JPH0616588A - Production of alpha-methylenealdehyde - Google Patents

Abstract

PURPOSE:To obtain an alpha-methylenealdehyde on an industrial scale at a low cost by reacting an aldehyde compound with formaldehyde in the presence of an organic carboxylic acid salt of a secondary amide, contacting the obtained reaction liquid with an organic solvent and efficiently recovering, recycling and reutilizing the catalyst. CONSTITUTION:A compound of formula I (R is H or hydrocarbon group) is subjected to condensation reaction with formaldehyde in the presence of an organic carboxylic acid salt of a secondary amine (having a total carbon number of >=12, especially preferably 12-22, e.g. dimethylamine stearic acid salt) in an aqueous medium at 80-160 deg.C (preferably 100-150 deg.C) to synthesize the compound of formula II. At least a part of the obtained reaction mixture is extracted with preferably 50-100 pts.vol. (based on 100 pts.vol. of the reaction mixture) of an organic solvent having low polarity (especially preferably a hydrocarbon) preferably at 10-60 deg.C and the separated fractions are distilled to obtain the objective compound of formula II and a distillation residue containing the catalyst. The recovered catalyst is reused in the reaction.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improved process for producing an .alpha.-methylene aldehyde compound by subjecting an aldehyde compound and formaldehyde to a condensation reaction.
The α-methylene aldehyde compound, especially methacrolein, is an industrially important compound as a raw material for methyl methacrylate.

[0002]

2. Description of the Related Art A reaction in which an aldehyde compound and formaldehyde are reacted in a liquid phase in the presence of a secondary amine to synthesize an .alpha.-methylenealdehyde compound is known as a Mannich reaction. Usually, secondary amines as catalysts are used in the form of carboxylates or mineral salts. A method of using a large amount of a salt of a secondary amine for increasing the yield of an α-methylene aldehyde compound has been proposed (see US Pat. No. 2,848,499). For the purpose of reducing the amount of secondary amine salt used and producing an α-methylene aldehyde compound in a high yield, the reaction is carried out in a liquid phase under pressure at a temperature of 150 to 300 ° C. for a maximum of 25 minutes. A method has been proposed in which the reaction time is used (JP-A-58-18).
8831). In these methods, after the reaction, the catalyst evaporates and collects the α-methylene aldehyde compound produced from the reaction mixture and a part of water, or discards it.

[0003]

In the Mannich reaction, an aqueous solution of formaldehyde is usually used as the raw material formaldehyde,
Moreover, since water is produced in the reaction, it is necessary to evaporate a large amount of water in order to recover the catalyst. In addition, since the amine carboxylate used is partially decomposed by heat, the amine,
It is necessary to recover the three components of the carboxylic acid and the carboxylic acid salt of the amine, and the catalyst recovery process must be extremely complicated. Further, when discarding the catalyst, it is necessary to perform wastewater treatment, incineration treatment, etc. so as not to cause environmental pollution, and a large amount of capital investment is required.

The object of the present invention is to efficiently recover the catalyst from the reaction mixture so as to be advantageous in recycling the catalyst into the reaction, and to obtain the α-methylene aldehyde compound in a high yield by the Mannich reaction. An object is to provide an industrially advantageous method that can be manufactured.

[0005]

According to the present invention, the above-mentioned object is achieved by the general formula (I)

[0006]

[Chemical 3]

A catalyst comprising an aldehyde compound represented by the formula (wherein R represents a hydrogen atom or a hydrocarbon group) and formaldehyde, and an organic carboxylic acid salt of a secondary amine having a total number of carbon atoms of 12 or more. By the condensation reaction at 80 to 160 ° C. in an aqueous medium in the presence of

[0008]

[Chemical 4]

An α-methylene aldehyde compound represented by the formula (wherein R is as defined above) is synthesized, and at least a part of the resulting reaction mixture is brought into contact with an organic solvent having a small polarity. An α-methylene aldehyde compound, characterized in that the α-methylene aldehyde compound and the catalyst are extracted and separated in a solvent, the α-methylene aldehyde compound and the organic solvent are respectively separated by distillation from the extract, and the distillation residue containing the catalyst is recovered. It is achieved by providing a manufacturing method of.

