JP5271598B2 - Method for producing oxazoline compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a purified oxazoline compound efficiently by using a reactive distillation device and using an N-(hydroxyalkyl)carboxylic acid amide as a raw material. <P>SOLUTION: This method for producing the oxazoline compound by feeding an N-(hydroxyalkyl)carboxyamide into the reactive distillation device and performing cyclodehydration is provided by using the reactive distillation device of which central part of the column is divided into a reaction part and distillation part, and having a structure of communicating the reaction part with the distillation part in each of the upper part and lower part of the column, and having a constitution of feeding the N-(hydroxyalkyl)carboxyamide into the reaction part filled with a solid catalyst, introducing the obtained reaction mixture into the distillation part, separately purifying the oxazoline compound at the distillation part and taking it out. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for producing an oxazoline compound.

Oxazoline compounds are highly reactive cyclic imino ethers having a hetero five-membered ring, and are very useful compounds as surfactants, corrosion inhibitors, various intermediate materials, polymers and cross-linking agents.
As a method for producing an oxazoline compound, a method in which amide alcohol is heated and subjected to dehydration cyclization in the presence of a catalyst is known. As a catalyst, an oxide or inorganic acid salt such as manganese or cobalt, an alkanoate of tin, or an iron salt Zinc organic acid salts have been proposed. However, any of these methods is a liquid phase reaction, and it is difficult to separate and recover the catalyst.
On the other hand, a method of obtaining an oxazoline compound by gas phase reaction of amide alcohol in the presence of a titanium-based catalyst has been proposed, but there is a problem that the yield is low.
Patent Document 1 discloses a method for producing 2-alkyl-2-oxazolines in which an N-hydroxyethyl derivative of a carboxylic acid amide is subjected to dehydration cyclization in a liquid phase and subjected to extractive distillation to separate water. .

On the other hand, since reactive distillation can continuously extract reaction products out of the reaction system using the difference in boiling point, a high reaction rate can be obtained even in a reaction with a small equilibrium constant, It is known as a method that can save thermal energy required for distillation separation and recycling, and generally a multistage distillation column or the like is used.
For example, Patent Document 2 discloses a reactive distillation apparatus and a reactive distillation method for supplying raw materials to three different stages. However, since Patent Document 2 is a method using a homogeneous catalyst (liquid catalyst), there are disadvantages that it is difficult to control the reaction time, separate reaction products, and reuse unreacted raw materials.
A method of reactive distillation using a solid catalyst such as an ion exchange resin is also known, but it requires three facilities, a reaction tower, a raw material recovery tower, and a product rectification tower. There are problems of by-products due to history and the difficulty of improving the reaction efficiency of equilibrium reactions.
Patent Document 3 discloses a distillation method using a distillation tower having a structure in which a middle part of the tower is divided into two distillation parts. However, Patent Document 3 discloses only the distillation method, and does not disclose the reactive distillation.

Japanese Patent Publication No. 1-31504 JP-A-9-308801 JP 2004-230251 A

  In the present invention, the reaction and distillation are simultaneously performed in one apparatus, and a reaction distillation apparatus capable of producing a reaction product in an efficient and high yield is used to purify N- (hydroxyalkyl) carboxylic acid amide as a raw material. It is an object of the present invention to provide a method for efficiently producing a prepared oxazoline compound.

  That is, the present invention is a method for producing an oxazoline compound by supplying N- (hydroxyalkyl) carboxamide to a reactive distillation apparatus and cyclizing by dehydration, wherein the central part of the tower is distilled from the reaction part. A reaction distillation apparatus having a structure in which the reaction section and the distillation section communicate with each other in the upper part and the lower part of the column, respectively, and N- (hydroxyalkyl) is added to the reaction part filled with a solid catalyst. Provided is a method for producing an oxazoline compound, which is configured to supply carboxamide, introduce the obtained reaction mixture into the distillation section, and separate and purify the oxazoline compound in the distillation section.

  According to the method of the present invention, a purified oxazoline compound can be efficiently produced using N- (hydroxyalkyl) carboxylic acid amide as a raw material.

