EP2081886A1

EP2081886A1 - Method for producing alkaline (meth)acrylamides

Info

Publication number: EP2081886A1
Application number: EP07818753A
Authority: EP
Inventors: Matthias Krull; Christoph Kayser; Roman MORSCHHÄUSER; Helmut Ritter; Sarah Schmitz
Original assignee: Clariant Finance BVI Ltd
Current assignee: Clariant International Ltd
Priority date: 2006-10-09
Filing date: 2007-10-05
Publication date: 2009-07-29
Also published as: DE102006047617B4; WO2008043492A1; JP2010505890A; CA2666171A1; BRPI0719516A2; CN101516832B; US9039870B2; KR20090080074A; DE102006047617A1; US20100032284A1; JP5553404B2; CN101516832A

Abstract

The invention relates to a method for producing alkaline amides or imides of ethylenically unsaturated C3 to C6carboxylic acids by reacting amines that contain at least one primary and/or secondary amino group and at least one tertiary amino group with ethylenically unsaturated C3 to C6 carboxlic acids to form an ammonium salt and said ammonium salt is subsequently converted into the alkaline amide or imide by means of microwave radiation, with the proviso that the primary and/or secondary amino group is devoid of alkoxy groups.

Description

description

Process for the preparation of basic (meth) acrylamides

Ethyenically unsaturated compounds carrying functional groups of basic character are sought after as monomers for the preparation of functional polymers. Such basic-functionalized copolymers are widely used, for example as sizing aids in fiber preparation, in aqueous systems in viscosity modification, in wastewater treatment, as flocculation aids in the extraction of minerals as well as auxiliaries in metalworking and as a detergent additive in lubricating oils. In particular, N-alkylacrylamides and N-alkylmethacrylamides, which carry at least one basic character-imparting tertiary amino group in addition to the amide group, are preferred because they have an increased relative to corresponding esters

Have hydrolysis stability. Depending on the intended use, the polymers produced therewith are used as such or after polymer-analogous reaction, for example, to quaternary ammonium compounds, N-oxides or else betaines. Often, however, it is difficult to achieve the high molecular weights of such basic functionalized homo- and copolymers required for the performance properties.

To meet the growing demand for existing and new applications, various methods have been developed for the production of tertiary amino groups bearing ethylenically unsaturated amides. In the preparation of such monomers, the targeted implementation of each bifunctional reactants requires special attention. Thus, the carboxyl group of the underlying ethylenically unsaturated carboxylic acid with the primary or secondary amino group of unsymmetrically substituted diamine must be targeted to give both the ethylenic double bond and the tertiary

Amino group can be implemented. So far, one relies on costly and lengthy production process to achieve a commercially interesting yield. The known production methods require highly reactive Carboxylic acid derivatives such as acid anhydrides, acid halides such as acid chlorides, esters or in situ activation through the use of coupling reagents such as N.N'-dicyclohexylcarbodiimide or very special and therefore expensive catalysts. In some cases, large amounts of unwanted by-products such as alcohols, acids and salts, which must be separated from the product and disposed of, are formed in these production processes. But also the remaining in the products remains of the by-products and by-products can sometimes cause very undesirable effects. For example, halide ions as well as acids lead to corrosion; Coupling reagents and the by-products formed by them are sometimes toxic, sensitizing or carcinogenic.

The direct thermal condensation of ethylenically unsaturated carboxylic acid and diamine leads to no satisfactory results, since various side reactions reduce the yield. These include, for example, a

Michael addition of the amine to the double bond of the ethylenically unsaturated carboxylic acid, an uncontrolled, thermal polymerization of the ethylenically unsaturated carboxylic acid or of the amide formed, an oxidation of the amino group during long heating and in particular the thermally induced degradation of the amino group. Since such secondary reactions lead inter alia to the formation of additional C = C double bonds, compounds with two polymerizable centers can be formed in this way from amides formed once, which in the subsequent polymerization of the basic (meth) acrylamides lead to crosslinking and thus insoluble polymers. Thus, for example, N- [3- (N, N-dimethylamino) -propyl] acrylamide is formed by Hofmann degradation in the presence of acids N- (allyl) acrylamide, which is a typical, but for the preparation of soluble polymers highly undesirable crosslinker for polymerizations and therefore has to be disconnected.

Lannelli et al., Tetrahedron 2005, 61, 1509-1515 discloses the preparation of (R) -i-phenyl-ethylmethacrylamide by condensation of methacrylic acid with (R) -i-phenyl-ethylamine under microwave irradiation. Goretzki et al., Macromol. Rapid Commun. 2004, 25, 513-516 discloses the microwave assisted synthesis of various (meth) acrylamides directly from (meth) acrylic acid and amine. Various aliphatic and aromatic amines are used.

Gelens et al., Tetrahedron Letters 2005, 46 (21), 3751-3754 discloses a variety of amides synthesized with the aid of microwave radiation. However, none contain an additional tertiary amino group.

Accordingly, a process has been sought for the preparation of basic amides of ethylenically unsaturated carboxylic acids, in which ethylenically unsaturated carboxylic acids and amines carrying tertiary amino groups can be reacted directly and in high amides or imides of ethylenically unsaturated carboxylic acids which carry high yields of tertiary amino groups , Furthermore, no or only minor amounts are intended

By-products such as Michael adducts and in particular multiply ethylenically unsaturated compounds are obtained. Furthermore, basic amides of ethylenically unsaturated carboxylic acids were sought, which can be used to form particularly high molecular weight homopolymers and copolymers. Furthermore, the basic amides prepared according to the invention show virtually no intrinsic coloration, which is of great advantage for various applications such as fiber preparation.

It has been found that tertiary amino-containing amides or imides of unsaturated C ₃ - to C ₆ -carboxylic acids by direct reaction of at least one primary and / or secondary amino group and additionally carrying at least one tertiary amino group-bearing polyamines with C ₃ - to Cε-carboxylic acids can be produced in high yields by irradiation with microwaves. Surprisingly, no appreciable Hofmann elimination of the tertiary amino group occurs despite the presence of acids.

The invention relates to a process for the preparation of basic amides or imides of ethylenically unsaturated C ₃ - to C ₆ -carboxylic acids by Amines containing at least one primary and / or secondary amino group and at least one tertiary amino group are reacted with ethylenically unsaturated C ₃ - to C ₆ carboxylic acids to form an ammonium salt, and this ammonium salt is subsequently reacted under microwave irradiation to the basic amide or imide, with with the proviso that the primary and / or secondary amino group does not comprise alkoxy groups.

Another object of the invention are basic amides or imides of ethylenically unsaturated C ₃ - to C _δ carboxylic acids, which are substantially free of halide ions and coupling reagents derived byproducts, prepared by amines containing at least one primary and / or secondary amino group and at least carrying a tertiary amino group, are reacted with ethylenically unsaturated C ₃ - to C ₆ -carboxylic acids to an ammonium salt, and this ammonium salt is subsequently reacted under microwave irradiation to the basic amide or imide, with the proviso that the primary and / or secondary amino group no alkoxy groups includes.

