New method for producing anion-exchange resins

Abstract

FIELD: anion exchange resins.SUBSTANCE: method for producing an anion exchange resin of formula (I) is proposed, in which is a residue of a vinyl aromatic polymer in which, in step a) a chloromethylated vinyl aromatic polymer of formula (II), in which has the above-mentioned meaning, is reacted with at least one nitrile of formula R1CN (III), in which R1 is an unbranched, cyclic or branched C1-C8 alkyl, phenyl or benzyl, and phenyl and benzyl can be substituted with at least one unbranched, cyclic or branched C1-C8 alkyl residue, in the presence of a metal-containing catalyst selected from the group of zinc (II) perchlorate, zinc (II) chloride and iron (III) chloride and their hydrates or mixtures of these compounds, to form an amidomethylated vinyl aromatic polymer of formula (IV), in which R1 has the above-mentioned meaning, and the amidomethylated vinyl aromatic polymer of formula (IV) in step b) is hydrolyzed by reaction with an acid or a base to obtain an anion exchange resin of formula (I).EFFECT: production of anion exchange resin with high yield.12 cl, 5 ex

Description

[0001] The present invention relates to a new method for producing anion exchange resins.

[0002] A method for producing anion exchange resins, known, for example, from European Patent EP-B 1000660, involves reacting a chloromethylated vinyl aromatic polymer with ammonia to produce anion exchange resins with primary amine groups. However, a disadvantage of this method is the low yield achieved in this reaction. Therefore, chloromethylated vinyl aromatic polymers are typically reacted with primary, secondary, or tertiary amines and used as anion exchange resins.

[0003] When chloromethylated vinyl aromatic polymer reacts with ammonia, primary or secondary amines, ion exchangers with lower exchange capacity than theoretically expected are obtained because the amine reacts several times with the chloromethylated groups and causes unwanted secondary crosslinking.

[0004] Patent DD-A 79152 describes the reaction of a chloromethylated vinyl aromatic polymer with hexamethylenetetramine to form an aminomethylated vinyl aromatic polymer. The drawback in this case is that only a small portion of the nitrogen is bound to the polymer.

[0005] Another method for producing anion exchange resins with primary amine functional groups is known from European patent EP-B 1 078 688. In this case, a vinyl aromatic polymer is amidomethylated using bis(phthalimidomethyl) ether and then hydrolyzed. Bis(phthalimidomethyl) ether is usually first obtained from phthalimide and formaldehyde in the presence of sulfuric acid, and then the vinyl aromatic polymer is added. After amidomethylation, an anion exchange resin with primary amine functional groups is obtained from the amidomethylated polymer by hydrolysis with acids or bases. Through functionalization with alkylating agents, this anion exchange resin can be further converted into strongly basic, weakly basic, and mixed-base anion exchange resins with secondary, tertiary, and quaternary amino functional groups.

[0006] This method also has disadvantages, as it produces unstable intermediates that make the reaction difficult, and it also produces by-products that must be recycled or disposed of at significant cost.

[0007] From Japanese patents JP-A 51005392 and JP-A 51034295, methods for producing anion exchange resins are known, in which, by reacting a vinyl aromatic polymer with organic nitriles and formaldehyde in a Friedel-Crafts reaction similar to the catalyzed alkylation of the phenyl ring, an acylaminomethylated vinyl aromatic polymer is obtained and, by hydrolysis, an anion exchange resin is obtained.

[0008] This method also produces unstable intermediate products, which makes the reaction difficult and leads to the formation of a large amount of environmentally hazardous solvents.

[0009] In this regard, there was still a need for a method by which the disadvantages of the prior art could be overcome and by which anion exchange resins could be obtained in high yield.

[0010] It was unexpectedly found that chloromethylated vinyl aromatic polymers can be converted in good yield into anion exchange resins by reaction with nitrile in the presence of a metal-containing catalyst and subsequent hydrolysis.

