Process for preparation of amidomethylated vinyl aromatic polymers

Abstract

The present invention relates to a process for preparing an amido methylated vinyl aromatic polymer.

Description

Technical Field

[0001] The present invention relates to a method for preparing an amide-methylated vinyl aromatic polymer. Background Art

[0002] The preparation of amide-methylated vinyl aromatic polymers has long been known. DE-A 2211134 discloses that crosslinked styrene bead polymers can be condensed with N-hydroxymethylphthalimide in the presence of a swelling agent and a Friedel-Crafts catalyst. The disadvantages of this method are that N-hydroxymethylphthalimide must first be prepared from phthalimide, water must be distilled off during the reaction, hydrohalic acid must be added, and the yield of the amide-methylated vinyl aromatic polymer is unsatisfactory.

[0003] Another method for preparing amide-methylated vinyl aromatic polymers is known from US-A 4232125, in which phthalimide, paraformaldehyde, and sulfuric acid are reacted in one step in the presence of 1,2-dichloroethane as a swelling agent and a vinyl aromatic bead polymer. Different swelling agents are mentioned as alternatives to 1,2-dichloroethane. Also disadvantageous about this method is that the yield of the amide-methylated vinyl aromatic polymer is unsatisfactory.

[0004] Another one-step method for preparing amide-methylated vinyl aromatic polymers is known from EP-A 3012272, in which the swelling agent used is 1,3-dichloropropane. This swelling agent can only be separated from the product by complex methods industrially and is therefore relatively costly to use. In addition, 1,3-dichloropropane is a suspected carcinogen and is therefore not a suitable swelling agent.

[0005] EP-B 3478727 discloses an amide-methylation method in the presence of trifluorotoluene. In this method, it has been found that hydrofluoric acid is formed, which leads to corrosion of the reactor and is therefore also not a viable method.

[0006] EP-B 3581595 discloses a method in which amide-methylation is carried out in the presence of bromoalkyl derivatives. However, there is currently discussion about the extent to which these compounds also have toxicity that may limit their use.

[0007] Therefore, there is still a need to overcome the disadvantages of the prior art and to have a method for preparing amide-methylated vinyl aromatic polymers with good yields. Summary of the Invention

[0008] It has now surprisingly been found that the reaction of vinyl aromatic polymers with formaldehyde condensate and a protonic acid in the presence of a C1-C5-difluoroalkane yields amide-methylated vinyl aromatic polymers in high yields.

[0009] The present invention thus provides a process for preparing an amide-methylated vinyl aromatic polymer, wherein at least one vinyl aromatic polymer is reacted with at least one compound of the formula (I) or a salt thereof

[0010] (I)

[0011] wherein R1 = -C(H(C1-C6-alkyl))- or -CH2- and R2 = -C(H(C1-C6-alkyl))- or -CH2-, or R1 and R2 are two carbon atoms of an aromatic C6 ring optionally substituted by one or two C1-C6-alkyl groups, or R1 and R2 are each -CH=,

[0012] and at least one formaldehyde condensate in the presence of at least one protonic acid and in the presence of at least one straight-chain or branched C1-C5-difluoroalkane or at least one cyclic C5-difluoroalkane or a mixture of these compounds.

[0013] R1 and R2 preferably combine to form a C1-C6-alkyl-substituted aromatic C6 ring. More preferably, R1 and R2 form a benzene ring optionally substituted by C1-C4-alkyl. The compound of the formula (I) is very particularly preferably phthalimide, succinimide or maleimide. The compound of the formula (I) is even further preferably phthalimide. When phthalimide is used, phthalimide-methylated polymers are prepared according to the invention. The salt of the compound of the formula (I) is preferably understood to be an addition product of an inorganic or organic base and the compound of the formula (I), such as preferably ammonium salts and alkali metal salts or alkaline earth metal salts. Any salt used is more preferably the sodium salt and potassium salt of the compound of the formula (I).

[0014] In the context of the present invention, C1-C6-alkyl and C1-C4-alkyl are straight-chain or branched or cyclic alkyl groups having 1 to 6 or 1 to 4 carbon atoms. For example and preferably, C1-C6-alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, cyclopropyl, n-propyl, 1-methylbutyl.

[0015] For example and preferably, C1-C4-alkyl is methyl, ethyl, n-propyl and isopropyl.