Basic amides or imides are understood as meaning amides or imides whose amide or imide nitrogen atom carries at least one hydrocarbon radical substituted by at least one tertiary amino group. Tertiary amino groups in the sense of the present invention are structural units in which a nitrogen atom does not carry an acidic proton. Thus, the nitrogen of the tertiary amino group carry three hydrocarbon radicals or be part of a heteroaromatic system. Free fatty acid amides free of halide ions contain no more than the ubiquitous amounts of halide ions amounts of these ions.

The proviso that the primary and / or secondary amino group does not comprise alkoxy groups means that the primary and / or secondary amino group or, if any of such groups are present, all of them, do not have a substituent comprising alkoxy groups. Ethylenically unsaturated C ₃ - to C 6 -carboxylic acids are understood as meaning those carboxylic acids having 3 to 6 C atoms which have a C =C double bond conjugated to a carboxyl group. Preferred ethylenically unsaturated carboxylic acids may carry one or more carboxyl groups, in particular one or two carboxyl groups. Examples of suitable carboxylic acids according to the invention are acrylic acid, methacrylic acid, crotonic acid, 2,2-dimethylacrylic acid, maleic acid, fumaric acid and itaconic acid. Particularly preferred are acrylic acid and methacrylic acid.

Also in the use of ethylenically unsaturated dicarboxylic acids in the form of their anhydrides such as maleic anhydride process of the invention is advantageous. The condensation of the amidocarboxylic acid formed intermediately from dicarboxylic acid and primary and / or secondary and tertiary amino groups leads, in contrast to thermal condensation, in high yields to imides of ethylenically unsaturated carboxylic acids carrying tertiary amino groups.

Amines suitable according to the invention have two or more amino groups. Of these amino groups, at least one is tertiary, that is, it carries three alkyl groups or is part of a heteroaromatic system. At least one amino group carries one or two, preferably two hydrogen atoms.

In a preferred embodiment, the object of the invention is a process for the preparation of basic amides or imides of ethylenically unsaturated C ₃ - to C 6 -carboxylic acids, by reacting amines of the formula

HNR ¹ - (A) _n -Z

in which R ^{1 is} hydrogen, C ₁ -C 4 -alkyl, C ₅ -C ₁₂ -cycloalkyl, C ₆ -C ₁₂ -aryl,

C ₇ -C ₂ -aralkyl or a heteroaromatic group having 5 to 12 ring members, A is an alkylene radical having 1 to 12 C atoms, a cycloalkylene radical having 5 to 12 ring members, an arylene radical having 6 to 12 ring members or a heteroarylene radical having 5 to 12 ring members n is 0 or 1, Z is a group of the formula -NR ² R ³ or for a nitrogen-containing cyclic hydrocarbon radical having at least 5 Ringgliedem and

R ² and R ³ independently of one another represent C ₁ - to C ₂ o-carbon hydrogen radicals or represent polyoxyalkylene radicals,

as well as the basic amides or imides of ethylenically unsaturated C ₃ - to C ₆ -carboxylic acids which can be prepared by this process and which are essentially derived from

Halide ions and derived from coupling reagents by-products are free.

Preferably, R ^{1 is} hydrogen or methyl, in particular hydrogen.

A is preferably a linear or branched alkylene radical having 1 to 12 C atoms and n is 1.

Particularly preferably, when Z is a group of the formula -NR ² R ^{3, A} is a linear or branched alkylene radical having 2, 3 or 4 C atoms, in particular an ethylene radical or a linear propylene radical. On the other hand, when Z is a nitrogen-containing cyclic hydrocarbon radical, compounds are particularly preferred in which A is a linear alkylene radical having 1, 2 or 3 C atoms, in particular a methylene, ethylene or a linear propylene radical.

Cyclic radicals which are preferred for the structural element A can be monocyclic or polycyclic and contain, for example, two or three ring systems.

Preferred ring systems have 5, 6 or 7 ring members. Preferably, they contain a total of about 5 to 20 C-atoms, in particular 6 to 10 C-atoms. Preferred ring systems are aromatic and contain only C atoms. In a special Embodiment, the structural elements A are formed from arylene radicals. The structural element A may carry substituents such as, for example, alkyl radicals, halogen atoms, halogenated alkyl radicals, nitro, cyano, nitrile, hydroxyl and / or hydroxyalkyl groups. If A is a monocyclic aromatic hydrocarbon, the substituents carrying amino groups or amino groups are preferably in the ortho or para position relative to one another.

Z preferably represents a group of the formula -NR ² R ³ . R ² and R ³ independently of one another are preferably aliphatic, aromatic and / or araliphatic hydrocarbon radicals having 1 to 20 carbon atoms. As R ² and R ^{3 are} particularly preferred alkyl radicals. If R ² and / or R ^{3 are} alkyl radicals, they preferably carry 1 to 14 C atoms, for example 1 to 6 C atoms. These alkyl radicals can be linear, branched and / or cyclic. R ² and R ³ particularly preferably represent alkyl radicals having 1 to 4 C atoms, such as, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl.

The radicals R ² and R ³ may be substituted by heteroatoms such as O and / or S, and / or bear substituents containing such heteroatoms. However, they preferably contain not more than 1 heteroatom per 2 C atoms. Thus, in a further preferred embodiment, R ² and / or R ³ independently of one another represent polyoxyalkylene radicals of the formula

- (BO) _m -R ⁴ ,

wherein

B is a linear or branched C ₂ -C ₄ -alkylene radical, in particular a

Group of the formula -CH ₂ -CH ₂ - and / or -CH (CH ₃ ) -CH ₂ -, m is a number from 1 to 100, preferably 1 to 20 and R ^{4 is} hydrogen, an alkyl radical having 1 to 20 C. Atoms, a cycloalkyl radical having 5 to 12 ring atoms, an aryl radical having 6 to 12 ring atoms, a

Aralkyl radical having 7 to 30 carbon atoms, a heteroaryl radical having 5 to 12 ring atoms or a heteroaralkyl radical having 6 to 12 carbon atoms. As R ² and / or R ³ particularly suitable aromatic radicals include ring systems having at least 5 ring members. They may contain heteroatoms such as S, O and N. Araliphatic radicals which are particularly suitable as R ² and / or R ³ include ring systems having at least 5 ring members which are bonded to the nitrogen via a C ₁ -C ₆ -alkyl radical. They may contain heteroatoms such as S, O and N. The aromatic as well as the araliphatic radicals may carry further substituents such as alkyl radicals, halogen atoms, halogenated alkyl radicals, nitro, cyano, nitrile, hydroxyl and / or hydroxyalkyl groups.

