DE2721910A1 - PROCESS FOR THE POLYMERIZATION OF 2-PYRROLIDONE - Google Patents

Description

I ₁ . f3, May 1977

BEIL, WfOLFF & BEIL

RIGHT ^ AN ¹ VALTE ADELONS Uv ^ L 53 6230 FRANKFURT AM MAIN

Our No. 21 167 Pr / br

Chevron Research Company San Francisco, CaI., V.St.A.

Process for the polymerization of 2-pyrrolidone

709848/0999

NAOHGLi El '.

Poly-2-pyrrolidone is produced by polymerizing 2-fyrrolidone under catalysis with alkali. The catalyst system can contain a partially carbonized pyrrolidonate, which is prepared, for example, by reacting an alkali hydroxide with 2-pyrrolidone or by reacting a quaternary ammonium hydroxide with 2-pyrrolidone, and dehydrating, whereupon the product is brought into contact with carbon dioxide (US Pat. No. 3,721,652). . Japanese patent specification 47-26195 describes a process for the preparation of a catalyst in which an alkali metal compound which does not form water is reacted with 2-pyrrolidone, whereupon the product is brought into contact with a quaternary ammonium halide under v.-water-free conditions . In US Pat. No. 3,835,100, the production of the catalyst by reacting an alkali metal alkoxide with a quaternary ammonium halide and further reacting the aeronium alkoxide formed with 2-pyrrclidone also avoids the formation of water. The last two processes mentioned are carried out under anhydrous conditions, but no poly-2-pyrrolidone of very high molecular weight is obtained within the usual reaction times. But it iat for some purposes advantageous to use a poly-2-pyrrolidone, high molecular weight, for example, be able to produce quickly in good yield over 500 000th

According to the invention is a process for the polymerization of 2-pyrrolidone in the case of 2-pyrrolidone brought into contact with a catalyst, characterized in that the 2-pyrrolidone with a catalyst

in Kο ntak t ^
'' is brought from an alkali pyrrolidonate, a quaternary

!, or ^ ect-ei i I worcior: int.

27rrrrtr

While poly-2-pyrrolidone with a medium molecular weight

(Weight average) ^of 300,000 within one

Polymerization time of less than 24 hours when using a partially carbonized potassium pyrrolidonate3 can be produced as a catalyst, it is with the invention Possible catalyst, poly-2-pyrrolidone with a medium

(Weight average)

Molecular weight / of less than 1,000,000 under the same conditions to create. With the catalyst according to the invention Furthermore, high yields and high conversion rates are achieved without lowering the molecular weight of the catalyst, there is no need to use an alkali pyrrolidonate produced under anhydrous conditions. The Pyrroll Donat can also be achieved by reacting 2-pyrrolidone with your Hydroxide instead of an alkali metal or an alkali aUcoxid are formed.

Catalyst system

> In the process according to the invention for the polymerization of.2-pyrrolidone throws a "catalyst prepared by adding an alkali pyrrolidonate, certain quaternary ammonium salts and carbon dioxide, preferably in a molar ratio of about 1: 0.1-2 to 0.1-0.5" more favorable in the molar ratio from about 1i 0.2-1.5 J 0.1-0.5 and in the most favorable case in a molar ratio of about 1: 1: 0.3.

The reactants, i.e. the pyrrolidonate, the ammonium- salt and carbon dioxide, can be used in any order

are brought into contact with one another, starting with the pyrrolidonate as one of the components. It is advantageous, but not necessary, to add the quaternary ammonium salt to the previously carbonized pyrrolidonate An alkali hydroxide is added to excess 2-pyrrolidone, with which it reacts to form a solution of the alkali pyrrolidonate and water in 2-pyrrolidone. The solution is dehydrated until it is less than about 0.1-0. contains 2 weight percent of water, carbon dioxide is in noisy required Molverhältnie to the Pyriolidonat in the solution at a temperature of about 20-5O ⁰ C, preferably 25-35 ⁰ C, was added. Subsequently, da3 quaterräre Ammoniuasalz ia required mole ratio to your Pyrroiidonat at about added at the same temperature.