In the above general formula, the hydrocarbon group which R may represent may be a saturated hydrocarbon group, an unsaturated hydrocarbon group or an aromatic hydrocarbon group and has 1 to 2 carbon atoms.
0 is preferable. The hydrocarbon group may have a substituent inert to the reaction. Examples of particularly preferable saturated hydrocarbon groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, isoheptyl, n-nonyl and the like having 1 to 1 carbon atoms.
0 alkyl group; 5 to 5 carbon atoms such as cyclohexyl
Examples of the particularly preferable unsaturated hydrocarbon group include a cycloalkyl group having 10 to 10 carbon atoms, and an alkenyl group having 2 to 10 carbon atoms such as vinyl and 5-hexenyl. A particularly preferable aromatic hydrocarbon group. Examples of include an aryl group having 6 to 10 carbon atoms such as a phenyl group.

Examples of the aldehyde compound represented by the general formula (I) [hereinafter, this may be referred to as aldehyde compound (I)] include, for example, acetaldehyde, propanal, n-butanal, n-pentanal and 3-methylbutanal. Nal, n-hexanal, n-heptanal, n-
Octanal, 7-methyloctanal, n-undecanal, n-octadecanal, 3-butene-1-al, 7-octen-1-al, cyclohexylacetaldehyde, phenylacetaldehyde, methoxyacetaldehyde, p-chlorophenylacetaldehyde, etc. Can be used.

From the viewpoint of handling, formaldehyde is preferably an aqueous solution having a concentration of 10 to 70%.
More preferably, a 0-70% aqueous solution is used. The use of a high-concentration formaldehyde aqueous solution is advantageous in terms of reactor efficiency and wastewater treatment after the reaction. The amount of formaldehyde used is preferably in the range of 0.5 to 2.0 mol, and 0.8 to 1 mol with respect to 1 mol of the aldehyde compound (I).
The range of 1.2 mol is more preferable, and the range of around 1.0 mol is particularly preferable.

The condensation reaction in the present invention is carried out in the presence of a catalyst comprising an organic carboxylic acid salt of a secondary amine having a total number of carbon atoms of 12 or more. The use of such a catalyst is important for reducing the loss of the catalyst and effectively recovering the catalyst. When the total number of carbon atoms of the organic carboxylic acid salt of the secondary amine is less than 12, it becomes difficult to efficiently recover the organic carboxylic acid salt from the aqueous solution containing the organic carboxylic acid salt, and the loss amount is Will increase. When an organic carboxylic acid salt of a secondary amine having an excessively large total number of carbon atoms is used, the reaction rate becomes slow and the α-methylene aldehyde compound represented by the general formula (II) [hereinafter,
It may be referred to as a methylene aldehyde compound (II)], which is not preferable because the selectivity tends to decrease. The organic carboxylic acid salt of a secondary amine has a total number of carbon atoms of 1
2-26 are preferable, 14-26 are more preferable, and 16-22 are particularly preferable. The secondary amine constituting the catalyst in the present invention has 1 carbon atom.
It is preferable to have one to 20 hydrocarbon groups, and the hydrocarbon group may be any of a saturated hydrocarbon group, an unsaturated hydrocarbon group and an aromatic hydrocarbon group, and the two hydrocarbon groups are the same. Or may be different. As the secondary amine, dimethylamine, diethylamine,
Di-n-propylamine, diisopropylamine, di-
n-butylamine, diisobutylamine, di-n-hexylamine, di-n-octylamine, di (2-ethylhexyl) amine, diphenylamine, piperidine, N
-Methyl-N-hexylamine, N-ethyl-N-hexylamine and the like can be exemplified, but not limited thereto. The organic carboxylic acid constituting the catalyst preferably has 2 to 20 carbon atoms, and may be any of saturated aliphatic carboxylic acid, unsaturated aliphatic carboxylic acid and aromatic carboxylic acid. As the organic carboxylic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, caproic acid, heptanoic acid, caprylic acid, lauric acid, 2-ethylhexanoic acid,
Examples thereof include, but are not limited to, myristic acid, palmitic acid, stearic acid, and benzoic acid.