In a further preferred embodiment Z is a nitrogen-containing, cyclic hydrocarbon radical whose nitrogen atom is not capable of forming amides. The cyclic system can be mono-, di- or also polycyclic. It preferably contains one or more five- and / or six-membered rings. This cyclic hydrocarbon may contain one or more, such as two or three, nitrogen atoms that are not acidic

Protons carry, more preferably, it contains an N-atom. Particularly suitable are nitrogen-containing aromatics whose nitrogen is involved in the formation of an aromatic π-Elektronensextetts such as pyridine. Likewise suitable are nitrogen-containing heteroaliphatic compounds whose nitrogen atoms do not carry any protons and, for example, are all saturated with alkyl radicals. The linking of Z with A or the group of the formula NHR ¹ (if n = 0) is preferably carried out here via a nitrogen atom of the heterocycle, for example in the case of 1- (3-aminopropyl) pyrrolidine. The cyclic hydrocarbon represented by Z may carry further substituents such as, for example, C ₁ -C ₂₀ -alkyl radicals, halogen atoms, halogenated alkyl radicals, nitro, cyano, nitrile, hydroxyl and / or hydroxyalkyl groups.

Examples of suitable amines are N, N-dimethylethylenediamine, N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, N, N-dimethyl-2-methyl-1,3-propanediamine , 3-propanediamine N, N- (2 ^{'-hydroxyethyl)} -1, 1- (3-aminopropyl) - pyrrolidine, 1 - (3-aminopropyl) -4-methylpiperazine, 3- (4-morpholino) -1 - propylamine, 2-aminothiazole, the various isomers of N, N-dimethylaminoaniline, aminopyridine, aminomethylpyridine, aminomethylpiperidine and Aminoquinolines, as well as 2-aminopyrimidine, 3-aminopyrazole, aminopyrazine and 3-amino-1,2,4-triazole.

The process is particularly suitable for the preparation of N- [3- (N, N-dimethylamino) propyl] acrylamide, N- [3- (N, N-dimethylamino) propyl] methacrylamide, N- [3- (N, N-dimethylamino) propyl] crotonylamide, N- [3- (N, N-dimethylamino) propyl] itaconylimide, N - [(pyridin-4-yl) methyl] acrylamide and N - [(pyridin-4-yl) methyl] methacrylamide.

In the process according to the invention, ethylenically unsaturated carboxylic acid and amine can be reacted with one another in any ratio. For the preparation of the pure monomers are preferably molar ratios between ethylenically unsaturated carboxylic acid and amine from 10: 1 to 1:10, preferably from 2: 1 to 1: 2, especially from 1, 0: 1, 2 to 1, 2: 1 , 0 and in particular equimolar.

In many cases, it has proved to be advantageous, with a slight excess of amine, that is, molar ratios of amine to carboxylic acid of at least 1, 01: 1, 00 and in particular between 1, 02: 1.00 and 1, 2: 1 For example, to work between 1, 05: 1, 0, and 1, 1: 1. Here is the

Acid practically quantitatively converted to the basic amide. This process is particularly advantageous when the amine used, at least one primary and / or secondary and at least one tertiary amino group bearing amine is highly volatile. Volatile here means that the amine has a boiling point at atmospheric pressure of preferably below 200 ⁰ C such as below 150 ⁰ C and thus can be separated by distillation from the amide.

If the basic amides or imides according to the invention are to be used to prepare copolymers with the ethylenically unsaturated C ₃ -C ₆ -carboxylic acids used for their preparation, it is also possible to use higher excesses of ethylenically unsaturated carboxylic acid. Thus, it has proven useful with molar ratios of carboxylic acid to amine of at least 1.01: 1.00 and in particular between 1, 02: 1, 00 and 50: 1, 0 such as between 1, 05: 1, 0 and 10: 1. The excess acid can then be used for the in-situ preparation of copolymers with the monomers according to the invention.

The preparation of the amides / imides is carried out by reacting the ethylenically unsaturated carboxylic acid and the amine to the ammonium salt and subsequent irradiation of the salt with microwaves. The ammonium salt is preferably generated in situ and not isolated. Preferably, the temperature rise caused by the microwave irradiation is limited to a maximum of 300 ^° C. by regulation of the microwave intensity and / or cooling of the reaction vessel. Proven particularly suitable to carry out the reaction at temperatures between 100 and 240 ⁰ C and especially between 120 and 200 ° C such as at temperatures of 125-175 ° C.

The duration of the microwave irradiation depends on various factors such as the reaction volume, the geometry of the reaction space and the desired degree of conversion. Usually, the microwave irradiation is carried out for a period of less than 60 minutes, preferably between 0.01 seconds and 15 minutes, more preferably between 0.1 seconds and 10 minutes and in particular between one second and 5 minutes, for example between 5 seconds and 2 minutes , The intensity (power) of the microwave radiation is adjusted so that the reaction mixture reaches the desired reaction temperature in the shortest possible time. For the subsequent maintenance of the temperature, the reaction mixture can be further irradiated with reduced and / or pulsed power. In order to maintain the maximum temperature with maximum possible microwave irradiation, it has proven useful to cool the reaction mixture by means of cooling jacket, cooling tubes located in the reaction chamber by intermittent cooling between different irradiation zones and / or by boiling cooling via external heat exchangers. In a preferred embodiment, the reaction product is cooled as soon as possible after completion of the microwave irradiation to temperatures below 12O ⁰ C, preferably below 100 ° C and especially below 60 ° C. The reaction is preferably carried out at pressures between 0.1 and 200 bar and especially between 1 bar (atmospheric pressure) and 50 bar. Working in closed vessels in which above the boiling point of the reactants or products, of the optionally present solvent and / or above that formed during the reaction, has proven particularly useful

Reaction water is worked. Usually, the pressure which builds up due to the heating of the reaction batch is sufficient to successfully carry out the process according to the invention. However, it is also possible to work under elevated pressure and / or by applying a pressure profile. In a further preferred variant of the method according to the invention is under atmospheric pressure, as it sets, for example, in an open vessel worked.

In order to avoid side reactions and to produce products which are as pure as possible, it has proven useful to carry out the process according to the invention in the presence of an inert protective gas such as, for example, nitrogen, argon or helium.

In a preferred embodiment, to accelerate or complete the reaction in the presence of dehydrating

Catalysts worked. Preferably, one works in the presence of an acidic inorganic, organometallic or organic catalyst or mixtures of several of these catalysts.

Examples of acidic inorganic catalysts for the purposes of the present invention are sulfuric acid, phosphoric acid, phosphonic acid, hypophosphorous acid, aluminum sulfate hydrate, alum, acidic silica gel and acidic aluminum hydroxide. Furthermore, for example, aluminum compounds of the general formula Al (OR ⁵ ) ₃ and titanates of the general formula Ti (OR ⁵ ) ₄ can be used as acidic inorganic catalysts, wherein the radicals R ^{5 may be} the same or different and are independently selected from Ci-Cio Alkyl radicals, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neo-pentyl, 1,2-dimethylpropyl, iso-amyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexy, n-nonyl or n-decyl, C ₃ -C ₁₂ -cycloalkyl radicals, for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl; preferred are cyclopentyl, cyclohexyl and cycloheptyl. The radicals R ⁵ in Al (OR ⁵ ) ₃ or Ti (OR ⁵ ) 4 are preferably identical and selected from isopropyl, butyl and 2-ethylhexyl.

