SU990760A1 - Process for producing 2,2,6,6-tetramethyl-4-aminopiperidine - Google Patents

Description

(54) METHOD FOR OBTAINING 2,2,6,6,6-TETRAMETHYL4-AMINOPIPERIDINE

The invention relates to an improved process for the preparation of 2,2,6, b-tetramethyl 4-aminopiperidine, which is an intermediate in the synthesis of effective stabilizers of polymeric materials, as well as biologically active compounds.

Known methods for the preparation of aminopiperidine by electrochemical reduction of a mixture of 2,2,6, b-tetramethyl-4-oxopiperidine (TAA) and the hydroxylamine mineral salts and a mixture of 2,2,6, 6-tetramethyl-4-oxopiperidine (TAA) and nitric acid in solutions of mineral acids. The yield of the final product by substance is 95-99%, by current 20-83%.

The disadvantage of these methods is carrying out the process in a strongly acidic medium.

The closest in technical essence and the achieved effect is the method of obtaining aminopiperidine by electrochemical reduction of 2, 2,6,6-tetramethyl-4-hydroxyimopiperidine (azomethine derivative) in a strongly acidic aqueous medium at 15-20 ° C on various cathode materials. The yield of aminopiperidine by this method reaches 95% in substance and 20-55% in current.

The disadvantage of this method is the need to carry out the process in a strongly acidic environment, which, being aggressive, affects the process equipment, reduces its service life and requires additional costs for the corrosion shield. In addition, since electrolysis by a known method is carried out in a strongly acidic medium, it becomes necessary to automatically control the process.

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The purpose of the invention is to simplify the process technology and expand the raw material base.

This goal is achieved by offering the method of producing 2,2,6,6-tetramethyl-4-aminopiperidine by electrochemical reduction of azine 2,2,6,6-tetramethyl-4-oxopiperidine in aqueous solutions of alkali metal phosphate salts at 20-55s.

In the proposed method, aminopiperidine is obtained with a substance yield of 93-99% and in current - 30-88%. Electroreduction is carried out with the help of 30–10 A / dm current. Example. A lead cathode and a lead cathode are discharged into the electrolyzer, which is a glass cylindrical vessel with a jacket for temperature control, separated by a cation exchange Mambra brand MK-40, cathode and anode spaces; anode. The analyte is 20% sulfuric acid. 37.5 ml of a 1M solution of Na and 12.5 ml of a saturated solution are poured into the cathode space, and 2 g of azine 2.2, 6, b-tetramethyl-4-oxopiperdine are added with stirring. The process is carried out at a current density of 4 A / dm, and 20–25 C. At the same time, the aminopiperidine output is 98.7% in substance and 35.6% in current. The resulting product is a clear, colorless, transparent liquid. 78-79 with (7 mm Hg) 1.4699; 0.8966. EXAMPLE 2 Differs from Example 1 in that electrostating is carried out at a current density of 2 A / dm (current of 1 A). The yield of aminopiperidine in substance is 97.3% and in current. Example 3. Differs from Example 1 in that electroreduced is carried out at 50 ° C. Substance of aminopiperndia is 98.5%, current is 53.2%. Example 4. Differs from Example 1 in that 5 g of azine2.2.6 6-tetrmethyl-4-oxopiperid is subjected to electroreduction with the yield of the target product rio substance 99.0 % and on line 38.0%. EXAMPLE 5 37.5 ml of 1M UaHiPO4il2.5 ml of saturated solution are poured into the cathode space of the electrolyzer and 2 g of azine 2,2,6,6-tetramethyl-4-oxo-piperidine are added to it. The process at njfoTHOCTH current 4 A / dm ve) FLS on mercury at 20 s. The yield of aminopiperidine is 98.1% for the substance and 88.4% for the current. Example 6. Analogously to Example 1, electroreduction is carried out on cathodes of zinc, copper, tin, cadmium, rn algamine-free lead and copper. The substance yield of aminopiperidine varies between 93-99%. Example 7. It differs from Example 1 in that the process is carried out at a current density of 10 A / dm. Example 8: Differs from Example 1 in that 47.5 ml of a 1M solution and 2.5 ml of a 1M solution are poured into the cathode space. The yield of 2,2,6,6-tetramethyl-4-aminopiperidine substance by substance 97%, by current 68.6%. The use of the proposed method for the preparation of 2,2,6,6-tetramethyl-4-aminopiperidine will provide a higher yield of the target product, as compared with the known, an increase in the durability and reliability of the technology s. equipment, simplifying control over the process, the use of cheaper and more affordable: The invention of 2,2,6,6-tetramethyl-4-aminopiperdine by the electrochemical reduction of azomethine derivatives of 2,2,6,6-tetramethyl-4-oxopiperidine in an aqueous medium, characterized in that, with the aim of simplifying the process technology and. expansion of the raw material base, azine 2,2,6,6-tetramethyl-4-oxopiperid is used as the azomethine derivative and reduction is carried out in solutions of alkali metal phosphate salts at 20--53 ° C.

Claims (1)

Claim A method for producing 2,2,6,6-tetramethyl-4-aminopiperidine by electrochemical reduction of the azomethine derivatives of 2,2,6,6-tetramethyl-4-oxopiperidine in an aqueous medium, characterized in that, in order to simplify the process technology and. expansion of the feed base, the azine of 2,2,6,6-tetramethyl-4-oxopiperidine is used as the aeromethine derivative and the reduction is carried out in solutions of alkali metal phosphate salts at 20-5if C.