WO1995002007A1

WO1995002007A1 - Method of preparing polyaspartic acid

Info

Publication number: WO1995002007A1
Application number: PCT/EP1994/002083
Authority: WO
Inventors: Matthias Kroner; Thomas Meyer; Gunnar Schornick; Jürgen Hofmann
Original assignee: Basf Aktiengesellschaft
Priority date: 1993-07-10
Filing date: 1994-06-27
Publication date: 1995-01-19
Also published as: DE4323191A1

Abstract

Described is a method of preparing polymers of aspartic acid by heating (a) maleic acid anhydride with (b) acid derivatives of ammonia or adsorption media charged with ammonia, essentially to form hemi-amides of maleic acid or fumaric acid or ammonium salts of the hemi-amides of these acids, followed by thermal condensation of the hemi-amides or their salts, optionally in the presence of co-condensable compounds.

Description

Process for the preparation of polyaspartic acid

description

The invention relates to a process for the preparation of polymers of aspartic acid by thermal condensation of half-amides of maleic acid, fumaric acid or the ammonium salts of the half-amides of these acids, optionally in the presence of cocondensable compounds.

JP-A-85/197646 discloses the production of DL-asparagine by reacting maleic anhydride with aqueous ammonia in the presence of ammonium chloride. The reaction is carried out, for example, in an autoclave at a temperature of 110 ° C. After a reaction time of 3 hours, a yield of 69% of theory of DL-asparagine is obtained.

EP-B-0256366 discloses a process for the preparation of polyaspartic acid and its salts, in which maleic acid and ammonia are reacted in a molar ratio of 1: 1 to 1.5 at temperatures from 125 to 140 ° C. and the acids optionally converted into their salts. The reaction may also be based on maleic anhydride, but maleic acid is first prepared therefrom by adding water.

From Annalen der Chemie, Volume 259, page 138 (1890), the production of maleic amide by introducing ammonia into a solution of maleic anhydride in benzene is known. According to the information in Compt.rend. , Volume 31, 433 (1850) are obtained from the dry distillation of ammonium salts of fumaric acid, malic acid and maleic acid polymers.

From US-A-4,696,981 it is known, by the action of microwave radiation on ammonium salts or amides of maleic acid,

Fumaric acid or malic acid to produce polyamino acids. If the condensation is carried out in the presence of aminocarboxylic acids, copolycondensates are formed.

From the older, unpublished DE application

P 43 00 020.7 discloses a process for the preparation of polymers of aspartic acid, in which gaseous ammonia is first allowed to act on solid or molten maleic anhydride and the resulting half-amides of maleic acid, fumaric acid or their ammonium salts at temperatures above 100 ° C. condensed thermally and the condensates optionally hydrolyzed.

The conversion of maleic anhydride with ammonia in an organic solvent to maleic amide can be carried out easily in the laboratory, but is not suitable for industrial production because the recovery of the solvents is technically complex.

The object of the present invention is to provide a process which is technically easy to carry out for the production of polymers of aspartic acid.

The object is achieved according to the invention with a process for the preparation of polymers of aspartic acid by thermal condensation of half-amides of maleic acid, fumaric acid or the ammonium salts of the half-amides of these acids, if appropriate in the presence of co-condensable compounds, if the halides and the ammonium salts of the Half amides by heating

a) maleic anhydride with b) acid derivatives of ammonia or adsorbents loaded with ammonia,

manufactures in bulk and cleans it if necessary before the condensation. In a preferred embodiment of the invention, one sets

a) Maleic anhydride with b) ammonium salts

around. in a further embodiment of the method according to the invention

a) maleic anhydride is reacted with b) reaction products of ammonia and carbon dioxide or component b) is used as an adsorbent loaded with ammonia, such as activated carbon, silica gel or zeolite.

The thermal condensation of the half-amides or the ammonium salts of the half-amides of maleic acid and fumaric acid initially produces polyaspartimides which can easily be hydrolyzed in aqueous solutions or after addition of bases to give the corresponding polyaspartic acids or the salts. The production of the half-amides of maleic acid or fumaric acid and their ammonium salts is assumed

a) Maleic anhydride, which can be present, for example, in the form of flakes, briquettes, pellets, granules, powder or as a melt.