  The method for producing an oxazoline compound of the present invention is a method for producing an oxazoline compound by supplying N- (hydroxyalkyl) carboxamide to a reactive distillation apparatus and subjecting it to dehydration cyclization. A reaction distillation apparatus that is divided into a reaction section and a distillation section, and has a structure in which the reaction section and the distillation section communicate with each other at the upper and lower portions of the column. (Hydroxyalkyl) carboxyamide is supplied, and the resulting reaction mixture is introduced into the distillation section, and the oxazoline compound is separated and purified by the distillation section and extracted.

(N- (hydroxyalkyl) carboxamide)
In the present invention, N- (hydroxyalkyl) carboxamide is preferably a compound represented by the following general formula (1).

(In the formula, R ¹ represents an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 3 to 5 carbon atoms, and R ^{2 to} R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Is shown.)
Specific examples of R ¹ in the general formula (1) include CH ₃ —, C ₂ H ₅ —, C ₃ H ₇ —, C ₄ H ₉ —, CH ₂ = CH—, CH ₂ = C (CH ₃ ). -A methyl group, an ethyl group, a propyl group, a vinyl group, and an isopropenyl group are more preferable.
Moreover, as a suitable example of R < ² > -R < ⁵ >, a hydrogen atom, a methyl group, an ethyl group etc. are mentioned each independently.
N- (hydroxyalkyl) carboxamide represented by the general formula (1) can be obtained by reacting the corresponding carboxylic acid or carboxylic acid ester with the corresponding ethanolamine by a known method.

(Oxazoline compound)
As the oxazoline compound in the present invention, a compound represented by the following general formula (2) is preferable.

(Wherein R ^{1 to} R ⁵ are the same as described above.)
Specific examples of the oxazoline compound include 2-methyl-2-oxazoline, 2-ethyl-2-oxazoline, 2-isopropyl-2-oxazoline, 2,4-dimethyl-2-oxazoline, 2-isopropenyl-2-oxazoline. Etc.
Among the oxazoline compounds, the 2-substituted substituent R ¹ is an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 3 to 5 carbon atoms, and R ^{2 to} R ⁵ are hydrogen atoms. 2-oxazoline is preferred, R ¹ is an alkyl group having 1 to 3 carbon atoms, and R ^{2 to} R ⁵ are hydrogen atoms, more preferably 2-substituted-2-oxazoline, particularly 2-methyl-2 -Oxazoline, 2-ethyl-2-oxazoline, 2-isopropyl-2-oxazoline are preferred.

(Reactive distillation equipment)
The reactive distillation apparatus used in the present invention is a reactive distillation apparatus having a structure in which a central part of a tower is divided into a reaction part and a distillation part, and the reaction part and the distillation part communicate with each other at the upper part and the lower part of the tower. N- (hydroxyalkyl) carboxamide is supplied to the reaction part filled with a solid catalyst, the resulting reaction mixture is introduced into the distillation part, and the oxazoline compound is separated and purified in the distillation part. It is configured.
The reactive distillation apparatus uses a so-called reactive distillation column, and consists of a single column (hereinafter, sometimes referred to as “divided column”) having a structure in which the central part of the column is divided into a reaction part and a distillation part. . The reaction part and the distillation part are preferably divided in the vertical direction in the column.
There is no particular limitation on the method for dividing the reaction section and the distillation section, and the column may be divided vertically by a partition plate so that one of them is a reaction section and the other is a distillation section. It is also possible to insert a tube and divide it into an outer side and an inner side of the inner tube, and the inner side of the inner tube can be a reaction part and the outer side of the inner pipe can be a distillation part.

FIG. 1 is a diagram showing an example of a reactive distillation apparatus in which a central part of a tower is divided into a reaction part and a distillation part using an internal partition plate. The central part of the reactive distillation apparatus (dividing tower) 1 is divided into a reaction part 3 and a distillation part 4 by an internal partition plate 2. The upper part 5 and the lower part 6 of the dividing column 1 communicate with the reaction part 3 and the distillation part 4, respectively. This communication part is the same as the structure of a normal distillation column.
The dividing column is not particularly limited as long as multi-component separation is possible, but a multi-stage distillation column such as “Column In Column” (Sumiju Plant Engineering Co., Ltd., registered trademark) is preferably used.