Preferred acidic organometallic catalysts are selected, for example, from dialkyltin oxides (R ⁵ ) ₂ SnO, where R ^{5 is} as defined above. A particularly preferred representatives of acidic organometallic catalysts is di-n-butyltin oxide, which is commercially available as so called oxo-tin or as Fascat ^® brands.

Preferred acidic organic catalysts are acidic organic compounds with, for example, phosphate groups, sulfonic acid groups, sulfate groups or phosphonic acid groups. Particularly preferred sulfonic acids contain at least one sulfonic acid group and at least one saturated or unsaturated, linear, branched and / or cyclic carbon hydrogen radical having 1 to 40 carbon atoms and preferably having 3 to 24 carbon atoms. In particular, preferred are aromatic sulfonic acids, especially alkylaromatic monosulfonic acids with one or more C-ι-C ₂₈ alkyl radicals and especially those with C ₃ -C ₂₂ -alkyl are. Suitable examples are methanesulfonic acid, butanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, 2-mesitylenesulfonic acid, 4-ethylbenzenesulfonic acid, isopropylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid; Dodecylbenzenesulfonic acid, didodecylbenzenesulfonic acid, naphthalenesulfonic acid. Acid ion exchangers can also be used as acidic organic catalysts, for example poly (styrene) -sulfonic acid-containing polyols which are crosslinked with about 2 mol% of divinylbenzene.

Particularly preferred for carrying out the process according to the invention are boric acid, phosphoric acid, polyphosphoric acid and polystyrenesulfonic acid. Especially preferred are titanates of the general formula Ti (OR ⁵ ) ₄ and especially titanium tetrabutylate and titanium tetraisopropylate.

If it is desired to use acidic inorganic, organometallic or organic catalysts, according to the invention 0.01 to 10% by weight, preferably 0.02 to 2% by weight, of catalyst is used. In a particularly preferred embodiment, working without a catalyst.

In a further preferred embodiment, the microwave irradiation is carried out in the presence of acidic solid catalysts. In this case, the solid catalyst is suspended in the optionally mixed with solvent ammonium salt or passed in continuous processes advantageously the optionally with solvent-added ammonium salt over a fixed bed catalyst and exposed to microwave radiation. Suitable solid catalysts are, for example, zeolites, silica gel, montmorillonite and

(Partially) crosslinked polystyrenesulphonic acid, which may optionally be impregnated with catalytically active metal salts. Suitable acidic ion exchanger based on polystyrene sulfonic acids that can be used as solid phase catalysts are for example available from the company Rohm & Haas under the trademark Amberlyst ^®.

It has been proven to work in the presence of solvents to lower, for example, the viscosity of the reaction medium to fluidize the reaction mixture, if it is heterogeneous and / or to improve the heat dissipation, for example by means of evaporative cooling. In principle, all solvents can be used which are inert under the reaction conditions used and do not react with the starting materials or the products formed. An important factor in the selection of suitable solvents is their polarity, which on the one hand determines the dissolving properties and on the other hand determines the extent of the interaction with microwave radiation. A particularly important factor in the selection of suitable solvents is their dielectric loss ε. ^" The dielectric loss ε ^" describes the proportion of microwave radiation which is converted into heat during the interaction of a substance with microwave radiation. Last mentioned Value has proven to be a particularly important criterion for the suitability of a solvent for carrying out the method according to the invention. Working in solvents which have the lowest possible microwave absorption and thus only a small contribution to the heating of the reaction system has proven particularly useful. Solvents which are preferred for the process according to the invention have a dielectric loss ε ^" of less than 10 and preferably less than 1, for example less than 0.5, measured at room temperature and 2450 MHz An overview of the dielectric loss of various solvents can be found, for example, in" Microwave Synthesis "by BL Hayes, CEM Publishing 2002. Suitable solvents for the process according to the invention are, in particular, solvents having ε ^" values below 10, such as N-methylpyrrolidone, N, N-dimethylformamide or acetone, and in particular solvents having ε ^" values below 1. EXAMPLES for particularly preferred solvents with ε ^" values below 1 are aromatic and / or aliphatic hydrocarbons such as toluene, XyIoI ₁ ethylbenzene, tetralin, hexane, cyclohexane, decane, pentadecane, decalin and commercial hydrocarbon mixtures such as gasoline fractions, kerosene, solvent Naphtha, ^® Shellsol AB, ^® Solvesso 150, ® Solvesso 200, ^® Exxsol, Isopar ^® and ^® Shellsol types. Solvent mixtures which have ε ^" values preferably below 10 and especially below 1 are equally preferred for carrying out the process according to the invention.

In principle, the process according to the invention is also possible in solvents having ε ^" values of 10 and higher, but this requires special measures for maintaining the maximum temperature and often leads to reduced yields between 2 and 95% by weight, especially between 5 and 90% by weight and in particular between 10 and 75% by weight, for example between 30 and 60% by weight The reaction is particularly preferably carried out solvent-free.

To prevent an uncontrolled thermal polymerization during the condensation, it has been proven to perform these in the presence of polymerization inhibitors. Particularly suitable are polymerization inhibitors based on phenols such as hydroquinone, Hydroquinone monomethyl ether and sterically hindered phenols such as 2,6-di-tert-butylphenol or 2,6-di-tert-butyl-4-methyphenol. Also suitable are thiazines such as phenothiazine or methylene blue and nitroxides, in particular sterically hindered nitroxides, ie nitroxides of secondary amines which carry three alkyl groups on the carbon atoms which are adjacent to the nitroxide group, two of these alkyl groups, especially those which are not are on the same carbon atom, form with the nitrogen atom of the nitroxide group or the carbon atom to which they are attached, a saturated 5- or 6-membered ring, such as in 2,2,6,6-tetramethypiperidine-1-oxyl (TEMPO) or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (OH-TEMPO). The same mixtures of the aforementioned inhibitors, mixtures of the aforementioned inhibitors with oxygen, for example in the form of air, and mixtures of mixtures of the aforementioned inhibitors with air are suitable. These are preferably added to the reaction mixture or one of the reactants in amounts of from 1 to 1000 ppm and in particular in amounts of from 10 to 200 ppm, based on the ethylenically unsaturated carboxylic acid.

The microwave irradiation is usually carried out in devices which have a reaction space made of a material which is as far as possible transparent to microwaves, into which microwave radiation generated in a microwave generator is coupled in via suitable antenna systems. Microwave generators, such as the magnetron and the klystron are known in the art.

Microwaves are electromagnetic waves having a wavelength between about 1 cm and 1 m and frequencies between about 300 MHz and 30 GHz. This frequency range is suitable in principle for the method according to the invention. For the inventive method, microwave radiation with the frequencies of 915 MHz, 2.45 GHz, 5.8 GHz or 27.12 GHz released for industrial, scientific and medical applications is preferably used. It can be used in mono or quasi-

Single mode as well as multimode. In the single mode, which places high demands on the geometry and size of the apparatus and the reaction space, a standing wave, in particular at its maximum, becomes a very large one generates high energy density. By contrast, in multimode the entire reaction space is largely homogeneously irradiated, which, for example, allows larger reaction volumes.

