A NEW METHOD FOR PRODUCING ANION-EXCHANGE RESINS

Abstract

The present invention relates to a novel method for producing anion exchangers.

Description

[0001] PROCESS FOR THE PRODUCTION OF ANION EXCHANGERS

[0002] The present invention relates to a new process for the production of

[0003] Anion exchangers.

[0004] A process known from e.g. EP-B 1000660 for the production of

[0005] Anion exchangers involve the reaction of chloromethylated vinylaromatic polymers with ammonia to produce anion exchangers containing primary amine groups. A disadvantage of this process, however, is the low yield achieved in the reaction. Therefore, the chloromethylated vinylaromatic polymers are typically reacted with primary, secondary, or tertiary amines and used as anion exchangers.

[0006] When chloromethylated vinylaromatic polymers are reacted with ammonia, primary or secondary amines, exchangers with a lower exchange capacity than theoretically expected are obtained, since the amine reacts several times with the chloromethylated groups and produces undesirable secondary crosslinking.

[0007] DD-A 79152 describes the reaction of a chloromethylated vinylaromatic polymer with hexamethylenetetramine to form an aminomethylated vinylaromatic polymer. The disadvantage of this process is that only a small portion of the nitrogen is bound to the polymer.

[0008] Another process for producing anion exchangers with primary amine functionalities is known from EP-B 1078688. Here, the vinylaromatic polymer is amidomethylated with a bis(phthalimidomethyl) ether and then hydrolyzed. The bis(phthalimidomethyl) ether is typically first prepared from phthalimide and formaldehyde in the presence of sulfuric acid, and then the vinylaromatic polymer is added. After amidomethylation, the anion exchanger with primary amine functionalities is produced from the amidomethylated polymer by hydrolysis with acids or bases. This anion exchanger can be further converted by functionalization with alkylating agents to produce strong, weak, and mixed-base anion exchangers with secondary, tertiary, and quaternary amine functionalities.

[0009] This process also has disadvantages, as it produces unstable intermediates that complicate the reaction process, and also byproducts that require complex processing or disposal. JP-A 51005392 and JP-A 51034295 disclose processes for the preparation of anion exchangers. The acylaminomethylated vinylaromatic polymer is prepared by reacting the vinylaromatic polymer with organic nitriles and formaldehyde in a Friedel-Crafts-analogous, catalyzed alkylation at the phenyl ring, and the anion exchanger is obtained by hydrolysis.

[0010] This process also produces unstable intermediates that complicate the reaction and produce large amounts of environmentally harmful solvents.

[0011] There was therefore still a need for a process that could overcome the disadvantages of the state of the art and produce anion exchangers in high yield.

[0012] It has now surprisingly been found that chloromethylated vinylaromatic polymers can be converted into anion exchangers in good yield by reaction with a nitrile in the presence of a metal-containing catalyst and subsequent hydrolysis.

[0013] The present invention therefore relates to a process for the preparation of anion exchangers of the formula (I) where WWW represents a vinylaromatic polymer residue, characterized in that in a step a) chloromethylated, vinylaromatic polymer of the formula (II) ifi \ = / / \ CD CI where W has the meaning given above, with at least one nitrile of the formula

[0014] (III) R 1 CN (III) where R 1= straight-chain, cyclic or branched C1-C8-alkyl, phenyl or benzyl, and the phenyl and benzyl may be substituted by at least one straight-chain, cyclic or branched C1-C8-alkyl radical, in the presence of a metal-containing catalyst to give an amidomethylated, vinylaromatic polymer of the formula (IV) is implemented and R 1 has the meaning given above and the amidomethylated, vinylaromatic polymer of formula (IV) is hydrolyzed in a step b) by reaction with an acid or base to give the anion exchanger of formula (I).

[0015] The scope of the invention includes all the radical definitions, parameters and explanations listed above and below, whether general or in preferred ranges, among each other, and therefore also between the respective ranges and preferred ranges in any combination.

[0016] Preferred is R 1a straight-chain or branched CrC4-alkyl. R is particularly preferably 1 = Methyl, ethyl, n-propyl or isopropyl. R is most preferably 1 = Methyl.

[0017] If R 1 = phenyl or benzyl, then it is preferably unsubstituted. If phenyl and benzyl are substituted, then it is preferably substituted by a straight-chain, cyclic, or branched C-Cs-alkyl radical.

