JPH08176081A - Production of n-alkoxymethyl(meth)acrylamide - Google Patents

Abstract

PURPOSE: To obtain the subject compound with low polymer content, useful for e.g. resin modification, by reaction of N-methylol (meth)acrylamide with an alcohol in the presence of an acid catalyst under aeration to adjust the pH level of the reaction system followed by concentration at reduced pressures. CONSTITUTION: (A) An N-methylol (meth)acrylamide of formula CH2 =C(R1 ) CONHCH2 OH (R1 is H or methyl) or a reaction liquor containing the same is reacted with (B) an alcohol of formula R2 OH (R2 is a 1-3C lower alkyl) in the presence of an acid catalyst under aeration to adjust the pH level of the reaction liquor to >=5 but <8 followed by concentration under reduced pressure under aeration, thus affording (C) the objective N-alkoxymethyl (meth)acrylamide of formula CH2 =C(R1 )CONHCH2 OR2 . Preferably the pH level of the reaction liquor before pH adjustment is 2-5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to N-alkoxymethyl acrylamide or N-alkoxymethyl methacrylamide (hereinafter simply referred to as N-alkoxymethyl) which is used as a crosslinkable monomer in the fields of paints, inks, resins and the like. (Meth) acrylamide).

[0002]

2. Description of the Related Art N-Alkoxymethyl (meth) acrylamide is a methylol derivative prepared by reacting acrylamide or methacrylamide (hereinafter simply referred to as (meth) acrylamide) with formaldehyde, and then reacting with alcohol under an acid catalyst. A method of reacting and producing is known (Japanese Patent Publication No. 38-23607). However, since (meth) acrylamide and its derivatives are inherently polymerizable, N-alkoxymethyl (meth) acrylamide containing a polymer may be provided in a considerable concentration depending on the operation in the manufacturing process, and other monomers or solvents may be used. When mixed with etc., white turbidity or aggregation may occur, which may cause practical difficulties. For example, when N-methoxymethyl acrylamide 1 containing a polymer is mixed with 3 methyl methacrylate, white turbidity occurs and a polymer is deposited. Therefore, such N-alkoxymethyl (meth) acrylamide is difficult to use for resin production. Is. On the other hand, as a general purification method of crude N-alkoxymethyl (meth) acrylamide, only a method such as flash distillation which is economically extremely disadvantageous and which further increases the polymer content in the purification process is known. Absent.

[0003]

The object of the present invention is to remedy the drawbacks of the prior art, without the need for purification operations.
Precipitation, when used as a modifying component for resins and paints,
An object of the present invention is to provide a method for economically producing N-alkoxymethyl (meth) acrylamide having a polymer concentration low enough to prevent clouding or aggregation. As a result of earnest studies to achieve the above object, the present inventors have found that N-methylol acrylamide or N-methylol methacrylamide (hereinafter simply referred to as N-methylol (meth)
(Acrylamide) and alcohol are reacted in the presence of an acid catalyst while blowing air, and then the pH of the reaction solution is adjusted to 5 or more and less than 8 and concentrated under reduced pressure while blowing air to reduce N-containing polymer concentration. The inventors have found that alkoxymethyl (meth) acrylamide can be obtained and have reached the present invention.

[0004]

That is, the present invention relates to the general formula (I) CH ₂ ═C (R ₁ ) CONHCH ₂ OR ₂ (I) (wherein R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a lower alkyl group having 1 to 3 carbon atoms)
In the method for producing alkoxymethyl (meth) acrylamide, it is represented by the general formula (II) CH ₂ ═C (R ₁ ) CONHCH ₂ OH (II) (wherein R ₁ represents a hydrogen atom or a methyl group). N-methylol (meth) acrylamide or a reaction solution containing them and the general formula (III) R ₂ OH (III) (in the formula, R ₂ represents a lower alkyl group having 1 to 3 carbon atoms)
N-alkoxy, characterized in that after reacting the alcohol represented by the formula in the presence of an acid catalyst while blowing air, the pH of the reaction liquid is adjusted to 5 or more and less than 8 and concentrated under reduced pressure while blowing air. The present invention relates to a method for producing methyl (meth) acrylamide.