Examples of the organic carboxylic acid salts of secondary amines having a total number of carbon atoms of 12 to 22 include:
Dimethylamine stearate, diethylamine laurylate, di-n-propylamine caprylate, di-n
-Propylamine decanoate, diisopropylamine benzoate, di-n-butylamine caprylate, di-n
-Butylamine pivalate, di-n-butylamine valerate, diisobutylamine caproate, di-n-hexylamine caproate, di-n-octylamine butyrate, di (2-ethylhexyl) amine propionate , Di (2-ethylhexyl) amine valerate, piperidine myristate, diphenylamine propionate and the like are used. These organic carboxylic acid salts of secondary amines may be added directly to the reaction system, or the organic carboxylic acid salts may be reacted by separately adding the above-mentioned secondary amine and organic carboxylic acid to the reaction system. It may be formed in a system. The amount of the organic carboxylic acid salt of the secondary amine used is 0.01 to 1 mol with respect to 1 mol of the aldehyde compound (I).
The range of 0.5 mol is preferable, and the range of 0.02 to 0.1 mol is more preferable. When the amount of the organic carboxylic acid salt of the secondary amine used is 0.01 equivalent or less, the reaction rate becomes slow, which is not preferable. The upper limit of the amount used is not particularly limited, but 0.5 mol or more is not preferable from the economical viewpoint.

The above condensation reaction is carried out in an aqueous medium, but if desired, it can be carried out in the presence of an organic solvent which is inert to the reaction and insoluble in water. As an organic solvent,
For example, it is suitable to use the same organic solvent having a small polarity used as an extraction solvent described later. When the organic solvent is used, it is preferable to use the organic solvent in the range of 1 to 300 parts by volume with respect to 100 parts by volume of the aqueous phase of the reaction system.

The condensation reaction in the present invention is carried out at 80 to 160.
It is carried out at temperatures in the range of ° C. When the reaction temperature is lower than 80 ° C, the reaction rate becomes slower and side reactions such as aldol condensation reaction easily occur, and when it exceeds 160 ° C, side reactions such as dimerization reaction and polymerization reaction occur. Is more likely to occur. From the viewpoint of suppressing side reactions such as aldol condensation reaction, the reaction temperature is preferably in the range of 100 to 150 ° C, particularly 110 to 145 ° C. The reaction pressure is appropriately determined depending on the pressure of water and the aldehyde compound at the reaction temperature adopted. The reaction is carried out by either a batch method or a continuous method. The reaction time is preferably within 30 minutes, more preferably 0.1 to 5 minutes. If the reaction time becomes long, the yield of the product α-methylene aldehyde compound (II) will be degraded due to decomposition, so it is desirable not to adopt a reaction time longer than necessary. It is recommended that the condensation reaction in the present invention is carried out by adding a polymerization inhibitor such as hydroquinone, metoquinone, phenothiazine, etc., if necessary. As an addition method, it may be added directly to the reactor or may be dissolved in the starting aldehyde compound (I) and added as a solution. The amount used is usually in the range of 10 to 5000 ppm, preferably 10 with respect to the aldehyde compound (I).
It is in the range of 0 to 2000 ppm.

Since the α-methylene aldehyde compound (II) does not have good thermal stability, the reaction mixture obtained immediately after the completion of the reaction has a temperature of 100 ° C. or less, preferably 6 ° C. or less.
Cooling to a temperature below 0 ° C is recommended.

As mentioned above, by contacting at least a portion of the reaction mixture with an organic solvent of low polarity,
The α-methylene aldehyde compound (II) and the catalyst are extracted and separated in the organic solvent. The organic solvent having a small polarity, which is an extraction solvent, preferably has a boiling point in the range of 0 to 200 ° C. under normal pressure, more preferably in the range of 30 to 160 ° C. Examples of the extraction solvent include isopentane, n-pentane, n-hexane, cyclohexane, n-heptane, isooctane, n-octane, isononane, n-nonane, isononene, n-decane, n-undecane, benzene, toluene, xylene. Hydrocarbons such as, cumene, mesitylene, petroleum ether, ligroin;
Diethyl ether, di-n-propyl ether, di-n
Ethers such as butyl ether, anisole, phenetole, and the like. Among these extraction solvents, hydrocarbon is particularly preferable. In addition, it is preferable to avoid using an organic solvent having a boiling point close to that of the α-methylene aldehyde compound (II) as the extraction solvent. The amount of extraction solvent used is 20 per 100 parts by volume of the reaction mixture.
To 500 parts by volume is preferable, and 50 to 150 parts by volume is more preferable. The extraction operation is preferably carried out at a temperature in the range of 0 to 80 ° C, more preferably 10 to 60 ° C. As the extraction device, an industrially widely used stirring type extractor, RDC type extractor, perforated plate tower and the like can be used. The extraction operation can be carried out either batchwise or continuously, but industrially it is carried out continuously by providing a stationary tank sufficient for phase separation.