[0018] In the context of the invention, C-C8-alkyl represents a straight-chain, cyclic, or branched alkyl radical having 1 to 8 (C-C8) carbon atoms, even more preferably having 1 to 4 (C1-C4) carbon atoms. Preferably, C-C8-alkyl represents methyl, ethyl, n-propyl, isopropyl, n-, i-, s-, or t-butyl, cyclopropyl, cyclobutyl, cyclopentyl, n-hexyl, cyclohexyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, or 3-methylbutyl. Particularly preferably, C-C8-alkyl or C-C4-alkyl represents ethyl, methyl, n-propyl, or isopropyl.

[0019] Chloromethylated, vinylaromatic polymers of formula (II) used are preferably copolymers of at least one monovinylaromatic monomer selected from the group consisting of styrene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene, or chloromethylstyrene, and mixtures of at least one of these monomers with at least one polyvinylaromatic compound (crosslinker) selected from the group consisting of divinylbenzene, divinyltoluene, trivinylbenzene, triallyl isocyanurate, divinylnaphthalene, and / or trivinylnaphthalene, or mixtures of these polyvinylaromatic compounds. A styrene copolymer, even more preferably a styrene-divinylbenzene copolymer, is particularly preferably used as the chloromethylated, vinylaromatic polymer of formula (II). A styrene-divinylbenzene copolymer is a copolymer crosslinked by the use of divinylbenzene. The chloromethylated, vinylaromatic polymer of formula (II) preferably has a spherical shape.

[0020] In the chloromethylated vinylaromatic polymer in formula (II), a -CH2-CI is bonded to a phenyl residue.

[0021] The chloromethylated vinylaromatic polymers of formula (II) used according to the invention preferably have a macroporous structure.

[0022] The terms "microporous," "gel-like," or "macroporous" have already been described in detail in the specialist literature, for example in Seidl, Malinsky, Dusek, Heitz, Adv. Polymer Sei., 1967, Vol. 5, pp. 113 to 213. Possible measurement methods for macroporosity, such as mercury porosimetry and BET determination, are also described there. Generally and preferably, the pores of the macroporous polymers of the chloromethylated, vinylaromatic polymers of formula (II) used according to the invention have an average diameter of 20 nm to 100 nm. The pore diameter is preferably determined using mercury porosimetry.

[0023] The chloromethylated vinylaromatic polymers of formula (II) used according to the invention preferably have a monodisperse distribution.

[0024] In the present application, substances are referred to as monodisperse if at least 90% by volume or mass of the particles have a diameter which lies in the interval with a width of + / - 10% of the most common diameter around the most common diameter.

[0025] For example, for a substance with a most common diameter of 0.5 mm, at least 90 volume or mass% lies in a size interval between 0.45 mm and 0.55 mm, for a substance with a most common diameter of 0.7 mm, at least 90 volume or mass% lies in a size interval between 0.77 mm and 0.63 mm.

[0026] The chloromethylated vinylaromatic polymer of formula (II) preferably has a diameter of 200 to 1500 pm.

[0027] The chloromethylated vinylaromatic polymer of formula (II) preferably has a spherical shape. The chloromethylated vinylaromatic polymer of formula (II) preferably contains 88 mol% to 98 mol% of monovinylaromatic monomers, based on the total amount of the polymer. The chloromethylated vinylaromatic polymer of formula (II) preferably contains 2 mol% to 12 mol% of polyvinylaromatic monomers, based on the total amount of the polymer.

[0028] The anion exchanger of formula (I) preferably has a diameter of 200 to 1500 pm.

[0029] The anion exchanger of formula (I) preferably has a macroporous structure.

[0030] The anion exchanger of formula (I) preferably has a monodisperse distribution.

[0031] The anion exchanger of formula (I) preferably contains 88 mol.% to 98 mol.% of monovinylaromatic monomers based on the total amount of the polymer.

[0032] The anion exchanger of formula (I) preferably contains 2 mol.% to 12 mol.% of polyvinylaromatic monomers based on the total amount of the polymer.

[0033] The preparation of the chloromethylated, vinylaromatic polymers of formula (II) used in step a) is preferably carried out by reacting, in a step 1a), la) monomer droplets of at least one monovinylaromatic compound and at least one polyvinylaromatic compound and at least one initiator, and lb) the polymer from step 1a) is chloromethylated.

[0034] In step 1a), at least one monovinylaromatic compound and at least one polyvinylaromatic compound are used. However, it is also possible to use mixtures of two or more monovinylaromatic compounds and mixtures of two or more polyvinylaromatic compounds.

[0035] As monovinylaromatic compounds within the meaning of the present invention, styrene, vinyltoluene, ethylstyrene, a-methylstyrene, chlorostyrene or chloromethylstyrene are preferably used in step 1a).

