DE1468533A1 - Process for the preparation of N-methylol methacrylic acid amide - Google Patents

Description

Process for the preparation of N-methylol methacrylic acid amide

The invention relates to a process for the preparation of pure crystallized methylol methacrylic acid amide by reaction of crystallized methacrylic acid amide with paraformaldehyde.

Various unsaturated organic carboxamides have become increasingly important in various fields in recent years attained. These include the monomeric methylol methacrylic acid amide and its polymers and copolymers. The monomer It is used, for example, to crease native and regenerated Cellulose used. (DAS 1 121 579) · Due to its hydrotropic properties it is also suitable as a solubilizer for other polymerizable monomers and can with these are copolymerized together from aqueous solutions. I.lothylolmethacrylsäureamid is also suitable for the production of cellulose graft polymers. The polymers and copolymers can also be used to make adhesives as well can be used for coating textiles and paper.

It is known that methylol acrylic acid amide can be used in good Yields and satisfactory purity in the crystallized state!. After a melting process in the presence of basic catalysts and can be obtained in the absence of solvents (DAS 1 085 149). It has also been proven experimentally that in contrast the methylol methacrylic acid amide is not accessible in this way (DAS 1 085 149) »because either none Reaction between methacrylic acid amide and paraformaldehyde occurs or because polymerisation occurs when the reaction temperature is increased . takes place.

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Monomeric methylol methacrylic acid amide has already been prepared by reacting methacrylic acid amide with paraformaldehyde in carbon tetrachloride using colloidal sodium as a catalyst (Journal of the American Chemical Society Vol. 75 £ 1953j ^s * ^{5027 to} 5029). The introduction of such a process in the chemical industry is opposed to three compartments;

1. The use of a large amount of an organic solvent which must be recovered.

2. The presence of finely divided sodium in a chlorinated hydrocarbon and those with it associated uncontrollable risk of explosion.

3. The relatively low yield of $ 70 based on the methacrylic acid amide used.

It is also possible to prepare methylol methacrylic acid amide in aqueous solution. However, when narrowing down such solutions considerable losses due to partial polymerization of the methylol methacrylic acid amide are accepted. With regard to The methylol methacrylic acid amide affects the shipping, storability, handling and reproducibility of the instructions for use in solid, crystallized form preferred to an aqueous solution.

DAS 1 085 149 states that it has not been possible to produce methylol methacrylic acid amide analogously to methylol acrylic acid amide by a melt process. Our own attempts earlier had led to the same negative result. It was therefore surprising that the crystallized methylol methacrylic acid amide can still be obtained from methacrylic acid amide and paraformaldehyde in excellent yields and good purity if one works in the presence of basic catalysts and very small amounts of organic solvents.

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BATH ORIGINAL

As catalysts for carrying out the invention Process become alkali carbonate! Alkali hydroxide, alkali alkali coliolates as well as tertiary amines used alone or in admixture with one another. Carbonates and hydroxides can be used in more concentrated form aqueous solution, hydroxides, alcoholates and tertiary amines are advantageously also used in concentrated alcoholic solution but should at least partially dissolve in the solvent mixture used.

Suitable organic solvents are methanol, ethanol, n-propanol, i-propanol, n-butanol, diethyl ether, dioxane, tetrahydrofuran, methylene chloride, chloroform, ligroin (Spd.90-100 ⁰ C) and mixtures thereof, in which at least one Fraction of the reactants and the catalyst are able to dissolve. If this requirement is met, a very small amount of solvent is sufficient to start the reaction. Since it is advantageous to work at temperatures above the melting point of the methylol methacrylic acid amide, the desired end product remains liquid and is constantly increased as the reaction progresses, so that in the end the methylol methacrylic acid amide also functions as a solvent. For this reason only very small amounts of organic solvents are required »

In general, 2% by weight of solvent, based on the methacrylic acid amide used, is sufficient for carrying out the process, but up to 20% by weight and more of solvent can be used if the reaction product is only sparingly soluble in it. He manages about to reclaim up to 90 $> dea solvent used again, which can then be used repeatedly without further purification * Preferably 1-3 but weight ^ of said organic solvent, based on methacrylic acid used.

Furthermore, it is generally sufficient to carry out the process 0.2 weight ^ catalyst, based on the methacrylo acid amide, however, up to 1.0 weight percent and more can be used

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if the catalyst is volatile and therefore does not remain completely in the reaction product. Preferably works but one with 0.1-0.3 weight ^ catalyst, based on the methacrylic acid amide used "

The reaction of paraformaldehyde with methacrylamide can already at temperatures which are substantially lower than the melting point of the methacrylic acid amide, are performed, temperatures above room temperature are preferred because then only short reaction times are required, "but the Reaktionsteeperatur should be kept below 85 ⁰ C as possible, otherwise there is a risk of polymerisation and / or splitting off of formaldehyde.

