SK352009A3 - Method for producing beta-hydroxyalkylamide compounds - Google Patents

Abstract

Described is a method for producing beta-hydroxyalkylamide compounds by the reaction of carboxylic acid with beta-amino alcohol in the presence of alkaline catalyst. The reaction is taken out at a temperature lower than the boiling temperature by reaction of formed alcohol, having conversion at least 50 %, optionally in the presence of a solvent, which is subsequently removed from the reaction mixture.

Description

Technical field

The invention relates to a process for the preparation of β-hydroxyalkylamides by reacting an alkyl ester of a carboxylic acid with a β-aminoalcohol in the presence of an alkali catalyst. β-Hydroxyalkylamides are suitable, for example, for the preparation of polyesters, polyamides, powder coatings, elastic polyurethane foams, as crosslinkers for various compositions, but also for stopping the formation of boiler stone.

BACKGROUND OF THE INVENTION β-Hydroxyalkylamides are prepared, as a rule, by reacting alkyl esters of carboxylic acids with β-aminoalcohols at temperatures of 80 to 140 ° C while distilling off the alcohol by-product resulting from amidation from the acid ester used. The reaction is carried out under atmospheric or reduced pressure, optionally in the presence of an inert gas as an auxiliary medium. The catalysts used are basic substances, in particular alkali metal hydroxides, alkali metal alcoholates or quaternary ammonium hydroxides US 4,493,909; US 4,801,680).

The reaction time is controlled by the amount of alcohol distilled off, optionally by the viscosity and miscibility of the reaction mixture. The process is carried out by adding hydroxyalkylamine to a mixture of esters of organic acids and an alkali catalyst, generally without solvent. After dosing, the reaction conditions are maintained for 2 to 5 hours until the alcohol formed is distilled off. The reaction mixture is then neutralized with inorganic or organic acids and the excess hydroxyalkylamine is distilled off in vacuo. This gives a product of 80 to 90% hydroxyalkylamide (J. Coat. Tech. 50 (643), 49-55 (1978); U.S. Pat. No. 4,076,917; U.S. Pat. No. 4,727,111).

If a purer product was needed, the impurities from the crude product were separated by recrystallization using solvents, in particular methanol and acetone. In this way, a product with an ethanolamine content of less than 1.0 wt. (US 4,076,917).

Rohm & Haas prepares solid, very pure hydroxyamides by reacting alkyl esters of carboxylic acids with alkanolamines under reaction temperature control, removing alcohol by-products, controlling reaction temperature to form a slurry, maintaining the slurry, and isolating hydroxyamides (US 5,101,073).

According to EP 960 878, β-hydroxyalkylamides are prepared by reacting an alkyl ester with β-aminoalcohols without a solvent in the presence of a basic catalyst, improving the selectivity so that the ratio of ester equivalent to amine equivalent is 1: 1.001 to 8 and the alcohol formed is removed by distillation.

These processes are disadvantageous since, after reaching a certain degree of conversion, the product begins to solidify, which makes it difficult to stir and drive the reaction to a high degree of conversion and unproductive synthesis. Increasing the reaction temperature above the melting point of the desired product causes an increase in the by-product content and thus a decrease in selectivity. The total yield of the products after purification is less than 75% of theory.

SUMMARY OF THE INVENTION

The present invention relates to a process for the preparation of β-hydroxyalkylamides of the general formula (I) or (II)

(I) or ** (II) wherein R is an alkyl or alkenyl group and each R 'separately is H, or a methyl group, R is preferably an alkyl group having 1-8 backbone carbon atoms or an alkenyl group having 2-8 the carbon atoms in its main chain by reacting an alkyl ester of a carboxylic acid with a β-aminoalcohol in the presence of an alkali catalyst at which the reaction proceeds below the boiling point by reaction of the resulting alcohol and optionally in the presence of a solvent; and / or remove the solvent from the reaction mixture.

It is preferred to carry out the reaction until the feedstock conversion is above 90% without removal by reaction of the resulting alcohol and solvent from the reaction mixture.

The process according to the invention ensures homogeneity and good miscibility of the reaction mixture, high quality and yields of the desired product with the possibility of reaction at lower reaction temperatures at which no decomposition of the product occurs even at longer reaction times.

The present invention has surprisingly been found that removal of the alcohol formed as a by-product is not necessary to shift the equilibrium of the reaction. This makes it possible to conduct the reaction in a homogeneous, miscible phase, as opposed to the known process, when, after reaching a certain degree of conversion, the product begins to solidify, which makes it difficult to mix and conduct the reaction to a high degree of conversion. Increasing the reaction temperature above the melting point of the desired product causes an increase in the content of by-products and thus a decrease in the selectivity of the reaction.

Conversely, the process of the present invention can also be conducted in the presence of a solvent, even preferably by the addition of an alcohol formed by the reaction, either from the start of the reaction or only during the reaction, when the viscosity of the mixture begins to increase. Of course, the use of an alcohol other than a diluent is possible, but this in turn requires its separation from the reaction alcohol.