[0036] The monovinylaromatic compounds are preferably used in amounts of > 50 wt.%, based on the monomer or its mixture with other monomers, particularly preferably between 55 wt.% and 70 wt.%, based on the monomer or its mixture with other monomers.

[0037] Particular preference is given to using styrene or mixtures of styrene with the aforementioned monomers, preferably with ethylstyrene.

[0038] Preferred polyvinylaromatic compounds for the purposes of the present invention for step 1a) are divinylbenzene, divinyltoluene, trivinylbenzene, triallyl isocyanurate, divinylnaphthalene or trivinylnaphthalene, particularly preferably divinylbenzene.

[0039] The polyvinylaromatic compounds are preferably used in amounts of 1-20 wt.%, particularly preferably 2-12 wt.%, and especially preferably 4-10 wt.%, based on the monomer or its mixture with other monomers. The type of polyvinylaromatic compounds (crosslinkers) is selected with regard to the subsequent use of the polymer. If divinylbenzene is used, commercial grades of divinylbenzene containing ethylvinylbenzene in addition to the isomers of divinylbenzene are sufficient.

[0040] The formation of macroporous, vinylaromatic polymers is preferably achieved by adding inert materials, preferably at least one porogen, to the monomer mixture during polymerization to create a macroporous structure in the polymer. Particularly preferred porogens are hexane, octane, isooctane, isododecane, pentamethylheptane, methyl ethyl ketone, butanol, or octanol, and their isomers. Organic substances that dissolve in the monomer but poorly dissolve or swell the polymer (precipitants for polymers), for example, aliphatic hydrocarbons (Farbenfabriken Bayer DBP 1045102, 1957; DBP 1113570, 1957), are particularly suitable.

[0041] In US-B 4382124, alcohols having 4 to 10 carbon atoms, which are also preferred in the present invention, are used as porogens for the preparation of macroporous vinylaromatic polymers based on styrene / divinylbenzene. Furthermore, an overview of the preparation methods for macroporous vinylaromatic polymers is provided.

[0042] Porogens are preferably used in an amount of 25 wt.% to 45 wt.% based on the amount of the organic phase.

[0043] Preferably, at least one porogen is added in step 1a).

[0044] The vinylaromatic polymers prepared according to step 1a) can be prepared in heterodisperse or monodisperse form. Heterodisperse vinylaromatic polymers are prepared by general processes known to those skilled in the art, e.g., by suspension polymerization.

[0045] Preferably, monodisperse vinylaromatic polymers are prepared in step 1a).

[0046] In a preferred embodiment of the present invention, microencapsulated monomer droplets are used in step 1a) in the production of monodisperse, vinylaromatic polymers.

[0047] Materials known for use as complex coacervates, in particular polyesters, natural and synthetic polyamides, polyurethanes or polyureas, can be used for the microencapsulation of the monomer droplets.

[0048] Gelatin is preferably used as the natural polyamide. This is used in particular as a coacervate and complex coacervate. Gelatin-containing complex coacervates within the meaning of the invention are primarily understood to mean combinations of gelatin with synthetic polyelectrolytes. Suitable synthetic polyelectrolytes are copolymers with incorporated units of, for example, maleic acid, acrylic acid, methacrylic acid, acrylamide, and methacrylamide. Acrylic acid and acrylamide are particularly preferred. Gelatin-containing capsules can be hardened with conventional hardening agents, such as formaldehyde or glutaraldehyde. The encapsulation of monomer droplets with gelatin, gelatin-containing coacervates, and gelatin-containing complex coacervates is described in detail in EP-A 0 046 535. Methods of encapsulation with synthetic polymers are known.Preference is given to interfacial condensation, in which a reactive component dissolved in the monomer droplet (in particular an isocyanate or an acid chloride) is reacted with a second reactive component dissolved in the aqueous phase (in particular an amine).

[0049] The heterodisperse or optionally microencapsulated, monodisperse monomer droplets contain at least one initiator or mixtures of initiators (initiator combination) to initiate the polymerization. Preferred initiators for the process according to the invention are peroxy compounds, particularly preferably dibenzoyl peroxide, dilauroyl peroxide, bis(p-chlorobenzoyl)peroxide,

[0050] Dicyclohexyl peroxydicarbonate, tert-butyl peroctoate, tert-butylperoxy-2-ethyl-hexanoate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane or tert-amylperoxy-2-ethylhexane, as well as azo compounds such as 2,2 ' -Azobis(isobutyronitrile) or 2,2 '-Azobis(2-methylisobutyronitrile).