[0011] Therefore, the object of the present invention is a method for producing anion exchange resins of formula (I):

[0012]

[0013] in which is a residue of a vinyl aromatic polymer,

[0014] characterized by the fact that

[0015] in step a) a chloromethylated vinyl aromatic polymer of formula (II)

[0016]

[0017] in which has the above meaning, is reacted with at least one nitrile of formula (III)

[0018]

[0019] 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,

[0020] in the presence of a metal-containing catalyst to form an amidomethylated vinyl aromatic polymer of formula (IV)

[0021]

[0022] in which R 1 has the above meaning, and the amidomethylated vinyl aromatic polymer of formula (IV) in step b) is hydrolyzed by reaction with an acid or base to obtain an anion exchange resin of formula (I).

[0023] The scope of the invention includes all of the above and below, general or specified in preferred ranges, definitions of residues, parameters and refinements in any combination with each other, as well as between the corresponding ranges and the preferred ranges.

[0024] Preferred, R 1 is a linear or branched alkyl residue having 1-6 carbon atoms. Particularly preferred is R 1 is methyl, ethyl, n-propyl, or isopropyl. Most preferably R 1 is methyl.

[0025] In case R 1 If phenyl or benzyl is phenyl or benzyl, it is preferably unsubstituted. If phenyl or benzyl is substituted, it is preferably substituted with an unbranched, cyclic, or branched C1-C8 alkyl residue.

[0026] In the context of the present invention, C1-C8 alkyl is an unbranched, cyclic or branched alkyl residue with 1 to 8 (C1-C8) carbon atoms, even more preferably with 1 to 4 (C1-C4) carbon atoms. Preferably, C1-C8 alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, n-hexyl, cyclohexyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl. Particularly preferably, C1-C6 alkyl or C1-C4 alkyl are ethyl, methyl, n-propyl or isopropyl.

[0027] As chloromethylated vinylaromatic polymers of formula (II), copolymers of at least one monovinylaromatic monomer selected from the group of styrene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene or chloromethylstyrene, and mixtures of at least one of these monomers with at least one polyvinylaromatic compound (crosslinking agents) from the group of divinylbenzene, divinyltoluene, trivinylbenzene, triallyl isocyanurate, divinylnaphthalene and / or trivinylnaphthalene or mixtures of these polyvinylaromatic compounds are preferably used.

[0028] It is particularly preferable to use a styrene copolymer as the chloromethylated vinyl aromatic polymer of formula (II), and even more preferably a styrene-divinylbenzene copolymer. The styrene-divinylbenzene copolymer is a copolymer crosslinked by using divinylbenzene. The chloromethylated vinyl aromatic polymer of formula (II) is preferably spherical.

[0029] In the chloromethylated vinyl aromatic polymer of formula (II), the -CH2-Cl fragment is linked to a phenyl residue.

[0030] The chloromethylated vinyl aromatic polymers of formula (II) used according to the invention preferably have a macroporous structure.

[0031] The terms "microporous" or "gel-like" or "macroporous" respectively have already been described in detail in the specialist literature, for example in Seidl, Malinsky, Dusek, Heitz, Adv. Polymer Sci., 1967, Vol. 5, pp. 113-213. Possible methods for measuring macroporosity are also described there, for example mercury porosimetry and BET determination. Basically and preferably, the pores of the macroporous polymers of the chloromethylated vinyl aromatic polymers of formula (II) used according to the invention have an average diameter of 20 to 100 nm. Preferably, the pore diameter is determined by mercury porosimetry.

[0032] The chloromethylated vinyl aromatic polymers of formula (II) used according to the invention preferably have a monodisperse distribution.

[0033] In accordance with the present invention, monodisperse substances are defined as substances in the form of particles, at least 90% by volume, or 90% by mass, respectively, of which have a diameter deviating from the most probable value by an amount equal to + / - 10%.

[0034] For example, in the case of a substance with a most common diameter of 0.5 mm, at least 90% by volume or mass are in the size range between 0.45 mm and 0.55 mm, in the case of a substance with a most common diameter of 0.7 mm, at least 90% by volume or mass are in the size range between 0.77 mm and 0.63 mm.

[0035] The chloromethylated vinyl aromatic polymer of formula (II) preferably has a diameter of 200 to 1500 μm.

[0036] The chloromethylated vinyl aromatic polymer of formula (II) is preferably in spherical shape.