By subjecting the extract obtained by the extraction operation to a distillation operation, the α-methylene aldehyde compound (II) and the organic solvent used as the extraction solvent are separately obtained. The recovered organic solvent is reused as an extraction solvent. Further, by this distillation operation, the distillation residue containing the catalyst is recovered. Since the obtained distillation residue mainly consists of the catalyst component, the catalyst component contained therein can be reused as a part of the catalyst by circulating the distillation residue as it is in the reaction system. However, since a small amount of high-boiling-point by-products is contained in the distillation residue, when circulating the distillation residue to the reaction system, it is necessary to wash at least part of the distillation residue with water in advance to remove the high-boiling-point by-product. It is preferred to remove the product. The amount of water used for washing is not limited, but is preferably in the range of 10 to 300 parts by volume with respect to 100 parts by volume of the distillation residue to be washed. The washing operation can be carried out either batchwise or continuously, and is usually carried out using an extraction / washing device which is commonly used.

[0020]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

Example 1 A stainless steel autoclave having an internal capacity of 100 ml (reaction volume of 20 ml) equipped with a thermometer, an electromagnetic stirrer, a raw material feed port, a gas blowing port, and a sampling port was subjected to a nitrogen pressure of 50 kg / cm ² , and a temperature of 130 302g / hr of propanal in which 500ppm of hydroquinone which was preheated to ℃ was dissolved, and 422g of 37% formalin /
di-n-butylamine at 26.9 g / hr,
And caprylic acid were continuously fed at 30.0 g / hr, respectively, and the reaction was carried out at 130 ° C. The residence time was 1.5 minutes. A sample overflowing at 781 g / hr was collected under ice-cooling, and the product was analyzed by gas chromatography. Unreacted propanal is 0.9 g / hr and methacrolein is 345.5 g / hr.
Each of them spilled for an hour. The yield of methacrolein based on the propanal charged was 94.8%, and the selectivity was 95.0.
%, And the conversion rate of propanal was 99.7%.

200 g of the above-recovered sample (88.4 g of methacrolein, 92.0 g of water, 6.3 g of di-n-butylamine, 7.7 g of caprylic acid, 5.0 other components)
50 g of toluene was added to g), and the aqueous phase and the organic phase were separated by phase separation. The respective compositions are shown in Table 1.

[0023]

[Table 1]

A reflux distributor is provided at the top of the column, and SUS316
Inner diameter 17mmφ and height 3 loaded with McMahon filling
A three-necked flask equipped with a 00 mm distillation column and a thermometer was charged with 155 g of the recovered organic phase and distilled under reduced pressure. Component 6 distilled at 50 ° C / 400mmHg
As a result of analyzing 1.3 g, the component was methacrolein 9
It contained 7.4%, 2.1% water and 0.5% toluene. Next, as a result of analyzing 47.3 g of the component distilled at 51.5 ° C./100 mmHg, the component was found to be toluene 9
It contained 9.0% and 1.0% methacrolein. To the distillation residue 23.2 g, toluene 27.0%, caprylic acid 31.5%, di-n-butylamine 25.4%,
And 16.1% of other components were contained. The recoveries with respect to the charged amounts of caprylic acid and di-n-butylamine were 95.2% and 78.4%, respectively.
23.2 g of the distillation residue was washed with 10 g of water to remove high boiling point components. After distillation, after washing with water, 7.
3 g, di-n-butylamine 5.8 g, toluene 6.3
g, and 1.5 g of other components. The recoveries with respect to the charged amounts of caprylic acid and di-n-butylamine were 95.1% and 75.5%, respectively.