[0051] The initiators are preferably used in amounts of 0.05 to 2.5 wt.%, particularly preferably 0.1 to 1.5 wt.%, based on the monomer mixture. The optionally monodisperse, microencapsulated monomer droplet may optionally also contain up to 30 wt.% (based on the monomer) of crosslinked or uncrosslinked polymer. Preferred polymers are derived from the aforementioned monomers, particularly preferably from styrene.

[0052] In the preparation of monodisperse, vinylaromatic polymers in step 1a), in a further preferred embodiment, the aqueous phase may contain a dissolved polymerization inhibitor. Both inorganic and organic substances are suitable as inhibitors in this case. Preferred inorganic inhibitors are nitrogen compounds, particularly preferably hydroxylamine, hydrazine, sodium nitrite and potassium nitrite, salts of phosphorous acid such as sodium hydrogen phosphite, and sulfur-containing compounds such as sodium dithionite, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium thiocyanate, and ammonium thiocyanate. Examples of organic inhibitors are phenolic compounds such as hydroquinone, hydroquinone monomethyl ether, resorcinol, catechol, tert-butylcatechol, pyrogallol, and condensation products of phenols with aldehydes. Further preferred organic inhibitors are nitrogen-containing compounds.Particularly preferred are hydroxylamine derivatives such as N,N-diethylhydroxylamine, N-isopropylhydroxylamine, and sulfonated or carboxylated N-alkylhydroxylamine or N,N-dialkylhydroxylamine derivatives; hydrazine derivatives such as N,N-hydrazinodiacetic acid; and nitroso compounds such as N-nitrosophenylhydroxylamine, N-nitrosophenylhydroxylamine ammonium salt, or N-nitrosophenylhydroxylamine aluminum salt. The concentration of the inhibitor is 5-1000 ppm (based on the aqueous phase), preferably 10-500 ppm, particularly preferably 10-250 ppm.

[0053] The polymerization of the optionally microencapsulated, monodisperse monomer droplets to form the monodisperse, vinylaromatic polymer preferably takes place in the presence of one or more protective colloids in the aqueous phase. Suitable protective colloids are natural or synthetic water-soluble polymers, preferably gelatin, starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, or copolymers of (meth)acrylic acid and (meth)acrylic acid esters. Cellulose derivatives, in particular cellulose esters and cellulose ethers, such as carboxymethylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, and hydroxyethylcellulose, are also preferred. Gelatin is particularly preferred. The amount of protective colloids used is generally 0.05 to 1% by weight, based on the aqueous phase, preferably 0.05 to 0.5% by weight.

[0054] In an alternative preferred embodiment, the polymerization to form the monodisperse, vinylaromatic polymer can be carried out in the presence of a buffer system. Buffer systems that adjust the pH of the aqueous phase at the start of polymerization to a value between 14 and 6, preferably between 12 and 8, are preferred. Under these conditions, protective colloids containing carboxylic acid groups are present entirely or partially as salts. This favorably influences the effect of the protective colloids. Particularly suitable buffer systems contain phosphate or borate salts. The terms phosphate and borate within the meaning of the invention also encompass the condensation products of the ortho forms of corresponding acids and salts. The concentration of the phosphate or borate in the aqueous phase is preferably 0.5–500 mmol / l, particularly preferably 2.5–100 mmol / l.

[0055] The stirring speed during polymerization to form the monodisperse, vinylaromatic polymer is less critical and, unlike conventional polymerization, has no influence on the particle size. Low stirring speeds are used, which are sufficient to keep the suspended monomer droplets in suspension and to assist in the dissipation of the polymerization heat. Various stirrer types can be used for this task. Lattice stirrers with axial action are particularly suitable.

[0056] The volume ratio of encapsulated monomer droplets to aqueous phase is preferably 1:0.75 to 1:20, particularly preferably 1:1 to 1:6.

[0057] The polymerization temperature to form the monodisperse, vinylaromatic polymer depends on the decomposition temperature of the initiator used. It is preferably between 50 and 180°C, particularly preferably between 55 and 130°C. The polymerization preferably lasts from 0.5 to about 20 hours. It has proven advantageous to use a temperature program in which the polymerization begins at a low temperature, preferably 60°C, and the reaction temperature is increased as the polymerization conversion progresses. In this way, the requirement for a reliable reaction and a high polymerization conversion can be very well met. After polymerization, the monodisperse, vinylaromatic polymer is isolated using conventional methods, for example by filtration or decantation, and washed if necessary.

[0058] The preparation of monodisperse, vinylaromatic polymers using the jetting principle or the seed-feed principle is known from the prior art and is described, for example, in US-A 4444 961, EP-A 0 046 535, US 4419245 or WO 93 / 12167.

