JP2015044775A - METHOD FOR PRODUCING α-METHYLENEALDEHYDE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such the problem that a catalyst cannot be efficiently recycled in the production of α-methylenealdehyde using secondary amine salt as a catalyst, and to provide a technology for being capable of easily separating the catalyst, and efficiently recycling the catalyst and thereby efficiently and economically producing α-methylenealdehyde.SOLUTION: A method for producing α-methylenealdehyde which is produced by condensation of formaldehyde and an aldehyde compound represented by Formula (1) (in the formula, R is hydrogen atom or aliphatic hydrocarbon group having 1 to 7 carbon atoms) uses salt formed of a weakly acidic cation-exchange resin and a secondary amine as a catalyst.

Description

  The present invention relates to a method for producing α-methylene aldehyde by condensation using an aldehyde compound and formaldehyde as raw materials.

  α-methylene aldehyde is a compound useful as an intermediate for raw material monomers such as acrylic resins, and is produced, for example, by condensation of an aldehyde compound and formaldehyde using a secondary amine salt as a catalyst.

  In the method for producing α-methylene aldehyde, condensed water of aldehyde compound and formaldehyde is generated, so that the concentration of the catalyst solution containing the secondary amine salt as the catalyst is lowered. In addition, when formalin is used as a raw material, water contained in formalin also reduces the concentration of the catalyst in the catalyst solution. Therefore, in order to use the catalyst again for the reaction, it is necessary to distill off the water of the catalyst solution by distillation to suppress a decrease in reactivity due to a decrease in the catalyst concentration in the catalyst solution. However, in order to distill off water, it is necessary to heat the catalyst solution at a high temperature for a long time. When heating is performed for a long time, there is a problem that formaldehyde and the like act on the catalyst, thereby deteriorating the catalyst and reducing the reactivity.

  In order to reduce the water distilled off after the reaction, Patent Document 1 reduces the amount of water charged during the reaction by mixing and dissolving paraformaldehyde at a high concentration in an aqueous solution of a secondary amine salt having a pH value of 2 to 5. .

  As a method for avoiding the operation of distilling off water, Patent Document 2 reports a method for distilling and recovering a liberated secondary amine by adding an alkali metal or alkaline earth metal basic compound to an aqueous catalyst solution.

JP 2006-45160 A Japanese Patent Laid-Open No. 06-263683

In the method of Patent Document 1, since condensed water is generated during the reaction, it was not possible to avoid the distillation of water by distillation after all.
Further, the method of Patent Document 2 can avoid a large amount of water from being distilled off, but has a drawback that the operation becomes complicated because the acid component of the catalyst needs to be recovered. In addition, distillation for separating α-methylenealdehyde and the catalyst is required before the secondary amine recovery operation. When the secondary amine is used in the form of an aqueous solution as a catalyst, the α-methylenealdehyde and the catalyst are separated. Due to the separation, a distillation operation could not be avoided after all.
In both methods of Patent Documents 1 and 2, as described above, distillation had to be performed to separate α-methylene aldehyde and the catalyst after the reaction. However, regardless of whether or not there is an operation for avoiding a large amount of water to be distilled off, both of them heat the catalyst solution, and thus the alteration of the catalyst cannot be avoided.
Therefore, in the manufacturing method of (alpha) -methylene aldehyde which used the secondary amine salt for the catalyst, the method of suppressing the quality change of the catalyst resulting from a heating was not discovered. Therefore, the catalyst for synthesizing α-methylene aldehyde cannot be efficiently recycled, making it difficult to economically produce α-methylene aldehyde. Accordingly, an object of the present invention is to provide a technique for efficiently and economically producing α-methylene aldehyde useful as an intermediate for raw material monomers such as methacrylic resins.

  The present inventor has started to study an efficient and economical production method of α-methylene aldehyde, and has worked on the development of a technology for suppressing catalyst alteration. As long as an aqueous solution of the secondary amine salt is used as the catalyst, it is judged that the alteration of the catalyst is unavoidable, and attention was paid to making the secondary amine salt into a solid form. Therefore, in order to make the secondary amine salt into a solid form, an acidic ion exchange resin is used as the acid component. However, since the contact efficiency between the raw material and the catalyst is lowered by making the catalyst into a solid form, there is a problem that the reactivity is lowered. Furthermore, the secondary amine salt is more likely to be altered when it is in the form of a salt with an acidic ion exchange resin than when a secondary amine salt is used as a catalyst in an aqueous solution. As a result of extensive studies, it was found that α-methylene aldehyde can be produced without reducing the reactivity by using a salt composed of a weakly acidic cation exchange resin having a carboxyl group and a secondary amine as a solid catalyst. The invention has been reached.