Distilling off the solvent used, optionally by reaction of the resulting alcohol, is preferably carried out under reduced pressure and temperature.

The product can be recovered from the reaction mixture by cooling, also by filtration, whereby the filtrate containing the solvent together with the dissolved amide can be recycled back to the apparatus into another batch.

The process for the preparation of hydroxyalkylamides of acids is apparent from the examples where the individual preparation processes are described, which can be combined in various ways.

DETAILED DESCRIPTION OF THE INVENTION

Example 1 - Reference

A 0.5 dm ³ glass flask was equipped with a stirrer, a thermometer, a nitrogen inlet to the bottom of the flask, and a downstream condenser to distill the alcohol from the flask. The flask was tempered with a heat transfer bath in which the temperature was maintained by means of a contact thermometer. Dietanolamine (DEA) with a content of 99% and a water content of 0.23% by weight was charged to the flask. Sodium hydroxide in an amount of 0.02 mol per 1 mol of dimethyl adipate (DMAD) was used as the catalyst. After heating the contents of the flask to 100 ° C under a nitrogen atmosphere, adipic acid dimethyl ester was metered into the mixture with stirring for 0.25 h so that the DEA: DMAD molar ratio was 1.95: 1.0 while distilling off methanol. After 2.5 hours of reaction, the viscosity of the mixture increased and the product was difficult to stir.

Continuous samples were taken over the next 18.5 hours and the diethanolamine content was determined by gas chromatography. Even after that time, the DEA did not respond.

The content was as follows:

h - 8.6% h - 5.7% h - 2.6%

18.5 h - 1.6%

After this time, a product containing 90.4% of Ν, Ν, Ν ', Ν'-tetrakis (2-hydroxyethyl) adipamide was obtained after cooling. Recrystallization from butanol-acetone gave a product in 70% yield containing 0.97% diethanolamine and 97.7% N, N, N ', N'-tetrakis (2-hydroxyethyl) adipamide.

Example 2 - Reference

The experiment was repeated using sodium methanolate as a catalyst and with a DEA: DMAD molar ratio of -1.99: 1. At 0.25 h dosing of DMAD at 100 ° C with simultaneous distillation of methanol and 5.5 h reaction at 120 ° C, a product with a DEA content of 4.0%, a content of THEA 93.7% and OH was obtained after cooling and drying. 669.5 mg KOH / g; after 2 h of reaction, the viscosity of the solution gradually increased and the solution was only very difficult to stir. A yield of 80% was achieved, but the product quality was unsatisfactory. The product had to be recrystallized.

Example 3 - modified

In the apparatus as in Example 1, the solvent addition procedure was tested. The feedstock feed was 128 g DEA and 106 g DMAD, i. mole ratio 2.0, 1.8 g of 30% sodium methoxide was used and the reaction temperature was 100 ° C while distilling off methanol. After a 2.75 h reaction, when viscosity began to rise, 20 g of isopropyl alcohol were added to the reaction mixture, and after 5.5 h a further 180 g. The mixture was cooled, the crystals filtered and dried. 126.8 g of crystals with a DEA content of 2.3%, a THEA content of 96.3% and a melting point of 122 ° C were obtained.

Although the modified process was able to increase the conversion of DEA, the product yield was only 63.4%.

Example 4

In a device as in Example 1, where a reflux condenser was placed in place of a drop cooler for distilling off the alcohol, feedstocks were charged at 20 ° C with 128 g DEA, 106.1 g

DMAD and 2.2 g of sodium methanolate (mole ratio of raw materials 2.0: 1.0: 0.02); the temperature gradually increased to 37 ° C over 2.25 hours due to the reaction heat. The viscosity of the reaction mixture increased and the initially biphasic mixture became clear. To the reaction mixture from which methanol was not distilled off, after a further hour of reaction at 45 ° C, 150 g of isopropyl alcohol was added in one portion. The mixture was cooled to 20 ° C, filtered and dried. The filtrate - a mixture of isopropyl alcohol and methanol - was worked up separately.

The product in an amount of 171.9 g contained 0.75% diethanolamine, 97.4% THEA, melting point 125-126 ° C and OH number 676.5 mg KOH / g. The product yield was 90% of the theoretical.

Example 5

In the apparatus of Example 4, the amidation of adipic acid diisopropyl ester (DIPA) with diethanolamine (DEA) was performed using NaOH catalyst at a molar ratio of 2.0: 1: 0.03 (weight: 128 g DEA; 169 g DIPA and 0.75) g of NaOH) and 150 g of isopropyl alcohol.

After mixing, the mixture was heated to 70 ° C and after 5.5 h of reaction and cooling, the crystalline product was filtered off, the crystals were washed with 50 g of isopropyl alcohol and dried. The diethanolamine content of 156.6 g of the product was 0.36% by weight; amide content 96.3%; OH number 651.3 and mp 122.5 ° C. The yield in this experiment was 81.1% of theoretical, the product quality was good.

