KR102551766B1 - Process for the purification of laurolactam and purifing apparatus thereof - Google Patents

Abstract

The method for purifying laurolactam and the apparatus for purifying the same according to the present invention have the effect of purifying laurolactam with high purity and high yield from a mixture containing laurolactam obtained in the process of synthesizing laurolactam. While realizing the effect, it is possible to minimize the cost required for equipment and processes, and it is practical, and has an advantageous effect for industrial mass purification compared to the prior art.

Description

Laurolactam purification method and purification apparatus thereof {Process for the purification of laurolactam and purifing apparatus thereof}

The present invention relates to a method for purifying laurolactam and a purification apparatus therefor.

Industrially useful laurolactam is synthesized by subjecting cyclododecanone oxime to Beckman rearrangement reaction. At this time, the Beckman rearrangement reaction process belongs to a fairly complicated process, and concentrated sulfuric acid and fuming sulfuric acid are used as catalysts, but these are strong acids that require a high content of stoichiometric or more, and a large amount of ammonium sulfate is produced as a by-product during neutralization. In the synthesis process, laurolactam is produced by mixing various by-products and unreacted materials.

Another conventional specific example for the production of laurolactam is a 'continuous method for preparing laurolactam in a liquid phase'. After oximating cyclododecanone in an isopropylcyclohexane solvent, the isopropylcyclohexane solution of cyclododecanone oxime obtained by the separation was gradually added in concentrated sulfuric acid under low temperature to prepare a sulfuric acid solution of the sulfuric acid adduct of cyclododecanone oxime, After separating and recovering propylcyclohexane, the temperature of the sulfuric acid solution of the sulfuric acid adduct of the remaining cyclododecanone oxime is raised to cause a Beckman rearrangement reaction with the oxime. After the rearrangement reaction, water is added to dilute the sulfuric acid, and then the produced laurolactam is extracted with an organic solvent. Here, isopropylcyclohexane is used as the extraction solvent. However, the method of recovering the extraction solvent by distillation and purifying laurolactam in the residue in the patent publication has a limitation in that the purification efficiency is not good.

The mixture containing laurolactam obtained in the synthesis process of laurolactam includes a solvent such as isopropylcyclohexane, unreacted substances such as cyclododecanone and cyclododecanone oxime, and various by-products. In addition, various impurities such as unreacted reactants for the synthesis of reactants used in the synthesis of laurolactam and unreacted reactants for the synthesis of the reactants may be included.

As such a process for synthesizing laurolactam may involve various step-by-step processes, a purification method for separating and recovering laurolactam from a mixture containing synthesized laurolactam is essentially required.

However, when this conventionally known purification method is applied to laurolactam, there are limitations in that the purity of the final purified laurolactam is not high, the yield is not good, and the process efficiency is low.

Japanese Registered Patent Publication JP4436839B2 (2010.01.08)

An object of the present invention is to provide a method for purifying laurolactam with high purity and high yield from a mixture containing laurolactam obtained in the process of synthesizing laurolactam, and a purification apparatus therefor.

Another object of the present invention is to provide a method for purifying laurolactam and an apparatus for purifying the laurolactam, which can minimize the cost required for equipment and processes while realizing the above objects, are practical, and are advantageous for industrial mass purification compared to the prior art. is to provide

A method for purifying laurolactam according to the present invention is a method for purifying laurolactam in which laurolactam is separated from a product of a synthesis process of laurolactam, wherein: a) the product is first distilled, and low boiling point substances are transferred to the top of the first still b) distilling the first mixture containing laurolactam discharged from the bottom of the first still to separate and obtain laurolactam from the top of the second still; c) step of separating and obtaining laurolactam from the top of the second still; Step 2 of contacting and thin-film evaporating a second mixture containing unseparated laurolactam discharged from the bottom of the still to a heat transfer surface to separate laurolactam at the top of the thin-film evaporator and separating and removing impurities at the bottom of the thin-film evaporator include

In one example of the present invention, laurolactam separated from the top of the thin film evaporator in step c) may be second distilled again in step b).

In one example of the present invention, the reflux ratio in step a), step b), or these steps may be 1 or more.