The N-methylol (meth) acrylamide represented by the general formula (II) used in the present invention may be itself or may be a reaction solution formed by a methylolation reaction of (meth) acrylamide and formaldehyde. In the latter case, the reaction conditions are not particularly limited, and any method can be used as long as a reaction product solution containing N-methylol (meth) acrylamide can be obtained. An example of preferable reaction conditions is described in R.W. Dowbenko, R .; M. Chr
istenson, A .; N. Salem, J.M. Org.
Chem. , 28, 3458 (1963).

In the etherification reaction, the molar ratio of alcohol to N-methylol (meth) acrylamide is 1 or more, preferably 1.5 to 8, more preferably 2.
It is preferable to use it in the range of 2 to 6.5. If the molar ratio is less than 1, by-products are likely to occur, and if it exceeds 8, a large amount of alcohol is used, which is not preferable in terms of economy. Examples of the alcohol represented by the general formula (III) used in the etherification reaction include alcohols having a lower alkyl group having 1 to 3 carbon atoms such as methyl alcohol, ethyl alcohol, normal propyl alcohol and isopropyl alcohol.

Examples of the acid catalyst used in the reaction include inorganic acids such as sulfuric acid, phosphoric acid and hydrochloric acid, oxalic acid, malonic acid,
Any of organic acids such as succinic acid, fumaric acid, maleic acid, and paratoluenesulfonic acid may be used. The reaction solution preferably has a pH in the range of 2-5.

The etherification reaction is usually carried out under reflux heating. Since this reaction is an equilibrium reaction involving dehydration, when water is removed from the system as the solvent is distilled off, the remaining N-methylol (meth) acrylamide is converted to the desired N-alkoxymethyl (meth) acrylamide. Therefore, the reaction yield can be further improved. Specifically, when the alcohol containing the reaction product water is distilled out of the system,
The effect can be enhanced by replenishing the system with anhydrous alcohol or alcohol that has been separately fractionally distilled to be substantially anhydrous.

After the reaction, the pH of the reaction solution is adjusted to 5 or more and less than 8, preferably 5.5 to 7, and concentrated. The temperature at the time of concentration is 50 to 100 ° C, preferably 55 to 90 ° C
It is good to do in the range of.

In the above etherification reaction and concentration step, it is necessary to positively blow air. As a result, by-products of the polymer in the etherification reaction and the concentration step can be suppressed. The amount of air blown is 10 to 400 Nml per mol of N-methylol (meth) acrylamide in the etherification reaction.
/ Hr, preferably in the range of 15 to 200 Nml / hr,
In the concentration step, 10 to 4000 Nml / hr,
Preferably, it may be appropriately selected within the range of 15 to 2000 Nml / hr. Further, when a conventionally known polymerization inhibitor such as hydroquinone monomethyl ether or hydroquinone is used in combination, more stable results are obtained, but the effect is insufficient when only the polymerization inhibitor is used.

The N-alkoxymethyl (meth) acrylamide thus obtained does not cloud or precipitate even if methyl methacrylate or acetone is added,
It can be suitably used as it is for production of general resins.

[0012]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. The concentration of the polymer in the product was evaluated by comparing the situation in which a 3-fold amount of methyl methacrylate or a 2-fold amount of acetone was added to cause clouding or precipitation. N containing 0.1% or more of polymer under these conditions
-Alkoxymethyl (meth) acrylamide produces a sediment depending on its content.

Example 1 215 g (6.16) of 86% paraformaldehyde was placed in a reaction vessel equipped with a stirrer, a thermometer, and a (reflux) condenser.
Mol), acrylamide 400 g (5.63 mol), methyl alcohol 170 g (5.31 mol), hydroquinone monomethyl ether 1.74 g and triethylamine 0.24 g, and heated at 60 ° C. for 4 hours to obtain N.
-Add 960 g (30 mol) of methyl alcohol to the reaction solution containing methylol acrylamide, and add about 1 g of oxalic acid.
After the pH is adjusted to 3.2 by the addition of 60 to 70 ° C,
The mixture was heated under reflux while blowing air at a rate of about 100 Nml / hr. After 5 hours, the reaction solution was pH adjusted with sodium hydroxide.
Adjusted to 6.3, concentrated under reduced pressure while blowing air at about 80 ° C. and about 7 Nl / hr, to recover 930 g of a distillate containing methyl alcohol as a main component, and a purity of 98.8%.
608 g of N-methoxymethyl acrylamide were obtained. A part of this was taken and mixed with 3 times the amount of methyl methacrylate to obtain a uniform transparent solution, and no cloudiness or precipitation was observed due to the addition of the solvent.