（式中Ｒは水素原子または炭素数１〜７の脂肪族炭化水素基を表す）

（式中Ｒは水素原子または炭素数１〜７の脂肪族炭化水素基を表す）

[２]
生成したα−メチレンアルデヒドを除去し、回収された弱酸性陽イオン交換樹脂と二級アミンからなる塩へ再びホルムアルデヒドの水溶液とアルデヒド化合物を加えることによってα−メチレンアルデヒドを生成させることを特徴とする[１]記載の−メチレンアルデヒドの製造方法。
[３]
弱酸性陽イオン交換樹脂が、カルボキシル基を有する樹脂であり、総イオン交換容量が２．０〜８．０ｍｅｑ.／ｍＬである[１]または[２]に記載のα−メチレンアルデヒドの製造方法。
[４]
弱酸性陽イオン交換樹脂が、アンバーライトＦＰＣ３５００、アンバーライトＩＲＣ７６、ダイヤイオンＷＫ１０、ダイヤイオンＷＫ１１、ダイヤイオンＷＫ１００およびダイヤイオンＷＫ４０Ｌから選ばれる少なくとも一つである[１]〜[３]のいずれか１項に記載のα−メチレンアルデヒドの製造方法。
[５]
二級アミンが、ジメチルアミン、ジエチルアミン、ジ−ｎ−プロピルアミン、ジ−ｉ−プロピルアミン、ジ−ｎ−ブチルアミン、ジ−ｉ−ブチルアミン、ジ−２−エチルヘキシルアミン、ジ−ｎ−オクチルアミン、メチルエチルアミン、メチル−ｎ−ブチルアミン、ジフェニルアミン、ジエタノールアミン、モルホリン、ピペリジン、ピペラジン、ピラゾリジン、ピロリジン、ピラゾールおよびインドールから選ばれる少なくとも１つである[１]〜[４]のいずれか１項に記載のα−メチレンアルデヒドの製造方法。
[６]
一般式（１）のＲがメチル基またはエチル基である[１]〜[５]のいずれか１項に記載のα−メチレンアルデヒドの製造方法。 That is, this invention relates to the manufacturing method shown to the following [1]-[6]) for manufacturing efficiently and economically (alpha) -methylene aldehyde.
[1]
In the production of α-methylene aldehyde represented by the general formula (2) by condensing formaldehyde and the aldehyde compound represented by the general formula (1), a salt composed of a weakly acidic cation exchange resin and a secondary amine is used as a catalyst. A method for producing α-methylene aldehyde represented by the general formula (2).

(Wherein R represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 7 carbon atoms)

(Wherein R represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 7 carbon atoms)

[2]
The produced α-methylene aldehyde is removed, and α-methylene aldehyde is produced by adding an aqueous solution of formaldehyde and an aldehyde compound again to the salt consisting of the weakly acidic cation exchange resin and the secondary amine recovered. [1] A process for producing -methylene aldehyde according to [1].
[3]
The method for producing α-methylene aldehyde according to [1] or [2], wherein the weakly acidic cation exchange resin is a resin having a carboxyl group, and the total ion exchange capacity is 2.0 to 8.0 meq./mL. .
[4]
The weakly acidic cation exchange resin is at least one selected from Amberlite FPC3500, Amberlite IRC76, Diaion WK10, Diaion WK11, Diaion WK100, and Diaion WK40L [1] to [3] The manufacturing method of (alpha) -methylene aldehyde as described in a term.
[5]
Secondary amines are dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, di-i-butylamine, di-2-ethylhexylamine, di-n-octylamine, Α according to any one of [1] to [4], which is at least one selected from methylethylamine, methyl-n-butylamine, diphenylamine, diethanolamine, morpholine, piperidine, piperazine, pyrazolidine, pyrrolidine, pyrazole and indole. -Method for producing methylene aldehyde.
[6]
The method for producing α-methylene aldehyde according to any one of [1] to [5], wherein R in the general formula (1) is a methyl group or an ethyl group.