Another method for preparing the catalyst systems according to the invention is that tetraalkylaramonium halide is generated in situ by reacting trialkylamine with an alkyl halide. Part of the 2-pyrrolidone monomer can be used as a solvent in this reaction

carried out v / ird. In this method, the trialkylamine in 2-pyrrolidone is dissolved and then treated with the alkyl halide, while the temperature in the range of from about IO is kept to 50 ⁰ C. After the end of the reaction, the solution obtained is reacted with alkali pyrrolidonate and carbon dioxide, for example by adding it to a pyrrolidone solution in which the carboxylated alkali salt has been produced by the usual methods. 709848/0999

- fl -

I N /> '! JUST I

y

The quaternary ammonium salts according to the invention are salts of Pornel (R) -N ⁺ X "* or R ₁ R ₂ R ₅ R-II ⁺ X", in which the radicals R are identical or different lower alkyl, alkylaryl or aralkyl groups, preferably AlVy groups with 1 to 6 carbon atoms, more favorable alkyl groups with 1 to 3 carbon atoms and, in the most favorable case, methyl groups, while X "is a halide or carboxylate anion.

The quaternary ammonium carboxylate preferred according to the invention is a tetraalkylaminonium carboxylate of a lower alkanoic acid, in which the alkyl substituents are lower alkyl groups. The tetraalkylammonium carboacylate can be prepared by neutralizing the carboxylic acid with the tetraalkylammonium hydroxide. The tetraalkylammonium carboxylate is preferably a tetraalkylammonium carboxylate in which the alkyl groups have 1 to 6 and more conveniently 1 to 3 carbon atoms. Suitable alkyl groups are, for example, the radicals methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, hexyl, etc. The carbocylate is preferably the alkanate of an alkanoic acid having 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms and, in the most favorable case, the acetate . Suitable alkylammonium * arboxylates are tetramethylammonium acetate, tetraethylaimnontuiaacetat, dimethyl diethylammonium propionate, etc. The ammonium carboxylate can also be used as a combination of suitable compounds, e.g. be used as a mixture of letramethylammonium acetate and tetraethylammonium acetate. The ammonium carboxylate should, however, under the alkaline conditions of the preparation of the rAtalysatorsystoms and the polymerization of the 2-Pyrrolidocfl

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-3 -

be essentially soluble to have a noticeable effect to exercise the Polymerisatlonsrealction. In this regard shows Tetramethylasunoniu & acetate a considerable advantage over the corresponding halide, tetramethylammonium chloride, because it is much more soluble in the polymerisation mixture is.

The quaternary ammonium halide according to the invention is an ammonium halide substituted with lower alkyl, alkylaryl or aralkyl groups. The quaternary ammonium halide is preferably a letraalkylammonium halide. The alkyl groups of the tetraalfrylammoniurahalogenide preferably have 1 to and in the most favorable case 1 to 3 carbon atoms. Suitable alkyl groups are, for example, the radicals methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, hexyl, etc. The ammonium halide is preferably a chloride, bromide or iodide, more preferably a chloride or bromide and, in the most favorable case, a chloride. The ammonium halide can be used as a combination of suitable compounds, for example as a mixture of tetraethylammonium chloride and tetraethylammonium bromide. The ammonium halide should be soluble in the soluble under the alkaline conditions of the preparation of the catalyst system in order to have a noticeable effect on the polymerization reaction.

