JP2002275166A - Method for cyclic imino ether production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cyclic imino ether production, with which a reaction is carried out with a small amount of a by-product in a high yield in a short time and a catalyst is readily separated and recovered and can be repeatedly used. SOLUTION: A nitrile is reacted with amino-alcohol in the presence of a basic zinc acetate to produce a cyclic imino ether represented by formula 1 or formula 2 (R<1> is a 1-20C alkyl group, a 5-7C cycloalkyl group, a 7-10C bicycloalkyl group or a phenyl group or a naphthyl group which is substituted with a 1-5C alkyl group or a halogen atom or nonsubstituted; R<2> is a 1-20C alkylene group, a 5-7C cycloalkylene group, a 7-10C bicycloalkylene group or a phenylene group or a naphthylene group which is substituted with a 1-5C alkyl group or a halogen atom or nonsubstituted; R<3> is a hydrogen atom, a methyl group or an ethyl group; n is 1 or 2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cyclic imino ether, which is useful as an aqueous paint, an adhesive, a resin modifier, a crosslinking agent, or an intermediate for medical and agricultural chemicals.

[0002]

2. Description of the Related Art Various methods are known for producing cyclic imino ethers from nitriles and amino alcohols. For example, in JP-A-6-56803,
A ruthenium or rhodium triphenylphosphine complex catalyst is used as a homogeneous catalyst. However, this is not an industrially advantageous method, such as the fact that the catalyst is expensive and the reaction is carried out in an argon atmosphere.Also, although the recovery and reuse of the catalyst is possible, the simple recovery method ignores the accumulation of impurities. Can not. Therefore, there is a report that an inexpensive acetate is used as a catalyst.
Japanese Patent Publication No. 9-108903 discloses that an equivalent cyclic imino ether can be obtained from acetonitrile or adiponitrile and monoethanolamine using dried zinc acetate as a catalyst, and Japanese Patent Publication No. 7-108903 discloses that norbornene carbonitrile using cadmium acetate as a catalyst. To give oxazolyl norbornene. However, these methods are not preferable as an industrial production method, for example, the yield is not sufficient in spite of the reaction for a long time, or a toxic metal is used. Further, when these acetates are used as a catalyst, the catalyst is dissolved in the reaction solution, so that the separation of the catalyst is not easy. However, there is a problem that it is practically difficult to repeatedly use the catalyst, for example, a reaction such as polymerization is caused to cause a decrease in yield. On the other hand, an example using a heterogeneous catalyst which is advantageous for recovery and reuse of the catalyst is disclosed in
No. 148246 discloses an ion-exchange layered clay such as Na-hectorite, smectite, and Na-tetrasilicic mica. However, they show very low activity in aliphatic nitriles,
Aromatic nitriles have a problem that the activity is exhibited but the yield is not sufficient, although the activity is exhibited.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a desired product in a small amount, with a high yield and in a short time.
Another object of the present invention is to provide a method for producing a cyclic imino ether which can easily separate a catalyst and can be used repeatedly.

[0004]

Means for Solving the Problems In order to solve the above problems, the present inventors have intensively studied various catalysts, and as a result, have found that basic zinc acetate can be suitably used as a catalyst, thereby completing the present invention. Reached. That is, the present invention provides (1)
Wherein R ¹ is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a bicycloalkyl group having 7 to 10 carbon atoms, or an alkyl group having 1 to 5 carbon atoms or halogen. been or unsubstituted phenyl group or a naphthyl group substituted with atoms represent a,.) or of 7 (wherein, R ²
Is substituted or unsubstituted by an arylene group having 1 to 20 carbon atoms, a cycloalkylene group having 5 to 7 carbon atoms, a bicycloalkylene group having 7 to 10 carbon atoms, or an alkyl group having 1 to 5 carbon atoms or a halogen atom. Represents a phenylene group or a naphthylene group. ) And R ³ is a hydrogen atom, a methyl group or an ethyl group, and n is 1
Or 2 is represented. ) And the amino alcohol represented by
Characterized by reacting in the presence of basic zinc acetate,
Wherein R ¹ , R ³ , and n are the same as defined above, or R 10, R ² , R ³ , and n are the same as defined above. (2) The method for producing a cyclic imino ether according to the above (1), wherein the basic zinc acetate is prepared by heating zinc oxide and an aqueous solution of zinc acetate.

