JPH04316547A - Method for producing N-methylol acrylamide - Google Patents

Abstract

PURPOSE:To produce N-methylol acrylamide having high purity while suppressing the production of by-product. CONSTITUTION:Acrylamide is made to react with paraformaldehyde in an aqueous solution in the presence of a basic catalyst and an oxyacid salt of palladium and/or an oxyacid salt of tungsten. The use of the oxyacid salt of palladium and/or oxyacid salt of tungsten in combination with the basic catalyst is effective for suppressing the formation of by-product to an extremely low level compared with conventional catalyst such as sodium hydroxide to enable the production of N-methylol acrylamide in high purity and yield. The mother liquor left after the separation of N-methylol acrylamide can easily be recycled because of low production rate of the by-product.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing N-methylolacrylamide by reacting acrylamide with formaldehyde or paraformaldehyde. N-methylol acrylamide is a crosslinking monomer widely used in fiber treatments, photosensitive resins, adhesives, paints, etc.

0002

BACKGROUND OF THE INVENTION Various methods have been known for producing N-methylolacrylamide. For example, a method in which acrylamide and formaldehyde are reacted in an aqueous solvent using sodium hydroxide as a catalyst at an acrylamide concentration of 60 to 97% (Japanese Patent Publication No. 38-153
58), a method of reacting acrylamide and formaldehyde without a solvent using tertiary amines such as triethylamine or triethanolamine as a catalyst (Japanese Patent Publication No. 35-4208), a method without a solvent or with water or an organic A method using a basic anion exchange resin as a catalyst in a solvent (JP-A-49-14418, JP-A-49-3
No. 6615 and Japanese Unexamined Patent Publication No. 127912/1983), etc. have been proposed.

However, in the conventional method for producing N-methylolacrylamide, the production of by-products is not sufficiently suppressed, and by-products accumulate in the reaction solution, which not only reduces the yield of N-methylolacrylamide, but also High purity N-
Obtaining methylol acrylamide requires a complicated purification process, requires a large amount of catalyst, or is relatively expensive.
There were problems that needed to be improved as a method for industrial implementation.

0004

OBJECTS OF THE INVENTION The present invention was made to solve the problems in conventional methods, and its purpose is to provide a method for producing N-methylolacrylamide that can be carried out industrially advantageously. There is a particular thing. More specifically, it provides a method for producing N-methylolacrylamide that can obtain high-purity N-methylolacrylamide in high yield by improving reaction selectivity and suppressing the production of side reaction products. It's about doing.

[0005]

[Means for Solving the Problem] As a result of intensive research to achieve the above object, the present inventors have developed a method for producing N-methylolacrylamide by coexisting a molybdenum oxyacid or a tungsten oxyacid with a catalyst. The present invention was achieved by discovering that by carrying out this process, the formation of by-products was suppressed and the reaction proceeded with high selectivity.

The present invention provides a method for producing N-methylolacrylamide by reacting acrylamide with formaldehyde or paraformaldehyde in the presence of a basic catalyst in an aqueous solvent, and the reaction is carried out using molybdenum oxyacid and/or tungsten oxyacid. The present invention relates to a method for producing N-methylolacrylamide, which is characterized in that it is carried out in the presence of a salt.

[0007] Embodiments of the present invention will be explained below. The method of the present invention involves reacting acrylamide, which is a starting material, with formaldehyde or paraformaldehyde in an aqueous solvent using a basic catalyst and one or both of molybdenum oxyacid and tungsten oxyacid as a catalyst. It consists of doing.

[0008] Acrylamide, which is a starting material used in the present invention, may be either an aqueous solution or a crystal. Further, formaldehyde is preferably an aqueous solution, and commercially available 37
% formalin can be used. Paraformaldehyde may also be commercially available with a purity of 70 to 95%.

[0009] The ratio of acrylamide and formaldehyde or paraformaldehyde used in the present invention is such that formaldehyde or paraformaldehyde (in terms of formaldehyde) is 0 per mole of acrylamide.
．． The amount ranges from 5 to 2 mol, preferably from 0.8 to 1.5 mol.

The solvent used in the present invention may be water or a mixed solvent of water and an organic solvent soluble therein. Examples of the organic solvent include methanol, ethanol, and acetone. When using a mixed solvent, the proportion of water is 5
It is preferably 0% (wt) or more.

Basic catalysts that can be used in the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, potassium carbonate, and trisodium phosphate. , alkali or alkaline earth metal salts such as disodium phosphate, sodium pyrophosphate, tripotassium phosphate, dipotassium phosphate, sodium borate, sodium aluminate and sodium silicate, triethylamine, triethanolamine, N- Tertiary amines such as ethylmorpholine and N,N-diethylhydroxylamine, metal alkoxides such as sodium alkoxide and potassium ethoxide, Amberlite I
Examples include strong basic anion exchange resins such as RA400 and Amberlyst A26.