Alkylarylanmonium halides such as phenyltrimethylammonium halide and toluyltriethylammonium halide, fall within the scope of the ammonium halides according to the invention. The ammonium halides, which are used in the context of the invention,

709848/0999

- VÖ - I NACt COURT ]

also include compounds such as _t RR ₂ R- (0CH ₂₎ MX ₁ wherein 0 is a phenyl radical, and R ^, R ₂ and R ₅ are the same or different lower alkyl groups or other lower aralkyl, and X is a halide. Accordingly, the quaternary ammonium halides as used here include the aralkyl anunonium halides.The aralkyl groups used in these compounds normally have 7 to 12 carbon atoms, such as the radicals benzyl, phenethyl, etc.

The alkali pyrrolidonate is preferably sodium or potassium pyrrolidonate. For certain purposes it can be advantageous to replace the pyrrolidate in whole or in part with an alkali metal caprolactamate or to replace the alkali salt of another low molecular weight lactam, but the use of these substances offers usually no advantages over that of pyrrolidonate. The alkali pyrrolidonate is preferably prepared by the alkali hydroxide is brought into contact with excess 2-pyrrolidone !:, but other methods can also be used e.g. the reaction of 2-pyrrolidone with an AIVaTicetali or an alkali alkoxide. In contrast to the production of luaternary ammonium pyrrolidonate from quaternary ammonium ' hydroxide, there is no such strong amine odor in the process according to the invention. The method using Nafcrium pyrrolidonate (e.g. made with NaOH) and quaternary Ammon i υτηη al ο genlct is practically odorless, for which reason is to give preference to Hatrium. Preference is given to the etraalkylammonium halide, the pyrrolidonate and carbon dioxide

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-U-

! NACHQEUEIQH TI

mw °

2721

in a solution of 2-pyrrolidone together in KonTakv g brings, but the 2-pyrrolidone can also be wholly or partially be replaced by inert solvents. Sulfur dioxide is to be regarded as a partial substitute for carbon dioxide, its use is therefore not excluded within the scope of the invention »

Polymerization initiators can also be used in the catalyst system according to the invention and polymerization accelerators are used. An unexpectedly rapid polymerization to poly-2-pyrrolidone with a satisfactorily high molecular weight is obtained with this catalyst system by adding 0.05-1.5 mol percent Acetic anhydride reached. Preferably 0.05-1.0 percent and in the most favorable case 0.05-0.5 mol percent acetic anhydride used. Suitable accelerators are also described in U.S. U.S. Patent 3,721,652, including N-acyllactars, especially N-acylpyrrolidones and preferably H-acetylpyrrolidone. 1- (i-Pyrrole: ax-2-yl) -2-pyrrolidone is a particularly suitable activator

Polymerization conditions

The polymerization process of the present invention is particularly applicable to the polymerization of 2-pyrrolidone with the formation of a polymeric carbonamide of very high molecular weight, which can be obtained in a reasonably short polymerization time of 4 to hours. They achieved mean molecular weights (weight average) were more than 1,000,000. The high molecular weight polymer can be formed into fibers are oriented essentially along the fiber axis

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and have high tensile strength and other properties that are favorable for processing into textiles. That Material can be after melt injection or melt extrusion processes are processed into molded articles and films.

To get a high quality poly-2-pyrrolidone, which can be processed into fibers, threads and yarn of commercial textile quality, the 2-pyrrolidone must have a high degree of purity »Depending on the manufacturing process Commercial 2-pyrrolidone contain appreciable amounts of various impurities, some of which cause polymerization likely to adversely affect the purification of the monomer to the degree necessary for the polymerization can be carried out by known methods, e.g. by distillation.

The inventive method is applicable to the production of polymers of C-alkyl-substituted pyrrolidones, such as 4-methyl-2-pyrrolidone, and copolymers of 2-pyrrolidona, for example with Caprolaotau, as well as on the production of poly-2-pyrrolidone · In general, therefore, unless otherwise stated, the term "monomer" means 2-pyrrolidone, substituted 2-pyrrolidone and any other compound which can be copolymerized with 2-pyrrolidone under the stated conditions of alkaline polymerization catalysis.

