DE1695859A1 - Process for the preparation of an optically active alpha-aminolactam from a mixture of the D- and L-forms of the alpha-aminolactam - Google Patents

Description

Code 1881 Δ Dr. F. Zumstein - D. E. Assmann

Dr. R. Koenigsberger Dipl. Phys. R. Hobbauer

Pafenfanwälte Munich 2, ijräuhausstralje 4 / III

STAAiICARBON N.V., HEERLEN (the Netherlands)

Process for the preparation of an optically active q-aminolactam from a mixture of the D- and! / - form of the OC-aminolactam

The invention relates to a process for the preparation of an optically active α-aminolactam by converting from a mixture of the D and L-form of this α-aminolactam is one of the optical antipodes liquid medium as the salt of one of the optical antipodes of pyrrolidone carboxylic acid precipitates, separates this precipitate from the liquid, whereby an L-oc -aminolactam-rich and a D-α -aminolactam-rich phase and then from the first phase the! / - form or from the second phase the D-Forra of the α-aminolactam wins, with one Solution is assumed in which the D- and Ir-Ot-aminolactam and the optical active pyrrolidonecarboxylic acid or a compound of these substances dissolved have been, as a liquid medium, one that is immiscible with this solution Liquid is used and the liquid medium and the aforementioned solution are brought together with evaporation of the solvent of this solution will. *

In this known method (see Dutch patent specification 101,415) it is obvious the solution and the one not with the

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Solution miscible liquid with evaporation of the solvent in one to bring together a vessel equipped with a stirrer. For an implementation Such a stirrer vessel proves to be on a small scale extremely suitable. A suspension of the precipitated salt is obtained, which can be pumped easily and in a simple manner, e.g. can be separated into solid and liquid by means of filtration. But if such processing is carried out on a large scale in a stirrer vessel carried out, great difficulties arise. The secluded Solid salt clumps together and for the most part sits down on the vessel wall or on the stirrer. The further transport and the divorce the mixture of agglomerated salt and liquid is difficult to perform.

Surprisingly, it has now been found that this. editing excellent on a large scale in a rotating thin film evaporator can be carried out with a constant gap width. The inventive The method is then also characterized in that the solution in which the D- and L-α-aminolactam and the optically active pyrrolidonecarboxylic acid or a compound of these substances is dissolved, as well as the liquid medium in a rotating thin-film evaporator with a constant gap width feeds the solvent of said solution in the thin film evaporator evaporated and the precipitated salt is discharged from the thin-film evaporator together with the remaining liquid. Can be used as a solvent any polar solvent that is immiscible with the liquid medium, e.g. water or an alcohol, can be used. Suitable liquid media are: Dioxane, gasoline, kerosene, hexane, heptane, benzene, toluene, xylene, mesitylene, Cyclohexane and alkylcyclohexane.

The thin-film evaporator used here is well known and

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is also sometimes referred to as a rotating thin film evaporator, its Rotor filigrees do not move with respect to the rotor shaft during operation.

That said process in this type of thin film evaporator can be carried out on a large scale is completely contrary to expectations. In Experts are of the opinion that in the case of education of solids during an evaporation process the application of a rotating Thin-film evaporator with constant gap width is out of the question, rather, a rotating thin-film evaporator with a varying gap width should be used. With the latter type of evaporator, the Rotor blades arranged movably with respect to the rotor shaft, so that at the formation of solids during evaporation increases the gap width the thickness of the solid-containing thin layer on the evaporator wall can be adjusted. Use of a rotating thin film evaporator with varying However, it has a gap width in the evaporation process referred to in this application no success.

The gap opening in rotating thin-film evaporators with constant The gap width is generally between 0.5 and 2.5 mm. which Gap width to carry out the inventive method on most suitable, depends on various factors, such as concentration the solution, the capacity of the evaporator, the amount and type of liquid medium, and should be determined experimentally. This can be done in a simple manner by using a rotating thin film evaporator happen with a constant gap width, whereby this gap width can be set to several values within a certain range. Such a setting to several values can easily be done in a thin film evaporator realize, in whole or in part, to some extent runs conically. By moving the rotor towards the rotor shaft

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the gap width can be set to a certain value several times.