[0016] The C1-C5-difluoroalkanes are preferably C1-C3-difluoroalkanes. The C1-C5-difluoroalkanes are, for example and preferably, difluoromethane, 1,1-difluoroethane, 1,2-difluoroethane, 1,1-difluoropropane, 1,2-difluoropropane, 1,3-difluoropropane, 1,1-difluorobutane, 1,2-difluorobutane, 1,3-difluorobutane, 1,4-difluorobutane, 2,3-difluorobutane, 1,3-difluoro-2-methylpropane, 1,1-difluoropentane, 1,2-difluoropentane, 1,3-difluoropentane, 1,4-difluoropentane, 1,5-difluoropentane, 2,3-difluoropentane, 2,4-difluoropentane and 1,5-difluoropentane or mixtures of these compounds. The cyclic C5-difluoroalkanes are preferably 1,1-difluorocyclopentane and 1,2-difluorocyclopentane. More preferably, the C1-C5-difluoroalkanes are difluoromethane, difluoroethane and difluoropropane. Most preferably, the C1-C5-difluoroalkanes and the C1-C3-difluoroalkanes are difluoromethane and 1,3-difluoropropane.

[0017] The C1-C5-difluoroalkanes and the cyclic C5-difluoroalkanes are swelling agents for polymers but also act as solvents for the other reactants in the amide methylation reaction. In the amide methylation reaction, additional organic swelling agents can also be added. The additional organic swelling agents added can be, for example and preferably, trifluorotoluene, dibromomethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,6-dichlorohexane, dichloromethane, tetrachloromethane, trichloroethane, chlorobenzene, 1,2-dichlorobenzene or nitro-substituted hydrocarbons, such as nitropropane, nitrobenzene, or, for example, cycloalkanes, such as cyclohexane and methylcyclohexane. It is preferred not to use additional swelling agents or / and solvents.

[0018] Preferably, the amount by weight of the C1-C5-difluoroalkanes and / or the cyclic C5-difluoroalkanes in the swelling agent used is 80% to 100% by weight. More preferably, the amount by weight of the C1-C5-difluoroalkanes and / or the cyclic C5-difluoroalkanes in the swelling agent used is 90% to 100% by weight. Most preferably, the amount by weight of the C1-C5-difluoroalkanes and / or the cyclic C5-difluoroalkanes in the swelling agent used is 98% to 100% by weight.

[0019] Condensed formaldehyde means a condensate of formaldehyde. Compounds of this type are prepared by conventional methods known to those skilled in the art. Compounds used as condensed formaldehyde include, for example and preferably, those having the formula (II)

[0020] (II)

[0021] where n = 8 to 100. It is preferred to use a compound of formula (II), where n = 8 to 30.

[0022] However, cyclic condensates such as trioxane can also be used. The formaldehyde condensate used is more preferably paraformaldehyde or trioxane, or a mixture of these compounds. The formaldehyde condensate used is most preferably paraformaldehyde.

[0023] The protonic acid used can be, for example, an inorganic or organic protonic acid. The inorganic protonic acid used is, for example, hydrochloric acid, sulfuric acid, fuming sulfuric acid, nitric acid, nitrous acid, sulfurous acid, aliphatic or aromatic methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid, or phosphoric acid. The organic protonic acid used can be, for example, oxalic acid, acetic acid or formic acid. It is preferred to use an inorganic protonic acid. The protonic acid used is more preferably sulfuric acid or fuming sulfuric acid.

[0024] The polymer of the present invention is preferably spherical. The polymer preferably has a diameter of 200 µm to 1000 µm. The polymer in the form of beads is called a bead polymer.

[0025] In the context of the present invention, the term "vinyl aromatic" includes polyvinyl aromatic and monovinyl aromatic monomers. For example, vinyl aromatic polymers are prepared using at least one monovinyl aromatic compound and at least one polyvinyl aromatic compound. However, mixtures of two or more monovinyl aromatic compounds and mixtures of two or more polyvinyl aromatic compounds can also be used. It is preferred to use at least one monovinyl aromatic compound and at least one polyvinyl aromatic compound to prepare the vinyl aromatic polymer.

[0026] In the context of the present invention, the monovinyl aromatic compound used is preferably styrene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene and chloromethylstyrene.