Preferably the catalyst system makes up about 0.5-30 mole percent or more of the 2-pyrrolidone catalyst mixture, based on Total 2-pyrrolidone, from, cheaper etvra 5-20 mole percent and in Favorable case about 10 mole percent. The total 2-pyrrolidone

709848/0999

I NACHQERPOHT

"consists of the 2-pyrrolidonate catalyst, the alkali pyrrolidonate mad quaternary ammonium pyrrolidonate as well as carbonized Alkali pyrrolidone and carbonated cjuaternary aminonium pyrrolidonate contains, so \ / ie from 2 ~ pyrrolidone, the solvent serves for the catalyst, and any other monomers added to the mixture for the Polymerlsationsrealction have been. The catalyst system for the polymerization is said to be mainly quaternary ammonium pyrrolidonate and carbonized quaternary ammonium pyrrolidonate, but it can also contain substantial amounts of alkali pyrrolidonate and carbonized alkali pyrrolidonate (carboxypyrrolidonate) may be present, depending on the selected wood ratios. Also alkali halide can be present, but i3t compared to the polymer! - sationareaktion to be considered inert.

In general, 2-pyrrolidone can be at a temperature of about 15 ⁰ C to about 10O ⁰ C, preferably 25 ° C to 70 ⁰ C and, at best, about 40 ⁰ C to about 60 ⁰ C at reduced pressure, normal pressure or elevated pressure in the presence of de3 catalyst system are polymerized, for which about 4 to about 100 hours or more, preferably about 8 to about 72 hours and generally about 8 to about 48 hours are required. In a continuous process, the polymerization time refers to the mean residence time under the polymerization conditions, in a small amount of water, not more than about 0.1-0.2 percent by weight based on the total 2-pyrrolidone, is permissible in the reaction mixture, but preferably no more than 0.1 percent by weight should be present.

709848/0999

I REQUIRE J

In the production of polymers of 2-pyrrolidona according to the customary process according to the invention, monomers, catalysts, inert liquids that do not serve as solvents, initiators and other additives can be used in various proportions - the amount of each component being chosen so that it contributes to the most effective polymerization possible - and the reaction mixture can be stirred or not and it can be carried out continuously or batchwise according to the process, bulk polymerization, solution polymerization or some other process. The preferred conditions for carrying out the reaction and Ά & Λ ^ βη of the components have been specified, but it goes without saying that there are no restrictions associated with this, but that polymerizations can also be carried out successfully outside the preferred ranges.

EXAMPLES

hex game 1

100 g of 2-pyrrclidone (1.175 mol) were with 1.55 g of 85 »5 ftLgen £ 0H-? Ellet & (0.0236 moles) mixed to make a solution of 2 mole percent Produce potassium pyrrolidonate. This was dehydrated, by heating it at a pressure of 2 mm Ug for 11 minutes until the start of the distillation. To dehydrate the So much carbon dioxide was added to the solution that a polymerization mixture was obtained which contained 30 mol percent CO « based on valium anthielt. The carbonized pyrrolidonate

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1 il ".—— I

solution was poured into 2 bottles, of which one (a) (b) 8 hours at 5O ⁰ C and the other was stored for 22 hours at 50 ⁰ C. At the end of this time, the contents of the vessels were crushed, washed with water, dried, weighed and, as described, subjected to the viscosity measurement to determine the molecular weight. The results are shown in Table I. Examples 2-3 were carried out essentially as Example 1.

