic hydrogenation. - Alma-Ata: Nauka, 1981. P.105.).

 Known methods for producing amines by electrocatalytic hydrogenation of nitriles, pyridines, azomethines in a single-chamber or ion-exchange diaphragm two-chamber electrolyzer with a copper cathode activated by a skeletal nickel or cobalt catalyst and an anode of magnetite or platinum (A.P. Tomilov, I.V. Synthesis of Organic Preparations. - Alma-Ata: Nauka, 1982. P.39, 57, 62, 71).

 We found (see examples 2.5) that during the implementation of the aforementioned processes, relatively rapid passivation of the catalyst occurs: for 2 syntheses carried out without changing the catalyst, the hydrogenation rate decreases by more than 10%.

 The proposed technical solution allows to significantly increase the duration of the catalyst without decreasing the current and substance yield in the processes of electrocatalytic hydrogenation of nitriles, pyridanes and can be used to obtain primary and secondary amines with aliphatic, arylaliphatic, hetarylaliphatic radicals. The validity of Raney nickel is increased by more than 10 times. In addition, a catalyst used in electrocatalytic hydrogenation using aqueous solutions consisting exclusively of alkali can be used.

In the proposed technical solution, when carrying out hydrogenation in a two-chamber electrolyzer with an ion-exchange diaphragm, either aqueous solutions containing non-oxidizing salts of alkali metals and alkali or aqueous solutions containing only non-oxidizing salts of alkali metals can be used as catholyte. The concentration of non-oxidizing salts of alkali metals is 1-15 wt.%, The concentration of alkali 0-5 wt.%. The one-solution electrolyzer uses aqueous solutions containing non-oxidizing alkali metal salts and alkali. In this case, the concentration of non-oxidizing alkali metal salts is 1-15 wt.%, The alkali concentration is 1-5 wt.%. Exceeding the specified limits is possible, but does not make practical sense, since it does not lead to an improvement in the performance of the process. The process is carried out at a temperature of 20-60 ^o C.

 In the proposed technical solution for hydrogenation, pyridines, nitriles, oximes, azomethines can be used.

 The following examples illustrate the proposed technical solution.

 Example 1. Electrocatalytic hydrogenation in aqueous solutions containing non-oxidizing salts of alkali metals in a two-chamber electrolyzer with an ion-exchange diaphragm.

A Ni-Al alloy (Ni content 50 wt.%) In an amount of 10 g is processed according to (A.P. Tomilov, I.V. Kirilus. Cathodic syntheses of organic preparations. Alma-Ata: Nauka, 1982. P. 39, 57, 62, 71), then introduced into the cathode chamber of the electrolyzer with 400 ml of catholyte containing non-oxidizing salts. Anolyte is 250 ml of a 20% KOH solution. Platinum or magnetite anode. Ion exchange diaphragm MA-40. Turn on the current 5A and saturate the catalyst with hydrogen for 30 minutes, then the compound containing the unsaturated nitrogen-carbon bond is introduced into the cathode space. The current strength is increased to 20 A (current density 5 kA / m ² ) and the process is carried out with stirring until complete absorption of hydrogen.

 At the end of electrolysis, the catholyte is decanted from the catalyst and extracted with benzene. Amine isolation is carried out in the usual way (A.P. Tomilov, I.V. Kirilus. Cathodic syntheses of organic preparations. - Alma-Ata: Nauka, 1982. P. 39, 57, 62, 71). To study the operability of the catalyst, the process is repeated under the same conditions until the hydrogenation rate decreases by 10% compared to the initial one. A 10% reduction in hydrogenation rate is considered a loss of catalyst performance. The results are presented in table 1.

 Example 2. Electrocatalytic hydrogenation in aqueous solutions of alkalis in a two-chamber electrolyzer with an ion-exchange diaphragm.

 The syntheses are carried out analogously to example 1, using as a catholyte 5% solution of KOH. The results are shown in table 2.

Example 3. The synthesis is carried out in a two-chamber electrolyzer with an ion-exchange diaphragm on Raney nickel, which lost activity when used in the conditions of example 2. Catholyte-10% aqueous solution of Na ₂ SO ₄ . Temperature -25 ^o C. The results are shown in table 3.

 Example 4. The study of the health of the catalyst in the processes of electrocatalytic hydrogenation of compounds with an unsaturated nitrogen-carbon bond in aqueous solutions containing non-oxidizing salts of alkali metals in a single chamber electrolyzer.

 The synthesis is carried out analogously to example 1, using a single chamber electrolyzer and a solution containing non-oxidizing salts of alkali metals (see table 4).

 Example 5. The study of the health of the catalyst in the processes of electrocatalytic hydrogenation of compounds with unsaturated nitrogen-carbon bonds in aqueous solutions of alkalis in a single chamber electrolyzer.

 The synthesis is carried out analogously to example 1 in a single chamber electrolyzer using a 5% KOH solution (see table 5).

Claims (6)

1. The method of producing amines by electrocatalytic hydrogenation of pyridines, nitriles, oximes, azomethines in an aqueous solution in an electrolyzer with a cathode activated by a skeletal nickel catalyst, and an anode of magnetite or platinum, characterized in that the non-oxidizing alkali metal salts or said salts are used in the aqueous solution alkalis. 2. The method according to claim 1, characterized in that one-solution electrolyzers are used. 3. The method according to claim 2, characterized in that the concentration of the non-oxidizing alkali metal salt in the solution is 1-15 wt.%, The alkali concentration is 1-5 wt.%. 4. The method according to claim 1, characterized in that two-chamber electrolyzers with an ion-exchange diaphragm are used. 5. The method according to claim 4, characterized in that the concentration of the non-oxidizing alkali metal salt in the catholyte is 1-15 wt.%, The alkali concentration is 0-5 wt.%. 6. The method according to claim 1, characterized in that the hydrogenated compounds have aliphatic and / or heteroaromatic and / or aromatic radicals.

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