[0059] The monodisperse, vinylaromatic polymers are preferably produced using the jetting principle or the seed-feed principle. Preferably, a macroporous, monodisperse, vinylaromatic polymer is produced in step 1a).

[0060] In step 1b) the vinylaromatic polymer is converted into the chloromethylated vinylaromatic polymer of formula (II) where WWW is a vinyl aromatic polymer, by chloromethylation.

[0061] In step 1b), chloromethyl methyl ether is preferably used as the chloromethylating agent. The chloromethyl methyl ether can be used in unpurified form, and may contain, for example, methylal and methanol as secondary components. The chloromethyl methyl ether is preferably used in excess in step 1b). The chloromethylation reaction is catalyzed by the addition of a Lewis acid. Suitable Lewis acids are preferably iron(III) chloride, zinc chloride, tin(IV) chloride, and aluminum chloride. The reaction temperature in step 1b) is preferably in the range from 40 to 80°C. In a preferred embodiment, step 1b) is carried out at atmospheric pressure and at a temperature of 50 to 60°C. During the reaction, the volatile constituents, such as preferably hydrochloric acid, methanol, methylal, formaldehyde, and partly chloromethyl methyl ether, are removed, preferably by evaporation.To remove the residual chloromethyl methyl ether and to purify the chloromethylate, washing is preferably carried out with a mixture of methylal, methanol and water.

[0062] Preferably, in step 1b), a macroporous, chloromethylated, vinylaromatic polymer of formula (II) is prepared.

[0063] The chloromethylated vinylaromatic polymer of formula (II) prepared in step 1b) is preferably used as starting material in step a).

[0064] In step a), acetonitrile, propionitrile, butyronitrile, isovaleryl nitriles, benzonitrile, o-methylbenzonitrile, m-methylbenzonitrile, p-methylbenzonitrile, and phenylacetonitrile are preferably used as nitriles of formula (III). Acetonitrile is very particularly preferably used as the nitrile of formula (III). In step a), inorganic or organic metal(II), metal(III), or metal(IV) salts or mixtures of such salts are preferably used as metal-containing catalysts. Preferably, iron(II) salts, iron(III) salts, zinc(II) salts, tin(II) salts, or tin(IV) salts, and mixtures of these compounds are used as metal-containing catalysts.Particularly preferred metal-containing catalysts are iron(II) chloride, iron(II) bromide, iron(II) nitrate, iron(II) sulfate, iron(II) perchlorate, iron(II) phosphate, iron(II) acetate, iron(III) chloride, iron(III) bromide, iron(III) nitrate, iron(III) sulfate, iron(III) perchlorate, iron(III) phosphate, iron(III) acetate, zinc(II) chloride, zinc(II) bromide, zinc(II) nitrate, zinc(II) sulfate, zinc(II) perchlorate, zinc(II) phosphate, zinc(II) acetate, tin(II) chloride, tin(II) bromide, tin(II) nitrate, tin(II) sulfate, tin(II) perchlorate, tin(II) phosphate, tin(II) acetate, tin(IV) chloride, tin(IV) bromide, tin(IV) nitrate, tin(IV) sulfate, tin(IV) perchlorate, tin(IV) phosphate or Tin(IV) acetate or mixtures of these salts are used. Zinc(II) perchlorate, zinc(II) chloride, and iron(III) chloride, as well as their hydrates, are particularly preferred as metal-containing catalysts.Zinc(II) perchlorate, in particular the hexahydrate, is particularly preferably used as a metal-containing catalyst.

[0065] In step a), the nitriles of formula (III) are preferably used in a ratio of 100:1 to 1:1, particularly preferably in a ratio of 50:1 to 1:1, based on the molar amount of chlorine in the chloromethylated, vinylaromatic polymer of formula (II) used.

[0066] In step a), the metal-containing catalyst is preferably used in a ratio of 1:100 to 1:1, particularly preferably in a ratio of 1:50 to 1:0.5, based on the molar amount of chlorine in the chloromethylated, vinylaromatic polymer of the formula (II) used.

[0067] Step a) of the process according to the invention can be carried out in the presence or absence of polar or non-polar, inert solvents. Preferably, step a) of the process according to the invention is carried out in the absence of solvents. Polar, inert solvents used are preferably water or alcohols, such as methanol, ethanol, propanol, or butanol, or mixtures of these polar, inert solvents.