Example 4

The procedure was as in Example 1, but 2.59 g were obtained (0.0236 Hol) tetramethylammonium chloride added after carbonation, including the dried onium salt in a dry Vessel weighed and placed in an Np atmosphere with stirring Room temperature was added to the polymerization mixture over 5 minutes. The rest of the procedure was as in Example 1 carried out. Examples 5-9 essentially corresponded to Example 4

Examples 10-12

A 3 liter flask fitted with a stirrer, thermometer and a distillation attachment was charged with 1,000 ml of benzene and 108 g (2 mol) of sodium methoxide. The mixture was heated to the boiling point and 100 ml of benzene were distilled off. Then, with further distillation, 187.24 g (2.2 mol) of pyrrolidone were added over the course of 38 minutes. The distillation was continued until no more methanol passed over. During this time, 1,200 ml of benzene was added and the amount Gesaatdestillat 998 ml · After cooling to 21 ⁰ C 24.5 g COp were slurry initiated within 40 minutes to the Avf. The down

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27219

Impact was separated off by filtration, washed with benzene and then with pentane and finally dried under an Np atmosphere, with 238.67 g of a white solid substance being obtained. The analysis showed that a mixture of sodium pyrrolidonate and CO ₂ sodium pyrrolidonate in a molar ratio of 7: 3 was present. Three flasks were charged with 24.26 g (0.285 mol) of granulated 2-pyrrolidone and 1.8 g (0.015 mol) of the solid described above. The mixture obtained was ^{heated to 100 °} C. for 10 minutes in order to bring the substance into solution. The mixture was then cooled to room temperature before 1.64 g of tetramethylammonium chloride were added to the flask from Example 11 and 2.48 g of tetraethylaanaonium chloride were added to the flask from Example 12. The flask of Example 10 was left without any further suspension. The contents of the three flasks were polymerized at 50 ° C. over a period of 22 hours. The results are shown in Table III.

Example 13

100 grams (1.175 moles) of 2-pyrrolidone was mixed with 3.85 grams of 85.5 # KOH pellets (0.0588 moles) to give a solution containing 5 mole percent potassium pyrrolidonate. This was dehydrated by heating it at a pressure of 2 mm Hg for 10 minutes until the start of distillation. 30 mole percent carbon dioxide based on potassium was added to the dehydrated solution. Then 0.12 g of acetic anhydride (0.1 mol percent based on the total monomer) were added dropwise to the stirred polymerization mixture, which was then ^{polymerized at 30 °} C. over the course of 8 hours. The product was comminuted, washed, dried, weighed

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and subjected to molecular weight determination. The results are listed in Table IV

Example 14

Procedure as in Example 13, but 6.44 g (0.0588 Hol) of tetramethylammonium chloride were added after carbonization, resulting in a solution with a content of 5 percent by weight based on the total monomer. Then 0.12 g of acetic anhydride was added. The further procedure was carried out as in Example 13

According to the polymerization process according to the invention, a high molecular weight poly-2-pyrrolidone is obtained at a high conversion rate, without the unpleasant odor occurring, which is sometimes found in the dehydration of mixtures of quaternary ammonium hydroxide and 2-pyrrolidone.The combination of polymerization activation by carbon dioxide and production the polymerization catalyst with quaternary ammonium halide leads to a polypyrrolidone with an extremely high molecular weight. The addition of about one percent acetic anhydride also has the effect that the rate of polymerization is increased considerably.

Table I shows various polymerization experiments in the presence of potassium pyrrolidonate and carbon dioxide (Py-K / CO «) with and without the addition of tetramethylammonium chloride. It was shown that tetraethyl or tetraethylammonium chloride, in combination with silicon dioxide and potassium pyrrolidonate, was able to produce a polyrrolidone with the extraordinarily high

IT SUFFICIENT

ZTTOTC

produce high average molecular weights of over one million. All molecular weights are given as weight average molecular weights, determined.

from the specific viscosity of 0.1 g of the polymer in a solution of 100 ml of m-cresol at 25 ^° C.