In one example of the present invention, the product of the laurolactam synthesis process is s3) synthesizing cyclododecanone oxime by oximating cyclododecanone, and s4) in a solvent containing isopropylcyclohexane. ) may be prepared by reacting a catalyst containing cyanuric chloride with a product containing cyclododecanone oxime synthesized in step to synthesize laurolactam. In this case, the product of step a) may be a product containing the laurolactam synthesized in step s4).

In one example of the present invention, the product of the laurolactam synthesis process may be prepared by including steps s3) and s4), and prior to step s3), s1) cyclododecatriene is partially The step of synthesizing cyclododecene by hydrogenation reaction and s2) synthesizing cyclododecanone by oxidizing the product containing cyclododecene synthesized in step s1) with nitrous oxide to synthesize cyclododecanone. can In this case, the cyclododecanone of step s3) may be a product containing the cyclododecanone synthesized in step s2).

An apparatus for purifying laurolactam according to the present invention is an apparatus for purifying laurolactam that separates laurolactam from a product of a laurolactam synthesis process. A first still to separate and remove; a second still for second distilling the first mixture containing laurolactam discharged from the bottom of the first still, and separating and discharging laurolactam from the top of the second still; and contacting the second mixture containing the unseparated laurolactam discharged from the bottom of the second still with a heat transfer surface and evaporating the thin film to separate and discharge the laurolactam through the top of the thin film evaporator, and separate the impurities through the bottom of the thin film evaporator. And a thin film evaporator to remove; includes.

In one example of the present invention, laurolactam separated and discharged from the top of the thin film evaporator may be recycled to the second still.

The method for purifying laurolactam and the purification apparatus thereof according to the present invention have an effect of purifying laurolactam with high purity and high yield from a mixture containing laurolactam obtained in the process of synthesizing laurolactam.

The method for purifying laurolactam and the purification apparatus thereof according to the present invention can minimize the cost required for equipment and processes while implementing the above effects, are practical, and have an advantageous effect for industrial mass purification compared to the prior art. there is.

Even if the effects are not explicitly mentioned in the present invention, the effects described in the specification expected by the technical features of the present invention and the inherent effects thereof are treated as described in the specification of the present invention.

1 is a schematic process diagram of an apparatus for purifying laurolactam according to the present invention.

A method for purifying laurolactam and an apparatus for purifying the laurolactam according to the present invention will be described in detail with reference to the following drawings.

The drawings described in the present invention are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented, and the drawings may be exaggerated to clarify the spirit of the present invention.

Unless otherwise defined, the technical terms and scientific terms used in the present invention have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of known functions and configurations that may unnecessarily obscure are omitted.

Singular forms of terms used in the present invention may be interpreted as including plural forms unless otherwise indicated.

In the present invention, the unit of % used unambiguously without particular notice means weight %.

A method for purifying laurolactam (LRL) according to the present invention is a method for purifying laurolactam by separating laurolactam from a product of a laurolactam synthesis process.

The method for purifying laurolactam includes the steps of a) first distilling the product to separate and remove low-boiling substances from the upper part of the first still, b) a first step containing laurolactam discharged from the lower part of the first still Separating and obtaining laurolactam by second distilling the mixture to the top of the second still, and c) contacting the second mixture containing unseparated laurolactam discharged to the bottom of the second still to the heat transfer surface and forming a thin film Evaporation to separate laurolactam through the top of the thin film evaporator, and separation and removal of impurities through the bottom of the thin film evaporator.

The distiller referred to in the present invention may refer to a distiller commonly used in a purification process through distillation. Specifically, the first still may be a conventionally known still equipped with an overhead condenser at the top of the still and a reboiler at the bottom of the still. However, the second still is equipped with a thin film evaporator instead of a reboiler, and by combining this configuration, the boiling point rise problem can be minimized, and laulolactam can be separated and recovered with high purity and high yield.

Unless otherwise defined, the 'distiller' or 'thin film evaporator' referred to in the present invention may be used appropriately depending on the scale and environment of the process, so for one specific element of the still not separately mentioned in the present invention Not limiting. In addition, in each reactor, various inlet pipes, outlet pipes, and connection pipes for connecting materials may be provided, and specific devices for controlling the inflow and outflow of materials may be used. Doing is not limited because it is a matter that can be properly adjusted for those skilled in the art.