(Reaction part)
The reaction section of the reactive distillation apparatus of the present invention is filled with a solid catalyst. The raw material N- (hydroxyalkyl) carboxamide (hereinafter, also simply referred to as “raw material”) is supplied to the reaction part and reacts when passing through in contact with the solid catalyst layer, and the resulting reaction mixture is the reaction part. It is introduced into a distillation section that communicates with.
It is preferable to supply the raw material to the reaction section continuously from the viewpoint of taking advantage of the features of the reactive distillation apparatus of the present invention.

(Solid catalyst)
There is no particular limitation on the solid catalyst used in the present invention, but in the tower, the contact area with the raw material is large, and there are sufficient voids to enable smooth flow of steam, and the voids are in the catalyst layer. A shape that is uniformly distributed is preferable.
The shape of the solid catalyst is granular, pellet, saddle type used as packing material for distillation tower, Raschig ring, terralet, hollow cylinder with crease around the periphery, coil shape, etc. These may be in the form of a woven fabric, a nonwoven fabric, a string shape, a net shape, a bundle of fibrous materials, a woven fabric or a nonwoven fabric wound in a column with a net, and the like. Moreover, what hold | maintained the shaping | molding catalysts, such as the said granular form and a pellet form, to the regular packing used for the distillation column packing material can also be used.
Furthermore, it is also possible to use a film type solid catalyst in which a metal, ceramics, or other high mechanical strength support is formed into a tubular, flat plate, honeycomb, monolith shape, etc., and a catalyst coating layer is formed on the support surface. it can.

Examples of solid catalysts include single or mixed metal oxides, metal phosphates, metal sulfates, immobilized acids supported or immobilized on supports, natural minerals and layered compounds, solid heteropolyacids, fluorinated sulfones Examples thereof include resins, synthetic zeolites, ion exchange resins, and graft polymers obtained by grafting various reactive groups to a resin.
Examples of the single or composite metal oxide include aluminum oxide, calcium carbonate, barium titanate, calcium titanate, hydrous zirconium oxide, niobic acid, silica alumina, silica titania, silica zirconia, titania zirconia, and zinc oxide. It is done. Examples of the metal phosphate include aluminum phosphate and iron phosphate, and examples of the metal sulfate include aluminum sulfate.
Examples of the immobilized acid supported or immobilized on the support include sulfate ion supported zirconia, sulfate ion supported titania, and antimony pentafluoride supported silica alumina. Examples of natural minerals and layered compounds include acid clay, kaolin, and montmorillonite.
Among the solid catalysts, one or more catalysts selected from spherical aluminum oxide, aluminum phosphate, and zinc oxide are more preferable. Further, as a form of the catalyst, a spherical shape having a diameter of preferably 1 to 10 mm, more preferably 2 to 8 mm is preferable.
These solid catalysts can be produced by known methods.

(Distillation part)
The structure of the distillation part 4 is basically the same as the structure of a normal distillation column. Further, the communication parts 5 and 6 (the upper part 5 and the lower part 6 of the dividing column 1) with the reaction part 3 and the distillation part 4 are basically the same as the distillation part of a normal distillation column. From the viewpoint of the rectification effect, the distillation unit 4 and the communication units 5 and 6 are two or more stages, preferably three or more shelves, or two or more stages, preferably three or more packed beds. Either can be used.
Examples of trays used for the shelves include valve trays, bubble bell trays, perforated plate trays, lift trays, flexi trays, and nutter float valve trays.
The packing used in the packed bed includes ring-type packings such as Raschig rings and pole rings, saddle (horse-shoe-shaped) packings such as bell saddles and interlock saddles, as well as McMahon packing, Canon packing and Dixon packing. , Terralet, Spray Pack, Panapack, Interpack, Good Low Packing, Stedman Packing, Sulzer Packing (manufactured by Sulzer Chemtech), SFLOW (manufactured by Sumiju Plant Engineering Co., Ltd.), and Monz Pack (manufactured by Monz). Among these, there are many stages per tower height, and from the viewpoint of reducing the thermal load on the product, Sulzer Packing (manufactured by Sulzer Chemtech), SFLOW (manufactured by Sumiju Plant Engineering Co., Ltd.), and Monz Pack It is preferable to use a regular packing such as (manufactured by Monz).