; j

8 hours ¹ % Py-K / CO « ² % ² 3O; (CH -), NCl % Unw ^a Tifllimit Mm ι χ 10 " ⁵ Example 1a 2 O 8.5 117 Example 2a 5 O 16.3 285 Example 3a 10 O 14.4 305 Example 4a 2 2 15.0 210 Example 5a 5 5 40.0 575 Example 6a 10 10 53.9 980 22 hours ¹ Example 1b 2 O 20.1 220 Example 2b 5 O 45.2 380 Example 3b 10 O 48.3 500 Example 4b 2 2 37.7 330 Example 5b 5 5 69.1 1050 Example 6b 10 10 59.4 820 ¹ 50 ° C Mole percent CO _n , based on Z

ταβκγ.τ, τ; ii ¹

Molar ratio % (CIL,) _, NC1 (CEJ.NCI / K % conversion

Mw χ

Example 2b Example 7 Example 8 Example 5b Example 9

0 1.5

5 7.7

0.3 0.6 1.0

1.5

45.2 62.9 68.7 69.1
69.2

22 hours, 50 ° C, 5 mol percent Py-K / C0 _o (30 mol #

380 555 635 1050 605

based on K)

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_lg 1 WfeOiQKFgac ^

TABLE IXI

Carbonated ammonium

Pyrrolidonet, 5 / S halide _f 5 # ^ Untwandlunff Mw χ

Example 2b Py-K / COg ¹ 0 45.2 330

Example 5b "(CH ₃ ) ^ ₁ NCl 69.1 1050

Example 10 Py-Na / CO ₂ ² 0 '34.8 295

Example 11 ^w (UIL ^) ₄ NCl 48.5 380

Example 12 "(C ₂ H ₅ J ₄ IICl 67.4 385

¹ AuS KOH, 50 ° C, 22 hours, 30 MoISi CO ₂ based on K

² NA-alkoxLd, 50 ⁰ C, 22 Hours, 30 app # CO ₂ based on Ha

TABLE IV

LNCl ^ (ΟΊΜΣΟ ^ Ο ¹

Example 2a O O 16

Example 13 O 0.1 47

Example 5a 5 O 40

Example 14 5 0.1 76

Acetic anhydride, mol%
² 8 hours at 50 ° C, 5 mol% Py-K / C0 ₂ (30 mol # CO ₂ based on K)

The examples in Table I show the remarkably high mean Molecular weights (COweights). t ** · with the catalyst system according to the invention at good conversion rates of the monomer in poly-2-pyrrolidone can be achieved ', with regard to the achieved in this reaction Molecular weights of remarkably short polymerizations are required · The conversion in percent is calculated as 100 χ (weight of the polymer) / (weight of the total 2-pyrro-HdOnS) Y where the Gesaxnt-2-pyr: eolidon defined above became.

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The examples in Table II show the effect that the pick ratio from alkali hydroxide, e.g. potassium hydroxide, to tetraalkylamonium halides hac. The highest molecular weights appear to be reached, if equiinolar (equivalent) amounts of alkali pyrrolidonate and tetraalkylammonium halide for Application.

Table III shows the effect that working under anhydrous conditions versus working under water formation, i. the reaction of alkali hydroxide with 2-pyrrolidone, exercises, examples with and without addition of 5 mol percent of the specified Halides are listed. In general, in the case of the catalyst system according to the invention, the hydroxide can be used in a very satisfactory manner Result can be used to introduce the alkali metal.

Table IV shows the remarkable effect exerted on the rate of polymerization by adding a small amount of acetic anhydride to the catalyst system according to the invention. A conversion of 76% can be achieved after only 8 hours of polymerization at 50 ^° C., a product with a molecular weight of 175,000 being obtained.

TABLE TK (UB ^ CO) ₂ O ¹ % (CE _z ) j ^ 01 ^ Conversion ⁴ Mw. χ 10 " ³

Example 15? 0 0 4.1 35

Example 162 0 5 35.4 165

Example 17, 0.6 5 43.2 150

Example 18 ^P 1.11 5 75.7 56

1 mol percent acetic anhydride

»10 percent KOH (K-pyrrolidonate), no CO-

? 5 mole percent KOH (Tf-pyrrolidonai;}, no COf

⁴ 22 hours, 50 ° C *

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Table V shows the effect caused by the absence of CO ₂ in the catalyst system. Eg it turned out that the erlaitteltön Mol ekulargevi elite were lower. The addition of acidic anhydride achieves a high conversion rate within 22 hours, but the average molecular weight is nevertheless reduced "in the absence of carbon dioxide.