[0068] Halogenated, aliphatic or aromatic hydrocarbons, such as dichloromethane, dichloroethane, dibromomethane, trichloromethane, carbon tetrachloride or benzotrifluoride or mixtures of these solvents, are preferably used as non-polar, inert solvents. In a preferred embodiment of the invention, the chloromethylated, vinylaromatic polymers of the formula (II) are initially introduced and then reacted with the nitrile of the formula

[0069] (III) and the metal-containing catalyst. The mixture is then heated to the reaction temperature.

[0070] The reaction temperature in step a) is preferably between 60 and 140°C, more preferably between 70 and 110°C.

[0071] In step a) the pressure is preferably in a range of 0.8 to 3 bar.

[0072] The reaction is preferably completed within 1 to 24 hours, more preferably within 4 to 12 hours.

[0073] The processing is carried out according to processes known to the person skilled in the art for the processing of corresponding process products, such as, for example, by neutralization and filtration of the resulting amidomethylated, vinylaromatic polymers of the formula

[0074] (IV).

[0075] The hydrolysis of the amidomethyl group and thus the exposure of the aminomethyl group takes place in step b) by treatment with at least one base or at least one acid. Alkali metal hydroxides, alkaline earth metal hydroxides, ammonia, or hydrazine are preferably used as bases in step b) for the hydrolysis of the amidomethylated, vinylaromatic polymers of formula (IV). Nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, sulfurous acid, or nitrous acid are preferably used as acids in step b). Preferably, at least one base is used in step b) to hydrolyze the amidomethyl group and thus to expose the aminomethyl group.

[0076] The hydrolysis of the amidomethyl group in step b) preferably takes place at a temperature of 80°C to 250°C, preferably from 80°C to 190°C if an acid is used for the hydrolysis. The concentration of the acid in step b) is preferably in the range of 5 wt.% to 90 wt.%, particularly preferably between 10 wt.% and 70 wt.%, based on the aqueous phase.

[0077] Particularly preferably, the hydrolysis of the amidomethyl group and thus the exposure of the aminomethyl group in step b) is carried out by treating the amidomethylated, vinylaromatic polymer of formula (IV) with aqueous or alcoholic solutions of an alkali hydroxide, such as preferably sodium hydroxide or potassium hydroxide, at temperatures of 80°C and 250°C, preferably from 120°C to 190°C. The concentration of the sodium hydroxide solution is preferably 20 wt.% to 60 wt.% based on the aqueous phase.

[0078] The hydrolysis of the amidomethyl group to the aminomethyl group in step b) is preferably carried out in an excess of acid and / or base relative to the amount of amidomethyl groups used.

[0079] The anion exchanger of formula (I) produced in step b) is generally washed with demineralized water until neutral. However, it can also be used without post-treatment.

[0080] The anion exchangers of formula (I) can be further functionalized by known processes by reaction with alkylating agents into secondary, tertiary and quaternary amine group-containing anion exchangers and chelate resins.

[0081] The process according to the invention allows the production of anion exchangers in large quantities.

[0082] Determination of the amount of basic groups

[0083] 100 ml of the aminomethylated polymer is shaken on a tamping volumeter and then rinsed into a glass column with deionized water. 1000 ml of 2 wt.% sodium hydroxide solution is filtered over it over a period of 1 hour and 40 minutes. Deionized water is then filtered over it until 100 ml of eluate, mixed with phenolphthalein, requires a maximum consumption of 0.1 N (0.1 normal) hydrochloric acid of 0.05 ml.

[0084] In a beaker, 50 ml of this resin is mixed with 50 ml of deionized water and 100 ml of 1 N hydrochloric acid. The suspension is stirred for 30 minutes and then poured into a glass column. The liquid is drained off. Another 100 ml of 1 N hydrochloric acid is filtered through the resin over 20 minutes. Subsequently, 200 ml of methanol is filtered through. All eluates are collected and combined, and titrated against methyl orange with 1 N sodium hydroxide solution.

[0085] The amount of aminomethyl groups in 1 liter of aminomethylated resin is calculated using the following formula: ( 200 - V ) 20 = mol of aminomethyl groups per liter of resin, where V is the volume of 1 N sodium hydroxide solution used in the titration.

[0086] The amount of basic groups corresponds to the molar amount of aminomethyl groups in the resin.

[0087] Determination of the amount of chloromethylated groups The amount of chloromethylated groups is calculated by determining the chlorine content of the dried resin by elemental analysis.