[0005]

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[0006]

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[0007]

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[0008]

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[0009]

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According to the present invention, a nitrile is reacted with an amino alcohol in the presence of basic zinc acetate. The basic zinc acetate, which is a catalyst used in the present invention, is prepared by heating zinc oxide and an aqueous solution of zinc acetate, and for example, according to the method described in the Chemical Dictionary, Vol. 3, page 812 (Kyoritsu Shuppan). Easily adjusted. It is preferable that the prepared catalyst is pulverized and used in the form of a powder because the dispersibility increases. However, the catalyst may be formed into pellets or the like to facilitate filtration. The amount of the catalyst used is 1 to 30% by weight, preferably 3 to 20% by weight, based on the total weight of the nitrile and the amino alcohol. Since it is a heterogeneous system, not only does it have no effect even if it is added excessively, but also the concentration of slurry in the reaction system becomes high, which increases the power required for stirring and makes filtration difficult, which is not preferable. Since the catalyst is insoluble in the reaction solution, an ordinary filtration device such as a Nutsche or filter can be used as a method for recovering the catalyst after the reaction.

The nitrile used in the present invention may be any of the aliphatic, alicyclic, aromatic and heterocyclic nitriles represented by the above formulas (6) and (7). Examples of the nitrile represented by Chemical formula 6 include acetonitrile, propionitrile, butyronitrile, caprynitrile, benzonitrile, norbornenecarbonitrile, and the like. Examples of the nitrile represented by Chemical formula 7 include adiponitrile, isophthalonitrile, terephthalonitrile, dinitrile malonate, dinitrile succinate, and dinitrile glutarate.

Examples of the amino alcohol represented by the above formula include 2-aminoethanol, 2-amino-1-propanol, 1-amino-2-propanol, and 3-amino-
Examples include 2-butanol, and homologs thereof.

The cyclic imino ethers represented by the above formulas 9 and 10, which are objects of the present invention, include methyl oxazoline, ethyl oxazoline, propyl oxazoline, phenyl oxazoline, oxazolyl norbornene, tetramethylene bis oxazoline, phenylene bis Oxazoline and the like.

The molar ratio of the nitrile to the amino alcohol is arbitrary, but using one in excess promotes the completion of the reaction. In general, there are many cases where an amino alcohol is used in excess with respect to nitrile. In this case, the use of excess nitrile gives a higher yield. This is because the cyclic imino ether generated due to high catalytic activity and the amino alcohol further react to give an amide compound. Therefore, in the present invention, the molar ratio of nitrile / amino alcohol (to one cyano group) is 0.2 to 5
Mole, preferably 0.5 to 2 mole.

The reaction can be carried out in the absence of a solvent. However, if the starting nitrile or the resulting cyclic imino ether is solid at room temperature and has low solubility, a solvent is added in order to carry out the reaction smoothly. Is preferred. Examples of the solvent used include aromatic hydrocarbons such as xylene, chlorobenzene, and toluene, and alcohols such as cyclohexanol, butanol, pentanol, and ethylene glycol. The reaction temperature is 60-140 ° C,
It is preferably 80 to 120 ° C., and when the nitrile used has a low boiling point, a closed reactor such as an autoclave can be used. The reaction time varies depending on the raw materials, reaction conditions and the like, but usually about 4 to 20 hours is sufficient.
Since this reaction system is a heterogeneous reaction, stirring is important, but it is sufficient that the catalyst is uniformly dispersed throughout the reaction system, and no particularly strong shearing force is required.