The 'thin film evaporator' referred to in the present invention refers to an evaporation device in which a solution is heated and concentrated while flowing in the form of a thin film on the heat transfer surface, as long as it is commonly known, and the present invention Items not specifically mentioned in are not limited because various devices and methods of use may be applied.

The product of the laurolactam synthesis process includes, in addition to laurolactam, one or more compounds selected from a solvent, various unreacted materials, side reactants, etc. Since these compounds act as impurities, separating and purifying laurolactam from them process is required.

In general, laurolactam can be synthesized by Beckmann rearrangement reaction of cyclododecanoneoxime (CDOX) in a solvent. In this case, isopropylcyclohexane (IPCH) is usually used as the solvent etc. are used. Therefore, laurolactam prepared through this process may typically include a solvent such as isopropylcyclohexane and may include an unreacted material such as cyclododecanone oxime.

In addition, since the cyclododecanone oxime can be prepared through a process of synthesizing cyclododecanone oxime by oxidizing cyclododecanone (CDON), the product of the laurolactam synthesis process is cyclododecanone, etc. may contain unreacted substances of

In the present invention, as primary distillation, secondary distillation, and tertiary distillation through a thin-film evaporator are performed, laurolactam can be purified from the above-described product containing laurolactam with high purity and high yield. The materials to be separated and purified in the present invention are not particularly limited, but are preferably selected from solvents such as isopropylcyclohexane, unreacted materials used in the laurolactam synthesis process such as cyclododecanone oxime and cyclododecanone. It may contain one or two or more, and these compounds have the effect of effectively separating and removing them. However, in the present invention, since various impurities other than laurolactam can be effectively separated and removed, the present invention should not be construed as being limited thereto.

As a specific example, the product of the laurolactam synthesis process is s4) synthesizing laurolactam by reacting cyclododecanone oxime with a catalyst containing cyanuric chloride in a solvent containing isopropylcyclohexane. It may be prepared including the steps. In this case, the product of the laurolactam synthesis process may be a product containing the laurolactam synthesized in step s4). Accordingly, the product of the laurolactam synthesis process may include at least one selected from isopropylcyclohexane and cyclododecanone oxime.

As a specific example, the product of the laurolactam synthesizing process may include, before step s4), s3) synthesizing cyclododecanone oxime by oximating cyclododecanone. In this case, the cyclododecanone oxime of step s4) may be a product containing the cyclododecanone oxime synthesized in step s3). Accordingly, the product of the laurolactam synthesis process may include cyclododecanone.

As a specific example, the product of the laurolactam synthesis process is prepared by including the step of s2) synthesizing cyclododecanone by oxidizing cyclododecene with nitrous oxide (N ₂ O) before step s3). it could be In this case, the cyclododecanone of step s3) may be a product containing the cyclododecanone synthesized in step s2). Accordingly, the product of the laurolactam synthesis process may include cyclododecene.

As a specific example, the product of the laurolactam synthesis process is cyclododecene (CDEN) obtained by partial hydrogenation of s1) cyclododecatriene (CDT) prior to step s2). It may be prepared by including the step of synthesizing. In this case, the cyclododecene in the step s2) may be a product containing the cyclododecene synthesized in the step s1). Accordingly, the product of the laurolactam synthesis process may include cyclododecatriene.

As another specific example, the product of the laurolactam synthesis process is obtained by s3) synthesizing cyclododecanone oxime by oximating cyclododecanone and s4) in a solvent containing isopropylcyclohexane in step s3) It may be prepared by including the step of synthesizing laurolactam by reacting a catalyst containing cyanuric chloride with a product containing synthesized cyclododecanone oxime. In this case, the product of step a) may be a product containing the laurolactam synthesized in step s4).