In the same autoclave as used above, nitrogen pressure of 50 kg / cm ² was applied, 302 g / hr of propanal in which 500 ppm of hydroquinone which had been preheated to 130 ° C. was dissolved, and 422 g of 37% formalin /
The solution obtained by adding 0.74 g of di-n-butylamine to 20.9 g of the recovered catalyst (the above-mentioned distillation residue after washing with water) was continuously fed at 88.9 g / hr, respectively. The reaction was carried out at 130 ° C. The residence time was 1.5 minutes. A sample overflowing at 813 g / hr was collected under ice-cooling, and the product was analyzed by gas chromatography. The yield of methacrolein based on the propanal charged was 93.2%, the selectivity was 93.8%, and the conversion of propanal was 99.4%.
Met.

Example 2 The same autoclave as in Example 1 was charged with a nitrogen pressure of 50.
37 kg of propanal in which 500 ppm of hydroquinone was dissolved at 90.6 g / hr by applying kg / cm ^2.
Formalin at 127 g / hr, di-n-butylamine at 8.1 g / hr, and caprylic acid at 9.0 g / h.
The reaction was carried out at 130 ° C. for 5 minutes, each continuously fed at r. A sample overflowing at 234.6 g / hr was collected under ice cooling and analyzed for product by gas chromatography. Unreacted propanal 0.9 g / hr, methacrolein 98.5 g / hr
Each leaked out. The yield of methacrolein based on the charged propanal was 90.0%, the selectivity was 90.9%, and the conversion of propanal was 99.0%. The distillation residue containing caprylic acid and di-n-butylamine was recovered by performing the extraction operation of the obtained reaction mixture with toluene and the vacuum distillation operation of the obtained organic phase in the same manner as in Example 1. . The recoveries with respect to the charged amounts of caprylic acid and di-n-butylamine contained in the distillation residue were 96.2% and 73.8%, respectively.

Comparative Example 1 The reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 200 ° C. Unreacted propanal is 0.
6 g / hr and methacrolein were discharged at 254.8 g / hr, respectively. The yield of methacrolein based on the propanal charged was 69.8%, and the selectivity was 69.9%.
The conversion of propanal was 99.8%.

Comparative Example 2 The reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 50.degree. 11 unreacted propanal
7.2 g / hr, methacrolein is 161.8 g / hr
Each leaked out. The yield of methacrolein based on the propanal charged was 44.4%, the selectivity was 72.5%, and the conversion of propanal was 61.2%.

Examples 3 to 12 In the same manner as in Example 1, continuous reaction was carried out in an autoclave, the obtained reaction mixture was subjected to extraction operation with toluene, and then the obtained organic phase was distilled under reduced pressure. . The feed composition of the aldehyde compound (I), 37% formalin, secondary amine and organic carboxylic acid is shown in Table 2, and the reaction temperature, reaction time, reaction results and recovery of secondary amine and organic carboxylic acid in the distillation residue were shown. Rate (based on the amount charged)
Is shown in Table 3. In addition, in these tables, reaction conditions, reaction results and the like in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 are also shown.

[0030]

[Table 2]

[0031]

[Table 3]

Example 13 200 g of the sample recovered in Example 1 (88.4 g of methacrolein, 92.0 g of water, di-n-butylamine 6.
Di-n-butyl ether (50 g) was added to 9 g, caprylic acid (7.7 g) and other components (5.0 g), and the aqueous phase and the organic phase were separated by phase separation. Table 4 shows each composition. The obtained organic phase was distilled under reduced pressure to obtain methacrolein and di-n-
Butyl ether and butyl ether were separately obtained to obtain a residual residue. The recoveries with respect to the charged amounts of caprylic acid and di-n-butylamine in the distillation residue were 95.8% and 82.0%, respectively.