Example 6

128 g of DEA, 106 g of DMA, 3.3 g of 30% sodium methoxide solution and 80 g of methanol were weighed into the apparatus of Example 4. The reaction mixture was allowed to react at 45 ° C for 5 h and then poured into a vacuum rotary evaporator, where methanol was distilled off at 45 ° C under a reduced pressure of 6.67 to 2.67 kPa. This procedure yielded a powdered product in an amount of 194.4 g with a DEA content of 0.8% by weight, a content of THEA

99.1%, OH number 694.7, mp 122 ° C, product yield 99.7%.

Yield and product quality were excellent, close to theoretical.

Example 7

128.3 g (1.22 mol) diethanolamine, 9 g 29.2 wt. KOH in methanol and 107.8 g (0.619 mol) of dimethyl adipate were charged into a 1 L rotary evaporator flask. The residue was immersed in a water bath at 40 ° C and rotated. After 1 h the contents were determined

3.1 wt. diethanolamine with a conversion of 92.9%. Subsequently, the reaction was continued with simultaneous drying under vacuum (13.1 kPa). After another hour the conversion rose to 97.9% and after 3 hours the conversion was 98.4%. This gave 36.4 g of methanol, i. 1.14 mol, corresponding to a 91.6% yield. Subsequently, the vacuum was increased to 1 kPa for 1 h. The evaporation residue, the obtained amide 199.5 g contained 0.6% diethanolamine and 99% diamide content (determined by HPLC).

Both yield and quality were close to theoretical.

Example 8

52.8 g of dimethyl malonate, 84 g of diethanolamine, 4 g of 30% methanolic sodium methanolate solution and 80 g of methanol were metered into the apparatus of Example 4. The contents of the flask were maintained at 45 ° C, with gentle nitrogen bubbling, with stirring for 6 h. Subsequently, methanol was distilled off in a vacuum rotary evaporator at 40 ° C and 13 kPa. 120 g of N, N, N ', N'-tetra (2-hydroxyethyl) malondiamide with a 97.0% diamide content as determined by FT-IR were obtained.

Both yield and quality were close to theoretical.

Example 9

Under the conditions of Experiment 8, a mixed bis (dihydroxyethylamide) was prepared from a mixture of adipic, glutaric and succinic esters (adipic acid dimethyl ester content of 17.5%, glutaric acid dimethyl ester of 60% and succinic acid dimethyl ester of 21%).

Weigh 80 g of a mixture of esters, 96 g of diethanolamine, 4 g of methanolic sodium methoxide solution and 80 g of methanol into a flask. After 6 hours of reaction at 45 ° C, the product was dried on a rotary evaporator to give a mixture containing 96% of the bis- (dihydroxyethylamides) acids mentioned.

The yield was close to the theoretical value.

Example 10

100 g of di (2-methyl-2-hydroxyethyl) amine, 65.4 g of dimethyl adipate and 2.0 g of KOH solution in 50 g of methanol were weighed into the apparatus of Example 4. After 6 hours of reaction at 55 ° C and subsequent distillation of methanol under reduced pressure of 13.0 kPa, 170 g of product with OH number 566 mg KOH / g, corresponding to 95% of bis- (2-methyl-2-hydroxyethyl) diamide of the acid, were obtained. adipic.

Example 11

116.2 g of butyl acetate were weighed into the apparatus of Example 4; 105.2 g of diethanolamine; 2.8 g of a 30% sodium methoxide solution and 100 g of n-butanol. The reaction was conducted at 45 ° C for 6 hours with stirring under nitrogen atmosphere (flow rate 61 / h).

After 6 h, 162 g of butanol was evaporated from the reaction solution at 8 kPa. 144.8 g of 98.6% acetic acid dihydroxyethylamide as determined by FT-IR analysis were obtained. Industrial usability

The product can be used especially for the preparation of polyesters and polyurethanes.

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Claims (4)

PATENT CLAIMS Process for preparing β-hydroxyalkylamides of formula (I) or (II) HC R ' R ' OH OH OH R ¹ R ' OH (I) (II) Second Third 4th Second Third 4th wherein R is an alkyl or alkenyl group and each R 'is H, or a methyl group, preferably R is an alkyl group having 1-8 carbon atoms in the backbone or an alkenyl group having 2-8 carbon atoms in its backbone by reaction of an alkyl carboxylic ester an acid with a β-aminoalcohol in the presence of an alkali catalyst, characterized in that the reaction is carried out at a temperature below the boiling point by reaction of the resulting alcohol and optionally in the presence of a solvent and after reaching at least 50% conversion eliminated. The process according to claim 1, characterized in that the alcohol and solvent formed are removed after a conversion of more than 90%. The method of claim 1 wherein the solvent is the same alcohol as formed during the reaction. The process according to claims 1 and 2, characterized in that the alcohol and solvent are removed by distillation under reduced pressure, by filtration and / or by centrifugation.