The for carrying out the method according to the invention in the

The reaction vessel to be irradiated microwave power is particularly dependent on the geometry of the reaction space and thus the reaction volume and the duration of the required irradiation. It is usually between 100 W and several 100 kW and in particular between 200 W and 100 kW such as between 500 W and 70 kW. It can be applied at one or more points of the reactor. It can be generated by one or more microwave generators.

The reaction can be carried out batchwise or, preferably, continuously, for example in a flow tube. It can also be carried out in semi-batch processes such as continuously operated stirred reactors or cascade reactors. In a preferred embodiment, the reaction is carried out in a closed vessel, wherein the forming condensate and optionally starting materials and, if present, solvents lead to a pressure build-up. After completion of the reaction, the excess pressure can be used by relaxation for volatilization and separation of water of reaction and optionally solvent and excess starting materials and / or cooling of the reaction product. In a further embodiment, the water of reaction formed after cooling and / or venting by conventional methods such as phase separation, distillation and / or absorption is separated. The process according to the invention can likewise be carried out successfully in an open vessel with boiling-cooling and / or removal of the water of reaction.

In a preferred embodiment, the process according to the invention is carried out in a discontinuous microwave reactor. The microwave irradiation is carried out in a stirred vessel. Prefers are located to dissipate excess heat in the reaction vessel cooling elements such as cold fingers or cooling coils or flanged to the reaction vessel reflux condenser for evaporative cooling of the reaction medium. For the irradiation of larger reaction volumes, the microwave is here preferably operated in multimode. The discontinuous

Embodiment of the inventive method allows by varying the microwave power fast as well as slow heating rates and in particular holding the temperature for long periods such as several hours. The reactants and, if appropriate, solvents and further auxiliaries can be initially introduced into the reaction vessel before the beginning of the microwave irradiation. Preferably, they thereby have temperatures below 100 ⁰ C, for example between 10 ° C and 35 ⁰ C. In a preferred embodiment, the reactants or parts of the reaction vessel are supplied only during the irradiation with microwaves. In a further preferred embodiment, the discontinuous microwave reactor is operated under continuous supply of educts and simultaneous discharge of the reaction mixture in the form of a semi-batch or cascade reactor.

In a particularly preferred embodiment, the process according to the invention is carried out in a continuous microwave reactor. The

To this end, the reaction mixture is passed through a pressure-resistant reaction tube which is inert with respect to the reactants and largely transparent to microwaves and built into a microwave oven. This reaction tube preferably has a diameter of one millimeter to about 50 cm, especially between 2 mm and 35 cm, for example between 5 mm and 15 cm. Reaction tubes are understood here to be vessels whose ratio of length to diameter is greater than 5, preferably between 10 and 100,000, particularly preferably between 20 and 10,000, for example between 30 and 1,000. In a specific embodiment, the reaction tube is designed in the form of a double-walled tube through its inner and outer space, the reaction mixture can be successively countercurrently, for example, to increase the temperature control and energy efficiency of the process. The length of the reaction tube is that of the reaction mixture to understand a total flowed through track. The reaction tube is surrounded on its length by at least one, but preferably by several such as, for example, two, three, four, five, six, seven, eight or more microwave radiators. The microwave radiation preferably takes place via the tube jacket. In a further preferred embodiment, the microwave irradiation takes place by means of at least one antenna via the tube ends. The reaction tube is usually provided at the inlet with a metering pump and a pressure gauge and at the outlet with a pressure-holding valve and a heat exchanger. Preferably, the starting materials polyamine and Cs-C _δ carboxylic acid, both optionally diluted with solvent, if appropriate, are mixed shortly before they enter the reaction tube. Further preferably, the reactants are fed to the process according to the invention in liquid form at temperatures below 100 ⁰ C, preferably between 10 and 80 ⁰ C, such as between 20 and 5O ⁰ C.

By varying the tube cross-section, length of the irradiation zone (this is understood to mean the proportion of the reaction tube in which the reaction mixture is exposed to microwave radiation), flow rate, geometry of the microwave radiator, the irradiated microwave power and the temperature reached thereby, the reaction conditions are adjusted so that the maximum reaction temperature is reached as quickly as possible and the residence time at maximum temperature remains so short that so few side or subsequent reactions occur as possible. The continuous microwave reactor is preferably operated in monomode or quasi-monomode. The residence time in the reaction tube is generally less than 30 minutes, preferably between 0.01 seconds and 15 minutes, for example between 0.1 seconds and 5 minutes, for example between one second and 3 minutes. To complete the reaction, if appropriate after intermediate cooling, the reaction mixture can pass through the reactor several times, it being possible for the product formed and / or the by-product to be separated off, if appropriate, in an intermediate step. It has proven particularly useful if the reaction product immediately after leaving the reaction tube z. B. is cooled by jacket cooling or relaxation. It was particularly surprising that, despite the residence time of the ammonium salt in the microwave field, which is only very short in the continuously flowing flow tube, such extensive amidation takes place without formation of significant amounts of by-products. In a corresponding implementation of these ammonium salts in a flow tube under thermal jacket heating extremely high wall temperatures are required to achieve suitable reaction temperatures, which lead to polymerization and formation of Mannich adduct and various amine derivatives, but only to the formation of minor amounts of basic amides ethylenically unsaturated carboxylic acids.

To complete the reaction, it has proven useful in many cases to suspend the resulting crude product after removal of water of reaction and optionally discharging product and / or by-product again the microwave irradiation.

Usually, amides prepared via the route according to the invention are obtained in a sufficient purity for further use. For special requirements, however, they can be further purified by customary purification processes such as distillation, recrystallization, filtration or chromatographic processes.

The amides prepared according to the invention are particularly suitable for homopolymerization as well as for copolymerization with other ethylenically unsaturated compounds. Based on the total mass of the (co) polymers, their content of amides prepared according to the invention may be from 0.1 to 100% by weight, preferably from 20 to 99.5% by weight, particularly preferably from 50 to 98% by weight. As comonomers, it is possible to use all ethylenically unsaturated compounds whose reaction parameters permit copolymerization with the amides prepared according to the invention in the respective reaction media.

Preferred comonomers are ethylenically unsaturated carboxylic acids, such as for example, (meth) acrylic acid, maleic acid, fumaric acid and itaconic acid and their anhydrides, esters, amides and salts. Also sulfonic acids such as styrenesulfonic acid, vinylsulfonic acid, allylsulfonic acid and methallylsulfonic acid and phosphonic acids such as vinylphosphonic acid and allylphosphonic acid and salts thereof are suitable as comonomers.

Preferred esters of these acids are those with aliphatic alcohols having 1 to 30 carbon atoms, cycloaliphatic alcohols having 5 to 30 carbon atoms and arylaliphatic or aromatic alcohols having 6 to 30 carbon atoms such as methyl acrylate, methyl methacrylate,

Lauryl methacrylate and stearyl acrylate. The aliphatic radicals may be linear or branched and saturated or unsaturated.