Comparative Example 1 In Example 1, when the reaction solution containing N-methylolacrylamide and the reaction of methyl alcohol at PH 3.2 and the concentration under reduced pressure at PH 6.3 were performed, 1.3 g of hydroquinone monomethyl was used instead of blowing air. When the reaction was carried out in the same manner as in Example 1 except that ether was added as a polymerization inhibitor, 600 g of N-methoxymethylacrylamide was obtained. When a part of this was taken and mixed with 3 times the amount of methyl methacrylate, it became cloudy and the sediment concentration was 0.5%.

Comparative Example 2 In Example 1, in the reaction of the reaction liquid containing N-methylolacrylamide and methyl alcohol at PH 3.2 and the concentration under reduced pressure at PH 6.3, 1.3 g of hydroquinone was added instead of blowing air. When the reaction was carried out in the same manner as in Example 1 except that a polymerization inhibitor was added,
606 g of N-methoxymethylacrylamide was obtained. When a part of this was taken and mixed with 3 times the amount of methyl methacrylate, it became cloudy and the sediment concentration was about 1%.

Example 2 N-methylol acrylamide (manufactured by Soken Chemical Industry Co., Ltd., purity 9)
7.6%) 1313 g (12.7 mol), 85.5% denatured ethanol 2798 g (52 mol) and hydroquinone monomethyl ether 3.9 g were added to the mixture of about 7 g of oxalic acid to adjust the pH to 2.6, 85-85%. 87 ° C, approx. 6
3.5 while blowing air at a speed of 00 Nml / hr
Heated for hours. The distillate was removed outside the system, and instead a total of 59
6 g of denatured ethanol was added to the system. After that, the reaction solution was adjusted to pH 6.3 with sodium hydroxide, about 80 ° C,
The mixture was concentrated under reduced pressure while blowing air at a rate of about 20 Nl / hr to obtain 1562 g of N-ethoxymethylacrylamide having a purity of 97.6%. A part of this was taken and mixed with 3 times the amount of methyl methacrylate to obtain a uniform transparent solution.

Comparative Example 3 In Example 2, in the reaction of the reaction solution containing N-methylolacrylamide with ethyl alcohol at PH 2.6 and concentration under reduced pressure at PH 6.3, 1.3 g of hydroquinone monomethyl was used instead of blowing air. A reaction was performed in the same manner as in Example 2 except that ether was added as a polymerization inhibitor, and N-ethoxymethylacrylamide 153
8 g was obtained. When a part of this was taken and mixed with 3 times the amount of methyl methacrylate, it became cloudy and the concentration of the precipitate was 0.8%.

Example 3 In a reaction vessel equipped with a stirrer, a thermometer, and a (reflux) condenser, 102.3 g (3.0 mol) of 88% paraformaldehyde, 255.3 g (3.00 mol) of methacrylamide and 120% of water were added.
g and hydroquinone monomethyl ether 0.9 g were added and adjusted to pH 12.6 with sodium hydroxide at 60 ° C.
After heating for 1 hour, a reaction solution containing N-methylolmethacrylamide was obtained. Methyl alcohol 480g (15.0
Mol) and then add about 0.9 g of oxalic acid to obtain PH3.2.
Then, the mixture was heated under reflux at 70 ° C. while blowing air at a rate of about 50 Nml / hr. Stop heating after 3 hours,
Adjust the pH of the reaction solution to 5 with sodium hydroxide, and
Concentrate while blowing air at a rate of about 5 Nl / hr to give almost pure N-methoxymethylmethacrylamide 3
64.7 g were obtained. When a part of the solution was taken and mixed with twice the amount of acetone, cloudiness or precipitation did not occur, and a transparent homogeneous solution was obtained.