As another specific example, the product of the laurolactam synthesis process may be prepared by including steps s3) and s4), and prior to step s3), s1) partial hydrogenation of cyclododecatriene It may be prepared by further comprising synthesizing cyclododecene and s2) synthesizing cyclododecanone by oxidizing the product containing cyclododecene synthesized in step s1) with nitrous oxide. In this case, the cyclododecanone of step s3) may be a product containing the cyclododecanone synthesized in step s2).

Describing the method for purifying laurolactam according to the present invention in detail, a product of the laurolactam synthesis process, for example, a mixture including laurolactam, cyclododecanone, and isopropylcyclohexane, is transferred to a first still. In the first still, the temperature and pressure are controlled so that each component is first distilled. Specifically, low-boiling compounds such as isopropylcyclohexane are distilled and then condensed through the first overhead condenser at the top of the first still to form an overhead effluent. As it is discharged, it is separated and removed. In the first still, cyclododecanone is discharged as a side cut and separated and removed.

In the first still, the first mixture containing laurolactam, which is the bottom residual oil, is transferred to the second still through the bottom of the first still and subjected to second distillation under controlled temperature and pressure. In the second still, laurolactam is distilled and then condensed through a second overhead condenser at the top of the second still and separated and recovered as discharged as an overhead effluent. At the bottom of the second still, a second mixture containing unseparated laurolactam and high-molecular-weight materials (heavies) with high viscosity is transferred to a thin-film evaporator.

In the thin film evaporator, temperature and pressure are controlled so that laurolactam is evaporated in contact with the heat transfer surface, and the evaporated laurolactam is discharged from the top of the thin film evaporator to be separated and recovered.

In the present invention, the temperature and pressure of the first and second stills may be appropriately adjusted according to the boiling point of the compound.

In one example of the present invention, the temperature and pressure of the thin film evaporator may be appropriately adjusted according to the boiling point of the compound, preferably controlled at 200 to 250 ° C. and 10 to 50 torr, but this is preferable. It is only an example, and the present invention is not limited thereto, of course.

By going through the above-mentioned steps, it is possible to separate and recover high-purity, high-yield laurolactam from the top of the second still and/or the top of the thin-film evaporator. More preferably, the thin-film evaporator in step c) By further going through a step of circulating the laurolactam discharged from the upper end of the second distillation again in the step b), laurolactam can be separated and recovered from the upper end of the second still with a higher yield. As laurolactam evaporated from the thin film evaporator or a mixture containing the laurolactam is circulated to the second still, the yield of final purified laurolactam can be remarkably increased to a very high level.

In a preferred example, the reflux ratio in step a), step b) or these steps may be 1 or more, preferably in the range of 1 to 2. More specifically, when the reflux ratio in the above range is satisfied, when laurolactam is separated at the bottom of a still or at the bottom of a thin-film evaporator, fouling caused by a high-viscosity polymer material can be prevented, and further, mixing of the polymer material There is an effect that can prevent the phenomenon. In addition, the purity of the finally purified laurolactam is remarkably high, and the yield is also remarkably high as the impurity separation characteristics are precise.

The 'reflux ratio' referred to in the present invention may be interpreted as having a conventional meaning in the art. Specifically, in the distillation operation, when some or all of the vapor from the top of the distillation column is condensed in a condenser to become a liquid, some of the liquid is returned to the top as a reflux liquid, and the rest is discharged as an effluent. The ratio of the reflux liquid volume to the reflux ratio is called the reflux ratio.

An apparatus for purifying laurolactam according to the present invention is an apparatus for purifying laurolactam for separating laurolactam from a product of a laurolactam synthesis process, and is an apparatus for effectively carrying out the above-described method for purifying laurolactam.

The apparatus for purifying laurolactam may include: a first distillation unit that first distills the product and separates and removes low-boiling materials from the top of the first distiller; a second still for second distilling the first mixture containing laurolactam discharged from the bottom of the first still, and separating and discharging laurolactam from the top of the second still; and contacting the second mixture containing the unseparated laurolactam discharged from the bottom of the second still with a heat transfer surface and evaporating the thin film to separate and discharge the laurolactam through the top of the thin film evaporator, and separate the impurities through the bottom of the thin film evaporator. And a thin film evaporator to remove; includes.

In a preferred example, laurolactam separated and discharged from the top of the thin film evaporator may be recycled to the second still.