Preferred amides of these acids are derived from ammonia and amines with one or two hydrocarbon radicals each having 1 to 24 carbon atoms. Examples of particularly preferred amides are acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide and N, N-diisopropylacrylamide.

Preferred salts of these acids carry, for example, Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Al ³⁺ , NH ⁴⁺ , monoalkylammonium, dialkylammonium, trialkylammonium and / or tetraalkylammonium cations The alkyl substituents of the ammonium ions independently of one another can be carbon hydrogen radicals having 1 to 22 C atoms, hydroxyalkyl groups having 3 to 10 C atoms or poly (oxyalkylene) groups. The degree of neutralization of the carboxylic acids can be between 0 and 100%.

Also preferred as comonomers are vinyl esters of carboxylic acids having 2 to 20 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl 2-ethylhexanoate and vinyl neodecanoate, open-chain N-vinylamides such as N-vinylformamide (VIFA), N-vinylmethylformamide,

N-vinylmethylacetamide (VIMA) and N-vinylacetamide, cyclic N-vinylamides (N-vinyllactams) having a ring size of 3 to 9 such as N-vinylpyrrolidone (NVP) and N-vinylcaprolactam, alkoxylated acrylic and Methacrylic acids and amides such as hydroxyethyl methacrylate, hydroxymethylmethacrylamide, hydroxyethylmethacrylamide, hydroxypropylmethacrylamide and succinic mono [2- (methacryloyloxy) ethyl ester], N, N-dimethylaminomethacrylate and diethylamino-methylmethacrylate. Examples of further preferred comonomers are acrylonitrile, acrylic and methacrylamidoglycolic acid, vinyl ethers of alcohols having 1 to 22 carbon atoms, olefins having 2 to 20 carbon atoms, styrene, alkylstyrenes, vinyl chloride, vinylidene chloride, tetrafluoroethylene, 2- and 4-vinylpyridine and methacrylate. Mixtures of various comonomers are also suitable for copolymerization.

The inventive method allows a very fast and inexpensive production of basic amides of unsaturated carboxylic acids in high yields and with high purity. There are no significant amounts of by-products. The products made by the process according to the invention are also almost colorless, that is they have APHA color numbers of less than 100 and often less than 50, such as between 30 and 15. Therefore, usually no up or reworking steps are required. Such rapid and selective reactions can not be achieved by conventional methods and were not to be expected by heating to high temperatures alone. Since the amides prepared by the process according to the invention and the (co) polymers derived from them contain no residues of coupling reagents or their secondary products due to the process, they can also be used without problems in toxicologically sensitive areas such as, for example, cosmetic and pharmaceutical preparations. Furthermore, due to their process-related freedom from halide ions, they can be used in areas prone to corrosion such as, for example, in plants for oil and gas production and treatment. Examples

The reactions under microwave irradiation were carried out in a single-mode microwave reactor of the "Discover" type from CEM at a frequency of 2.45 GHz.The reaction vessels were cooled by means of compressed air take place at the bottom of the cell. Comparative tests with a dipping into the reaction mixture of glass fiber optics, it was found that the temperature in the reaction medium in the temperature range relevant here about 50 to 8O ⁰ C above the temperature measured by the IR sensor at the base of the cuvette.

The discontinuous reactions were carried out in closed, pressure-resistant glass cuvettes with a volume of 8 ml under magnetic stirring. Continuous reactions were carried out in pressure-resistant, cylindrical glass cuvettes (about 10 × 1.5 cm, reaction volume about 15 ml) with the introduction tube ending above the cuvette bottom and product removal at the upper end of the cuvette (double-jacket tube). The pressure built up during the reaction was limited to a maximum of 20 bar via a pressure-maintaining valve and released into a receiver. The ammonium salt was pumped into the cuvette through the inlet tube and the residence time in the irradiation zone adjusted to about 1 minute by modifying the pumping capacity.

The ethylenically unsaturated carboxylic acids used were stabilized with 200 ppm hydroquinone monomethyl ether.

The products were analyzed by means of ¹ H NMR spectroscopy at 500 MHz in CDCl ₃ or by GC / MS. Water determinations were carried out by Karl Fischer titration.

Example 1: Preparation of N- (3- (N, N-dimethylamino) propyl) methacrylamide

With cooling, 1 g of N, N-dimethylaminopropylamine was mixed with an equimolar amount of methacrylic acid and mixed. After the subsidence of Cation of heat, the resulting ammonium salt was exposed in a closed cuvette for 1 minute under maximum cooling power of a microwave irradiation of 100 W. It was measured by an infrared sensor temperature of 15O ⁰ C, the pressure rose to 10 bar. Subsequently, the reaction mixture was cooled to 3O ⁰ C within 2 minutes.

The crude product obtained contained as main components 82% N- (3- (N, N-dimethylamino) propyl) methacrylamide, 4% Michael adduct, 9% water and unreacted starting materials. After drying the reaction mixture over MgSO ₄ , again irradiating for one minute with microwaves of 100 W and drying over molecular sieve N- (3- (N, N-dimethylamino) propyl) methacrylamide was obtained with over 98% purity. The APHA color number was 45.

Example 2: Preparation of N- (3- (N, N-dimethylamino) propyl) acrylamide

With cooling, 2 g of N, N-dimethylaminopropylamine were mixed with an equimolar amount of acrylic acid and mixed. After quenching of the heat of reaction, the ammonium salt thus obtained was exposed in a closed cuvette for 1 minute under maximum cooling power of a microwave irradiation of 25 W. It was a measured by IR sensor temperature of 8O ⁰ C at a pressure of about 1.3 bar achieved. After the end of the irradiation, the reaction mixture was cooled to 30 ^° C. within 2 minutes.

The crude product obtained contained as main components 61% N- (3- (N, N-dimethylamino) propyl) acrylamide, 12% Michael adduct, 7% water and unreacted starting materials. After drying the reaction mixture over MgSO ₄ , re-irradiation for a minute with microwaves of 50 W and drying over molecular sieve N- (3- (N, N-dimethylamino) propyl) acrylamide was obtained with over 95% purity. The APHA color number was 35. Example 3: Preparation of N- (p- [N, N-dimethylamino] phenylene) methacrylamide

While cooling, 1 g of p- (N, N-dimethyl) phenylenediamine was mixed with 2 molar equivalents of methacrylic acid and mixed. After quenching of the heat of reaction, the resulting ammonium salt was exposed in a closed cuvette under maximum cooling power of a microwave power of 150 W. The mixture was heated to 185 ^° C. within one minute, and this temperature was maintained under air cooling of the cuvette for 10 minutes, the pressure gradually increasing to 2 bar. It was then cooled by air cooling to below 50 ⁰ C within two minutes.

In the crude product, 92% of p- (N, N-dimethyl) phenylenediamine had been converted to N- (p- [N, N-dimethylamino] phenylene) methacrylamide. The other constituents of the crude product were water of reaction and unreacted educts. After removal of the water of reaction, again microwave irradiation for 10 minutes and distillative removal of excess methacrylic acid and water of reaction, 98% N- (p- [N, N-dimethylamino] phenylene) methacrylamide was obtained. The APHA color number was 41.