Acid derivatives of ammonia or adsorbents loaded with ammonia are used as component b) according to the invention, the reaction taking place in bulk, i.e. in the absence of inert solvents or diluents. The acid derivatives of ammonia or the adsorbents loaded with ammonia each have positive values for the enthalpy of formation, i.e. their formation starting from ammonia is exothermic, while the decomposition of the acid derivatives of ammonia or the desorption of ammonia from the adsorbents is an endothermic process.

Acid derivatives of ammonia should be understood to mean, for example, all reaction products of ammonia and inorganic or organic acids. Examples of suitable inorganic acids are hydrogen chloride, hydrogen fluoride, hydrogen bromide, sulfuric acid, sulfurous acid, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, nitric acid, nitrous acid, hydrogen sulfide and carbonic acid. Thermally stable acid derivatives of ammonia, e.g. such from strong mineral acids and ammonia only give off ammonia at relatively high temperatures. Examples of this are ammonium hydrogen phosphate, which only reacts with maleic anhydride at temperatures of around 90 ° C. When using ammonium chloride as a compound of component b), the reaction temperature with maleic anhydride is about 140 ° C. Acid derivatives of ammonia with weak acids, e.g. Carbonic acid, formic acid, oxalic acid or acetic acid react even at relatively low temperatures, e.g. in the range of 40 to 80 ° C.

Of particular interest as a compound of component b) are reaction products of ammonia and carbon dioxide. These are carbonic acid derivatives of ammonia, which contain ammonia in salt or covalent form. Salt-like derivatives are, for example, ammonium bicarbonate, ammonium carbonate and ammonium carbaminate. Covalently bonded carbonic acid derivatives are, for example, urea, N-alkylureas, urethanes, carbamic acid, alkyl carbamates, alkali or alkaline earth metal carbates, ammonium carbamate, isocyanic acid, cyanic acid, cyanuric acid, ammonium cyanate, biuret, acetyl uranium carbonate, guanidium hydrogenated guanidine , Semicarbazide, cyana id, calcium cyan amide, dicyandiamide, biguanide, nitroguanidine, aminoguanidine, allophanates, melamine, amidine urea, cyanurea and thiourea. Formamide, acetamide, urotropin, monoammonium dihydrogen phosphate, ammonium chloride and ammonium nitrate are also suitable as compounds of component b ⁾ . Compounds of component b) used with particular preference are ammonium hydrogen carbonate, ammonium carbonate and ammonium carbaminate.

Suitable compounds b) are also ammonia-laden adsorbents. Substances of this type are obtained, for example, by passing ammonia over solid adsorbents. Suitable adsorbents are, for example, activated carbon, zeolite, aluminum oxide, silica gel, ammonium nitrate as a diverse liquid, acidic ion exchanger, chlorides of calcium, cobalt, zinc, kieselguhr, silica, water glass gel, iron hydroxide, aluminum hydroxide, clays, titanium dioxide, iron oxide, zeolite and Bentonite.

Metal compounds which contain ammonia in a complex bond, for example iron (II) ammonium sulfate, copper-tetramine complexes and nickel-II-hexamine complexes, can also be used as compounds b).