[0037] Preferably, the chloromethylated vinyl aromatic polymer of formula (II) contains from 88 mol% to 98 mol% of monovinyl aromatic monomers, based on the total amount of the polymer. Preferably, the chloromethylated vinyl aromatic polymer of formula (II) contains from 2 mol% to 12 mol% of polyvinyl aromatic monomers, based on the total molar amount of the polymer.

[0038] The anion exchange resin of formula (I) preferably has a diameter of 200 to 1500 μm.

[0039] Preferably, the anion exchange resin of formula (I) has a macroporous structure.

[0040] Preferably, the anion exchange resin of formula (I) has a monodisperse distribution.

[0041] Preferably, the anion exchange resin of formula (I) contains from 88 mol% to 98 mol% of monovinyl aromatic monomers, based on the total molar amount of the polymer.

[0042] Preferably, the anion exchange resin of formula (I) contains from 2 mol% to 12 mol% of polyvinyl aromatic monomers, based on the total molar amount of the polymer.

[0043] The preparation of the chloromethylated vinyl aromatic polymers of formula (II) used in step a) is preferably carried out so that in step 1a)

[0044] 1a) monomer droplets of at least one monovinyl aromatic compound and at least one polyvinyl aromatic compound and at least one initiator are subjected to interaction and

[0045] 1b) the polymer from step 1a) is chloromethylated.

[0046] In step 1a), at least one monovinyl aromatic compound and at least one polyvinyl aromatic compound are used. Mixtures of two or more monovinyl aromatic compounds and mixtures of two or more polyvinyl aromatic compounds can also be used for this purpose.

[0047] The monovinyl aromatic compounds according to the present invention in step 1a) are preferably styrene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene or chloromethyl styrene.

[0048] Monovinyl aromatic compounds are preferably used in amounts of >50% by weight based on the monomer or its mixture with other monomers, particularly preferably from 55 to 70% by weight based on the monomer or its mixture with other monomers.

[0049] It is particularly preferable to use styrene or mixtures of styrene with the above monomers, preferably with ethyl styrene.

[0050] According to the present invention, divinylbenzene, divinyltoluene, trivinylbenzene, triallyl isocyanurate, divinylnaphthalene or trivinylnaphthalene are preferably used as the polyvinyl aromatic compound in step 1a), particularly preferably divinylbenzene.

[0051] Polyvinyl aromatic compounds are preferably used in amounts of 1 to 20% by weight, particularly preferably 2 to 12% by weight, and even more preferably 4 to 10% by weight, based on the monomer or its mixture with other monomers. The type of polyvinyl aromatic compound (crosslinking agent) is selected based on the subsequent use of the corresponding polymer. When using divinylbenzene, commercially available grades of divinylbenzene, which in addition to divinylbenzene isomers also contain ethylvinylbenzene, are suitable.

[0052] The formation of macroporous vinylaromatic polymers is preferably carried out by adding inert materials, preferably at least one blowing agent, to the monomer mixture during polymerization in order to create a macroporous structure in the polymer. Particularly preferred blowing agents are hexane, octane, isooctane, isododecane, pentamethylheptane, methyl ethyl ketone, butanol or octanol and their isomers. Particularly suitable are organic substances that dissolve in the monomer, but in which the polymer is poorly soluble or, correspondingly, poorly swells (precipitating agents for polymers), for example, aliphatic hydrocarbons (see Farbenfabriken Bayer patents DBP 1045102, 1957, and DBP 1113570, 1957).

[0053] US Patent No. 4,382,124 describes alcohols with 4 to 10 carbon atoms as blowing agents for producing macroporous vinylaromatic polymers based on styrene / divinylbenzene, which are also preferred for use in the present invention. Furthermore, a review of methods for producing macroporous vinylaromatic polymers is provided.

[0054] Foaming agents are preferably used in an amount of 25 to 45% by weight, based on the amount of the organic phase.

[0055] Preferably, at least one foaming agent is added in step 1a).

[0056] The vinyl aromatic polymers obtained according to step 1a) may be in heterodisperse or monodisperse form.

[0057] Heterodisperse vinylaromatic polymers are generally obtained by methods known to those skilled in the art, for example, by suspension polymerization.

[0058] Preferably, in step 1a) monodisperse vinyl aromatic polymers are obtained.