In the method according to the invention, it is not cumbersome that part of the liquid medium going to the evaporator does not leave the evaporator as liquid but as vapor. This can even be done hardly avoid. For a good process flow in the evaporator, the amount is allowed of the supplied liquid medium, which as a liquid from the evaporator going off, but not be too small. It is therefore important that the evaporator is not supplied with too much heat. However, this is allowed The amount of heat should also not be too small, because in this case too little The amount of solvent evaporates and the salt to be precipitated in whole or in part Parts remain in solution.

It has now emerged that the problem is determining Proper heat bypassing it from the vaporizer outgoing steam condenses, the condensate then in solvent and liquid medium separates and the separated liquid medium on direct Routes back into the evaporator. The amount of liquid medium leaving the evaporator in the form of liquid is then independent of the the amount going to the evaporator; In addition, the heat supply to the evaporator can be set without hesitation to a value at which in abundant Amount of heat to evaporate the solvent is added.

The invention is explained in the following example without she limits herself to it.

example

An aqueous solution of racemic α-amino-e-caprolactam and L-pyrrolidonecarboxylic acid was used together with toluene on a rotating thin film evaporator added with a constant gap width. The additional amounts per hour were: 30 kg a-amino e-caproläctara, 12 kg pyrrolidone carbon

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acid, 28 kg of water and 560 kg of toluene.

The thin film evaporator had an evaporation area of 1 ω, one

clear width of 30 cm and was equipped with a four-blade rotor of 300 rpm. The gap width was 1.2 mm. To generate the required

A jacket heater is provided, which is supplied with steam at 180 C. Every hour, 27 kg of water and about 390 kg of toluene were discharged from the thin-film evaporator at a temperature of 99 ° C. in the form of steam. This vapor was condensed, after which the condensate was separated into toluene and water. The separated toluene was returned directly to the thin-film evaporator. There the solid salt of L-Ct -amino- ε- caprolactam with L-pyrrolidonecarboxylic acid was formed. This solid salt was removed from the thin-film evaporator in a finely divided state together with the non-evaporated liquid. Every hour, 24 kg of solid salt and 579 kg of liquid left the evaporator. This 579 kg of liquid consisted of 560 kg of toluene, 18 kg of α-amino-β-caprolactam and 1 kg of water. -

Claims (3)

PATENT CLAIMS 1. A process for the preparation of an optically active α-aminolactam by precipitating one of the optical antipodes in a liquid medium as the salt of one of the optical antipodes of pyrrolidonecarboxylic acid from a mixture of the D- and L-forms of this ot-aminolactam separates from the liquid, whereby an Is-ct -aminolactam-rich and a D- α -aminolactam-rich phase is obtained and then from the first phase the L-form or from the second phase the D-form of the α-aminolactam wins, with one solution it is assumed that the D- and L-Gt -aminolactam and the optically active pyrrolidoncarboneaure 10 9 8 19/2158 or a compound of these substances are dissolved, furthermore a liquid that is not miscible with this solution is used as the liquid medium and the liquid medium as well as the. said solution are brought together with evaporation of the solvent of this solution, characterized in that the solution in which the D- and L-ct -aminolactam and the optically active pyrrolidonecarboxylic acid or a compound of these substances have been dissolved, and the liquid medium a rotating thin layer A vaporizer with a constant gap width supplies, the solvent of the above-mentioned solution evaporates in the thin-film evaporator and the precipitated salt is discharged from this thin-film evaporator together with the remaining liquid. 2. The method according to claim 1, characterized in that the vapor leaving the evaporator is condensed, then the condensate is separated into solvent and liquid medium and the liquid medium which has separated out is fed back directly to the evaporator. 3. Optically active α-aminolactam, produced using the method ψ according to one of the preceding claims. 109819/2158