[0027] Particularly preferably, styrene or a mixture of styrene and the above monomers is used.

[0028] In the context of the present invention, the preferred polyvinyl aromatic compounds are divinylbenzene, divinyltoluene, trivinylbenzene, triallyl isocyanurate, divinylnaphthalene or trivinylnaphthalene.

[0029] Based on the monomer or a mixture thereof with further monomers, the polyvinyl aromatic compound is preferably used in an amount of 1% to 20% by weight, more preferably in an amount of 2% to 12% by weight, and most preferably in an amount of 4% to 10% by weight. The type of polyvinyl aromatic compound (crosslinking agent) is selected according to the subsequent use of the polymer. In many cases, divinylbenzene is suitable. For most applications, commercial divinylbenzene grades are sufficient, which contain ethylvinylbenzene in addition to the isomers of divinylbenzene.

[0030] In a preferred embodiment, the vinyl aromatic polymer is a styrene / divinylbenzene crosslinked copolymer.

[0031] In a preferred embodiment of the present invention, microencapsulated monomer droplets are used.

[0032] Possible materials for the microencapsulation of monomer droplets are those known for use as complex coacervation layers, in particular polyesters, natural and synthetic polyamides, polyurethanes, and polyureas.

[0033] As a natural polyamide, for example and preferably, gelatin has particularly good applicability. This is used especially as a coacervation layer and a complex coacervation layer. For the purposes of the present invention, a gelatin-containing complex coacervation layer is especially understood to mean a combination of gelatin with a synthetic polyelectrolyte. Suitable synthetic polyelectrolytes are copolymers incorporating units of, for example, maleic acid, acrylic acid, methacrylic acid, acrylamide, and methacrylamide. Particular preference is given to the use of acrylic acid and acrylamide. Gelatin-containing capsules can be hardened with conventional hardeners such as formaldehyde or glutaraldehyde. The encapsulation of monomer droplets with gelatin, gelatin-containing coacervation layers, and gelatin-containing complex coacervation layers is described in detail in EP-A 0 046 535. Methods for encapsulating with synthetic polymers are known. Examples of highly suitable methods are examples of interfacial condensation, in which reactive components (such as isocyanates or acyl chlorides) dissolved in the monomer droplets are reacted with a second reactive component (such as an amine) dissolved in the aqueous phase.

[0034] Optionally, the microencapsulated monomer droplets may optionally contain an initiator or a mixture of initiators to induce polymerization. Suitable initiators for the method of the present invention are preferably peroxides such as benzoyl peroxide, lauroyl peroxide, bis(4-chlorobenzoyl) peroxide, dicyclohexyl peroxydicarbonate, tert-butyl peroxyoctanoate, tert-butyl peroxy-2-ethylhexanoate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, or tert-amyl peroxy-2-ethylhexane, and also azo compounds such as 2,2'-azobis(isobutyronitrile) or 2,2'-azobis(2-methylisobutyronitrile). Most preferably, benzoyl peroxide is used.

[0035] Based on the monomer mixture, the initiator is preferably used in an amount of 0.05% to 2.5% by weight, more preferably in an amount of 0.1% to 1.5% by weight.

[0036] A pore former can optionally be used as an additional additive in the optionally microencapsulated monomer droplets in order to produce a macroporous structure in the polymer. Suitable pore formers include organic solvents that are poor solvents and / or swelling agents for the polymer being formed. Preference is given to hexane, octane, isooctane, isododecane, methyl ethyl ketone, butanol or octanol and their isomers. Particular preference is given to using isododecane as the pore former. Preference is given to using a pore former in the preparation of the amide-methylated vinyl aromatic polymers of the present invention.

[0037] The terms "microporous" and "in gel form" / "macroporous" have been described in detail in the technical literature.

[0038] For the purposes of the present invention, the preferred polymers have a macroporous structure.

[0039] In the context of the present invention, "macroporous" preferably means that the average diameter of the pores in the polymer is ≥ 25 nm. More preferably, the pores in the macroporous polymer have an average diameter of 30 nm to 1000 nm. Most preferably, the pores in the macroporous polymer have an average diameter of 30 nm to 100 nm.

[0040] In the context of the present invention, "in gel form" means that the BET surface area is ≤ 2 m 2 / g. In the case of a polymer in gel form, the BET surface area is preferably 0.02 m 2 / g to 2 m 2 / g.