[0059] In one preferred embodiment of the invention, microencapsulated monomer droplets are used in step 1a) to obtain monodisperse vinyl aromatic polymers.

[0060] For microencapsulation of monomer droplets, known materials used as complex coacervates are suitable, in particular polyesters, natural and synthetic polyamides, polyurethanes or polyureas.

[0061] Gelatin is preferably used as the natural polyamide. It can be used, in particular, as a coacervate and complex coacervate. According to the invention, gelatin-containing complex coacervates are primarily combinations of gelatin with synthetic polyelectrolytes. Suitable synthetic polyelectrolytes are copolymers that, for example, contain monomer units of maleic acid, acrylic acid, methacrylic acid, acrylamide, and methacrylamide. Monomer units of acrylic acid and acrylamide are particularly preferred. Gelatin-containing capsules can be cured with conventional hardeners, 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 European patent application EP-A 0 046 535. Methods of encapsulation with synthetic polymers are also known.The preferred method of encapsulation is interfacial condensation, in which a reactive component (particularly an isocyanate or acid chloride) dissolved in monomer droplets reacts with a second reactive component (particularly an amine) dissolved in the aqueous phase.

[0062] For initiating the polymerization, the heterodisperse or optionally microencapsulated monodisperse monomer droplets contain at least one initiator or mixtures of initiators (combinations of initiators). Preferred initiators used to carry out the process according to the invention are peroxy compounds, particularly preferably dibenzoyl peroxide, dilauroyl peroxide, bis(p-chlorobenzoyl peroxide), dicyclohexyl peroxydicarbonate, tert-butyl peroctoate, tert-butyl peroxy-2-ethylhexanoate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane or tert-amylperoxy-2-ethylhexane, as well as azo compounds, for example 2,2'-azobis-(isobutyronitrile) or 2,2'-azobis(2-methylisobutyronitrile).

[0063] The initiators are preferably used in amounts of 0.05 to 2.5% by weight, particularly preferably 0.1 to 1.5% by weight, respectively, based on the monomer mixture.

[0064] If desired, the microencapsulated monomer droplets may also contain up to 30% by weight (based on the monomer) of a cross-linked or non-cross-linked polymer. Preferred polymers are derivatives of the above-mentioned monomers, particularly preferably derivatives of styrene.

[0065] In another preferred embodiment of the invention, in the preparation of monodisperse vinylaromatic polymers in step 1a), the aqueous phase may contain a dissolved polymerization inhibitor. In this case, suitable polymerization inhibitors are both inorganic and organic substances. Preferred inorganic polymerization inhibitors are nitrogen-containing compounds, particularly preferably hydroxylamine, hydrazine, sodium nitrite and potassium nitrite, phosphorous acid salts, such as sodium hydrogen phosphite, as well as sulfur-containing compounds, in particular sodium dithionite, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium thiocyanate and ammonium thiocyanate. Examples of organic inhibitors are phenolic compounds such as hydroquinone, monomethyl ether of hydroquinone, resorcinol, pyrocatechol, tert-butylpyrocatechol, pyrogallol and condensation products of phenols with aldehydes.Other preferred organic polymerization inhibitors are nitrogen-containing compounds. Particularly preferred are hydroxylamine derivatives, such as N,N-diethylhydroxylamine or N-isopropylhydroxylamine, as well as sulfonated or carboxylated derivatives of N-alkylhydroxylamine or NN-dialkylhydroxylamine, hydrazine derivatives, such as N,N-hydrazinodiacetic acid, nitroso compounds, such as N-nitrosophenylhydroxylamine, the ammonium salt of N-nitrosophenylhydroxylamine or the aluminum salt of N-nitrosophenylhydroxylamine. The inhibitor concentration is from 5 to 1000 ppm (based on the aqueous phase), preferably from 10 to 500 ppm, particularly preferably from 10 to 250 ppm.

[0066] The polymerization of optionally microencapsulated monomer droplets to a monodisperse vinylaromatic polymer is preferably carried out 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 with (meth)acrylic acid esters. Preferred protective colloids are also cellulose derivatives, in particular cellulose esters and ethers, such as carboxymethyl cellulose, methyl hydroxyethyl cellulose, methylhydroxypropyl cellulose or hydroxyethyl cellulose. Gelatin is particularly preferred. The amount of protective colloids used is generally from 0.05 to 1% by weight, based on the aqueous phase, preferably from 0.05 to 0.5% by weight.

