CS277344B6 - Process for preparing N, N-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine - Google Patents

Abstract

The method for the preparation of N,N'-bis(2,2,6,6tetramethyl-4-piperidine)hexamethylenediamine by the reaction of hexamethylenediamine with 2,2,6,6-tetramethyl-4-piperidone and with hydrogen in an aqueous medium in the presence of a catalyst selected from the group including platinum, palladium, nickel and cobalt, at a temperature of 5 to 100°C and a pressure of 1 to 15 MPa, has been solved. The resulting reaction mixture freed from the used catalyst is cooled to a temperature of 5 to 35°C and the precipitated final product is isolated from it. He may have used it as an intermediate for the production of oligomeric polymer light stabilizers.

Description

The invention relates to a process for the preparation of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine. It is a known intermediate for the production of polyaminotriazine light stabilizers for synthetic polymers.

For the preparation of various N, N'-bis (2,2,6,6-tetraalkyl-4-piperidyl) diamines, the reaction of the corresponding diamine with 2,2,6,6-tetraalkyl-4-piperidone and hydrogen under pressure is generally used. and in the presence of a hydrogenation catalyst.

U.S. Pat. No. 4,104,248 describes a process for preparing N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) ethylenediamine using platinum supported on activated carbon as a catalyst and methanol as a solvent. The solution according to U.S. Pat. No. 4,605,743 uses palladium metal or its oxide as hydrogenation catalyst and water, up to C ₁₀ aliphatic alcohols, C ₂ to C 8 aliphatic glycols or mixtures thereof as the reaction medium. The solution works with the same solvents according to their mixture. The solution according to U.S. Pat. No. 4,607,104 also works with the same solvents, but it uses platinum metal, nickel or cobalt or their oxides as hydrogenation catalyst and uses 2,2,6,6-tetramethyl-4-piperidone in excess. In all the above processes, the obtained N, N'-bis (2,2,6,6-tetraalkyl-4-piperidyl) diamine is isolated from the resulting reaction mixture by filtering off the used hydrogenation catalyst and removing the solvent and impurities, including unreacted starting reactants, by vacuum by distillation. Said known processes for the preparation of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) diamines, including N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine have several significant shortcomings. These include, in particular, considerable energy and investment requirements related to the need for vacuum distillation of the resulting reaction mixture, the presence of significant amounts of impurities and unreacted starting materials in the final product, conditioned by close boiling temperatures, losses on the product in pre-drip, etc.

These shortcomings eliminate the process for the preparation of N, N'-bis (2,2,6 -,6-tetramethyl-4-piperidyl) hexamethylenediamine by the reaction of hexamethylenediamine with 2,2,6,6-tetramethyl-4-piperidone and with hydrogen in an aqueous medium. , in the presence of a catalyst selected from the group consisting of platinum, palladium, nickel and cobalt, at a temperature of 50 to 100 ° C and an amount of 1 to 15 MPa according to the invention. The essence of the invention is that the resulting reaction mixture, freed of used catalyst, is cooled to a temperature of 5 to 35 ° C and the precipitated final product is isolated therefrom.

The process of the invention is based on the surprising and as yet undescribed finding that N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine is indefinitely miscible with water at a temperature of about 66.5 ° C and very sparingly soluble in water at lower temperatures. Its solubility in water at 10 ° C is 1.2%, at 20 ° C 1.4% and at 40 ° C 3.8%.

The process according to the invention has several remarkable advantages in comparison with known processes. These include lower energy and investment intensity, high yield and purity of the final product - up to 99.7%, due to significant differences between its rozCS 277344 B6

the solubility and solubility of the impurities and unreacted starting materials present in the resulting reaction mixture, in water.

The hydrogenation catalyst selected from the group consisting of platinum, palladium, nickel and cobalt can be used in the process according to the invention in metallic form or in oxide form, preferably supported on a suitable support, such as activated carbon, alumina and the like. The final product can be precipitated in the resulting reaction mixture, freed of spent catalyst, over a wide temperature range, preferably at a temperature of 15 to 25 ° C, which can be achieved by a technically simple way of cooling the mixture. The process according to the invention can be carried out batchwise or continuously.