Compared to the reaction of maleic anhydride with gaseous ammonia in the absence of diluents, the advantage of the process according to the invention is that the reaction partners a) and b) are mixed at low temperatures, for example in the range from 0 to about 30 ° C. can without a noticeable reaction. The reaction of maleic anhydride with the compounds of group b) is triggered by increasing the temperature of the mixture, for example to values of 40 to 100 ° C., and can be brought to an end at temperatures of up to 140 ° C. However, if a higher reaction rate is desired, the reaction of the compounds a) and b) can be carried out at temperatures at which the condensation begins or takes place, ie in the temperature range from 140 to 350 ° C. The formation of the monomer and the condensation then take place in one process step. The reaction can be carried out under normal pressure, under reduced pressure or under increased pressure. In order, for example, to prevent the carbon dioxide formed when ammonium carbamate decomposes when the maleic anhydride is reacted with ammonium carbaminate, the reaction can be carried out in closed apparatus. For example, it is possible to dissolve maleic anhydride in molten ammonium carbamate and to use the ammonium carbamate melt as a solvent and diluent for the reaction. This has the particular advantage that the Reactions can be carried out in reactors equipped with a stirrer. The excess ammonium carbamate can be removed again after the reaction by relaxing the reaction mixture, so that the maleic acid amide remains in the form of a solid. Ammonium carbaminate can also be produced in situ, for example by adding maleic anhydride in the temperature range from 20 to 140 ° C. under pressure with gaseous carbon dioxide and then pressing in ammonia. However, one can also first react carbon dioxide with ammonia to ammonium carbaminate in one reaction space and then react it with maleic anhydride in another reactor. The carbon dioxide released during the reaction is then returned to the first reaction space, in which it can react again with ammonia to form ammonium carbaminate. 5

The molar ratio of maleic anhydride: ammonia which is released from the acid derivative or the adsorbents can be varied within a wide range and is, for example, 1: 0.9 to 1: 2, preferably 1: 1 to 1: 1, 3rd Maleic acid amide and 0 the ammonium salt of maleic acid monoarnide melt endothermically in the temperature range from about 100 to 140 ° C. to a yellowish, low-viscosity melt which polycondenses exothermically from 145 ° C. Gaseous components escape, among other things. Ammonia and water. In the course of the polycondensation, the viscosity of the reaction mass increases rapidly, so that a viscous, sticky resin is formed which, upon further annealing, solidifies into a brittle mass which can be easily pulverized. The reaction of components a) and b) is preferably carried out at temperatures from 0 to 140 ° C. Afterwards the condensation of the converted

30 products from a) and b) at temperatures up to 350 ° C. Component a) and b) can also be mixed at temperatures at which the polycondensation is carried out, in particular when compounds b) are particularly stable, i.e. in the temperature range of 140 to 350 ° C, preferably 150 to

35 250 ° C.

The polycondensation, for example, proceeds particularly favorably if the reaction products of maleic anhydride and ammonium salts are subjected to cleaning before the polycondensation.

40 gen. This can be done, for example, by converting the crude maleic acid amide or its ammonium salts in water with the addition of sodium hydroxide solution into an aqueous sodium salt solution and driving off the non-chemically bound ammonia from the aqueous solution. The ammonia-free sodium salt solution of

45 maleic acid monoarnide is then acidified to pH 2 by adding, for example, hydrochloric acid. The maleic acid monoxide precipitates in the form of a white powder. It is from the mother liquor separated, dried and polycondensed, for example, in the temperature range from 140 to 250 ° C. Processing aids can be added in the production of maleic acid amide and in the polycondensation. Such processing aids have the effect that the maleic acid amide particles do not cake, but always remain easily pourable. Processing aids can also lower the melt viscosity of the polycondensate or serve as a release agent in order to keep it in powder form. Examples of such processing or processing aids are, for example, detergent ingredients such as nonionic, anionic or cationic surfactants, fatty acids, vegetable oils and talc. If they are used, up to 5% by weight of the processing aids are used, based on the polycondensate formed.

Suitable devices for handling powders are, for example, paddle mixers, single-shaft and twin-screw extruders, fluidized beds, fluidized beds, unstirred or stirred fixed beds, rotary tubes, cone mixers, tumble mixers, double-cone mixers, silos, tubular reactors, stirred tanks (especially with cross-bar stirrers), heated or insulated conveyor belts, kneaders, drum and ploughshare mixers.

To facilitate the polycondensation of maleic acid monoamides and to increase the biodegradability of the condensation products, various additives can be used in the polycondensation. For example, acidic or basic reacting substances in amounts of 0.01 to 200 mol%, based on maleic amide, are suitable. Such substances are, for example, mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, phosphoric acid, hypophosphorous acid, polyphosphoric acid, boron trifluoride, boron trichloride, carbon dioxide, sulfur dioxide, aluminum oxide, zinc chloride, iron III chloride, iron 11 sulfate, Oxalic acid, citric acid, tartaric acid and aluminum sulfate. Suitable basic additives are, for example, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, potassium carbonate, sodium carbonate, potassium silicate and sodium silicate, calcium oxide, calcium carbonate, magnesium oxide and magnesium carbonate. The additives are preferably used, for example, in a two-stage procedure in the 2nd stage, in which the formation of the half-amides takes place in the 1st stage and the condensation takes place in the 2nd stage.