The dividing tower 1 preferably has a reflux section at the top of the tower. As the reflux apparatus, a known reflux apparatus used in an ordinary distillation column can be used. The reflux liquid is supplied to the distillation section in order to give a rectifying effect, but may be supplied to the reaction section when the unreacted raw material is used again for the reaction.
The dividing tower 1 preferably has a heating device at the bottom of the tower. As the heating device, a known heating device used in a normal distillation tower can be used. Specifically, a natural circulation type (thermo siphon type), an external circulation type, an insertion type, an overflow tube bundle type (kettle type), or the like can be used. Among these, the external circulation type is preferable from the viewpoint of preventing deterioration due to the thermal history of the fraction containing the high-boiling component (b). As the heat medium, hot oil, high-pressure steam, or the like can be used.

  It is preferable that the dividing column 1 has an extraction part in at least one of the upper part 5 and the lower part 6 of the tower in addition to the extraction part provided in the distillation part 4. For example, when the reaction mixture is (i) a reaction product (oxazoline compound) (m), (ii) a component having a lower boiling point than the reaction product (m) [low boiling point component (a)], (iii) a reaction product (m ) When the component has a higher boiling point [high-boiling component (b)], the low-boiling component (a) is introduced from the upper part (top) of the dividing tower, and the high-boiling component (b) is applied to the lower part ( The reaction product (m) may be extracted from the distillation part (column central part) from the bottom part, and in this case, the extraction part is three places.

In the method for producing an oxazoline compound of the present invention, by using a reactive distillation column having a reaction part and a distillation part, the reaction mixture can be purified by distillation operation in the same apparatus simultaneously with the reaction for obtaining the oxazoline compound. The oxazoline compound is a compound sensitive to heat history, but the yield can be improved by using the reactive distillation apparatus in the present invention.
In the present invention, the distillation method is not particularly limited as long as the distillation operation is performed using a dividing column. The distillation operation may be either batch or continuous, and continuous distillation with a short heating residence time is more preferable. Examples of the distillation method include rectification, molecular distillation, steam distillation, azeotropic distillation performed by supplying an organic solvent as a third component, and extractive distillation. These can be performed alone or in combination of two or more.

In the present invention, from the viewpoint of separation of the oxazoline compound and water, it is preferable to carry out azeotropic distillation by supplying an azeotropic solvent from the upper part (top part) of the dividing tower.
Any azeotropic solvent may be used as long as it forms an azeotrope with water in the dividing column 1 and the boiling point of the azeotrope is lower than the boiling point of the oxazoline compound or the azeotrope thereof with water. Examples of the azeotropic solvent include cyclohexane, benzene, toluene, xylene, ethylbenzene, chlorobenzene, benzine, butanol, propanol, octanol and the like. Among these, cyclohexane, benzene, and toluene are more preferable.
The amount of the azeotropic solvent used is preferably 5 to 50 times, more preferably 15 to 40 times the amount of water. These azeotropic solvents can be recovered and reused. Further, the azeotropic solvent is preferably separated from water at room temperature because it can be easily recovered and reused.
When performing azeotropic distillation, it is preferable to provide an azeotropic solvent supply port 13 at the top of the dividing column 1 of FIG. 1 and continuously supply the azeotropic solvent therefrom.