The following examples illustrate but do not limit the scope of the invention.

Example 1

618.85 g (3.97 mol) of 2,2,6,6-tetramethyl-4-piperidone with a purity of 99.5% and 288.08 g (1.98 mol) of an 80% aqueous solution were weighed into a Paar autoclave. hexamethylenediamine, 1700 g of water and 2.26 g of 5% Pt on activated carbon were added as catalyst. After sealing, the autoclave was purged with nitrogen and then hydrogen and the reaction mixture was stirred for 3.5 h at 80 ° C and a hydrogen pressure of 6 MPa. After completion of the reaction, the mixture was gradually cooled to 20 ° C with stirring, the precipitated product was filtered off on a centrifuge, washed with 100 g of cold water at 5 ° C and dried at 40 ° C under vacuum. 766.2 g of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine with a purity of 99.7% are obtained in the form of white crystals with a melting point of 63.5 to 65.0 g , which represents a yield of 97.9%.

Example 2

23.70 kg (0.15 kmol) of technical grade 2,2,6,6-tetramethyl-4-piperidone with a purity of 98.2% and 10.89 kg (0.75 kmol) of 80% were metered into a 100 l Jahndorf autoclave. of an aqueous solution of hexamethylenediamine, 37.5 kg of water and 140 g of 3% Pt on activated carbon were added as catalyst. After sealing, the autoclave was purged with nitrogen and then hydrogen and its contents were stirred for 2 h at a temperature of 60 ° C and a hydrogen pressure of 10 MPa. After completion of the reaction and filtration of the spent catalyst, the mixture in the 100 l reactor was slowly cooled to 5 ° C, the formed suspension was diluted by adding 5 kg of water and centrifuged, and the resulting product was washed with 10 kg of water. Drying gave 28.1 kg of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine with a purity of 99.5% as a white crystalline solid, m.p. 63.0-65.0 ° C, which represents a yield of 94.98%.

Example 3

23.88 kg (0.15 kmol) of technical grade 2,2,6,6-tetramethyl-4-piperidone with a purity of 97.5% and 14.53 kg (0.075 kmol) of a 60% aqueous solution were metered into a 100 l Jahndorf autoclave. hexamethylenediamine, 25 kg of water and 84 g of 5% Pt supported on activated carbon as catalyst were added. After sealing, the autoclave was purged with nitrogen followed by hydrogen and stirred for 3.5 h at

100 ° C and a hydrogen pressure of 2 MPa. After completion of the reaction and filtration of the spent catalyst under heated pressure, 10 kg of water were added to the mixture and slowly cooled to 35 ° C with stirring, the resulting suspension was filtered under pressure and the product was washed with 15 kg of water. Drying gave 27.6 kg of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine with a purity of 99.3% as a white crystalline solid, m.p. 61.5-64. 0 ° C, which represents a yield of 93.29%.

Claims (1)

. 5 3 CS 277344 B6 100 ’C and a hydrogen pressure of 2 MPa. After the reaction was completed and the catalyst used was filtered off on a heated pressure filter, 10 kg of water was added to the mixture and cooled slowly to 35 ° C with stirring, the resulting suspension was filtered through a pressure filter and washed with 15 kg of water. Drying gave 27.6 kg of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine with a purity of 99.3% as a white crystalline solid, mp 61.5-64. , 0 ° C, yield 93.29%. PATENT REQUIREMENTS A process for preparing N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine by reacting hexamethylenediamine with 2,2,6,6-tetra-methyl-4-piperidone and hydrogen in an aqueous medium, in the presence of a catalyst selected from the group consisting of platinum, palladium, nickel and cobalt, at a temperature of 50 to 100 ° C and a hydrogen pressure of 1 to 15 MPa, characterized in that the resulting reaction mixture is cooled to a temperature of 5 to 35 ° C and the precipitated end product is isolated therefrom. End of document