Example 4: Preparation of N- (triazolyl) methacrylamide

With cooling, 0.5 g of 3-amino-1,2,4-triazole were mixed with the equimolar amount of methacrylic acid and mixed. After quenching of the heat of reaction, the ammonium salt thus obtained in a closed cuvette with a

Microwave power of 100 W irradiated. It was heated to 150 ^° C. within one minute, and this temperature was maintained under air cooling of the cuvette for 2 minutes, the pressure rising to 2 bar. It was then cooled by air cooling to 50 ⁰ C within two minutes.

The crude product contained 86% N- (triazolyl) -methacrylamide, 3% Michael adduct and 10% water. After drying over MgSO 4 and again irradiating for one minute with a microwave power of 100 W, N- (triazolyl) methacrylamide with more than 98% purity and APHA color number of 53 was obtained.

Example 5: Preparation of N - ((pyridin-4-yl) methyl) methacrylamide

While cooling, 1 g of 4-aminopyridine was mixed with 2 molar equivalents of methacrylic acid and mixed. After quenching of the heat of reaction, the ammonium salt thus obtained was exposed in a closed cuvette under maximum cooling power within 2.5 minutes of a microwave power of 100 W. The temperature rose to about 18O ⁰ C, the pressure gradually to 20 bar. It was then cooled by air cooling to below 50 ⁰ C within two minutes.

In the crude product 81% of the 4-aminopyridine used were converted to N - ((pyridin-4-yl) methyl) methacrylamide. The other constituents of the crude product were water of reaction and unreacted educts. After removal of the water of reaction, again microwave irradiation for 2 minutes and distillative removal of excess methacrylic acid and water of reaction 98% N- (p- [N, N-dimethylamino] -phenylene) - methacrylamide with APHA color number of 62 was obtained. Example 6: Continuous preparation of N- (3- (N, N-dimethylamino) propyl) methacrylamide

With cooling and stirring, 100 g of N, N-dimethylaminopropylamine were dissolved in 100 g of xylene and slowly admixed with an amount of methacrylic acid which was equimolar with respect to the amine. After quenching of the heat of reaction, the resulting ammonium salt was continuously pumped through the bottom inlet through the glass cuvette mounted in the microwave cavity. The delivery rate of the pump was adjusted so that the residence time in the cuvette and thus in the irradiation zone was about 50 seconds. It was worked under maximum cooling power with a microwave power of 200 W, with a measured by IR sensor temperature of 150 ⁰ C was reached. After leaving the glass cuvette, the reaction mixture was cooled to 3O ⁰ C via a short Liebig condenser.

The crude product obtained contained as main components 80% N- (3- (N, N-dimethylamino) propyl) methacrylamide, 7% Michael adduct, 8% water and unreacted starting materials. After drying the reaction mixture over MgSO ₄ and re-running the above process and drying again N- (3- (N, N-dimethylamino) propyl) methacrylamide was obtained with over 98% purity. The APHA color number was 23.

Example 7: Continuous Preparation of N- (3-N, N-dimethylamino) -propyl) -methacrylamide

A 50% solution of the ammonium salt of methacrylic acid and dimethylaminopropylamine (equimolar mixture stabilized with 200 ppm phenothiazine) in toluene was continuously pumped through the glass cuvette mounted in the microwave cavity. The delivery rate of the pump was adjusted so that the residence time in the cuvette and thus in the irradiation zone was about 5 minutes. The microwave power was regulated between 25 W and 150 W so that under maximum cooling power a measured by IR sensor Temperature was maintained between 150 and 160 ⁰ C. After leaving the glass cuvette, the reaction mixture was cooled to 30 ⁰ C.

The crude product obtained contained as main components 84% N- (3- (N, N-dimethylamino) propyl) methacrylamide, 2% Michael adduct, 9% water and unreacted starting materials. After drying the reaction mixture over MgSO ₄ and re-running the above process and drying again N- (3- (N, N-dimethylamino) propyl) methacrylamide was obtained with over 98% purity. The APHA color number was 27.

Example 8: Continuous Preparation of N- (3- (N, N-dimethylamino) propyl) methacrylamide

A 50% solution of the ammonium salt of methacrylic acid and dimethylaminopropylamine (equimolar mixture, stabilized with 200 ppm

Phenothiazine) in toluene was continuously pumped through the glass cuvette mounted in the microwave cavity. The delivery rate of the pump was adjusted so that the residence time in the cuvette and thus in the irradiation zone was about 2 minutes. The microwave power was controlled between 25 W and 200 W such that, under maximum cooling power, a temperature measured by means of the JR sensor was kept between 175 and 185 ^° C. After leaving the glass cuvette, the reaction mixture was cooled to 30 ° C.

The crude product obtained contained as main components 85% N- (3- (N, N-dimethylamino) propyl) methacrylamide, 1% Michael adduct, 9% water and unreacted starting materials. After drying the reaction mixture over MgSO ₄ and re-running the above process and drying again N- (3- (N, N-dimethylamino) propyl) methacrylamide was obtained with over 98% purity. The APHA color number was 17. Examples 9 and 10:

Continuous thermal reaction of methacrylic acid with

Dimethylaminopropylamine (comparative examples)

Analogously to Examples 7 and 8, a 50% solution of the ammonium salt of methacrylic acid and dimethylaminopropylamine (equimolar mixture, stabilized with 200 ppm phenothiazine) in toluene was pumped continuously through the located in a 300 ⁰ C hot sand bath pressure resistant glass cuvette. The delivery rate of the pump was adjusted so that the residence time of the reactants in the cuvette and thus in the heating zone was about 2 and 5 minutes, respectively. The temperature of the reaction mixture was measured at the outlet of the cuvette. The observed maximum temperatures were 150 and 180 ⁰ C (see table below). After leaving the glass cuvette, the reaction mixture was cooled rapidly to room temperature.

The experiments led to the following results.

The remaining 100% of the shares are attributable essentially to unreacted starting materials, water of reaction and other unidentified by-products.

After the experiment, the reactor had solid, brown deposits on the walls and floor indicating polymer formation and decomposition.

In order to investigate differences between the basic acrylamides prepared according to the invention and corresponding basic acrylamides conventionally prepared by reaction of methyl acrylate with dimethylaminopropylamine, both products were used for the preparation of high molecular weight Copolymers used with acrylamide. The copolymers thus prepared were then tested for their suitability as flocculation aids.

Examples 11 and 12: Copolymerization of N- (3- (N, N-dimethylamino) -propyl) acrylamide (DiMAPAM) with acrylamide

In an isolated polymerization vessel, the amounts of monomers and ABAH (2,2'-azobis-amidinopropane dihydrochloride) listed in Table 1 and bis (2-aminoethyl) -amine-N, N, N \ N ~, N ^" - pentaacetic acid dissolved in the stated amount of water. Under ice cooling, the reaction mixture was cooled to 10 ⁰ C and thereby made inert by bubbling nitrogen for 90 minutes. Subsequently, tert-butyl hydroperoxide, and further 5 minutes later added to the pyrosulfite solution. A temperature rise showed the use in the polymerization. After the peak temperature had been reached, the polymer was about 12 hours, allowed to stand at 7O ⁰ C to react. the resultant polymer gel was crumbled, dried and milled.