[0041] The optionally microencapsulated monomer droplets can also optionally contain up to 30% by weight (based on the monomer) of a crosslinked or non-crosslinked polymer. Preferred polymers are derived from the aforementioned monomers, particularly preferably derived from styrene.

[0042] The polymers can be prepared in a heterodisperse or monodisperse form. The preparation of heterodisperse polymers is accomplished by general methods known to those skilled in the art, for example by means of suspension polymerization.

[0043] Preference is given to preparing monodisperse vinyl aromatic polymers in the process of the present invention.

[0044] In the present application, monodisperse materials are those in which at least 90% by volume or at least 90% by mass of the particles have a diameter within ±10% of the most common diameter.

[0045] For example, in the case of a material having a most common diameter of 0.5 mm, at least 90% by volume or at least 90% by mass is in the size range between 0.45 mm and 0.55 mm; in the case of a material having a most common diameter of 0.7 mm, at least 90% by volume or at least 90% by mass is in the size range between 0.63 mm and 0.77 mm.

[0046] The monodisperse polymer can be prepared by methods known in the literature. The aqueous phase involved in the preparation of the monodisperse vinyl aromatic polymer can optionally contain a dissolved polymerization inhibitor. Preferably, the aqueous phase does not contain a dissolved polymerization inhibitor. For the purposes of the present invention, both organic and inorganic inhibitors are useful. Examples of inorganic inhibitors are nitrogen compounds such as hydroxylamine, hydrazine, sodium nitrite and potassium nitrite, phosphites such as sodium hydrogen phosphite, and also sulfur 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 and aldehydes. Suitable organic inhibitors further include nitrogen compounds. These include hydroxylamine derivatives such as, for example, N,N-diethylhydroxylamine, N-isopropylhydroxylamine and also sulfonated or carboxylated N-alkylhydroxylamine or N,N-dialkylhydroxylamine derivatives, hydrazine derivatives such as, for example, N,N-hydrazinediacetic acid, nitroso compounds such as, for example, N-nitrosophenylhydroxylamine, ammonium salt of N-nitrosophenylhydroxylamine or aluminum salt of N-nitrosophenylhydroxylamine. The concentration of the inhibitor is preferably 5 - 1000 ppm, more preferably 10 - 500 ppm and even further preferably 10 - 250 ppm based on the aqueous phase. It is preferred to use resorcinol as the polymerization inhibitor. It is preferred to use a polymerization inhibitor.

[0047] As already mentioned above, the polymerization of optionally microencapsulated monomer droplets is optionally carried out in the presence of one or more protective colloids in the aqueous phase to form a monodisperse vinyl aromatic polymer. Useful protective colloids include natural or synthetic water-soluble polymers, for example, gelatin, starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid or copolymers formed from (meth)acrylic acid and (meth)acrylates. Very useful protective colloids further include cellulose derivatives, especially cellulose esters and cellulose ethers, such as carboxymethyl cellulose, methylhydroxyethyl cellulose, methylhydroxypropyl cellulose and hydroxyethyl cellulose. Gelatin has particularly good applicability and is preferably used. The amount of the protective colloid used is preferably 0.05% to 1% by weight, more preferably 0.05% to 0.5% by weight based on the aqueous phase.

[0048] The polymerization for forming the monodisperse vinyl aromatic polymer can also optionally be carried out in the presence of a buffer system. Preferably, a buffer system is given that adjusts the pH of the aqueous phase to a value between 14 and 6, preferably 12 to 8, at the start of the polymerization. Under these conditions, the protective colloids having carboxylic acid groups are present completely or partly as salts. This has a favorable effect on the action of these protective colloids. Particularly very suitable buffer systems contain phosphates or borates. For the purposes of the present invention, the terms "phosphate" and "borate" also cover the corresponding acids and the condensation products of the ortho forms of the salts. The concentration of phosphate / borate in the aqueous phase is preferably 0.5 - 500 mmol / l, more preferably 2.5 - 100 mmol / l.

[0049] The stirrer speed in the polymerization is less critical and has no influence on the particle size. A low stirrer speed is used that is sufficient to keep the suspended monomer droplets in suspension and to promote the removal of the heat of polymerization. For this task, different stirrer types can be used. Particularly suitable stirrers are axially acting paddle stirrers.

