JP3181361B2 - Method for stabilizing α-alkylacrolein - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compound of the formula (I)

[0002]

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(Wherein R ₁ is a hydrogen atom or a carbon atom having 1 to 10 carbon atoms)
R ₂ represents a hydrogen atom or a carbon chain having 1 to 5 carbon atoms which forms a cyclic structure by bonding to R ₁ . The present invention relates to an improved method for stabilizing an α-alkylacrolein represented by the formula (1) against alteration due to polymerization or the like.

[0004]

2. Description of the Related Art The α-alkylacrolein represented by the general formula (I) is an industrially useful intermediate material, and particularly, R ₁ in the general formula (I).
And R ₂ by R ₁ is a methyl group acrolein or in the general formula (I) is a hydrogen atom, methacrolein R ₂ is a hydrogen atom as a resin monomer precursors, are already produced on an industrial scale. On the other hand, many methods for synthesizing α-alkylacrolein have been proposed, for example, JP-A-55-87737.
JP-A-57-150628 discloses a synthesis method based on the so-called Mannich reaction in which a corresponding aldehyde is reacted with formaldehyde in the presence of an amine catalyst.
No. 1 proposes a method for the synthesis of α-alkylacrolein by dehydrogenation of the corresponding saturated aldehyde. All of these proposed synthetic methods give the desired α-alkylacrolein in relatively high yield and high selectivity.

However, the formed α-alkylacrolein is very unstable, and easily undergoes polymerization and the like under general handling conditions and deteriorates. For example, acrolein easily undergoes thermal polymerization at about room temperature or higher, and Diels-Al
Gives der type high molecular weight polymer In addition, radical polymerization, anionic polymerization, and the like are extremely likely to occur. Moreover, the polymer of acrolein is insoluble in water and various organic solvents, and it is difficult to decompose even if a strong acid or a strong base is used. These characteristics depend on the degree of polymerization, but various α
-A characteristic common to all polymers of alkyl acrolein. Furthermore, since a polymer of α-alkylacrolein has very high strength and emits a bad odor in many cases, physical removal is also difficult. For these reasons, in the conventional α-alkylacrolein production plant, clogging of piping and tower tanks due to polymerization of α-alkylacrolein was the most important and frequently occurring trouble.

On the other hand, there is no effective method for preventing deterioration such as polymerization of α-alkylacrolein, and it is known that the addition of hydroquinone or methoquinone as a radical scavenger is effective for preventing polymerization. Only. However, in the case of acrolein and methacrolein, the amount of hydroquinone or metoquinone to be added usually needs to be at least 1000 ppm or more, and cannot be stably stored in a refrigerator even at 5 ° C. or less for more than one week after addition.
As described above, since stable long-term storage of α-alkylacrolein is extremely difficult, in a plant consuming α-alkylacrolein, α-alkylacrolein can be used more quickly after it is produced, or At present, α-alkyl acrolein production plants frequently strive to maintain quality and prevent clogging by frequently washing high-pressure steam in tower tanks and pipes. Therefore, there is a strong demand for the development of an effective technique for preventing deterioration such as polymerization of α-alkylacrolein.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides a compound represented by the general formula (I):

[0008]

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(Wherein R ₁ is a hydrogen atom or a C 1-10
R ₂ represents a hydrogen atom or a carbon chain having 1 to 5 carbon atoms which forms a cyclic structure by bonding to R ₁ . )) (Hereinafter abbreviated as α-alkylacrolein (I)) as a stabilizer represented by the general formula (II):

[0010]

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(Wherein, R ₃ , R ₄ and R ₅ each represent a hydrogen atom or an alkanol group having 1 to 5 carbon atoms.
R ₃ , R ₄ and R ₅ must not be simultaneously hydrogen atoms. Wherein the alkanolamine compound (hereinafter abbreviated as alkanolamine compound (II)) is added to the α-alkylacrolein (I) at a concentration of 50 to 2000 ppm. The present invention provides a method for stabilizing acrolein. Further, the present invention relates to α-alkylacrolein (I) as a stabilizer represented by the general formula (III):

[0012]

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(Wherein R ₆ is a hydrogen atom or a carbon number of 1 to 5)
Wherein R ₇ and R ₈ each have 1 to 1 carbon atoms
5 represents an alkyl group. ), Wherein the secondary or tertiary amine (hereinafter abbreviated as amine (III)) is added to α-alkylacrolein (I) in a concentration of 1 to 1000 ppm. It also provides a method for stabilizing alkyl acrolein.