HCl

HBr

494
(CH ₅ ) ₃ (CH ₂ CH ₂ OH) II Cl

TABLE VI egg Mw χ icr ³ 590 1050 420 380 1025 610 590 880 510 410 95 - _- Conversion 52.9 69.1 55.0 55 75.2 51.6 55 65.9 49.1 25.9 17.9 0 0

₅ HtICl

'With a molar ratio of annnonium aalt / K = 1-0.77. 5 MoISi KOH (K-pyrrclidonate), 1.5 MoISi CO ₂ ; "Based on Saat-2-Oyrrolidon
^ 22 hours at 50 ⁰ C "j

Table VI shows the results obtained with a variety of Amnonium halides obtained in combination with Potassium pyrrolidonate and carbon dioxide to form the erfindungagemäsüeii ! Catalyst to be used. The results contain remarkably high molecular weights for poly-2-pyrrolidone.

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Example 19

200 g of purified 2 pyrrolidone (2.3 Hol) were brought into contact with 7.7 g of KOH pellets (0.117 KoI, 85.5% KOH) in a stirred reaction vessel Temperature of about 115 ⁰ C heated. The mixture was then cooled and a measured amount of carbon dioxide was added to produce a polymerization mixture containing 30 percent carbon dioxide based on potassium. About 10 grams of the polymerization mixture was poured into several consecutive polyethylene bottles, three of which were 6 millimoles of the dried ones listed in Table VII. Contained onium salts. The vessels were shaken well and ^{kept at 50 °} C. for 22 hours. The polymer was then removed, washed, dried and weighed. The molecular weight was determined as described elsewhere. The results are shown in Table YII.

Example 20

The method according to the invention was tested in a further example, which otherwise corresponded to Example 19. » 50 g of purified 2-pyrrolidone were mixed with 1.93 g KOH pellets (85, 5% KOH) housed in a stirred Heaktlonsgefäss in contact "and the mixture was concentrated under reduced pressure up to of distilled» - start-point to a temperature of about 110 ⁰ C heated. The mixture was then cooled and mixed with a measured amount of carbon dioxide in order to produce a polymerization mixture containing 30 percent carbon dioxide based on potassium.

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held. 1.5 millimoles of the previously dried tetramethylammonium acetate were weighed into a polyethylene jar, then 10 g of the polymerization mixture were added. The container was shaken well and polymerized at 50 ° C. for 22 hours. The product was worked up as described in Example 19. The results are shown in Table VII.

TABLE VII Comparison of the polyization results

Molar ratio 3 _

Example onium salt K / QrHumsalz ffiJmw ^ vHdlung Mw χ

19 None 37 405

20 (CH ₃ ) ^ ⁺ OCOCH ₃ - 1.2 56 720 19 (CH ₃ J ₄ H ⁺ ClO ₄ - 1 31 400 19 (CHj) ₄ N ⁺ BP ₄ - 1, i 35 415 19 (CH ₃ J ₄ H ⁺ PP ₆ "1 33 405

5 percent potassium pyrrolidonate from KOH.

30 percent by mol of C0 "based on K

Polymerization within Γ2 hours at 50 C.

Table VII contains a comparison of the polymerization results in the presence of potassium pyrrolidonate and carbon dioxide, with and without the addition of tetramethylammonium acetate. It showed that the Tetraalkylanaioniuacarboxylat in combination with carbon dioxide and potassium pyrrolidonate was able to produce a polypyrrolidone with an extremely high average molecular weight to create.