[0050] The volume ratio of the encapsulated monomer droplets to the aqueous phase is preferably 1 : 0.75 to 1 : 20, more preferably 1 : 1 to 1 : 6.

[0051] The polymerization temperature depends on the decomposition temperature of the initiator used. It is preferably between 50 °C and 180 °C, more preferably between 55 °C and 130 °C. The polymerization preferably lasts from 0.5 hour to several hours. It has been found useful to use a temperature program in which the polymerization starts at a low temperature, for example 60 °C, and the reaction temperature is increased as the polymerization conversion increases. In this way, the requirements for, for example, a reliable reaction run and a high polymerization conversion can be met very effectively. After the polymerization, the polymer is separated by conventional methods, preferably by filtration or decantation, and optionally washed.

[0052] The vinyl aromatic polymer is reacted with at least one compound of formula (I), at least one formaldehyde condensate in the presence of a C1 - C5 - difluoroalkane or a cyclic C5 - difluoroalkane or a mixture of these compounds and in the presence of at least one protonic acid to form an amide - methylated vinyl aromatic polymer.

[0053] For example, it is possible to first swell the vinyl aromatic polymer in the presence of a C1-C5-difluoroalkane and / or a cyclic C5-difluoroalkane and mix it in this state with a mixture formed from a compound of formula (I), paraformaldehyde, and a protonic acid. However, it will also be possible to first add the compound of formula (I) to the crosslinked polymer in the presence of a C1-C5-difluoroalkane and / or a cyclic C5-difluoroalkane, and then add paraformaldehyde and then add the protonic acid. Or add the protonic acid to the initial charge of the compound of formula (I), paraformaldehyde, C1-C5-difluoroalkane and / or cyclic C5-difluoroalkane, and then add the vinyl aromatic polymer thereto. Preferably, the crosslinked polymer is first swollen in the presence of a C1-C5-difluoroalkane and / or a cyclic C5-difluoroalkane, and then the compound of formula (I) or paraformaldehyde is added and then the protonic acid is added. The C1-C5-difluoroalkane and / or cyclic C5-difluoroalkane is preferably separated off by distillation or by reducing the pressure. The reaction product is treated by methods known to those skilled in the art. The reaction mixture is preferably heated. The reaction is preferably carried out as a one-pot reaction.

[0054] Preferably, the weight ratio of the C1-C5-difluoroalkane and / or cyclic C5-difluoroalkane to the vinyl aromatic polymer is from 15:1 to 3:1. More preferably, the weight ratio of the C1-C5-difluoroalkane and / or cyclic C5-difluoroalkane to the vinyl aromatic polymer is from 10:1 to 4:1.

[0055] The molar ratio of the aromatic groups in the vinyl aromatic polymer to the compound of formula (I) is preferably from 0.2:1 to 2.5:1. The molar ratio of the aromatic groups in the vinyl aromatic polymer to the compound of formula (I) is more preferably from 0.5:1 to 1.8:1.

[0056] The molar ratio of the compound of formula (I) to paraformaldehyde is preferably from 0.7:1 to 1.3:1. The molar ratio of the compound of formula (I) to paraformaldehyde is more preferably from 0.95:1 to 1.1:1.

[0057] The molar ratio of the compound of formula (I) to the protonic acid used is preferably between 10:1 and 1:10. The molar ratio of the compound of formula (I) to the protonic acid used is more preferably from 1:1 to 1:10.

[0058] If the protonic acid used is sulfuric acid, the concentration of the sulfuric acid used is preferably from 70% by weight to 100% by weight. Even more preferably, the concentration of the sulfuric acid used is from 90% by weight to 100% by weight.

[0059] The reaction temperature for converting a vinyl aromatic polymer into an amide-methylated vinyl aromatic polymer is preferably from 0 °C to 130 °C. The reaction is preferably carried out at a pressure and temperature at which the solvent is liquid. The pressure is preferably from 1 to 60 bar. The reaction temperature is preferably from 30 °C to 90 °C.

[0060] These amide-methylated vinyl aromatic polymers are particularly important intermediates for the preparation of ion exchangers and chelating resins. Thus it is possible, for example, to prepare ion exchangers (in particular anion exchangers) and chelating resins from the amide-methylated vinyl aromatic polymers prepared by the process according to the invention.