  Since the production catalyst for α-methylene aldehyde of the present invention is a solid, the product α-methylene aldehyde can be separated and recovered by an easy method such as filtration or centrifugation. Moreover, since there is no heating operation in filtration or centrifugation, the catalyst alteration due to heating, which has been a problem in the separation and recovery operation of the catalyst by distillation, can be suppressed. Therefore, since the recovered catalyst hardly loses the reaction activity, it can be used again for the production of α-methylene aldehyde. Furthermore, since there is no heating operation in the catalyst separation step, the energy cost can be suppressed, so that α-methylene aldehyde can be produced efficiently and economically in the present invention.

  In the present invention, α-methylene aldehyde is produced by carrying out a condensation reaction using an aqueous formaldehyde solution and an aldehyde compound as raw materials using a salt composed of a weakly acidic cation exchange resin and a secondary amine as a catalyst. Further, after the reaction, a salt composed of a weakly acidic cation exchange resin and a secondary amine is separated and recovered from α-methylene aldehyde, and a condensation reaction is performed again using an aqueous solution of an aldehyde compound and formaldehyde as raw materials.

[Weakly acidic cation exchange resin]
The weakly acidic cation exchange resin used as a catalyst component in the present invention is a weakly acidic ion exchange resin having a carboxyl group as an acidic functional group. The polymer matrix of the weakly acidic cation exchange resin may be any of styrene, acrylic and methacrylic. When the resins are classified based on the degree of cross-linking or porosity, examples thereof include gel type, porous type, and high porous type, but a gel type having a small volume of the resin itself is preferable from the viewpoint of improving productivity.
The total ion exchange capacity of the resin is preferably 2.0 to 8.0 meq./mL, more preferably 2.2 to 8.0 meq./mL. In particular, 3.5 to 6.0 meq./mL is most preferable. If it is 2.0 meq./mL or more, since the volume of the resin itself is not excessive, the reaction solution can be efficiently stirred and the reaction tends to proceed rapidly. If it is 8.0 meq./mL or less, there is a tendency that side reactions other than the intended purpose can be suppressed.
The heat resistant temperature of the resin is preferably 100 ° C. or higher because the temperature during the reaction tends to be increased and the reaction can be accelerated. Moreover, if the heat-resistant temperature of resin is 150 degrees C or less, there exists a tendency which is preferable from the surface of availability and cost.
Examples of weakly acidic cation exchange resins that can be used in the reaction include Amberlite FPC3500, Amberlite IRC76, Diaion WK10, Diaion WK11, Diaion WK100, and Diaion WK40L. Among them, Amberlite IRC76 and Diaion WK40L having a large ion exchange capacity are preferable. In particular, Diaion WK40L having a high heat-resistant temperature of the resin is most suitable.
In addition, these weakly acidic cation exchange resins may be used in at least one kind or two or more kinds at the same time.

[Secondary amine]
In the present invention, the secondary amine used as a catalyst component together with the weakly acidic cation exchange resin is dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, di-i-. Examples include butylamine, di-2-ethylhexylamine, di-n-octylamine, methylethylamine, methyl-n-butylamine, diphenylamine, diethanolamine, morpholine, piperidine, piperazine, pyrazolidine, pyrrolidine, pyrazole, and indole. Furthermore, dimethylamine, diethylamine, diethanolamine and morpholine are preferred because the reaction proceeds rapidly. In particular, diethanolamine is most preferable because side reactions derived from the nucleophilicity of the amine itself hardly occur.
Moreover, these secondary amines should just use 1 type or more, and may use 2 or more types simultaneously.

  0.1-2 mol times is preferable with respect to the ion exchange capacity of weakly acidic cation exchange resin, and, as for the usage-amount of the amine at the time of preparing a catalyst, 0.5-1.5 mol times is more preferable. Furthermore, 0.8 to 1.2 mol times is most suitable for increasing the life of the catalyst and the selectivity of the reaction. If it is 0.1 mol times or more, there exists a tendency for reaction to advance rapidly. If it is 2 mol times or less, the selectivity of the reaction is high, and the alteration of the catalyst tends to be suppressed.