[0014] substituent R ₁ in the general formula (I) of α- alkyl acrolein used in the present invention (I) is an alkyl group having a carbon number of hydrogen atoms or 1 to 10. The alkyl group may have a linear, branched or cyclic structure, and may be partially substituted with an aromatic group. R ₂ represents a hydrogen atom or a carbon chain having 1 to 5 carbon atoms which forms a cyclic structure by bonding to R ₁ . Examples of the α-alkylacrolein (I) used in the present invention include acrolein, methacrolein, 2-ethylacrolein, 2-propylacrolein, 2-isopropylacrolein, 2-butylacrolein, 2-isobutylacrolein, and 2 -Pentyl acrolein, 2-methylidenecyclopentanone, 2-
And methylidenecyclohexanone. According to the present invention, acrolein, methacrolein, 2
-Effective for stabilizing ethyl acrolein.

On the other hand, the substituents R ₃ , R ₄ and R ₅ in the general formula (II) of the alkanolamine compound (II) used in the present invention represent a hydrogen atom or an alkanol group having 1 to 5 carbon atoms. . However, the substituents R ₃ , R ₄ and R ₅ must not be simultaneously hydrogen atoms. This alkanol group may be linear or branched. Examples of the alkanolamine compound (II) used in the present invention include monomethanolamine, dimethanolamine, trimethanolamine, monoethanolamine, diethanolamine, triethanolamine, monopropanolamine,
Examples include dipropanolamine, monobutanolamine, monopentanolamine, monomethanol monoethanolamine, and monomethanol diethanolamine. Among them, according to the present invention, diethanolamine, triethanolamine and trimethanolamine are particularly effective.

The substituent R _{6 in} the general formula (III) of the amine (III) used in the present invention may be a hydrogen atom or a C 1 -C 1 atom.
5 represents an alkyl group, and R ₇ and R ₈ each represent an alkyl group having 1 to 5 carbon atoms. This alkyl group may be linear or branched. Examples of the amine (III) used in the present invention include dimethylamine, trimethylamine, diethylamine, triethylamine, dipropylamine, monomethylmonoethylamine, and monomethyldiethylamine. Among them, according to the present invention, diethylamine, triethylamine and trimethylamine are particularly effective.

In the present invention, α-alkylacrolein (I) produced by any conventional production method is used.
It is also effective for stabilizing water,
Even if it contains a lower ketone, a lower aldehyde, a lower carboxylic acid, or a lower carboxylic acid ester, there is no obstacle at all. Further, the alkanolamine compounds (II) and amines (III) added as stabilizers work effectively even if they are added together with various raw materials from the reaction stage as long as the reaction is not hindered. In the present invention, the alkanolamine compound (II) used is α-alkylacrolein (I)
At an addition concentration of 50 to 2000 ppm, preferably 100
A sufficient polymerization inhibitory effect is obtained at an addition concentration of from 1 to 1000 ppm.
If the concentration of the alkanolamine compound (II) is less than 50 ppm, no stabilizing effect can be obtained, and if it exceeds 2000 ppm, the polymerization of α-alkylacrolein is accelerated, which is not preferable. When the alkanolamine compound (II) is added, polymerization beyond thermal dimerization does not occur under a temperature condition of 60 ° C. or less. It is particularly preferable to carry out stabilization within a pH range of 9 or less.