The following examples explain the invention »

Example It

425.5 g of methacrylic acid amide and 150.5 g of paraformaldehyde are mixed in an open reaction vessel and with a Solution of

150 mg sodium

in 10 ecm isopropanol

and heated with stirring to 60-70 ⁰ C. After 15-20 minutes, the reaction mixture is liquefied "It still holds 15 minutes at 7O ⁰ C and then allowed to cool, whereupon the reaction product crystallized. It is concentrated in a vacuum desiccator. Sulfuric acid freed from solvent residues. Yield 570 g Methylolmethacrylsäureamid, Pp. 48-52 ⁰ C.

Example 2i

21.2 g of methacrylic acid amide and 7.5 g of paraformaldehyde are mixed in a beaker with

0.5 ecm of ethanol

and 0.06ccm 10 weight aqueous

Soda solution

was added and stirring at 60 - 65 ⁰ C heated. After 10-15 minutes , a homogeneous reaction mixture has formed which is still

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Is held at 65 ^{0 C for 15 minutes.} Methylol methacrylic acid amide crystallizes out on cooling. The crystal pulp is left to stand in the air on a clay plate. Yield 28 g, pp. 46-50 C.

Example 3:

42.5 g of methacrylic acid amide and 15 »0 g of paraformaldehyde

v / ground in a round bottom flask fitted with a reflux condenser is mixed with

100 ecm ligroin (bp 90-100 ° C) and a solution of

20 mg sodium
in 0.5 ecm of methanol

the mixture was heated using a magnetic stirrer at 60-70 ⁰ C with continuous stirring and held for 15 minutes at 70 ⁰ C after liquefaction of the reaction mixture. When placing in ice water, the desired reaction product crystallizes out. By squeezing off the crystal mass, up to 90 $> of the solvent can be recovered. This can be used again without further purification. Yield 56 g methylolmethacrylamide, Pp. 43-48 ⁰ C.

Example 4 »

85.1 g methacrylic acid amide and 30.3 g paraformaldehyde are in a beaker with a solution of

0.5 ecm triethylamine in?, 0 ecm isopropanol

intimately mixed with stirring and heated to 70-80 ⁰ C. After 30 minutes, a further 0.3 ecm of triethylamine are added. After v / Eiteren 20-30 minutes, the reaction mixture is liquefied, whereupon it is held for 15 minutes at 75 ⁰ C. The reaction product solidifies on cooling to form a solid melt cake, which after crushing in a vacuum desiccator over conc. Sulfuric acid is freed from solvent and catalyst residues. Yield 114 g of ethylol methacrylic acid amide, mp 50-53 ° C.

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Example 5:

170.2 g methacrylic acid amide and 60.1 g paraformaldehyde

are placed in a round bottom flask fitted with a reflux condenser with

50 ecm diethyl ether as well as with a solution of

50 mg sodium

in 3 ecm isopropanol

added and heated to reflux with constant stirring by means of a magnetic stirrer. A homogeneous solution is formed in the course of 30-4 © minutes, which is refluxed for another 30 minutes. On cooling, a crystal slurry is obtained from which the solvent is recovered by pressing. Yield 224.5 g of methylol methacrylic acid amide, m.p. "^ 49-53 ⁰ C- The recovered solvent can be used again without further purification.

Claims (9)

Patent claims 1. A process for the preparation of pure crystallized methylol methacrylic acid amide by reacting methacrylic acid amide with paraformaldehyde at higher temperatures in the presence of small amounts of a solvent and in the presence of an alkaline catalyst, characterized in that crystallized methacrylic acid amide with powdered paraformaldehyde in the presence of small amounts of a solvent, preferably 1-3 weight "- ^ based on methacrylic acid amide, and in the presence of catalytic amounts, preferably 0.1-0.3 weight / ^^ based on methacrylic acid amide, of an alkali metal carbonate, alkali metal hydroxide, alkali metal alcoholate or tertiary amine which is at least partially soluble in the solvent used at temperatures above room temperature, but not above 85 ^° C., and mixing continues until the reaction has ended. 909811/1? 67 2. The method according to claim l _r, characterized in that the reaction is carried out in the presence of methanol, ethanol, n-propanol, i-propanol, n-butanol, diethyl ether, dioxane, tetrahydrofuran, methylene chloride, chloroform, ligroin or Minchungen the same in which the reactants are partially soluble, carries out 3 · The method according to claim 1, characterized in that the Reaction in the presence of sodium carbonate, sodium hydroxide, sodium methylate, sodium ethylate, sodium isopropyla.t, Triethylamine or triethanolamine. performs. Literature considered «DAS 1 085 149 Journal of the American Chemical Society, vol * 75 (1953) Pp. 5027 to 5029 Journal of Polymer Science, Vol. 50 (1961) S.Months of Chemistry, Vol. 78 (1948) S. Liebigs Annalen der Chemie, Vol. 343 (1905) p. 212 172, .173 209, 223 and 255, DAS 1 121 579
Macromolecular chemistry, Vol. 361 (1908) pp. 122, 126 and 128 Vol. 57 (1962) pp. 27 to 51 9 09811/1767