  In the batch reaction, a catalyst can be prepared in the reactor by previously charging a predetermined amount of weakly acidic cation exchange resin and secondary amine into the reactor and stirring and mixing them. Alternatively, a catalyst prepared by a method such as filtration or centrifugation can be obtained after a weakly acidic cation exchange resin is dispersed in water and a predetermined amount of secondary amine is mixed.

[Formaldehyde]
The form of formaldehyde used as a raw material is not particularly limited, but it is preferably used as a solution for convenience. In the case of a solution, the solvent here can also be a solvent for the reaction.
The solvent in the case of using as a formaldehyde solution should just be a thing which does not react with formaldehyde, another raw material, or a catalyst component at the time of reaction, and water, acetonitrile, a dioxane, and tetrahydrofuran are illustrated. Moreover, you may use these solvents in mixture of 2 or more types.
When acetonitrile, dioxane or tetrahydrofuran is used as the solvent, the reaction tends to proceed quickly by increasing the compatibility with the aldehyde that reacts with formaldehyde. However, from the viewpoint of cost and safety, the solvent is water and the aqueous formaldehyde solution is used. It is preferable to use as.
Although there is no restriction | limiting in particular in formaldehyde aqueous solution, You may use the formaldehyde aqueous solution obtained by making water act on the commercial formalin obtained by oxidation of methanol, paraformaldehyde, or trioxane. The concentration of formaldehyde in the aqueous solution is preferably 10 to 50% by weight, more preferably 30 to 50% by weight. Furthermore, a 37 to 50% by weight aqueous solution is most suitable because it is easy to handle. If it is 10% by weight or more, the reaction proceeds rapidly and the capacity of the reactor tends not to be excessive. If it is 50% by weight or less, there is a tendency that side reactions such as polymerization of formaldehyde and alteration of the catalyst can be suppressed.
In addition, the amount of formaldehyde charged into the reaction is 0.1 to 100 mol times, preferably 0.5 to 20 mol times relative to the secondary amine used for the catalyst. Furthermore, the reactivity and production efficiency are most suitable when charged at 1 to 10 mole times. If it is 0.1 mol times or more, alteration of the catalyst can be suppressed, and the production tends to be possible without lowering the production efficiency. Since it can react rapidly if it is 100 mol times or less, there exists a tendency which can also suppress a side reaction.

（式中Ｒは炭素数１〜７の脂肪族炭化水素基を表す）
[Aldehyde compound]
As the raw material aldehyde compound, an aldehyde compound represented by the general formula (1) is used.

(Wherein R represents an aliphatic hydrocarbon group having 1 to 7 carbon atoms)

  Examples of the aldehyde compound include propionaldehyde, n-butyraldehyde, valeraldehyde, isovaleraldehyde, n-hexylaldehyde, 3-methylvaleraldehyde, 4-methylvaleraldehyde, n-heptylaldehyde, and 3,3-dimethylpenta. Nar, 3,4-dimethylpentanal, 4,4-dimethylpentanal, 3-methylhexanal, 4-methylhexanal, 5-methylhexanal, 2-cyclopentylacetaldehyde, n-octylaldehyde, 3-methylheptanal, 4 -Methylheptanal, 5-methylheptanal, 6-methylheptanal, 3,4-dimethylhexanal, 3,5-dimethylhexanal, 4,5-dimethylhexanal, 3,3,4-trimethylpentanal, 3, 4 4- trimethyl pentanal, and the like. Among these, propionaldehyde and n-butyraldehyde having good contact property with the catalyst are preferable because the reaction proceeds promptly. Furthermore, propionaldehyde is particularly suitable because it allows easy recovery of unreacted raw materials and separation of the product and the catalyst.

  The amount charged into the reaction is 0.5 to 3.0 moles, preferably 0.8 to 2.0 moles, relative to formaldehyde used as a raw material. Furthermore, the selectivity of α-methylene aldehyde is most suitable when charged at 0.9 to 1.5 mole times. If it is 0.5 mol times or more, there exists a tendency for reaction to advance rapidly. If it is 3.0 mol times or less, there exists a tendency which can suppress side reactions, such as a self-condensation of a raw material aldehyde compound.