The condensation of the reaction products obtained from a) and b) to give polymers of aspartic acid can also be carried out in the presence of compounds which are treated with the halamides or

Ammonium salts of the half-amides of maleic acid or fumaric acid can be condensed. Suitable co-condensable compounds are for example all amino acids, carboxylic acids, anhydrides of polybasic carboxylic acids, alcohols, amines, alkoxylated alcohols, alkoxylated amines, amino sugars, carbohydrates, sugar carboxylic acids and / or non-proteinogenic amino acids. Based on part of the reaction products from components a) and b), the co-condensable compounds are used in amounts of 0 to 30% by weight.

The polycondensation of the half-amides of maleic acid, fumaric acid or the ammonium salts of these half-amides initially produces polyaspartimides which can be readily hydrolyzed in aqueous medium at pH values above 8 and converted into the corresponding alkali metal or ammonium salts of polyaspartic acid. The condensation products are in the form of the alkali metal or ammonium salts, for example as a detergent additive to low-phosphate (this is to be understood as detergent and cleaning agent formulations with a phosphate content of at most 25% by weight) and phosphate-free, solid or liquid cleaning agents in quantities up to 20% by weight, based on the detergent formulation, as an additive to dishwashing detergents or as a scale inhibitor in amounts of about 0.1 to 1000 ppm, based on the aqueous medium to be treated. The condensates can also be used as dispersants for solid, inorganic or organic particles in water.

The K values given in the examples were in the form of the polyaspartimides according to H. Fikentscher, Cellulose-Chemie, Vol. 13, 48 to 64 and 71 to 74 (1932) in 1% strength by weight solution in dimethylformamide or in the form the sodium salts of polyaspartic acids in 1% solution in water at pH 7 and 25 ° C.

The average molecular weights M _w are determined by means of GPc (calibration using polyacrylate standards). They are in the range 500 to 30,000, preferably 600 to 10,000. The ratio of weight average to number average M _w / M _n is usually 1.7 to 2.3.

Examples 1 to 3 In a 1 liter round-bottom flask, 98 g (1 mol) of maleic anhydride in flake form are mixed with the amount of ammonium salt given in the table at a temperature of 20 ° C. and for 1.5 Leave for hours at room temperature on a rotary evaporator with rotation. The temperature of the reaction mixture is then raised to 40 ° C. C0 escapes. The reaction mixture is mixed for 2 hours at 40 ° C. on a rotary evaporator and then indicated in Table 1 with the added amounts of ammonium compound. The temperature is immediately raised to 60 ° C. If water forms during the decomposition of the ammonium compound, the powdery mixture is dried to a white powder in a water jet vacuum.

The maleic acid amide obtainable in this way melts at a temperature of 140 to 145 ° C to a yellow mass, which is condensed by heating to a temperature of 200 ° C to form a tough, foamy, yellow-red resin that solidifies and becomes glassy after prolonged annealing can easily be pulverized when hot. The K value of the polycondensates obtained in each case is also given in Table 1. Polycondensate in the Na form means that the Na salt of polyaspartic acid is prepared from the polyaspartimide by treatment with aqueous NaOH. The K value of this salt is then measured.

Table 1

With addition of ammonium to drying, K value of the play bond in ammonium, or polycondensation.