[0067] In an alternative preferred embodiment, the polymerization to a monodisperse vinylaromatic polymer can be carried out in the presence of a buffer system. Preferred are buffer systems by which the pH of the aqueous phase is adjusted to a range of 14 to 6, preferably 12 to 8, before the start of the polymerization. Under these conditions, the protective colloids with carboxylic acid groups are completely or partially in the form of salts. This favorably influences the action of the protective colloid. Particularly suitable buffer systems contain phosphate or borate salts. According to the invention, phosphates and borates also include condensation products of the ortho-forms of the corresponding acids and salts. The concentration of phosphate or borate in the aqueous phase is preferably from 0.5 to 500 mmol / l, particularly preferably from 2.5 to 100 mmol / l.

[0068] The stirring speed during polymerization to monodisperse vinylaromatic polymer is a non-critical parameter that, unlike conventional polymerization, does not affect particle size. Low stirring speeds are used, sufficient to keep the suspended monomer droplets in suspension and facilitate the removal of the heat of polymerization. Various types of stirrers can be used for this purpose. Axial-impact frame stirrers are particularly suitable.

[0069] The volume ratio of the encapsulated monomer droplets to the aqueous phase is preferably from 1:0.75 to 1:20, more preferably from 1:1 to 1:6.

[0070] The polymerization temperature for producing a monodisperse vinylaromatic polymer is determined by the decomposition temperature of the initiator used for the polymerization. It is preferably between 50 and 180°C, particularly preferably between 55 and 130°C. The polymerization period is preferably between 0.5 and approximately 20 hours. A temperature program has proven effective in which the polymerization begins at a low temperature, preferably 60°C, and the reaction temperature increases with increasing polymerization conversion. This method can very well satisfy, for example, the requirement for reliable reaction progress and high polymerization conversion. After polymerization, the monodisperse vinylaromatic product is isolated by conventional methods, such as filtration or decantation, and washed if necessary.

[0071] The production of monodisperse vinyl aromatic polymers by the jetting principle or the seed-feed principle is known from the prior art and is described, for example, in US patent application US-A 4 444 961, European patent application EP-A 0 046 535, US patent US 4 419 245 or international application WO 93 / 12167.

[0072] The production of monodisperse vinyl aromatic polymers is preferably carried out in accordance with the injection principle or the seeding principle.

[0073] Preferably, in step 1a), a macroporous monodisperse vinyl aromatic polymer is obtained.

[0074] In step 1b), the vinyl aromatic polymer is converted by chloromethylation into a chloromethylated vinyl aromatic polymer of formula (II)

[0075]

[0076] in which is a residue of a vinyl aromatic polymer.

[0077] In step 1b), chloromethyl methyl ether is preferably used as the chloromethylating agent. Chloromethyl methyl ether can be used in crude form, and may contain, for example, methylal and methanol as by-products. 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 of 40 to 80°C. In one preferred embodiment, step 1b) is carried out at normal pressure and at a temperature of 50 to 60°C. During the reaction, volatile components such as preferably hydrochloric acid, methanol, methylal, formaldehyde and partly chloromethyl methyl ether are removed, preferably by evaporation.To remove the remaining chloromethyl methyl ether and to purify the chloromethylate, washing with a mixture of methylal, methanol and water is preferably carried out.

[0078] Preferably, in step 1b) a macroporous chloromethylated vinyl aromatic polymer of formula (II) is obtained.

[0079] The chloromethylated vinyl aromatic polymer of formula (II) obtained in step 1b) is preferably used in step a) as a starting product.

[0080] In step a), acetonitrile, propionitrile, butyronitrile, isovalerylnitrile, benzonitrile, o-methylbenzonitrile, m-methylbenzonitrile, p-methylbenzonitrile, and phenylacetonitrile are preferably used as nitriles of formula (III). Most preferably, acetonitrile is used as the nitrile of formula (III).