[Polymerization inhibitor]
The α-methylene aldehyde produced in the present invention has polymerizability. In order to suppress polymerization during the reaction, a polymerization inhibitor may be added to the reaction solution. The polymerization inhibitor to be added is not particularly limited. However, phenolic polymerization inhibitors such as hydroquinone and methoquinone, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter abbreviated as 4H-TEMPO). Nitroso polymerization inhibitors such as) can be used. The addition amount is 10 to 5000 ppm, preferably 100 to 2000 ppm, based on the theoretical production amount of α-methylene aldehyde. Furthermore, the addition of 500 to 1500 ppm is most preferable because the polymerization inhibitor can be easily removed.

[reaction]
The reaction of the present invention can be performed by a flow reactor or a batch reactor. When using a flow reactor, for example, a secondary amine is adsorbed onto a weakly acidic cation exchange resin and charged into a tubular reactor, and the reaction is carried out by passing an aqueous solution of formaldehyde and an aldehyde compound. When the raw material remains in the reaction liquid recovered from the flow reactor, the recovered reaction liquid can be circulated again to the reactor to advance the reaction. On the other hand, side reactions can be suppressed by appropriately adjusting the residence time in the reactor to complete the reaction.

  In the case of using a batch reactor, for example, a weakly acidic cation exchange resin and a secondary amine are charged into the reactor, and then an aqueous solution of raw material formaldehyde and an aldehyde compound are added to perform the reaction. In addition, after completion | finish of reaction by a batch reactor, the reaction liquid containing a catalyst and alpha-methylene aldehyde can be isolate | separated by well-known methods, such as filtration and centrifugation.

When either a flow reactor or a batch reactor is used, the reaction is preferably performed by heating with a temperature medium of 10 to 120 ° C, more preferably 30 to 110 ° C. Heating with a temperature medium of 50 to 110 ° C. that allows the reaction to proceed quickly and suppress side reactions is optimal. If it is 10 degreeC or more, there exists a tendency for reaction to advance rapidly. If it is 120 degrees C or less, there exists a tendency which can suppress a side reaction and the alteration of a catalyst.
However, when a flow reactor is used, if the reaction temperature is higher than the boiling point of the raw aldehyde, the contact efficiency between the aldehyde compound and the catalyst decreases due to boiling of the aldehyde compound, and the conversion rate of the aldehyde compound decreases. There is. In that case, contact efficiency can be improved and the reactivity can be increased by suppressing the boiling of the aldehyde compound by pressurizing the inside of the flow reactor.

  Although the reaction can be carried out in an air atmosphere, it is desirable to carry out the reaction in an atmosphere having a reduced oxygen concentration in order to suppress aldehyde oxidation. Moreover, you may react in inert gas atmosphere, such as nitrogen, argon, and a carbon dioxide. In this case, 4H-TEMPO or the like is desirable as a polymerization inhibitor added to the reaction.

  In the case of using a batch reactor, the production selectivity of α-methylene aldehyde is improved by mixing a weakly acidic cation exchange resin, a secondary amine, and an aqueous solution of formaldehyde in advance before adding the aldehyde compound. Catalyst alteration can also be suppressed. Moreover, when adding an aldehyde compound, the production | generation selectivity of (alpha) -methylene aldehyde can be improved by dripping, controlling the temperature of a reaction liquid in the range of 10-40 degreeC. Since the reaction liquid temperature and the vapor temperature increase with the progress of the reaction, the progress of the reaction can be traced by monitoring these temperatures. Therefore, after the reaction liquid temperature and the vapor temperature rise, it can be determined as the end point of the reaction when the temperature reaches a certain temperature, so that the side reaction caused by the prolonged reaction can be suppressed.

  By the method of the present invention, α-methylene aldehyde useful as an intermediate for raw material monomers such as methacrylic resin can be produced efficiently and economically.

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
The raw material aldehyde compound and the reaction product α-methylene aldehyde were quantitatively analyzed under the following GC conditions.
[Quantitative analysis of aldehydes]
Column: HP-1 (0.32 mm ID × 30 m, film thickness 0.25 μm)
Sample inlet temperature and sample injection method: 200 ° C., dilute reaction solution 5 times with tetrahydrofuran, add internal standard and inject by split method (split ratio 100: 1)
Detector and detector temperature: TCD, 250 ° C
Carrier gas and flow rate: Helium, 2.0 mL / min (flow rate control)
Column temperature: After holding at 40 ° C. for 5 minutes, the temperature is raised to 250 ° C. at 10 ° C./min. Hold at 250 ° C. for 5 minutes.
Quantification: Internal standard method using 1,4-dioxane as an internal standard.