The amount of water in the reaction system is likely to be a by-product of the corresponding hydrolysis impurities, and is preferably as small as possible. Since the water brought in is mainly derived from raw materials and catalysts,
Before the reaction, it is desirable to remove water using a distillation dehydration or a desiccant. In addition, ammonia gas generated as the reaction proceeds is desirably driven out of the reaction system by decompression or nitrogen bubbling to shift the equilibrium of the reaction to the production system. It is not preferable because the solvent and the solvent are diffused out of the system.

After completion of the reaction, the target substance is easily isolated and purified by a method such as distillation, extraction, crystallization and the like after removing the catalyst by filtration or the like, but contains no catalyst. No loss due to side reactions such as polymerization. The catalyst separated by filtration or the like can be reused as it is or after washing with a solvent such as acetone or methanol.

[0018]

EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. Preparation Example of Basic Zinc Acetate Catalyst 24.1 g of zinc acetate dihydrate (manufactured by Wako Pure Chemical Industries) in a 300 ml three-necked flask equipped with a stirrer and a nitrogen inlet tube.
(0.11 mol) and 66.7 g of deionized water, and an aqueous solution of zinc acetate and zinc oxide (manufactured by Wako Pure Chemical Industries) 8.9.
g (0.11 mol) at 80 ° C. under a nitrogen atmosphere.
Stirring was performed for hours. Thereafter, the water was substantially evaporated while stirring at 105 ° C. for 1 hour. The obtained white powder was taken out of the flask and completely dehydrated by heating in an oven at 110 ° C. for another 2 hours.
7.6 g (0.10 mol) were obtained.

Example 1 1 equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube
In a 00 ml four-necked flask, 20.0 g of 5-norbornene-2-carbonitrile (hereinafter abbreviated as NBCN) was added.
17 mol), 20.6 g of 2-aminoethanol (0.
34 mol) and 6.1 g of basic zinc acetate.
The reaction was performed at 130 ° C. for 12 hours. During this time, nitrogen was bubbled at 50 ml / min to remove by-produced ammonia.
After completion of the reaction, the reaction solution was analyzed by gas chromatography, and as a result, the reaction yield of oxazolyl norbornene (hereinafter abbreviated as NBOX) was 97%. After removing the catalyst by filtration, the reaction solution was distilled under reduced pressure to obtain a solution at 81-82 ° C. (5 mm
As a fraction of Hg), 24.9 g of NBOX was obtained. The purity was 99.6%, and the total yield including the reaction was 90%. In addition, there was almost no distillation residue, and polymerization during distillation was not recognized.

Example 2 In Example 1, the charging ratio, the amount of the catalyst and the reaction time are shown in Table 1.
The reaction was carried out according to the method described in Example 1, except that the reaction was carried out as described in Example 1. After completion of the reaction, the reaction solution was analyzed by gas chromatography, and as a result, the reaction yield was 83%.

Example 3 1 equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube
20.5 g of acetonitrile in a 00 ml four-necked flask
(0.50 mol), 20.6 g of 2-aminoethanol
(0.34 mol) and 2.65 g of basic zinc acetate, and reacted at 90 ° C. for 12 hours while excluding ammonia by-produced under a nitrogen stream. After completion of the reaction, the reaction solution was analyzed by gas chromatography, and as a result, 2-methyl-
The reaction yield of 2-oxazoline was 86%. After removing the catalyst by filtration, the reaction solution was distilled under reduced pressure to obtain 47-5.
2-methyl-2- as a fraction at 0 ° C. (100 mmHg)
23.4 g of oxazoline were obtained. The purity was 99.5%, and the total yield including the reaction was 81%. In addition, there was almost no distillation residue, and polymerization during distillation was not recognized.