[0081] In step a), inorganic or organic salts of metal (II), metal (III), or metal (IV), 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 preferably, the following are used as metal-containing catalysts: 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 nitrate (IV), tin(IV) sulfate, tin(IV) perchlorate, tin(IV) phosphate, or tin(IV) acetate, or mixtures of these salts. Zinc(II) perchlorate, zinc(II) chloride, and iron(III) chloride, and their hydrates, are particularly preferred as metal-containing catalysts.The most preferred metal-containing catalyst is zinc (II) perchlorate, in particular the hexahydrate.

[0082] In step a), 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 vinyl aromatic polymer of formula (II) used.

[0083] 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 vinyl aromatic polymer of formula (II) used.

[0084] 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. Water or alcohols, such as preferably methanol, ethanol, propanol or butanol, or mixtures of these polar inert solvents, are preferably used as polar inert solvents.

[0085] As non-polar inert solvents, halogenated, aliphatic or aromatic hydrocarbons are preferably used, such as preferably dichloromethane, dichloroethane, dibromomethane, trichloromethane, carbon tetrachloride or benzotrifluoride, or mixtures of these solvents.

[0086] In one preferred embodiment of the invention, chloromethylated vinyl aromatic polymers of formula (II) are introduced and then contacted with a nitrile of formula (III) and a metal-containing catalyst. The mixture is then heated to the reaction temperature.

[0087] The reaction temperature in step a) is preferably between 60 and 140°C, preferably between 70 and 110°C.

[0088] In step a), the pressure is preferably in the range of 0.8 to 3 bar.

[0089] The reaction is preferably completed within 1-24 hours, preferably within 4-12 hours.

[0090] The treatment is carried out in accordance with methods known to a person skilled in the art for the treatment of the corresponding process products, such as, for example, neutralization and filtration of the resulting amidomethylated vinyl aromatic polymers of formula (IV).

[0091] The hydrolysis of the amidomethyl group and thus the release of the aminomethyl group is carried out in step b) by treatment with at least one base or at least one acid. Preferably, alkali metal hydroxides, alkaline earth metal hydroxides, ammonia or hydrazine are used as bases in step b) for the hydrolysis of the amidomethylated vinylaromatic polymers of formula (IV). Preferably, nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, sulfurous acid or nitrous acid are used as acids in step b). Preferably, at least one base is used in step b) for the hydrolysis of the amidomethyl group and thus the release of the aminomethyl group.

[0092] Preferably, the hydrolysis of the amidomethyl group in step b) is carried out at a temperature of from 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 from 5% by weight to 90% by weight, particularly preferably between 10% by weight and 70% by weight, based on the aqueous phase.

[0093] The hydrolysis of the amidomethyl group and thus the release of the aminomethyl group in step b) is particularly preferably carried out by treating the amidomethylated vinyl aromatic polymer of formula (IV) with aqueous or alcoholic solutions of an alkali metal hydroxide, such as preferably sodium hydroxide or potassium hydroxide, at a temperature of from 80°C to 250°C, preferably from 120°C to 190°C. The concentration of the sodium hydroxide solution is preferably from 20% by weight to 60% by weight, based on the aqueous phase.

[0094] The hydrolysis of the amidomethyl group to an aminomethyl group in step b) is preferably carried out in an excess of acid and / or base based on the molar amount of amidomethyl groups used.

[0095] The anion exchange resin of formula (I) formed in step b) is typically washed with fully deionized water until the medium reaches neutrality. However, it can also be used without further treatment.

[0096] Anion exchange resins of formula (I) can be further functionalized by known methods by reacting with alkylating agents into anion exchange resins containing secondary, tertiary and quaternary amino groups, as well as chelating resins.

[0097] By means of the method according to the invention, it is possible to produce anion exchange resins in large quantities.

[0098] Determination of the number of alkaline groups

[0099] 100 ml of aminomethylated polymerizate is compacted with shaking on a volumetric compactor and then washed in a glass column with fully deionized water. 1000 ml of a 2% (by weight) aqueous sodium hydroxide solution is filtered through it for 1 hour and 40 minutes. Fully deionized water is then passed through the product until 100 ml of the eluate mixed with phenolphthalein consumes a maximum of 0.05 ml of 0.1 N (0.1 N) hydrochloric acid.