[Example 1]
24 mL of weakly acidic cation exchange resin Diaion WK40L (106 meq.) Was washed with 100 mL of concentrated hydrochloric acid and 500 mL of pure water. A Dimroth condenser was connected, and the washed resin and 50 ml of water were charged into a 200 mL round bottom flask previously substituted with nitrogen. Further, 11.1 g of diethanolamine (0.106 mol) and 0.024 g of 4H-TEMPO (0.14 mmol, corresponding to 1000 ppm of the theoretical yield of methacrolein) were added, and stirring with a mechanical stirrer was performed for 30 minutes. Add 28.0 g of 37% formaldehyde aqueous solution (0.345 mol in terms of formaldehyde), stir for 5 minutes, and adjust the dropping rate so that it does not exceed 40 ° C when the temperature of the reaction solution reaches 20 ° C. 20.0 g (0.344 mol) of aldehyde was added. Then, it stirred while heating a reaction liquid with a 70 degreeC warm water, and reacted for 1 hour. After the reaction, the reaction solution was suction filtered through a glass filter to separate the catalyst resin and obtain a reaction solution. Since the reaction solution was separated into two layers, each layer was quantified by GC. The upper layer contained 0.04 g of propionaldehyde and 15.3 g of methacrolein, and the lower layer contained 4.7 g of methacrolein. The conversion of propionaldehyde was 99.8%. The amount of methacrolein combined with the upper and lower layers of the reaction solution was 20.0 g (0.285 mol), and the yield based on propionaldehyde was 82.9%.

[Example 2]
The same procedure as in Example 1 was carried out except that diethanolamine was changed to morpholine.
As determined by GC, the upper layer contained 0.32 g of propionaldehyde and 18.0 g of methacrolein, and the lower layer contained 0.08 g of propionaldehyde and 3.9 g of methacrolein. The conversion of propionaldehyde was 98.0%. The amount of methacrolein combined with the upper and lower layers of the reaction solution was 21.9 g (0.312 mol), and the yield based on propionaldehyde was 90.8%.

[Comparative Example 1]
As in Example 1, 61 mL of washed strongly acidic cation exchange resin Diaion PK216 (106 meq.) And 50 ml of water were charged into a round bottom flask. In addition, 11.1 g of diethanolamine (0.106 mol) and 0.024 g of 4H-TEMPO were added, and stirring with a mechanical stirrer was performed for 30 minutes. 28.0 g (0.345 mol) of 37% formaldehyde aqueous solution was added, and 20.0 g (0.344 mol) of propionaldehyde was added in the same manner as in Example 1 to carry out the reaction. After the reaction, the catalyst was separated in the same manner as in Example 1 to obtain a uniform reaction solution. As determined by GC, the reaction solution contained 10.0 g of propionaldehyde, and the conversion rate of propionaldehyde was 50.0%. However, methacrolein was not detected. When a weakly acidic cation exchange resin was used for the acid component of the catalyst, methacrolein was obtained in good yield. However, methacrolein was not obtained when a strongly acidic cation exchange resin was used.

[Example 3]
A Dimroth condenser was connected, and the catalyst separated in Example 1 and 0.024 g of 4H-TEMPO were charged into a 200 mL round bottom flask previously substituted with nitrogen. 28.1 g (0.346 mol) of 37% aqueous formaldehyde solution was added, and 20.0 g (0.344 mol) of propionaldehyde was added in the same manner as in Example 1 to carry out the reaction. After the reaction, the catalyst was separated in the same manner as in Example 1 to obtain a reaction solution separated into two layers. As determined by GC, the upper layer contained 0.10 g of propionaldehyde and 19.0 g of methacrolein, and the lower layer contained 0.02 g of propionaldehyde and 4.1 g of methacrolein. The conversion of propionaldehyde was 99.4%. The amount of methacrolein combined with the upper and lower layers of the reaction solution was 23.1 g (0.330 mol), and the yield based on propionaldehyde was 95.7%.

[Examples 4 to 11]
The reaction was repeated in the same manner as in Example 3 using the catalyst separated in Example 3. Furthermore, the same repeated reaction was performed 7 times. Table 1 below shows the results of the reactions in Examples 1 and 3-11.