(Reactive distillation method)
An example of the method for producing the oxazoline compound of the present invention will be described in detail with reference to FIG.
In the dividing column 1 of FIG. 1, the reaction unit 3 is filled with solid catalysts (A, A ′) above and below the raw material supply port 7, and the distillation unit 4 is regularly packed above and below the reaction product distillation outlet 9. Products (B, B ′) are filled, and the communicating parts 5 and 6 with the reaction part 3 and the distillation part 4 are filled with regular packings (C, D), respectively. The shelf of the reaction unit 3 and the packed bed of the solid catalyst (A, A ′) can be provided only on either the upper or lower side of the raw material supply port 7.

N- (hydroxyalkyl) carboxamide, which is a reaction raw material, is supplied from the raw material supply port 7 to the reaction section 3 in the center (middle stage) of the dividing column 1. The supplied raw material reacts when passing in contact with the solid catalyst (A, A ′) filled in the reaction unit 3, and the obtained reaction mixture is introduced into the distillation unit 4 communicating with the reaction unit. .
A distillation outlet 8 for a fraction containing the low-boiling component (a) is provided at the top of the dividing column 1, and a refined product (oxazoline compound as a reaction product) outlet 9 is provided in the middle stage of the tower. At the bottom of the column, a fraction outlet 10 containing the high-boiling component (b) is provided. The refined product outlet 9 in the middle stage of the tower is provided in the distillation section 4 adjacent to the reaction section 3 divided by the internal partition plate 2.
The fraction containing the low-boiling component (a) from the top outlet 8 is discharged out of the tower as vapor, cooled by the condenser 11, and then partly taken out as a distillate and partly refluxed. It may be returned to the top, or all the condensate may be refluxed with an internal condenser (not shown) provided at the top of the column, and a part thereof may be taken out as a distillate. Moreover, the heater 12 for adjusting tower bottom temperature is provided in the tower bottom. In addition, the number and position of the outlet for each fraction in the dividing column 1 are not particularly limited.

The reaction product may change in quality due to heat load, or there may be substances that generate odors. Also, the reaction product itself may change in quality due to heat loads, which may be accompanied by generation of odorous substances. Therefore, the distillation operation is preferably performed under a condition with as low a heat load as possible in order to suppress thermal decomposition of the reaction product and other pyrolyzable substances.
Therefore, the column bottom liquid temperature in the dividing column is preferably 100 to 350 ° C., more preferably 150 to 280 ° C., and the column bottom pressure is preferably 10 to 80 kPa, more preferably 20 to 60 kPa. By performing the above, purified oxazoline can be produced efficiently and in high yield.
In addition, it is preferable to make low the liquid temperature in a division tower in the range which does not prevent the separation of a high boiling point component. Also, a method of blowing high-pressure steam or inert gas from the bottom of the dividing tower, a method of flash evaporation, or the like can be employed.
What is necessary is just to set the supply rate of a raw material from the residence time in the reaction part 3, F-factor (coefficient showing the load of ascending steam) in the distillation part 4, and the communication parts 5 and 6.
As the reflux ratio and the theoretical plate number of the dividing column, values calculated by a distillation simulator from the physical property values of the raw material components can be used. The number of stages of the dividing tower is preferably 2 to 50, more preferably 4 to 40, still more preferably 5 to 30, and particularly preferably 5 to 20.

(Other reactions to which reactive distillation equipment can be applied)
The reactive distillation apparatus in the present invention includes, for example, an esterification reaction between an organic hydroxy compound and an aromatic carboxylic acid, an ester exchange reaction between an aromatic hydroxy compound and an aliphatic carboxylic acid ester, an aromatic hydroxy compound and an aliphatic carbonate ester. It is effectively applied in conducting chemical reactions involving various equilibrium reactions, such as transesterification reactions, transesterification reactions of aromatic carboxylic acid esters with aliphatic carbonates and / or aliphatic / aromatic carbonates. be able to.
More specifically, a reaction to obtain ethyl acetate by esterification reaction of ethyl alcohol and acetic acid, a reaction to obtain diphenyl carbonate by transesterification reaction of phenol and dimethyl carbonate, a reaction to obtain dimethyl acetal by acetalization reaction of acetaldehyde and methanol, etc. Can be applied to.