The amine (III) used in the present invention
Is 1 to 10 relative to α-alkylacrolein (I).
A sufficient polymerization inhibitory effect is exhibited at an addition concentration of 00 ppm, preferably at an addition concentration of 1 to 500 ppm. If the concentration of amine (III) added is less than 1 ppm, the stabilizing effect cannot be obtained and
If it exceeds m, the polymerization of α-alkylacrolein is accelerated, which is not preferable. 40 ° C when adding amine (III)
Under the following temperature conditions, polymerization beyond thermal dimerization does not occur. It is particularly preferable to perform the stabilization within a pH range of 8 or less.

On the other hand, among the conventional findings, particularly, hydroquinone or methoquinone, which is frequently used as a polymerization inhibitor of α-alkylacrolein in a low temperature region, and the alkanolamine compound (II) proposed by the present invention. Or in combination with amine (III),
A better stabilizing effect is observed. Further, conventional chemical common sense indicates that under alkaline conditions in which amines coexist, the alteration and polymerization of α-alkylacrolein are most accelerated. On the other hand, in the present invention, a trace amount of alkanolamine compound (II) or amine (III)
Has been found to have an effect of preventing the alteration and polymerization of α-alkylacrolein, and the present invention proposes a new method for stabilizing α-alkylacrolein, which has not existed before.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention unless it exceeds the gist of the present invention. The parts in the examples are on a weight basis.

Example 1 0.05 parts of diethanolamine per 100 parts of methacrolein
(500 ppm) and left at pH 7.5, 20 ° C. for 48 hours.
After standing, 99.6 parts (99.6% of theory) of methacrolein were recovered.

Example 2 Diethanolamine 0.1 to 100 parts of methacrolein
(1000 ppm) and left at pH 7.9, 20 ° C. for 48 hours. After standing, 99.7 parts of methacrolein (theoretical 99.7 parts)
%) Collected.

Example 3 Diethanolamine 0.2 to 100 parts of methacrolein
Then, the mixture was left at pH 8.3 and 20 ° C. for 48 hours. After standing, add 99.6 parts of methacrolein (theoretical value of 99.6 parts).
%) Collected.

Example 4 0.1 parts of dimethanolamine was added to 100 parts of methacrolein.
(1000 ppm) and left at pH 8.0, 20 ° C. for 48 hours. After standing, add 99.4 parts of methacrolein (theoretical value of 99.4 parts).
%) Collected.

Example 5 Triethanolamine to 100 parts of methacrolein
0.1 part (1000 ppm) was added, and the mixture was left at pH 7.8 and 20 ° C. for 48 hours. After standing, add 99.5 parts of methacrolein (theoretical 99.5 parts).
%) Collected.

Example 6 Diethanolamine 0.1 to 100 parts of methacrolein
Then, the mixture was left at pH 7.9 and 40 ° C. for 48 hours. After standing, 98.3 parts (98.3% of theory) of methacrolein were recovered together with 1.5 parts of 2-methyl-2-formyl-5,6-dehydropyran which is a polymer of methacrolein.

Example 7 Diethanolamine 0.1 to 100 parts of methacrolein
(1000 ppm) and left at pH 7.9, 60 ° C. for 48 hours. After standing, 95.7 parts (95.7% of theory) of methacrolein were recovered together with 4.2 parts of 2-methyl-2-formyl-5,6-dehydropyran which is a polymer of methacrolein.

Example 8 0.05 parts of diethanolamine per 100 parts of acrolein
(500 ppm), and the mixture was left at pH 7.3 and 20 ° C. for 48 hours. After standing, 99.1 parts of acrolein (99.1% of theory) were recovered.

Example 9 0.1 part (1000 ppm) of diethanolamine was added to 100 parts of 2-ethylacrolein, and the mixture was left at pH 7.6 at 20 ° C. for 48 hours. After standing, 99.5 parts (99.5% of theory) of 2-ethylacrolein were recovered.

Example 10 0.05 part (50 parts) of diethylamine was added to 100 parts of methacrolein.
0 ppm) and left at pH 7.8, 20 ° C. for 48 hours. After standing, 94.4 parts (94.4% of theory) of methacrolein were recovered together with 5.4 parts of 2-methyl-2-formyl-5,6-dehydropyran which is a polymer of methacrolein.