[0061] Then in a further step the amide-methylated vinyl aromatic polymer can be converted into an aminomethylated vinyl aromatic polymer. Preferably the amide-methylated vinyl aromatic polymer is further converted into an aminomethylated vinyl aromatic polymer. This conversion is preferably carried out by treating the amide-methylated vinyl aromatic polymer with an aqueous or alcoholic solution of an alkali metal hydroxide (such as sodium hydroxide or potassium hydroxide) at a temperature between 100 °C and 250 °C, preferably at a temperature between 120 °C and 190 °C. It is preferred to use an alkali metal or alkaline earth metal hydroxide or a mixture of these compounds, more preferably an alkali metal hydroxide, in particular sodium hydroxide, for this conversion. This conversion is preferably carried out in the presence of an aqueous or alcoholic solution of the alkali metal hydroxide. The concentration of the sodium hydroxide solution is in the range from 10% to 50% by weight, preferably from 20% to 40% by weight.

[0062] The aminomethylated vinyl aromatic polymer formed here can be washed with completely deionized water to make it free of alkali.

[0063] The aminomethylated vinyl aromatic polymer can be reacted with a further alkylating agent to produce an anion exchanger or a chelating resin, or can alternatively be used as an ion exchanger.

[0064] It is further possible to react the aminomethylated vinyl aromatic polymer according to the invention with a halomethyl azacyclic compound (such as 2-chloromethylpyridine, 3-chloromethylpyridine or 4-chloromethylpyridine) and thereby to prepare a chelating resin.

[0065] The present invention provides a novel method for preparing amide-methylated vinyl aromatic polymers, by which it is possible to prepare, in particular, phthalimidomethylated polymers and aminomethylated polymers in high yields while taking into account environmental factors. Detailed Description

[0066] Example 1

[0067] 1.1 Preparation of monodisperse macroporous polymers based on styrene, divinylbenzene and ethylstyrene

[0068] Initially, 3000 g of demineralized water was charged into a 10 l glass reactor and 10 g of gelatin, 16 g of disodium hydrogen phosphate dodecahydrate and a solution of 0.73 g of resorcinol in 320 g of deionized water were added and mixed. The temperature of the mixture was adjusted to 25 °C. Subsequently, while stirring, 3200 g of a mixture of microencapsulated monomer droplets having a narrow particle size distribution, consisting of 3.1% by weight of divinylbenzene and 0.6% by weight of ethylstyrene (used in the form of a commercial mixture of isomers of divinylbenzene and ethylstyrene having 80% divinylbenzene), 0.4% by weight of dibenzoyl peroxide, 58.4% by weight of styrene and 37.5% by weight of isododecane (an industrial isomer mixture having a high proportion of pentamethylheptane), the microcapsules consisting of a formaldehyde-hardened complex coacervation layer of gelatin and a copolymer of acrylamide and acrylic acid, were added, and 3200 g of an aqueous phase having a pH of 12 was added.

[0069] The mixture was stirred and polymerized to completion by raising the temperature according to a temperature program starting at 25 °C and ending at 95 °C. The mixture was cooled, washed through a 32 µm sieve and then dried under reduced pressure at 80 °C.

[0070] This yielded 1893 g of a polymer having a narrow particle size distribution. The average pore diameter in the polymer was 42 nm.

[0071] 1.2 Preparation of phthalimidomethylated monodisperse macroporous polymers with the swelling agent 1,3-difluoropropane

[0072] Initially, 29.5 g of 1,3-difluoropropane was charged into a round-bottom flask. 4.1 g of the polymer from Example 1.1, 5.9 g (0.04 mol) of phthalimide, and 1.2 g (0.04 mol) of paraformaldehyde (n = 8 to 30) (96% by weight) were added thereto, and then the mixture was stirred at room temperature for 30 min. 14.6 g (0.14 mol) of sulfuric acid (96% by weight) was added dropwise within 30 min, and then the mixture was stirred at 40 °C for 24 h. Thereafter, the beads were separated on a sieve and washed with water, acetone, and water.

[0073] Volume yield: 23 ml

[0074] Nitrogen content (after drying): 5.1% by weight

[0075] In the context of the present invention, the yield means the degree of functionalization of the polymer as represented by the nitrogen content. This is greater in the examples of the present invention than in the comparative examples.