Examples 4 to 9 and 11, 12 The reaction was carried out according to the method described in Example 1 except that the nitrile, the amount of the catalyst, the reaction temperature and the reaction time were changed as described in Table 1. After completion of the reaction, the reaction solution was analyzed by gas chromatography. Table 1 shows the results.

Example 10 2 equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube
50.0 g of adiponitrile in a 00 ml four-necked flask
(0.46 mol), 113.1 g of 2-aminoethanol
(1.85 mol) and 7.36 g of basic zinc acetate were charged and reacted at 80 ° C. for 16 hours while excluding ammonia generated under a nitrogen atmosphere. After completion of the reaction, the reaction solution was analyzed by gas chromatography, and as a result, the yield of 1,4-tetramethylenebisoxazoline was 77%. After removing the catalyst by filtration, the reaction solution was distilled under reduced pressure to obtain 64.2 g of 1,4-tetramethylbisoxazoline as a fraction at 112 to 115 ° C. (0.1 mmHg). The purity was 99.1%, and the total yield including the reaction was 71%. The distillation residue was very small.

[0024]

[Table 1]

Comparative Example 1 In Example 1, except that the catalyst was zinc acetate.
The reaction was carried out according to the method described in Example 1. After the completion of the reaction, the reaction solution was analyzed by gas chromatography, and as a result, the reaction yield of NBOX was 88%. Since the catalyst was dissolved in the reaction solution, it was distilled under reduced pressure to obtain
NBOX 18.3 as a fraction at −82 ° C. (5 mmHg)
g was obtained. The purity is 99.5%, and the total yield including the reaction is 6
6%. A large amount of high-viscosity distillation residues remained in the flask.

Comparative Examples 2 to 9 In Comparative Example 1, the reaction was carried out according to the method described in Comparative Example 1, except that the nitrile, the catalyst, the amount of the catalyst, the reaction temperature and the reaction time were as shown in Table 2. The reaction solution was analyzed by gas chromatography. Table 2 shows the results.

[0027]

[Table 2]

Example 13 The catalyst separated by filtration in Example 1 was washed with acetone, and washed with acetone.
When dried in a 5 ° C. oven, it is 5.9 g,
The catalyst recovery was 96%. 0.2 g of a new catalyst was added to the recovered catalyst and reused in the reaction under the same conditions as in Example 1. As a result, NBOX was obtained with a reaction yield of 96%. Similarly, as a result of repeating the reaction three more times, a total of 5
The average reaction yield per cycle was 95.5%, and almost no decrease in activity was observed, confirming that the catalyst could be used repeatedly.

[0029]

As described above, according to the present invention, there is provided an industrially advantageous production method capable of producing a cyclic imino ether with little by-product, in a high yield and in a short time. Further, the catalyst can be easily separated and recovered, and can be used repeatedly.

Claims (2)

[Claims] During 1. A reduction 1 (wherein, ^{R 1} represents an alkyl group having 1 to 20 carbon atoms, cycloalkyl group having 5 to 7 carbon atoms, bicycloalkyl group having 7 to 10 carbon atoms or from 1 to carbon atoms
5 represents an unsubstituted or substituted phenyl or naphthyl group by an alkyl group or a halogen atom. ) Or Chemical Formula 2
(Wherein, R ² is an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 5 to 7 carbon atoms, a bicycloalkylene group having 7 to 10 carbon atoms, or an alkyl group having 1 to 5 carbon atoms or a halogen atom. A nitrile represented by a substituted or unsubstituted phenylene group or a naphthylene group; and R ³ represents a hydrogen atom, a methyl group or an ethyl group, and n represents 1 or 2. ) In the presence of basic zinc acetate, wherein R ¹ , R ³ , and n are the same as those described above, or 5 (formula 4). Wherein R ² , R ³ , and n are the same as those described above.) Embedded image Embedded image Embedded image Embedded image Embedded image 2. The method for producing a cyclic imino ether according to claim 1, wherein the basic zinc acetate is prepared by heating zinc oxide and an aqueous solution of zinc acetate.