[0100] 50 ml of this resin is mixed in a beaker with 50 ml of fully deionized water and 100 ml of 1 N hydrochloric acid. The suspension is stirred for 30 minutes and then loaded into a glass column. The liquid is decanted. Another 100 ml of 1 N hydrochloric acid is passed through the resin for 20 minutes. Then 200 ml of methanol is passed through the resin. All eluates are collected, combined, and titrated with 1 N sodium hydroxide solution in the presence of methyl orange.

[0101] The amount of aminomethyl groups in 1 liter of aminomethylated resin is calculated by the following formula: (200-V) ⋅ 20=mol of aminomethyl groups per liter of resin, where V means the volume of 1 N sodium hydroxide solution consumed during titration.

[0102] The number of alkaline groups corresponds to the molar amount of aminomethyl groups in the resin.

[0103] Determination of the amount of chloromethylated groups

[0104] The amount of chloromethylated groups is calculated by determining the chlorine content of the dried resin by elemental analysis.

[0105] Examples

[0106] Example 1

[0107] 1a) Obtaining a monodisperse, macroporous polymer based on styrene, divinylbenzene and ethylstyrene

[0108] 3000g of fully deionized water are placed in a 10L glass reactor, and a solution of 10g of gelatin, 16g of disodium hydrogen phosphate dodecahydrate, and 0.73g of resorcinol in 320g of deionized water is added thereto and stirred. The mixture is maintained at a temperature of 25°C. Then, a mixture of 3200g of microencapsulated droplets with a narrow particle size distribution of 3.1% by weight of divinylbenzene and 0.6% by weight of ethylstyrene (used as a commercially available mixture of divinylbenzene and ethylstyrene isomers containing 80% divinylbenzene), 0.4% by weight of dibenzoyl peroxide, 58.4% by weight of styrene, and 37.5% by weight of isododecane (a technical mixture of isomers with a high content of pentamethylheptane), the microcapsule consisting of a complex coacervate of gelatin and a copolymer of acrylamide and acrylic acid, hardened with formaldehyde, and 3200 g of an aqueous phase with a pH of 12 are added.

[0109] The loaded mass is subjected to polymerization while stirring by increasing the temperature according to a temperature program starting at 25°C and ending at 95°C. This loaded mass is cooled, washed on a sieve with a mesh size of 32 µm, and then dried in a vacuum at 80°C.

[0110] 1893 g of polymer with a monodisperse particle size distribution was obtained. The average pore diameter in the polymer was 42 nm.

[0111] 1b) Chloromethylation of monodisperse macroporous polymer from 1a)

[0112] 1120 ml of a mixture of monochlorodimethyl ether, methylal, and iron(III) chloride (14.8 g / l) were placed in a 2-l sulfination flask, and then 240 g of the bead polymer from 1a) was added. The mixture was heated to 50°C and stirred for 6 hours under reflux in the range of 50-55°C. During the reaction, hydrochloric acid and low-boiling organic compounds were separated or distilled off, respectively. The reaction suspension was then intensively washed successively with 1200 ml of methanol, 2400 ml of methylal, three times with 1200 ml of methanol, and finally with fully deionized water. 590 ml of wet, monodisperse, macroporous chloromethylated polymer with a chlorine content of 21.9% by weight were obtained.

[0113] Example 2

[0114] Reaction of the chloromethylated vinylaromatic polymer from Example 1b) with acetonitrile and iron(III) chloride to obtain an amidomethylated vinylaromatic polymer of formula (IV)

[0115] 21 g of wet chloromethylate (0.13 mol Cl) from Example 1b) are placed in a round-bottomed flask and washed twice with 100 ml of acetonitrile each time. Then 150 ml of acetonitrile (2.8 mol) and 35.1 g of iron(III) chloride hexahydrate (0.13 mol) are added to the granules. The mixture is refluxed for 6 hours, then cooled and mixed with 150 ml of a 7% by weight aqueous solution of hydrochloric acid at room temperature. The granules are separated from the reaction solution by filtration and washed three times with 200 ml of deionized water each time.