[Summary]
In the reaction using Diaion WK40L and diethanolamine, methacrolein could be obtained in good yield without reducing the reactivity in Example 11 as well. A catalyst composed of a weakly acidic cation exchange resin diamond ion and a salt of a secondary amine could be easily separated and showed high reactivity even in reuse.

[Example 12]
In the same manner as in Example 1, 24 mL of a weakly acidic cation exchange resin Diaion WK40L (106 meq.) And 50 ml of water were charged into a round bottom flask. Further, 11.1 g of diethanolamine (0.106 mol) and 0.024 g of 4H-TEMPO (0.14 mmol, corresponding to 1000 ppm of the theoretical yield of methacrolein) were added, and stirring with a mechanical stirrer was performed for 30 minutes. 28.0 g (0.345 mol) of 37% formaldehyde aqueous solution was added and stirred for 5 minutes, and 44.2 g (0.345 mol) of n-octylaldehyde was added dropwise while maintaining 20-30 ° C. Thereafter, the reaction solution was stirred while being heated in an oil bath set at 110 ° C., and reacted for 3 hours. After the reaction, the reaction solution was suction filtered through a glass filter to separate the catalyst resin and obtain a reaction solution. Since the reaction solution was separated into two layers, each layer was quantified by GC. In the upper layer, there were 6.6 g of n-octylaldehyde and 15.3 g of 2-methyleneoctanal. N-octylaldehyde and 2-methyleneoctanal were not detected in the lower layer. Therefore, the conversion of n-octyl aldehyde was 85.1%. Moreover, the amount of 2-methyleneoctanal was 24.3 g (0.173 mol), and the yield based on n-octylaldehyde was 50.1%.

[Example 13]
The same operation as in Example 12 was performed except that n-octylaldehyde was changed to 24.9 g (0.345 mol) of n-butyraldehyde. After separating the catalyst resin and obtaining a reaction solution that was separated into two layers, each layer was quantified by GC. In the upper layer, 0.4 g of n-butyraldehyde and 23.1 g of 2-methylenebutanal were present. In the lower layer, 0.4 g of n-butyraldehyde and 0.7 g of 2-methylenebutanal were present. Therefore, the conversion of n-butyraldehyde was 98.0%. The amount of 2-methylenebutanal combined with the upper and lower layers of the reaction solution was 23.8 g (0.283 mol), and the yield based on n-butyraldehyde was 82.0%.

When a secondary amine salt is used as a catalyst, the catalyst is altered by heating the catalyst solution at the time of catalyst separation, so that it is difficult to repeatedly use the catalyst economically. According to the present invention, α-methylene aldehyde useful as an intermediate of a raw material monomer such as a methacrylic resin can be produced efficiently and economically.

Claims (6)

In the production of α-methylene aldehyde represented by the general formula (2) by condensing formaldehyde and the aldehyde compound represented by the general formula (1), a salt composed of a weakly acidic cation exchange resin and a secondary amine is used as a catalyst. A method for producing α-methylene aldehyde represented by the general formula (2).

(Wherein R represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 7 carbon atoms)

(Wherein R represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 7 carbon atoms)   The produced α-methylene aldehyde is removed, and α-methylene aldehyde is produced by adding an aqueous solution of formaldehyde and an aldehyde compound again to the salt consisting of the weakly acidic cation exchange resin and the secondary amine recovered. The manufacturing method of the alpha-methylene aldehyde of Claim 1.   The method for producing α-methylene aldehyde according to claim 1 or 2, wherein the weakly acidic cation exchange resin is a resin having a carboxyl group and has a total ion exchange capacity of 2.0 to 8.0 meq./mL.   The weak acid cation exchange resin is at least one selected from Amberlite FPC3500, Amberlite IRC76, Diaion WK10, Diaion WK11, Diaion WK100, and Diaion WK40L. The manufacturing method of the alpha-methylene aldehyde of description.   Secondary amines are dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, di-i-butylamine, di-2-ethylhexylamine, di-n-octylamine, The α-methylene according to any one of claims 1 to 4, which is at least one selected from methylethylamine, methyl-n-butylamine, diphenylamine, diethanolamine, morpholine, piperidine, piperazine, pyrazolidine, pyrrolidine, pyrazole and indole. Method for producing aldehyde.   R of general formula (1) is a methyl group or an ethyl group, The manufacturing method of the alpha-methylene aldehyde of any one of Claims 1-5.