Example 4 A reaction vessel equipped with a stirrer, a thermometer, and a condenser was charged with N 2
-Methylol acrylamide 303g (3.0mol),
450 g (7.5 mol) of normal propyl alcohol,
Then, 0.9 g of hydroquinone monomethyl ether was charged, and the product adjusted to PH2,9 by adding oxalic acid was heated at 96 to 108 ° C at a rate of about 100 Nml / hr while blowing air. The distillate was removed from the system and instead a total of 25 normal propanols corresponding to the amount of distillate were added.
Added to the 2 g system. After heating for 8 hours, the heating was stopped and the reaction solution was adjusted to pH 6.5 with sodium hydroxide.
The mixture was concentrated while blowing air at a rate of about 5 Nl / hr to obtain 414 g of N-normal propoxymethyl acrylamide having a purity of 97.6%. Take a part of it, 3
When mixed with a double amount of methyl methacrylate, a uniform transparent solution was obtained, and no cloudiness or precipitation occurred in the solubility test with acetone.

Example 5 In a reaction vessel equipped with a stirrer, a thermometer, and a (reflux) condenser, 102 g (3.0 mol) of 88% paraformaldehyde, 213 g (3.0 mol) of acrylamide, 180. 7 g (3.0 mol), hydroquinone monomethyl ether 0.9 g and triethylamine 1.8 g were added, and the reaction solution containing N-methylol acrylamide obtained by heating at 58 to 61 ° C. for 4 hours was added with isopropyl alcohol 270.5 g (4 0.5 mol) was added, and the pH was adjusted to 3.32 by adding about 3.7 g of oxalic acid, and then the mixture was heated under reflux at 86 to 89 ° C. while blowing air at a rate of about 80 Nml / hr. After 16 hours, the reaction solution was adjusted to pH 6.3 with sodium hydroxide and heated to about 80 ° C.
The mixture was concentrated under reduced pressure while blowing air at a rate of about 5 Nl / hr to obtain 389.8 g of N-isopropoxymethylacrylamide having a purity of 95.2%. A part thereof was taken and mixed with 3 times the amount of methyl methacrylate to obtain a uniform transparent solution.

Comparative Example 4 In Example 5, in the reaction of N-methylolacrylamide and the reaction of isopropyl alcohol with PH 3.32 and concentration under reduced pressure with PH 6.3, 1.3 g of hydroquinone monomethyl was used instead of blowing air. N-isopropoxymethylacrylamide 382 was prepared in the same manner as in Example 5 except that ether was added as a polymerization inhibitor.
g was obtained. When a part of this was taken and mixed with 3 times the amount of methyl methacrylate, it became cloudy and the concentration of the sedimented substance was 0.5%.

[0022]

According to the method of the present invention, the by-product of the polymer can be effectively suppressed, and N-alkoxymethyl (meth) acrylamide useful for resin modification can be effectively produced. .

Front Page Continuation (72) Inventor Ryo Suzuki, 2 Miyanoshita No. 2 Miyashita, Joban-Sekisencho, Iwaki, Fukushima Prefecture Nitto RIKEN CORPORATION (72) Inventor Kazo Otsuka 1-5-1, Marunouchi, Chiyoda-ku, Tokyo Nitto Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. General formula (I) CH ₂ ═C (R ₁ ) CONHCH ₂ OR ₂ (I) (In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ is a lower group having 1 to 3 carbon atoms. In the method for producing N-alkoxymethylacrylamide or N-alkoxymethylmethacrylamide represented by the formula (II), the formula (II) CH ₂ ═C (R ₁ ) CONHCH ₂ OH (II) (wherein R ₁ represents a hydrogen atom or a methyl group), N-methylol acrylamide or N-methylol methacrylamide, or a reaction solution containing any of these and a general formula (III) R ₂ OH (III) (formula (Wherein R ₂ represents a lower alkyl group having 1 to 3 carbon atoms)
After reacting the alcohol represented by the formula in the presence of an acid catalyst while blowing air, the pH of the reaction solution is adjusted to 5 or more and less than 8 and the mixture is concentrated under reduced pressure while blowing air. A method for producing alkoxymethyl acrylamide or N-alkoxymethyl methacrylamide.