Hereinafter, the present invention will be described in detail through examples, but these are for explaining the present invention in more detail, and the scope of the present invention is not limited by the following examples.

[Production Example 1]

Preparation of mixtures containing laurolactam

Cyclododecene synthesis process

200 g of cyclododecatriene, 40 mg of RuCl ₃ , 5.56 g of triphenylphosphine (TPP), 0.5 g of acetic acid, 3.44 g of a 35% by weight aqueous solution of formaldehyde and 10.54 g of ethanol were added, and a reactor was fastened. And the reactor was purged three times with 5 kg/cm ² of nitrogen (N ₂ ), purged three times with hydrogen gas (H ₂ ), and then filled with hydrogen to adjust the reactor pressure to 10 bar. . Subsequently, the inside of the reactor was heated from 25°C to 160°C for about 40 minutes, and cooled naturally to reach 130°C. At this time, when the pressure of the reactor started to decrease, the reaction was started by pressurizing the reactor to 20 bar. The reaction proceeded for a total of 6 hours, at which time hydrogen was continuously supplied to maintain the initial pressure.

cyclododecanone synthesis process

After the reactor to which the first continuous flow reactor and the second continuous flow reactor were connected was controlled at 300° C., an excessive amount of nitrous oxide (N ₂ O) was flowed to adjust the reaction pressure to 100 bar and the downstream pressure to 3 bar.

After stabilizing the internal temperature of the reactor by flowing nitrous oxide into the reactor, the mixture (including cyclododecene (trans: cis = 2: 1)) and nitrous oxide obtained in the cyclododecene synthesis process were each 3.67 g /min and 0.97 g/min were introduced into the reactor through a pump. At this time, the reactor volume was 700 ml in total, and the residence time during the reaction was 1 hour. As soon as the introduction was finished, the flow rate of nitrous oxide was adjusted so that there was no change in the residence time in the reactor. The nitrous oxide was introduced in a liquid state and is in a supercritical state under the above reaction conditions. After the reaction, a liquid product was obtained through a separator, and nitrous oxide and inert substances present in nitrous oxide were discharged as off gas.

Cyclododecanone was synthesized through this process.

Synthesis process of cyclododecanone oxime

73 g of the mixture (including cyclododecanone) obtained last in the cyclododecanone synthesis process, 535 g of ethanol, 8.5 g of ammonium acetate, and titanium silicalite catalyst in a pressure reactor (2ℓ) with an agitator 30 g of powder (titanium silicalite, TS-1) was added and heated to 80°C. Subsequently, NH ₃ gas (Ammonia gas) was injected until 1.8 barg, and NH ₃ was stirred for 30 minutes at 500 rpm to dissolve well in the solution. Subsequently, an aqueous hydrogen peroxide solution having a concentration of 30% by weight was injected while stirring at a flow rate of 2.45 ml/min.

The reaction was performed for 25 minutes to synthesize cyclododecanone oxime.

laurolactam synthesis process

In a 100 ml round flask, 3 g of the mixture (cyclododecanone oxime) obtained in the above cyclododecanone synthesis process, 12 g of isopropylcyclohexane, 0.045 g of cyanuric chloride, and zinc chloride 0.03 g was added. And the temperature was adjusted to 95 ° C using a heating mantle, and the mixture was reacted for 5 minutes by stirring at 200 rpm or more.

Through the various synthetic processes described above, a mixture containing laurolactam, cyclododecanone, and isopropylcyclohexane was prepared.

As shown in FIG. 1, the mixture containing laurolactam, cyclododecanone, isopropylcyclohexane, etc. prepared in Preparation Example 1 is formed by an overhead condenser at the top and a reboiler at the bottom. High-purity laurolactam was purified using a distillation apparatus including a first distiller, a second distiller (a distiller equipped with a thin film evaporator instead of a reboiler) equipped with an overhead condenser at the top and a thin film evaporator at the bottom. .