[0012] The amount of basic catalyst used in the present invention is
It is selected from the range of 0.001 to 10 mol%, preferably 0.01 to 5 mol%, based on 1 mol of acrylamide.

The molybdenum oxyacid salts used in the present invention include lithium molybdate, sodium molybdate, potassium molybdate, lithium phosphomolybdate,
Examples include sodium phosphomolybdate, lithium seiimolybdate, and sodium seiimolybdate.

[0014] Furthermore, as tungsten oxyacid salts,
Lithium tungstate, sodium tungstate,
Examples include potassium tungstate, lithium phosphotungstate, sodium phosphotungstate, lithium silicotungstate, and sodium silicotungstate. Two or more types of these molybdenum oxyacids or tungsten oxyacids can also be used in combination.

The amount of molybdenum oxyacid or tungsten oxyacid to be used is selected from the range of 0.1 to 20 mol, preferably 0.5 to 12 mol, per mol of the basic catalyst coexisting.

The reaction is preferably carried out at a reaction temperature of from 20 to 80°C, preferably from 30 to 60°C, and at a pH of 7 or more, preferably from 8 to 12.

According to the method of the present invention, N
- Methylolacrylamide is obtained as an aqueous solution. When obtaining crystalline N-methylolacrylamide, highly pure one can be easily obtained by crystallizing and separating the amide from the reaction solution.

Furthermore, N-methylolacrylamide has good solubility, and the separated mother liquor after separating N-methylolacrylamide from the reaction solution contains the product N-methylolacrylamide as well as unreacted raw materials. Since the method of the present invention produces very few by-products, it is easy to recycle the separated mother liquor, unlike conventional methods.

Further, the N-methylol acrylamide-containing solution obtained by the method of the present invention can be used as an aqueous solution as it is without isolating the amide. Synthesis of acrylamide derivatives can be used.

[0020]

EXAMPLES The structure and effects of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples in any way. Example 1 A 200cc reactor equipped with a stirrer, a thermometer, and a pH meter was
Add 60 g of crystalline acrylamide and 14 g of water, and raise the internal temperature to 50°C to dissolve the acrylamide. Then,
A mixed aqueous solution of sodium hydroxide and sodium molybdate as a catalyst (sodium hydroxide concentration 1.0%, sodium molybdate:sodium hydroxide molar ratio 2:1)
) and adjust the pH of the solution to 10. Then, 95
% paraformaldehyde is added, and the reaction is carried out while maintaining the pH of the reaction solution at 10 using the catalyst solution. The amount of catalyst solution required for the reaction was 0.8g (
0.02 mol% of sodium hydroxide + 0.04 mol% of sodium molybdate). When the reaction solution was analyzed by high performance liquid chromatography, the production rate of N-methylolacrylamide in the reaction solution was 93% after 1 hour from the start of the reaction.
．． 0%, and by-products were 0.2%.

Examples 2 to 9 Acrylamide and formaldehyde or paraformaldehyde were reacted in the same manner as in Example 1 using the catalyst and reaction conditions shown in Table 1.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that sodium hydroxide was used as a catalyst.

Comparative Examples 2 and 3 A reaction was carried out in the same manner as in Example 1, except that the strongly basic ion exchange resin Amberlyst A26 or triethylamine was used as the catalyst.

Table 1 shows the reaction results in the above-mentioned Examples and Comparative Examples.

[0025]

[Table 1]

[0026]

According to the method of the present invention, N-methylolacrylamide with few by-products can be obtained in high yield. The present invention also has the following advantages. (1) There are few by-products and purification is easy. (2) Since there are few by-products, it is easy to recycle the separated mother liquor after obtaining crystalline N-methylolacrylamide. (3) The reaction rate is improved and the reaction time is shortened.

Claims (3)

[Claims] Claim 1. A method for producing N-methylolacrylamide by reacting acrylamide with formaldehyde or paraformaldehyde in the presence of a basic catalyst in an aqueous solvent, wherein the reaction is carried out using a molybdenum oxyacid salt and/or a tungsten oxyacid salt. 1. A method for producing N-methylolacrylamide, characterized in that it is carried out in the coexistence of N-methylolacrylamide. 2. The method according to claim 1, wherein the molybdenum oxyacid is an alkali metal salt of molybdate, an alkali metal salt of phosphomolybdate, or an alkali metal salt of silimolybdate. 3. The method according to claim 1, wherein the tungsten oxyacid is an alkali metal tungstate, an alkali metal phosphotungstate, or an alkali metal tungstate silicate.