Example 1
Reaction of the “column-in-column” tower shown in FIG. 1 (supplied by Sumiju Plant Engineering Co., Ltd., 12 theoretical plates (reaction unit 3, distillation unit 4, and communication units 5 and 6 in FIG. 1 are each three)) Part 3 is filled with spherical aluminum oxide (spherical with a diameter of 5 mm, manufactured by Sumitomo Chemical Co., Ltd., KHO-46) as a solid catalyst (A ′), and regular packing (Sumiju Plant) is used for distillation part 4 and communication parts 5 and 6. Using a reactive distillation apparatus (not using the azeotropic solvent supply port 13) filled with Engineering Corporation, SFLOW 700G), N- (2-hydroxyethyl) propionamide at 250 ° C. was supplied from the raw material supply port 7. Continuous supply was carried out at 10 kg / h, and operation was performed at a column bottom liquid temperature of 213 ° C., a column bottom pressure of 40 kPa, and a column top reflux ratio of 5.
In a steady state, the residence time of N- (2-hydroxyethyl) propionamide in the reaction part 3 (A ′) was 7 minutes. Also, the amount of the fraction containing the low boiling point component (a) from the top of the column is withdrawn to the outside is 2 kg / h, the amount of the purified product from the middle column is 1.3 kg / h, and the amount from the bottom of the column is high. The extracted amount of the fraction containing the boiling component (b) to the outside was 6.7 kg / h.
At this time, the purity of 2-ethyl-2-oxazoline of the fraction extracted from the purified product (reaction product) outlet 9 was 99.4%. The total yield (process yield) of 2-ethyl-2-oxazoline extracted from the purified product outlet 9 and the top of the column was 31.9%. The results are shown in Table 1.

Example 2
Reaction of the “column-in-column” tower shown in FIG. 2 (supplied by Sumiju Plant Engineering Co., Ltd., 12 theoretical plates (reaction section 3, distillation section 4, and communication sections 5 and 6 in FIG. 1 are each three stages)) Part 3 is filled with spherical aluminum oxide (spherical with a diameter of 5 mm, manufactured by Sumitomo Chemical Co., Ltd., KHO-46) as a solid catalyst (A ′), and regular packing (Sumiju Plant) is used for distillation part 4 and communication parts 5 and 6. Using a reactive distillation apparatus filled with SFLOW 700G manufactured by Engineering Co., Ltd., N- (2-hydroxyethyl) propionamide at 250 ° C. is continuously supplied at 10 kg / h from the raw material supply port 7, and the azeotropic solvent supply port 13. Was continuously supplied at 37 kg / h, and the operation was performed at a column bottom liquid temperature of 216 ° C. and a column bottom pressure of 40 kPa.
In a steady state, the residence time of N- (2-hydroxyethyl) propionamide in the reaction part 3 (A ′) was 7 minutes. The amount of the fraction containing the low-boiling component (a) from the top of the column is withdrawn to the outside is 38.1 kg / h, the amount of the purified product withdrawn from the middle column is 3.4 kg / h, The amount of the fraction containing the high-boiling component (b) extracted to the outside was 5.4 kg / h.
The low boiling point component (a) from the top of the column was condensed in the condenser 11 and then separated into an aqueous phase and a solvent phase. The amount of the solvent phase was 36.8 kg / h, and it was recycled to the azeotropic solvent supply port 13. The amount of the aqueous phase was 1.3 kg / h, and the components of the aqueous phase were 87.9% by weight of water and 9.2% by weight of 2-ethyl-2-oxazoline.
At this time, the purity of 2-ethyl-2-oxazoline of the fraction extracted from the purified product (reaction product) distillation outlet 9 was 99.6%. The total yield (process yield) of 2-ethyl-2-oxazoline extracted from the purified product outlet 9 and the top of the column was 43.6%. The results are shown in Table 1.