Specifically, the mixture containing laurolactam, cyclododecanone, isopropylcyclohexane, etc. prepared in Preparation Example 1 was transferred to a first distillation machine and subjected to first distillation, and the reflux ratio was controlled to be 0.8. At this time, in the first still, isopropylcyclohexane having a relatively low boiling point was distilled and condensed through the first overhead condenser to be separated and removed as an overhead effluent, and cyclododecanone was separated and removed as a side cut. has been removed

In addition, the first mixture containing laurolactam, which is the bottom residue of the first still, was transferred to the second still through the bottom of the first still and subjected to second distillation, and the reflux ratio was controlled to be 0.8. At this time, in the second still, laurolactam was distilled and then condensed through a second overhead condenser to separate and obtain an overhead effluent, containing unseparated laurolactam and high molecular weight materials (heavies) having high viscosity. The second mixture was transferred to the thin film evaporator through the bottom of the second still.

The second mixture containing laurolactam unseparated in the thin-film evaporator flows in contact with the thin film-shaped heat transfer surface inside the thin-film evaporator, so that the laurolactam is evaporated as a thin film, and the evaporated laurolactam or a mixture containing the same was transferred to the second still and recycled. In addition, the residual oil at the bottom of the thin film evaporator that was not evaporated was discharged as it was and separated and removed.

In Example 1, the same procedure as in Example 1 was performed except that the reflux ratio of the second still was controlled to be 1.0.

In Example 1, the same procedure as in Example 1 was performed except that the reflux ratio of the second still was controlled to be 1.2.

[Comparative Example 1]

The mixture containing laurolactam, cyclododecanone, isopropylcyclohexane, etc. prepared in Preparation Example 1 was mixed into one conventional unit equipped with an overhead condenser at the top and a reboiler at the bottom. Laurolactam was purified using a distillation machine.

Specifically, the mixture containing laurolactam, cyclododecanone, and isopropylcyclohexane prepared in Preparation Example 1 was transferred to a distiller and distilled. At this time, in the still, isopropylcyclohexane having a relatively low boiling point was distilled and then separated and discharged as an overhead condenser through an overhead condenser, and cyclododecanone was separated and removed as a side cut. At this time, the temperature of the distiller was set to the same temperature as that of the thin film evaporator of Example 1.

[Comparative Example 2]

The mixture containing laurolactam, cyclododecanone, isopropylcyclohexane, etc. prepared in Preparation Example 1 was mixed into two conventional units equipped with an overhead condenser at the top and a reboiler at the bottom. Laurolactam was purified using a distillation apparatus connected to a distiller.

Specifically, the mixture containing laurolactam, cyclododecanone, isopropylcyclohexane, etc. prepared in Preparation Example 1 was transferred to a first still and subjected to first distillation. At this time, in the first still, isopropylcyclohexane having a relatively low boiling point was distilled and then separated and discharged as an overhead effluent through the first overhead condenser, and cyclododecanone was separated and discharged as a side cut. . Then, the mixture containing laurolactam, which is a tower bottom residue, was transferred to a second distillation machine and subjected to a second distillation. At this time, in the second still, laurolactam was distilled and then separated and discharged as an overhead effluent through a second overhead condenser, and the residual oil at the bottom was discharged and separated and removed. At this time, the temperature of each distiller was set to the same temperature as that of the thin film evaporator of Example 1.

Evaluation of purity, yield and presence of fouling according to device configuration

In Example 2, Comparative Example 1 and Comparative Example 2, the purity and yield of the final purified laurolactam (Product) and the presence or absence of fouling that may occur at the bottom of the distillation machine were confirmed. The purity is calculated as the content of laurolactam with respect to the total weight of the mixture obtained through final purification, and the yield is calculated as the content of laurolactam obtained through final purification relative to the content of laurolactam introduced initially.

The yield is calculated as the ratio of final purified laurolactam to laurolactam initially introduced into the first still. and

As a result, in the case of Comparative Example 1 and Comparative Example 2, both the purity and yield of the final purified laurolactam were significantly lowered compared to Examples. Specifically, in the case of Comparative Example 1, it was confirmed that the mixture obtained from the bottom of the column contained a large amount of high-viscosity impurities in addition to laurolactam, and thus the purity was very low. In the case of Comparative Example 2, the purity of the final purified laurolactam was high compared to that of Comparative Example 1, but the mixture discharged and removed from the bottom of the second still contained a significant amount of laurolactam. The yield of laurolactam finally purified from the distillation was remarkably low. In addition, in the case of Comparative Example 2, the fouling phenomenon caused by the high-viscosity material was severe at the bottom of the still, and the amount of the high-viscosity material was considerably high.