[0033]

[Table 4]

Example 14 200 g of the sample recovered in Example 1 (88.4 g of methacrolein, 92.0 g of water, di-n-butylamine 6.
N to 9 g, caprylic acid 7.7 g, and other ingredients 5.0 g)
-Octane 50 g was added and the aqueous and organic phases were separated by phase separation. Table 5 shows each composition. The obtained organic phase was distilled under reduced pressure to separately obtain methacrolein and n-octane to obtain a distillation residue. The recoveries with respect to the charged amounts of caprylic acid and di-n-butylamine in the distillation residue were 95.5% and 81.4%, respectively.

[0035]

[Table 5]

Comparative Example 3 The same autoclave as in Example 1 was charged with a nitrogen pressure of 50.
over kg / cm ^2, propanal dissolved hydroquinone 500ppm at 312.7g / hr, 37
% Formalin at 437 g / hr, 50% dimethylamine aqueous solution at 19.4 g / hr, and acetic acid at 12.9 g / h.
Each was fed at r and the reaction was carried out at 130 ° C. for 1.5 minutes. A sample overflowing at 782 g / hr was collected under ice cooling and analyzed for the product by gas chromatography. 1.0 g of unreacted propanal
/ Hr and methacrolein flowed out at 353.6 g / hr. The yield of methacrolein based on the propanal charged was 93.7%, and the selectivity was 94.0%.

To 200 g of the above-recovered sample (90.4 g of methacrolein, 97.7 g of water, 2.5 g of dimethylamine, 3.3 g of acetic acid, 6.1 g of other components), 50 g of toluene was added, and phase separation was performed to obtain an aqueous phase. The organic phase was separated. Table 6 shows each composition. Most of acetic acid and dimethylamine were dissolved in the aqueous phase, and extraction separation into toluene was virtually impossible.

[0038]

[Table 6]

Comparative Example 4 The same autoclave as in Example 1 was charged with a nitrogen pressure of 50.
over kg / cm ^2, propanal dissolved hydroquinone 500ppm at 308.7g / hr, 37
% Formalin at 431.9 g / hr, di-n-butylamine at 27.4 g / hr and acetic acid at 12.7 g / hr.
Respectively, and the reaction was carried out at 130 ° C. for 1.5 minutes. A sample overflowing at 781 g / hr was collected under ice-cooling, and the product was analyzed by gas chromatography. 1.2 g / unreacted propanal
The amounts of hr and methacrolein were 353.2 g / hr, respectively. The yield of methacrolein based on the propanal charged was 94.8%, and the selectivity was 95.2%.

To 200 g of the above-recovered sample (90.6 g of methacrolein, 97.9 g of water, 6.0 g of di-n-butylamine, 3.1 g of acetic acid, 1.9 g of other components) was added 50 g of toluene, and phase separation was performed. The aqueous phase and the organic phase were separated. The respective compositions are shown in Table 7. The obtained organic phase was distilled under reduced pressure to separately obtain methacrolein and toluene to obtain a distillation residue. The recoveries with respect to the charged amounts of acetic acid and di-n-butylamine in the distillation residue were only 28% and 26.0%, respectively.

[0041]

[Table 7]

[0042]

EFFECTS OF THE INVENTION According to the present invention, the problem of the conventional catalyst recovery is solved and the catalyst is efficiently recovered from the reaction mixture, so that the catalyst can be effectively recycled and reused in the reaction.
Therefore, the present invention provides an industrially advantageous method for producing an α-methylene aldehyde compound.

Claims (2)

[Claims] 1. A compound represented by the general formula (I): (Wherein R represents a hydrogen atom or a hydrocarbon group) and formaldehyde, in the presence of a catalyst consisting of an organic carboxylate of a secondary amine having a total number of carbon atoms of 12 or more. In an aqueous medium, 80-1
By conducting a condensation reaction at 60 ° C., the compound of the general formula (II): (Wherein R is as defined above)
A methylene aldehyde compound is synthesized, and at least a part of the obtained reaction mixture is contacted with an organic solvent having a small polarity to extract and separate the α-methylene aldehyde compound and the catalyst from the organic solvent, and the α-methylene is extracted from the extract. An aldehyde compound and an organic solvent are separated by distillation, and a distillation residue containing a catalyst is recovered.
-Method for producing methylene aldehyde compound. 2. The method according to claim 1, wherein the condensation reaction is carried out at 100 to 150 ° C.