Comparative Example 1
The following reaction process, dehydration process, and rectification process were performed using three facilities.
(Reaction process)
480 g of liquid paraffin and 48.3 g of spherical aluminum oxide (spherical with a diameter of 5 mm, KHO-46, manufactured by Sumitomo Chemical Co., Ltd.) were charged into a 3 L glass flask equipped with a condenser and a fraction receiver. The temperature was raised to 230 ° C. with stirring, and 973 g of N- (2-hydroxyethyl) propionamide was added dropwise at a constant flow rate over 21 hours using a dropping funnel. 2-Ethyl-2-oxazoline and by-product water continuously produced during the dropping were received as a mixed solution in the condenser. The yield of 2-ethyl-2-oxazoline in the fraction was 47.2%.
(Dehydration process)
Into a glass 1 L four-round flask equipped with a condenser and a fraction receiver, 459 g of the fraction mixture obtained by the reaction and 230 g of cyclohexane were charged. While stirring, the pressure was set to 40 kPa, and while maintaining the temperature after raising the temperature to 45 ° C., the cyclohexane and water in the reaction fraction mixture were distilled off and received in a fraction receiver. The yield calculated from the amount of 2-ethyl-2-oxazoline present in the tank after dehydration was 64.2%.
(Rectification process)
Using a distillation column (regular packed sulzer lab packing, 12 theoretical plates), 250 g of the liquid in the tank obtained in the dehydration step was distilled under the conditions of a column bottom pressure of 20 kPa and a still temperature of 69 ° C. The yield obtained with a 2-ethyl-2-oxazoline purity of 99.8% of the fraction was 82.7%.
Therefore, the process yield of 2-ethyl-2-oxazoline was 25.1%. The results are shown in Table 1.

  In Table 1, when Comparative Example 1 and Example 1 are compared, according to the production method using the reactive distillation apparatus of the present invention, purified 2-ethyl-2 from N- (2-hydroxyethyl) propionamide. It can be seen that oxazoline can be produced efficiently and in high yield. It can also be seen that 2-ethyl-2-oxazoline can be produced in a higher yield by carrying out the reactive distillation method of the present invention while supplying an azeotropic solvent with water to the top of the column.

It is a figure which shows an example of the reactive distillation apparatus which divided the tower center part using the internal partition plate.

Explanation of symbols

1: Reactive distillation device (split tower)
2: Internal partition plate 3: Reaction unit 4: Distillation unit 5: Upper part of tower 6: Lower part of tower 7: Feed port for raw material (N- (hydroxyalkyl) carboxyamide) 8: Fraction containing low-boiling component (a) 9: Refined product (reaction product: oxazoline compound) distillation outlet 10: Drain outlet containing high-boiling component (b) 11: Condenser at the top of the tower 12: Heater at the bottom of the tower 13: Azeotropy Solvent supply port

Claims (6)

  A method of supplying N- (hydroxyalkyl) carboxamide to a reactive distillation apparatus to produce an oxazoline compound by dehydration cyclization, wherein the reactive distillation apparatus is divided into a reaction part and a distillation part at the center of the column, A reactive distillation apparatus having a structure in which the reaction part and the distillation part communicate with each other at the upper part and the lower part of a column, respectively, and supplying N- (hydroxyalkyl) carboxamide to the reaction part filled with a solid catalyst; A method for producing an oxazoline compound, wherein the obtained reaction mixture is introduced into the distillation part, and the oxazoline compound is separated and purified by the distillation part.   The method for producing an oxazoline compound according to claim 1, wherein the solid catalyst is one or more selected from aluminum oxide, aluminum phosphate, and zinc oxide.   The oxazoline compound is 2-substituted-2-oxazoline (provided that the substituent at the 2-position is an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 3 to 5 carbon atoms). The manufacturing method of the oxazoline compound of description.   The fraction containing the low boiling point component (a) is extracted from the upper part of the column, the fraction containing the high boiling point component (b) is extracted from the lower part of the column, and the oxazoline compound is extracted from the distillation part at the center of the column. 2. A method for producing an oxazoline compound according to 2.   The manufacturing method of the oxazoline compound in any one of Claims 1-4 which filled the distillation part with the regular packing.   The manufacturing method of the oxazoline compound in any one of Claims 1-5 performed by supplying an azeotropic solvent with water to a tower top part.

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