On the other hand, in the case of Example 2, compared to Comparative Examples 1 and 2, the separated and removed mixture contained almost no laurolactam, and the purity and yield of the final purified laurolactam were significantly higher. high was confirmed.

Evaluation of purity, yield and presence of fouling according to reflux ratio

The purity and yield of laurolactam finally purified in Examples 1 to 3 were calculated. The purity is calculated as the content of laurolactam with respect to the total weight of the mixture obtained through final purification, and the yield is calculated as the content of laurolactam obtained through final purification relative to the content of laurolactam introduced initially.

In the case of Example 1, fouling caused by the high-viscosity material was slightly observed during the separation of laurolactam at the bottom of the still, but in the case of Examples 2 and 3, no fouling was observed.

In addition, in Examples 2 and 3, the purity of laurolactam was significantly higher than in Example 1, and this is because the mixing of the polymeric material was prevented during separation of laurolactam at the top of the distillation. It is foreseeable.

As described above, the method or apparatus for purifying laurolactam according to the present invention not only has significantly higher purity of laurolactam to be finally purified, but also has a significantly higher yield due to precise separation of impurities.

10: 1st still
20: 2nd still
30: thin film evaporator

Claims (7)

s1) synthesizing cyclododecene by partial hydrogenation of cyclododecatriene;
s2) synthesizing cyclododecanone by oxidizing the product containing cyclododecene synthesized in step s1) with nitrous oxide;
s3) synthesizing cyclododecanone oxime by oximating the cyclododecanone synthesized in step s2), and
s4) synthesizing laurolactam by reacting a product containing cyclododecanone oxime synthesized in step s3) with a catalyst containing cyanuric chloride in a solvent containing isopropylcyclohexane; A method for purifying laurolactam by separating laurolactam from a product of a synthesis process,
a) first distilling the product containing laurolactam synthesized in step s4) to separate and remove low-boiling materials from the top of the first still;
b) second distillation of the first mixture containing laurolactam discharged from the bottom of the first still to separate and obtain laurolactam from the top of the second still; and
c) the second mixture containing the unseparated laurolactam discharged from the bottom of the second still is brought into contact with the heat transfer surface and evaporated as a thin film to separate laurolactam from the top of the thin film evaporator, separating impurities from the bottom of the thin film evaporator, and Including the step of removing
The laurolactam separated from the top of the thin film evaporator in step c) is second distilled again in step b). delete According to claim 1,
A method for purifying laurolactam wherein the reflux ratio in step a), step b) or these steps is 1 or more. delete delete s1) synthesizing cyclododecene by partial hydrogenation of cyclododecatriene;
s2) synthesizing cyclododecanone by oxidizing the product containing cyclododecene synthesized in step s1) with nitrous oxide;
s3) synthesizing cyclododecanone oxime by oximating the cyclododecanone synthesized in step s2), and
s4) synthesizing laurolactam by reacting the product containing cyclododecanone oxime synthesized in step s3) with a catalyst containing cyanuric chloride in a solvent containing isopropylcyclohexane; A laurolactam purification device that separates laurolactam from the product of the synthesis process,
a first still for first distilling the product containing the laurolactam synthesized in step s4) to separate and remove low-boiling materials from the top of the first still;
a second still for second distilling the first mixture containing laurolactam discharged from the bottom of the first still, and separating and discharging laurolactam from the top of the second still; and
The second mixture containing the unseparated laurolactam discharged from the bottom of the second still is brought into contact with the heat transfer surface and evaporated as a thin film to separate and discharge laurolactam through the top of the thin film evaporator, and to separate and discharge impurities through the bottom of the thin film evaporator Including; thin film evaporator to remove,
The laurolactam purifier is separated and discharged from the top of the thin film evaporator and recycled to the second still. delete

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