No. of the template binding after setting dates in the 2-hour product

Reaction tes imide form Na form

1 87 g 8 g; _mmonium- yes 14 16

(1.1 mol) ammonium carbonate hydrogen carbonate gene carbonate

2 0.55 mol 5 g ammonium yes 14 16 52 g carbonate

Ammonium carbonate

3 0.55 mol 4 g of ammonium no 14 16 43 g of ammoni carbamate carbamate

Example 4

100 g of maleic acid amide, which was prepared as described in Example 3 by reacting maleic anhydride with ammonium carbaminate, is slurried in 200 ml of water. The sodium salt of maleic acid monoamide is prepared by adding 25% aqueous sodium hydroxide solution up to pH 7. After everything has dissolved, excess ammonia is driven off in vacuo. The aqueous solution is then acidified with concentrated aqueous hydrochloric acid until it has a pH of 2. A powdery precipitate is formed, which is suctioned off and dried in the air.

100 g of the purified maleic acid monoamide are heated in a 1 liter round bottom flask on a rotary evaporator at a pressure of 15 mbar to a temperature of 80 ° C. By increasing the temperature to 200 ° C, the polycondensation takes place within 2 hours. The thin melt that initially forms becomes increasingly viscous. The polycondensation 10 has ended after 2 hours. The K value of the imide form is 16, the K value of the Na form 19 (Na salt of polyaspartic acid).

Examples 5 and 6

15 In a twin-screw extruder, which has a diameter of 28 mm and 8 closed units, maleic anhydride in flake form and the ammonium compounds given in Table 2 are metered in from each of two dosing devices via screws. The temperature in the mixing section of the extruder is

20 40 ° C, 60 ° C in the middle of the reactor and 80 ° C at the extruder outlet. The rotation speeds were set at 150 rpm. A white powder was obtained, which was polycondensed in a flat dish at 200 ° C. The polycondensates had the K values given in Table 2.

25

Table 2

MSA ammonium ammonium K value of the polymer (kg / h) carbonate carbaminate in the

30 (kg / h) (kg / h)

Imide form Na form

Example 2.97 1.59 - 14 16 5

Example 2.97 - 1.17 14 16

35 6

Example 7

In a 1-liter round-bottom flask, 98 g (1 mol) of maleic anhydride and 1.0 mol of urea are placed and heated to a temperature of 70 ° C. After about 1 hour, the urea dissolves in the molten maleic anhydride with stirring to give a clear reaction mixture which is then heated to 100.degree. To do that

To condense the reaction mixture, the flask contents are held at 150 ° C. for 1 hour, the entire mass forming a foam stares. The K value of the polycondensate in the imide form is 12.

Example 8

98 g (1 mol) of maleic anhydride in flake form and 77 g (1 mol) of ammonium acetate are introduced into a 1-liter round-bottomed flask and slowly heated to a temperature of 85 ° C. while mixing on a rotary evaporator. Within half an hour the initially pulpy flask contents solidify into a white crystal mass, which is kept at a temperature of 85 ° C. for a further 2 hours while rotating the flask. The acetic acid released is removed by applying a water jet vacuum. The crude maleic acid amide is then first slowly heated to a temperature of 80 ° C. in a flat glass dish, with dewatering occurring. The polycondensation is then completed by carefully heating the dried maleic acid amide to a temperature of 200 ° C. The reaction mixture is kept at 200 ° C. for a further hour. The polyaspartimide obtained in this way has a K value of 13 and in the Na form of 15 (Na salt of polyaspartic acid).

Claims

claims

1. Process for the preparation of polymers of aspartic acid by thermal condensation of half-amides of maleic acid, fumaric acid or the ammonium salts of the half-amides of these acids, if appropriate in the presence of co-condensable compounds, characterized in that the half-amides and the Ammonium salts of the half amides by heating

(a) Maleic anhydride with

(b) acid derivatives of ammonia or adsorbents loaded with ammonia,

manufactures in substance and, if necessary, cleans it before condensation.

2. The method according to claim 1, characterized in that (a) maleic anhydride is reacted with (b) ammonium salts.

3. The method according to claim 1 or 2, characterized in that one

(a) Maleic anhydride, with

(b) converts reaction products from ammonia and carbon dioxide.

4. The method according to claim 1, characterized in that activated carbon or zeolite is used as the adsorbent.

5. The method according to any one of claims 1 to 4, characterized gekenn¬ characterized in that the reaction of (a) with (b) at temperatures from 0 to 140 ° C and the subsequent condensation at temperatures up to 350 ° C is carried out .