SU550379A1 - Method for isolating cis- and trans-isomers of aminocyclohexanols - Google Patents

Description

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The invention relates to a new process for the isolation of the cis and gras isomers of amino-derived cyclohexane series, in particular the aminocyclohexvnols used in the manufacture of heat-resistant polymer fibers.

In the literature, a method for separating cis and gdans isomers of diaminocyclohexano in the interaction of a mixture of these isomers with glycols in a large amount of an inert solvent is described; the resulting polyolate products are subjected to fractionated or azeotropic times and the individual cis- and grain-isomers of 1,3-diaminocyclohexane 1 are obtained in free form.

However, there is no information on the method of isolation of sufficiently pure individual cis- and gran-aminocyclohexanols, which can be obtained as a mixture by hydrogenation of amyiophenols.

The proposed method consists in that the mixture of isomers of aminocyclohexanols obtained by hydrogenating the corresponding aminophenols in the presence of a ruthenium catalyst is treated with ethylene glycol dimethyl ether at an amino-cyclohexanol: ether ratio of 1: 0.1-3, preferably 1: 1, at a temperature of about -15 ° C, preferably 6-8 ° C. The isolation of individual isomers is carried out using various

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solubility of cis and trans isomers. In the case of 2-aminocyclohexanol, the 1 {y-isomer precipitates, and in the case of 4-aminocyclohexanol, the trans-isomer.

To increase the yield of trans-4-aminocyclohexanol, the mixture of isomers isolated from the filtrate is subjected to isomerization on a ruthenium catalyst at a temperature of 100-140 ° C and a pressure of 50-80 atm followed by

isolation of the trans isomer.

Example 1. In the autoclave load 50 g of o-aminophenol, 500 ml of water and 10 g of a 5% ruthenium catalyst on alumina. The hydrogenation is carried out at a temperature of

120 ° C and a pressure of 70–80 atm to ensure hydrogen uptake is about 0.5–1.5 h.

After cooling, the catalyst is filtered off. Distillation in vacuo gave 36.8 g of 2-aminocyclohexanol. Product purity 98%. Isomeric composition: 79% cis-, 21% trans. 36.8 g of a mixture of isomers of 2-amyocyclohexanol and 30-35 ml of ethylene glycol dimethylether are placed in a glass, the mixture is heated with stirring in a water bath

Claims (2)

until it becomes homogeneous, and then slowly cooled to O-15 ° C, preferably to 6-8 ° C. The precipitated crystals are separated by filtration, washed with 10-15 ml of ethylene glycol dimethyl ether and again transferred into a glass, 10-15 ml of ethylene glycol dimethyl ether are added and dissolved by heating in a water bath. The solution is cooled, the crystals are separated by filtration and washed with 10 ml of ethylene glycol dimethyl ether. 20.9 g of product were isolated, which was PIC-2-am Inocyclohexanol, 98% purity. 75% yield of theory, based on the content of i wc-nsoMCpa in the mixture. 10 After evaporation of the filtrate from two operations, 14.5 g of aminocyclohexanol with a composition of 51.7% of the cis, 48.3% of the trans isomer was isolated. Example 2. 50 g of an aminophenol, 500 ml of water and 10 g of a ruthenium-15 catalyst on alumina are charged to an autoclave. The hydrogenation is carried out at a temperature of 120 ° C and a pressure of 70-80 atm until the absorption of hydrogen is complete. After that, the reaction mixture is kept at this temperature for 20 hours for another 1 hour to isomerize the cys-isomer to trans. After cooling, the catalyst was filtered off. 46.4 g of 4-aminocyclohexanol are isolated by distillation in vacuo. The purity of the product is 98.5%. Isomeric composition: 25 53% cis-, 47% trans. 46.4 g of a mixture of 4-aminocyclohexanol isomers and 40 ml of ethylene glycol dimethyl ether are placed in a beaker. The order of separation, as in example 1. After double recrystallization, 15 of 15 g trins-1-soi crystals are isolated. Purity of trans-4-a.minocyclohexanol 93%. Yield 70%, calculated on the content of the i -rans isomer in the mixture. After evaporation of the filtrate from two operations, 29 g of amino-cyclohexanote (76% cis- and 24% trans) were isolated. During the separation of isomers, the loss did not exceed 5%. catalyst in the presence of hydrogen at a temperature of 100-140 ° C and a pressure of 5-80 MPa, followed by re-isolation of trans4-aminocyclohexanol as described above. Claim 1. The method of separation of cis and trans isomers of aminocyclohexanols, which is laugh s aminotsiklogeksaiola isomers obtained by hydrogenation amipofenolov, treated with ethylene glycol dimethyl ether LIS sootpo1penii aminocyclohexanol: ether 1: 0.1-3 at O-15 ° C. 2. A method according to claim 1, characterized in that the process is carried out at an amino-cyclohexanol: ether ratio of 1: 1 at 6-8 ° C. Information sources taken into account during examination 1. US Patent No. 3491149, cl. 260-563, 1970 (prototype).