709ΘΑ8 / 0999

Claims (1)

Patent claims: lJ process for the polymerization of 2-pyrrolidone, in which 2-pyrrolidone is brought into contact with a catalyst, characterized in that one Used catalyst, which is prepared by using an alkali metal pyrrolidonate, a quaternary ammonium salt and Carbon dioxide are brought into contact with one another. 2. The method according to claim 1, characterized in that a catalyst is used in which the alkali metal pyrrolidonate, the quaternary ammonium salt and the carbon dioxide are brought into contact with one another in a molar ratio of about 1: 0.1-2: 0.1-0.5 will. 3. The method according to claim 2, characterized in that a molar ratio of about 1: 0.2-1.5: 0.1-0.5 is used. ¹ I. The method according to claim 1, 2 or 3, characterized in that a catalyst is used which is prepared by bringing a solution of the alkali metal pyrrolidonate in 2-pyrrolidone at a temperature of about 20 to 50 C with carbon dioxide and the the resulting carbonized catalyst solution is then brought into contact with the quaternary ammonium salt. 5. Method according to one of the preceding claims, characterized in that that the quaternary ammonium salt is a tetraalkylammonium halide or tetraalkylammonium carboxylate is used. 6. The method according to any one of claims 1 to 4, characterized in that that the quaternary ammonium salt is a quaternary lower alkyl, alkyl; v * l- or aralkylammonium halide or -carboxylate is used. 709848/0999 ORIGINAL INSPECTED 7. Method according to one of Claims 1 to 4, characterized in that that the quaternary ammonium salt is tetramethyl, tetraethyl or tetrapropylammonium chloride or bromide used. 8. The method according to any one of claims 1 to 4, characterized in that that the quaternary ammonium salt is a TetraiC ^ -Cg) -alkylammonium chloride or bromide is used. 9. The method according to any one of claims 1 to 4, characterized in that that the quaternary ammonium salt is tetramethylammonium chloride used. 10. The method according to any one of claims 1 to 4, characterized in, that the quaternary ammonium salt is a tetraalkylanunonium formate, acetate or propionate is used. 11. The method according to any one of claims 1 to 4, characterized in, that the quaternary ammonium salt is a TetraiC ^ -C, -) - alkylammonium carboxylate used. 12. The method according to claim 11, characterized in that the tetra (C ₁ -Cg) alkylammonium carboxylate used is tetramethylammonium acetate. 13. The method according to any one of the preceding claims, characterized in that the alkali metal pyrrolidonate is potassium pyrrolidonate used. Ik. Process according to Claim 13, characterized in that a potassium pyrrolidonate is used which is produced by reacting potassium hydroxide with 2-pyrrolidone. 709848/0999 15. The method according to claim 1, 2 or 3, characterized in that a catalyst is used which is produced by bringing a solution of trialkylamine in 2-pyrrolidone with an alkyl halide at 10 to 50 C and then the resulting solution of the product is brought into contact with the alkali metal pyrrolidonate and carbon dioxide . 16. The method according to any one of claims 1 to ¹ J, characterized in that the quaternary ammonium salt used is tetramethyl ammonium chloride and potassium pyrrolidonate is used as the alkali metal pyrrolidonate. 17. The method according to any one of the preceding claims, characterized in that 0.05 to 1 mol percent of N-acylpyrrolidone, N-acylcaprolactam, acetic anhydride or l- (l-pyrrolin-2-yl) - 2-pyrrolidone is used as the polymerization activator. 18. The method according to claim 17, characterized in that there is used as N-acylpyrrolidone N-acetylpyrrolidone . 19. The method according to any one of the preceding claims, characterized in that the 2-pyrrolidone with the catalyst at a temperature of about 25 ° C to about 70 ° C to achieve a poly-2-pyrrolidone with an average molecular weight (weight average) of brings more than 1 000 000 into contact. 709848/0999