Table 1: Reaction approaches for polymerizations

The relative viscosity (according to Ubbelohde at 25 ^° C.) of 0.2% solutions of both polymers in water was determined:

Polymer A, prepared using N- (3- (N, N-dimethylamino) propyl) acrylamide prepared in accordance with the invention, results in a copolymer of significantly higher viscosity than comparative polymer B, indicating a higher molecular weight of polymer A, under the same procedure.

Example 13:

Suitability of polymers of N- (3- (N, N-dimethylamino) propyl) acrylamide as

Flockkulationshilfsmittel

In the extraction of various minerals, the raw materials obtained as aqueous suspensions must be dehydrated. Among other things, the fastest possible sedimentation of the particles suspended in water is desired. Polymers A and B were compared in a flocculation test to evaluate the rate of flocculation and especially the sedimentation of a mineral suspension.

Polymer A or Polymer B were prepared as 0.1% w / w stock solutions in tap water 12-24 hours before the start of the test. For this purpose, 500 mg of polymer in 49.5 g of water were stirred in a sealable sample tube at room temperature with a magnetic stirring bar for about 4 hours.

In a 2 L beaker, 1 L of a suspension consisting of 4% by weight of kaolin in tap water with various concentrations of polymer A or B to be tested as flocculants was added for 15 seconds at ca. 1000 rpm, stirred. Immediately after stirring, the suspension was transferred to a 1 L standing cylinder. The sedimentation rate was determined by measuring the time taken for the clear supernatant boundary and the kaolin suspension to cover the strip between two markers at a depth of 3 cm and 8 cm. The sedimentation rate is given in cm / min. The results of the measurements are summarized in Table 2:

Table 2: Sedimentation rate of additized kaolin suspensions

The test results show faster sedimentation of the polymer A-treated suspension at each tested test concentration as compared to that treated with polymer B (control).

These contaminants show that the use of monomers prepared according to the invention makes polymers with superior performance properties accessible.

Claims

claims

1. A process for the preparation of basic amides or imides of ethylenically unsaturated C ₃ - to Cε-carboxylic acids, by reacting amines which contain at least one primary and / or secondary amino group and at least one tertiary amino group, with ethylenically unsaturated C ₃ - to C ₆ carboxylic acids be converted to an ammonium salt, and this ammonium salt is subsequently reacted under microwave irradiation to the basic amide or imide, with the proviso that the primary and / or secondary amino group does not comprise alkoxy groups.

2. The method of claim 1, wherein the amines of the formula

HNR ¹ - (A) _n -Z

correspond, in which

R ¹ represents hydrogen, Ci-C ₁₂ alkyl, C ₅ -C ₁₂ cycloalkyl, C ₆ -C ₁₂ aryl, C ₇ -

Ci _2-aralkyl or a heteroaromatic group having 5 to 12 ring members, A is an alkylene radical having 1 to 12 carbon atoms, a cycloalkylene radical having 5 to 12 ring members, an arylene group having 6 to 12 ring members or a heteroarylene group having 5 to 12 ring members n for 0 or 1,

Z is a group of the formula -NR ² R ³ or a nitrogen-containing cyclic hydrocarbon radical having at least 5

Ring links and

R ² and R ³ independently of one another are d- to C _2O- hydrocarbon radicals or for polyoxyalkylene radicals.

3. The method of claim 2, wherein R ^{1 is} hydrogen or methyl.

4. The method of claim 2 and / or 3, wherein A is a linear or branched alkylene radical having 1 to 12 carbon atoms and n is 1.

5. The method according to one or more of claims 2 to 4, wherein R ² and R ^{3 are} independently aliphatic, aromatic and / or araliphatic carbons hydrogen radicals having 1 to 20 carbon atoms.

6. The method of claim 5, wherein R ² and R ^{3 are} independently alkyl radicals having 1 to 14 carbon atoms.

7. The method according to one or more of claims 2 to 4, wherein R ² and / or R ³ independently of each other for polyoxyalkylene radicals of the formula

- (BO) _m -R ⁴ ,

stand in which

B is a linear or branched C ₂ -C 4 -alkylene radical, m is a number from 1 to 100,

R ^{4 is} hydrogen, an alkyl radical having 1 to 20 C atoms, a cycloalkyl radical having 5 to 12 ring atoms, an aryl radical having 6 to 12 ring atoms, an aralkyl radical having 7 to 30 C atoms, a heteroaryl radical having 5 to 12 ring atoms or a Hetero-aralkyl radical having 6 to 12 carbon atoms.

8. The method according to one or more of claims 1 to 6, wherein the amine of N, N-dimethylethylenediamine, N, N-dimethyl-1, 3-propanediamine, N, N-diethyl-1, 3-propanediamine and N, N Dimethyl 2-methyl-1,3-propanediamine.

9. The method according to one or more of claims 2 to 8, wherein Z is a nitrogen-containing, cyclic hydrocarbon radical whose nitrogen atom is not capable of forming amides.

10. The method according to one or more of claims 1 to 9, wherein the ethylenically unsaturated carboxylic acid of acrylic acid, methacrylic acid, crotonic acid, 2,2-dimethylacrylic acid, maleic acid, fumaric acid and itaconic acid is selected.

11. The method according to one or more of claims 1 to 10, wherein the microwave irradiation is carried out in the presence of a dehydrating catalyst.

12. The method according to one or more of claims 1 to 11, wherein the microwave irradiation is carried out in the presence of a solvent.

13. The method of claim 12, wherein the solvent has an ε ^" value of less than 10.

14. The method according to one or more of claims 1 to 13, wherein the microwave irradiation is carried out at temperatures below 300 ⁰ C.

15. Basic amides or imides of ethylenically unsaturated C ₃ - to C ₆ -carboxylic acids preparable by reacting amines containing at least one primary and / or secondary amino group and at least one tertiary amino group with ethylenically unsaturated C ₃ - to C ₆ -carboxylic acids Ammonium salt are reacted, and this ammonium salt is subsequently reacted under microwave irradiation to the basic amide or imide, with the proviso that the primary and / or secondary amino group does not comprise alkoxy groups.

16. Basic amides or imides according to claim 15, which are substantially free of halide ions and coupling reagents derived by-products.

17. The method according to one or more of claims 1 to 16, wherein the reaction is carried out at pressures between 0.1 and 200 bar.

18. The method according to one or more of claims 1 to 17, wherein the reaction is carried out continuously by irradiation with microwaves in a reaction tube through which the ammonium salt flows.

19. The method of claim 18, wherein the reaction tube consists of a non-metallic, microwave-transparent material.

20. The method of claim 18 and / or 19, wherein the residence time of the reaction mixture in the reaction tube is less than 30 minutes.

21. The method according to one or more of claims 18 to 20, wherein the reaction tube has a length to diameter ratio of at least 5.