CS241297B1 - A method for separating cyclohexylidenecyclohexylamine from dicyclohexylamine - Google Patents

Abstract

The solution is from the field of chemistry and solves the method of separating cyclohexylidenecyclohexylamine from dicyclohexylamine by a combination of rectification and hydrolysis. The essence of the solution consists in the continuous addition of water to a boiling mixture containing cyclohexylidenecyclohexylamine and dicyclohexylamine, subsequent condensation of the mixture of water vapor and the organic phase, while the aqueous phase is returned back to the boiling mixture and the organic phase, which contains cyclohexylidenecyclohexylamine and its hydrolytic products cyclohexylamine and cyclohexanone, is removed from the system. The solution can be used in obtaining pure dicyclohexylamine, for example, in its production together with cyclohexylamine during the catalytic hydrogenation of aniline with hydrogen in the gas phase.

Description

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A process for separating cyclohexylidenecyclohexylamine from dicyclohexylamine

The solution is from the axis of chemistry and solves the method of separating cyclohexylidenecyclohexylamine from dioyclohexylamine by a combination of rectification and hydrolysis. The principle of the solution consists in the continuous addition of water to the boiling mixture containing cyclohexylidenecyclohexylamine and dicyclohexylamine, followed by condensation of the water vapor / organic phase mixture, the aqueous phase V being returned to the boiling mixture and the organic phase containing cyclohexylidenecyclohexylamine from the system.

The solution can be used to obtain pure dlcyclohexyl amine, for example by producing it together with cyclohexylamine in the catalytic hydrogenation of aniline with hydrogen in the gas phase.

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The present invention provides a process for separating cyclohexylidenecyclohexylamine from dicyclohexylamine by combining rectification and hydrolysis.

Catalytic hydrogenation of aniline produces, besides the main products, oyclohexylamine (hereinafter CHA) and dicyclohexylamine (hereinafter DCHA) as one of the by-products of cyclohexylidenecyclohexylamine (hereinafter CCHA). Separation of CCHA from DCHA is accomplished by rectification, the separation efficiency of these substances being very low and for commonly used rectifications the removal of CCHA from DCHA is below 0.6 wt%. practically unrealistic. Therefore, to reduce the CCHA content of DCHA, a process is used in which a mixture of CCHA and DCHA is mixed with water in an amount to form two liquid phases - organic and aqueous. Water partially hydrolyzes CCHA in DCHA to the components oyclohexylamine and cyclohexanone, which pass into the aqueous phase as soluble fractions. After a period of exposure, the F2C aqueous / dissolved CCHA hydrolytic products are pumped off from the - 3 241 297 organic phase · The disadvantage of this process is the low efficiency and the large amount of waste water ·

The above drawbacks are overcome by the invention of a combination of distillation and hydrolysis, in which the boiling mixture containing CCHA and DCHA is continuously supplied with water, which hydrolyzes CCHA to CHA and oyclohexanone and, together with them, leaves in the form of vapors. a heterogeneous mixture consisting of an aqueous phase which is returned to a boiling mixture containing CCHA and DCHA and an organic phase withdrawn from the system ·

In this way, a higher efficiency of separating CCHA from DCHA, essentially complete separation of CCHA from DCHA without waste water, is achieved in comparison with the method used so far. The introduction of the process requires minimal treatment and can therefore be applied to conventional distillation plants.

To remove CCHA from DCHA, water is added to the digester or column head. The amount of water supplied can be chosen freely with respect to the operating parameters of the distillation column.

Organic and water vapor condenses with cooling to form an aqueous and organic phase, the aqueous phase being returned to the column and the organic phase containing the hydrolytic decomposition products of CCHA is removed from the system · The amount of water in the system is kept constant ·

Example.

000 kg of a mixture of DCHA and CCHA with a concentration of 6.46% by weight. CCHA was at atmospheric pressure on a packed column of 15 theoretical

4,241,297 is rectified under simultaneous hydrolytic action of water. Water at 400 L / h was injected onto the top of the column and after condensation along with the organic phase vapors and separation in the separator was injected again onto the top of the column. The organic phase from the separator was fed to a reservoir. Periodic rectification was carried out for 3 hours under the above conditions. After 1 hour, the content of CCHA and its hydrolytic products in the digester dropped to 0.87% wt., And after 2 hours to 0.07% wt. and after 3 hours to 0.001 wt. A total of 540 L of organic phase with an average composition of 17.5 wt. CHA, 17.8 wt. % cyclohexanone, 33% by weight. CCHA and 31.0 wt. DCHA.

Claims (1)

SUBJECT OF THE INVENTION 241 297 A process for separating cyclohexylidenecyclohexylamine from dicyclohexylamine by a combination of distillation and hydrolysis, characterized in that water is added to the boiling mixture comprising cyclohexvlidencyclohexvlamine and dicyclohexvlamine, which hydrolyzes cyclohexylidenecyclohexylamine together with cyclohexyl amine to form cyclohexylemine, and the aqueous layer of the resulting heterogeneous mixture is returned to the boiling mixture and the organic layer is removed from the pale.