[0088] Examples

[0089] Example 1 la) Preparation of the monodisperse, macroporous polymer based on styrene, divinylbenzene and ethylstyrene

[0090] In a 10-liter glass reactor, 3000 g of deionized water are placed. A solution of 10 g of gelatin, 16 g of disodium hydrogen phosphate dodecahydrate, and 0.73 g of resorcinol in 320 g of deionized water is added and mixed thoroughly. The mixture is heated to 25°C. A mixture of 3200 g of microencapsulated monomer droplets with a narrow particle size distribution of 3.1 wt% divinylbenzene and 0.6 wt% ethylstyrene (used as a commercially available isomer mixture of divinylbenzene and ethylstyrene with 80% divinylbenzene), 0.4 wt% dibenzoyl peroxide, 58.4 wt% styrene and 37.5 wt% isododecane (technical isomer mixture with a high proportion of pentamethylheptane) is then added while stirring, whereby the microcapsule consists of a formaldehyde-hardened complex coacervate of gelatin and a copolymer of acrylamide and acrylic acid, and 3200 g of aqueous phase with a pH of 12 is added.

[0091] The mixture is polymerized with stirring by increasing the temperature according to a temperature program starting at 25°C and ending at 95°C. The mixture is cooled, washed through a 32 pm sieve, and then dried in vacuum at 80°C.

[0092] This yields 1893 g of a polymer with a monodisperse particle size distribution. The average pore diameter in the polymer is 42 nm. lb) Chloromethylation of the monodisperse, macroporous polymer from 1a)

[0093] 1120 ml of a mixture of monochlorodimethyl ether, methylal, and iron(III) chloride (14.8 g / l) were placed in a 2-liter sulfonation flask, and then 240 g of bead polymer from 1a) were added. The mixture was heated to 50 °C and stirred under reflux at 50-55 °C for 6 h. During the reaction time, hydrochloric acid and low-boiling organics were stripped off or distilled off. The reaction suspension was then thoroughly washed successively with 1200 ml of methanol, 2400 ml of methylal, three times with 1200 ml of methanol, and finally with deionized water. This yielded 590 ml of water-moist, monodisperse, macroporous, chloromethylated polymer with a chlorine content of 21.9 wt. %. Example 2

[0094] Reaction of the chloromethylated, vinylaromatic polymer from Example 1b) with acetonitrile and iron(III) chloride to give the amidomethylated, vinylaromatic polymer of formula (IV)

[0095] 21 g of water-moist chloromethylate (0.13 mol CI) from Example 1b) are placed in a round-bottom flask and washed twice with 100 ml of acetonitrile each time. 150 ml of acetonitrile (2.8 mol) and 35.1 g of iron(III) chloride hexahydrate (0.13 mol) are then added to the beads. The mixture is heated under reflux for 6 hours, then cooled and treated with 150 ml of 7 wt% aqueous hydrochloric acid at room temperature. The beads are separated from the reaction solution by filtration and washed three times with 200 ml of deionized water each time.

[0096] Yield: 64 ml resin

[0097] Nitrogen content: 5.5 wt.% (dried resin)

[0098] Example 3

[0099] Reaction of the chloromethylated, vinylaromatic polymer from Example 1b) with acetonitrile and zinc(II) chloride to give the amidomethylated, vinylaromatic polymer of formula (IV)

[0100] 21 g of water-moist chloromethylate (0.13 mol CI) from Example 1b) are placed in a round-bottom flask and washed twice with 100 ml of acetonitrile each time. 150 ml of acetonitrile (2.8 mol) and 8.9 g of zinc(II) chloride (0.07 mol) are then added to the beads. The mixture is heated under reflux for 6 hours, then cooled and treated with 150 ml of 7 wt% aqueous hydrochloric acid at room temperature. The beads are separated from the reaction solution by filtration and washed three times with 200 ml of deionized water each time.

[0101] Yield: 61 ml resin

[0102] Nitrogen content: 4.6 wt.% (dried resin)

[0103] Example 4

[0104] Reaction of the chloromethylated vinylaromatic polymer from Example 1b) with acetonitrile and zinc(II) perchlorate hexahydrate to give the anion exchanger of the formula

[0105] (I) a) 165.8 g of water-moist chloromethylate (1.085 mol CI) from Example 1b) are placed in a round-bottom flask and washed twice with 500 ml of acetonitrile each time. 1200 ml of acetonitrile (22.4 mol) and 201.1 g of zinc(II) perchlorate hexahydrate (0.54 mol) are then added to the beads. The mixture is heated under reflux for 20 hours, then cooled and treated with 1200 ml of 7 wt% aqueous hydrochloric acid at room temperature. The beads are separated from the reaction solution by filtration and washed three times with 200 ml of deionized water each time.