Example 11 0.05 parts of triethylamine per 100 parts of methacrolein
(500 ppm), and the mixture was left at pH 7.8 at 20 ° C. for 48 hours. After standing, a polymer of methacrolein, 2-methyl-2-
95.0 parts of methacrolein (95.0% of theory) were recovered together with 4.8 parts of formyl-5,6-dehydropyran.

Comparative Example 1 100 parts of methacrolein were left at pH 6.5 and 20 ° C. for 48 hours. After standing, add 70.6 parts of methacrolein (theoretical value of 70.6 parts).
%) Collected. However, a high polymer of methacrolein was formed, and the methacrolein solution became cloudy.

Comparative Example 2 Diethanolamine 0.0 to 100 parts of methacrolein
01 parts (10 ppm) was added, and the mixture was left at pH 6.8 and 20 ° C. for 48 hours. After standing, 76.7 parts of methacrolein (76.7% of theory)
Was recovered. However, a high polymer of methacrolein was formed, and the methacrolein solution became cloudy.

Comparative Example 3 One part (10000 ppm) of diethanolamine was added to 100 parts of methacrolein, and the mixture was allowed to stand at pH 9.8 and 20 ° C. for 48 hours. After standing, 75.0 parts of methacrolein (75.0% of theory)
Was recovered. However, a high polymer of methacrolein was formed, and the methacrolein solution became cloudy.

Comparative Example 4 0.2 parts (2 parts) of diethylamine to 100 parts of methacrolein
000 ppm) and left at pH 8.9, 40 ° C. for 48 hours. After standing, a polymer of methacrolein, 2-methyl-2-
78.1 parts of methacrolein (78.1% of theory) were recovered together with 1.6 parts of formyl-5,6-dehydropyran. But,
A high polymer of methacrolein was formed, and the methacrolein solution became cloudy.

[0036]

According to the present invention, alkanolamine compound (II) is added to α-alkylacrolein (I) in an amount of 50%.
The addition of amine (III) at a concentration of from 1 to 1000 ppm achieved the stabilization of α-alkylacrolein (I), which has heretofore been difficult. In addition, the same stabilizing effect is observed even in a system in which water and a lower carbonyl compound, which are expected to be mixed in with the ordinary synthesis method, coexist, and it is effective even under severe conditions at 40 ° C or higher where severe deterioration occurs. The present invention provides an extremely useful technique for stabilizing α-alkylacrolein.

Claims (4)

(57) [Claims] 1. A compound of the general formula (I) (In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ represents a carbon chain having 1 to 5 carbon atoms which forms a cyclic structure by bonding to the hydrogen atom or R _1. ) Α expressed by
-Alkyl acrolein as a stabilizer represented by the general formula (I
I) (Wherein, R ₃ , R ₄ and R ₅ each represent a hydrogen atom or an alkanol group having 1 to 5 carbon atoms, provided that R ₃ , R ₄ and
R ₅ must not be simultaneously a hydrogen atom. A method for stabilizing α-alkylacrolein, which comprises adding the alkanolamine compound represented by the formula (1) to the α-alkylacrolein (I) in a concentration of 50 to 2000 ppm. 2. The method for stabilizing α-alkylacrolein according to claim 1, wherein the method is carried out in a pH range of 9 or less. 3. A compound of the general formula (I) (In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ represents a carbon chain having 1 to 5 carbon atoms which forms a cyclic structure by bonding to the hydrogen atom or R _1. ) Α expressed by
-Alkyl acrolein as a stabilizer represented by the general formula (II
I) (Wherein, R ₆ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ₇ and R ₈ each represent an alkyl group having 1 to 5 carbon atoms.) Is added to the α-alkylacrolein (I) in a concentration of 1 to 1000 ppm. 4. The method for stabilizing α-alkylacrolein according to claim 3, wherein the method is carried out in a pH range of 8 or less.