[0116] Yield: 64ml resin

[0117] Nitrogen content: 5.5% by weight (dried resin)

[0118] Example 3

[0119] Reaction of the chloromethylated vinyl aromatic polymer from Example 1b) with acetonitrile and zinc(II) chloride to obtain an amidomethylated vinyl aromatic polymer of formula (IV)

[0120] 21 g of wet chloromethylate (0.13 mol CI) from Example 1b) are placed in a round-bottomed flask and washed twice with 100 ml of acetonitrile in each case. Then 150 ml of acetonitrile (2.8 mol) and 8.9 g of zinc(II) chloride (0.07 mol) are added to the granules. The mixture is refluxed for 6 hours, then cooled and mixed with 150 ml of a 7% by weight aqueous solution of hydrochloric acid at room temperature. The granules are separated from the reaction solution by filtration and washed three times with 200 ml of deionized water in each case.

[0121] Yield: 61ml resin

[0122] Nitrogen content: 4.6% by weight (dried resin)

[0123] Example 4

[0124] Reaction of the chloromethylated vinyl aromatic polymer from Example 1b) with acetonitrile and zinc(II) perchlorate hexahydrate to obtain an anion exchange resin of formula (I)

[0125] a) 165.8 g of wet chloromethylate (1.085 mol CI) from Example 1b) are placed in a round-bottomed flask and washed twice with 500 ml of acetonitrile each time. Then 1200 ml of acetonitrile (22.4 mol) and 201.1 g of zinc(II) perchlorate hexahydrate (0.54 mol) are added to the granules. The mixture is refluxed for 20 hours, then cooled and mixed with 1200 ml of a 7% by weight aqueous solution of hydrochloric acid at room temperature. The granules are separated from the reaction solution by filtration and washed three times with 200 ml of deionized water each time.

[0126] Yield: 548ml resin

[0127] Nitrogen content: 7.0% by weight (dried resin)

[0128] b) Hydrolysis of the amidomethylated vinyl aromatic polymer from Example 4a)

[0129] To 250 ml of the amidomethylated polymer from Example 4a, 103.2 g of a 50% aqueous sodium hydroxide solution and 232 ml of fully deionized water are added at room temperature. The suspension is heated to 180°C for 2 hours and stirred at this temperature for 8 hours. The resulting polymer is washed with fully deionized water.

[0130] Aminomethylated polymer yield: 188 ml

[0131] Determination of the amount of alkaline groups: 2.17 mol / liter resin

[0132] Example 5

[0133] Reaction of the chloromethylated bead polymer from Example 1b) with benzonitrile and zinc(II) chloride to produce an amidomethylated vinylaromatic polymer of formula (IV)

[0134] 17 g of wet chloromethylate (0.11 mol CI) from Example 1b) are placed in a round-bottomed flask and washed twice with 50 ml of benzonitrile in each case. Then 120 ml of benzonitrile (1.15 mol) and 7.2 g of zinc(II) chloride (0.05 mol) are added to the granules. The mixture is heated to 80°C for 6 hours, then cooled and mixed with 120 ml of a 7% by weight aqueous solution of hydrochloric acid at room temperature. The granules are separated from the reaction solution by filtration and washed three times with acetone (200 ml in each case) and three times with deionized water (200 ml in each case).

[0135] Yield: 50ml resin

[0136] Nitrogen content: 3.5% by weight (dried resin)

Claims

1. A method for producing an anion exchange resin of formula (I) in which is a residue of a vinyl aromatic polymer, characterized in that in step a) a chloromethylated vinyl aromatic polymer of formula (II) in which 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 selected from the group of zinc (II) perchlorate, zinc (II) chloride and iron (III) chloride and their hydrates or mixtures of these compounds, to form an amidomethylated vinyl aromatic polymer of formula (IV) in which R 1 has the meaning specified above, and 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 paragraph 1, characterized in that zinc (II) perchlorate is used as the metal-containing catalyst.

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

6. The method according to paragraph 5, characterized in that a chloromethylated copolymer of styrene and divinylbenzene of formula (II) is used as the chloromethylated vinylaromatic polymer.

7. 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.

8. 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.

9. 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.

10. 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).

11. 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.

12. The method according to one of paragraphs 1-11, characterized in that in stage a) a chloromethylated, macroporous vinyl aromatic polymer of formula (II) is used.

Images