[0106] Yield: 548 ml resin

[0107] Nitrogen content: 7.0 wt. % (dried resin) b) Hydrolysis of the amidomethylated vinylaromatic polymer from Example 4a)

[0108] 103.2 g of 50 wt.% sodium hydroxide solution and 232 ml of deionized water are added at room temperature to 250 ml of amidomethylated polymer from Example 4a). The suspension is heated to 180°C over 2 hours and stirred at this temperature for 8 hours. The resulting polymer is washed with deionized water.

[0109] Yield of aminomethylated polymer: 188 ml

[0110] Determination of the amount of basic groups: 2.17 mol / liter resin

[0111] Example 5

[0112] Reaction of the chloromethylated bead polymer from Example 1b) with benzonitrile and zinc(II) chloride to give the amidomethylated vinylaromatic polymer of formula (IV)

[0113] 17 g of water-moist chloromethylate (0.11 mol CI) from Example 1b are placed in a round-bottom flask and washed twice with 50 ml of benzonitrile each time. 120 ml of benzonitrile (1.15 mol) and 7.2 g of zinc(II) chloride (0.05 mol) are then added to the beads. The mixture is heated to 80°C for 6 hours, then cooled and treated with 120 ml of 7 wt% aqueous hydrochloric acid at room temperature. The beads are separated from the reaction solution by filtration and washed three times with 200 ml of acetone each time and three times with 200 ml of deionized water each time.

[0114] Yield: 50 ml resin

[0115] Nitrogen content: 3.5 wt.% (dried resin)

Claims

1. A method for producing an anion exchange resin of formula (I) , Where is a residue of a vinyl aromatic polymer, characterized in that in step a) a chloromethylated vinyl aromatic polymer of formula (II) , Where has the above meaning, is reacted with at least one nitrile of formula (III) , in which R 1 is an unbranched, cyclic or branched C1-C8 alkyl, phenyl or benzyl, and phenyl and benzyl may be substituted by at least one unbranched, cyclic or branched C1-C8 alkyl residue, in the presence of a metal-containing catalyst to form an amidomethylated vinyl aromatic polymer of formula (IV) , where R 1 has the above meaning, the amidomethylated vinyl aromatic polymer of formula (IV) is hydrolyzed in step b) by reaction with an acid or base to obtain an anion exchange resin of formula (I).

2. The method according to paragraph 1, characterized in that in formula (III) R 1 is an unbranched or branched C1-C4 alkyl.

3. The method according to claim 1, characterized in that acetonitrile is used as the nitrile of formula (III).

4. The method according to claim 1, characterized in that inorganic or organic salts of metal (II), metal (III) or metal (IV) or mixtures of such salts are used as metal-containing catalysts.

5. The method according to claim 1, characterized in that iron (II) salts, iron (III) salts, zinc (II) salts, tin (II) salts or tin (IV) salts and mixtures of these compounds are used as metal-containing catalysts.

6. The method according to claim 1, characterized in that zinc (II) perchlorate, zinc (II) chloride and iron (III) chloride and their hydrates or mixtures of these compounds are used as metal-containing catalysts.

7. The method according to claim 1, characterized in that zinc(II) perchlorate is used as the metal-containing catalyst.

8. The method according to claim 1, characterized in that a chloromethylated styrene copolymer is used as the chloromethylated vinyl aromatic polymer of formula (II).

9. The method according to claim 8, characterized in that a chloromethylated copolymer of styrene and divinylbenzene of formula (II) is used as the chloromethylated vinylaromatic polymer.

10. The method according to claim 1, characterized in that in stage a), nitriles of formula (III) are used in a ratio of 100:1 to 1:1, based on the molar amount of chlorine in the chloromethylated vinyl aromatic polymer of formula (II) used.

11. The method according to claim 1, characterized in that in stage a) metal-containing catalysts are used in a ratio of 1:100 to 1:0.5, based on the molar amount of the chloromethylated vinyl aromatic polymer of formula (II) used.

12. The method according to claim 1, characterized in that the chloromethylated vinyl aromatic polymer of formula (II) contains from 88 mol.% to 98 mol.% monovinyl aromatic monomers and from 2 mol.% to 12 mol.% polyvinyl aromatic monomers, based on the total molar amount of polymer.

13. The method according to claim 1, characterized in that the chloromethylated vinyl aromatic polymer of formula (II) used in step a) is obtained by reacting monomer droplets from at least one monovinyl aromatic compound and at least one polyvinyl aromatic compound and at least one initiator in step 1a) and by chloromethylation in step 1b).

14. The method according to paragraph 1, characterized in that the hydrolysis in stage b) is carried out at a temperature from 80°C to 250°C.

15. The method according to one of paragraphs 1-14, characterized in that in stage a) a chloromethylated, macroporous vinyl aromatic polymer of formula (II) is used.