[0076] Example 2

[0077] Comparative example (not of the present invention)

[0078] 2.1 Preparation of phthalimidomethylated monodisperse macroporous polymer using the swelling agent 1,2-dichloroethane

[0079] Initially, 29.7 g of 1,2-dichloroethane was charged into a round-bottom flask. 4.1 g of the polymer from Example 1.1, 5.9 g of phthalimide (0.04 mol), and 1.2 g (0.04 mol) of paraformaldehyde (n = 8 to 30) (96% by weight) were added thereto, and then the mixture was stirred at room temperature for 30 min. 14.6 g (0.14 mol) of sulfuric acid (96% by weight) was added dropwise within 30 min, and then the mixture was stirred at 40 °C for 24 h. Thereafter, the beads were separated on a sieve and washed with water, acetone, and water.

[0080] Volume yield: 25 ml

[0081] Nitrogen content (after drying): 4.9% by weight.

Claims

1. A method for preparing an amide-methylated vinyl aromatic polymer, characterized in that, react at least one vinyl aromatic polymer with at least one compound of formula (I) or a salt thereof (I) wherein R1 = -C(H(C1-C6-alkyl))- or -CH2- and R2 = -C(H(C1-C6-alkyl))- or -CH2-, or R1 and R2 are two carbon atoms of an aromatic C6 ring optionally substituted by one or two C1-C6-alkyl groups, or R1 and R2 are each -CH=, and at least one condensed formaldehyde in the presence of at least one protonic acid and in the presence of at least one linear or branched C1-C5-difluoroalkane or at least one cyclic C5-difluoroalkane or a mixture of these compounds.

2. The method according to claim 1, characterized in that, The C1-C5-difluoroalkane is selected from the group consisting of: difluoromethane, 1,1-difluoroethane, 1,2-difluoroethane, 1,1-difluoropropane, 1,2-difluoropropane, 1,3-difluoropropane, 1,1-difluorobutane, 1,2-difluorobutane, 1,3-difluorobutane, 1,4-difluorobutane, 2,3-difluorobutane, 1,3-difluoro-2-methylpropane, 1,1-difluoropentane, 1,2-difluoropentane, 1,3-difluoropentane, 1,4-difluoropentane, 1,5-difluoropentane, 2,3-difluoropentane, 2,4-difluoropentane and 1,5-difluoropentane or a mixture of these compounds.

3. The method according to any one of claims 1 and 2, characterized in that, The C1-C5-difluoroalkane used is difluoromethane or 1,3-difluoropropane.

4. The method according to one or more of claims 1 to 3, characterized in that, The cyclic C5-difluoroalkane used is 1,1-difluorocyclopentane and 1,2-difluorocyclopentane.

5. The method according to one or more of claims 1 to 4, characterized in that, The condensed formaldehyde used is paraformaldehyde or trioxane or a mixture of these compounds.

6. The method according to one or more of claims 1 to 5, characterized in that, The vinyl aromatic bead polymer used is a styrene-divinylbenzene copolymer.

7. The method according to one or more of claims 1 to 6, characterized in that, The compound of formula (I) used is phthalimide or a salt thereof.

8. The method according to one or more of claims 1 to 7, characterized in that, The vinyl aromatic polymer used is a monodisperse vinyl aromatic polymer.

9. The method according to one or more of claims 1 to 8, characterized in that The pores of the vinyl aromatic polymer used have a diameter of ≥ 25 nm.

10. The method according to one or more of claims 1 to 9, characterized in that, The weight ratio of C1-C5-difluoroalkane to the vinyl aromatic polymer is 10:1 to 4:

1.

11. The method according to one or more of claims 1 to 10, characterized in that, The molar ratio of aromatic groups in the vinyl aromatic bead polymer to the compound of formula (I) is 0.5:1 to 1.8:

1.

12. The method according to one or more of claims 1 to 11, characterized in that, The molar ratio of the compound of formula (I) to condensed formaldehyde is 0.95:1 to 1.1:

1.

13. The method according to one or more of claims 1 to 12, characterized in that, The molar ratio of the compound of formula (I) to the protonic acid used is 10:1 to 1:

10.

14. The method according to one or more of claims 1 to 13, characterized in that, The reaction temperature for converting the vinyl aromatic polymer into the amide-methylated vinyl aromatic polymer is between 30°C and 90°C.

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