DE2719903A1 - METHOD FOR PRODUCING MALEINIMIDES AND DIMALEINIMIDES - Google Patents

Description

FROM KREISLER SCHONWALD MEYER EISHOLD FUES FROM KREISLER KELLER SELTING

PATENT LAWYERS Dr.-Ing. by Kreisler f 1973

Dr.-Ing. K. Schönwald, Cologne

Dr.-Ing. Th. Meyer, Cologne

Dr.-Inij. K. W. Eishold. bad Soden

Dr. J. F. Fues, Cologne

Dipl.-Chem. Alek von Kreisler, Cologne

Dipl.-Chem. Carola Keller, Cologne

Dipl.-Ing. G. Selling, Cologne

5 Cologne 1 May 3, 1977

DLICHf. '. AtJl-liiAUS AM HAUPfLAIINHOt

AvK / Ax

EI Du Pont de Nemours and Company
Wilmington, Del., USA

Process for the preparation of maleimides and dimaleinimxden

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Telephone: (0221) 23 45 41-4 ■ Telex: 8i) 82307 dopa d Tck-yramm: Dompokni Cologne

-X-

Process for the preparation of maleimides and dimaleinimides

Certain N, N'-arylenedimaleinimides, especially those N, N'-m-phenylenedimaleinimides have long been used as vulcanization aids known for elastomers. The o-, m- and p-isomers of the N, N'-Arylenedimaleinimide are by Implementation of arylenediamines with maleic anhydride in the presence of a polar organic solvent Formation of an N, N'-aryldimaleamic acid precursor (N, N'-aryldimaleamic acid) and dehydration of the latter by ring closure with a lower fatty acid anhydride and an alkali salt of a lower fatty acid Formation of the corresponding dimaleinimide produced.

A typical example of this process is the preparation of N, N'-m-phenylenedimaleinimide. Here maleic anhydride is added to a solution of m-phenylenediamine in dimethylformamide (DMF), and the mixture is reacted at a temperature of 35 to 40 ° C., N, N'-m-phenylenedimaleamic acid being formed, which, however, is not isolated. This is followed by the addition of sodium acetate and acetic anhydride at a maximum reaction temperature for the ring closure of 55 to 60 ^° C. After this reaction has ended, a large excess of water is added, the N, N'-m-phenylenedimaleinimide being precipitated. This dimaleinimide is then filtered off, washed with water and dried at a moderately elevated temperature. This procedure is represented by a formula below:

NHCOCh = CHCO ₂ H

f ^ N min ^^

+ 2

NHCOCH = CHCo ₂ H

I. m-Phenylenediamine II. N, N'-m-phenylenedimalein-

amic acid (Ν, Ν'-rnphenylenedimaleamic acid) (in solution)

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Sodium,.

II + acetic acid- ^a ^ ^ta t) ° "* ^ ° ⁽²⁾

anhydride

N ₁ N'-m-phenylenedimaleinimide

This process has the disadvantage that the yields are low (60 to 65%) and that the isolation of the Product requires large amounts of water to precipitate the end product. The problem that the biggest However, the conversion process poses economic and environmental difficulties for this process of the expensive and moderately toxic dimethylformamide required as a solvent by the acetic acid in large amounts of dimethylacetamide and formic acid during the reaction. The solvent consumption requires expensive disposal measures to meet environmental pollution prevention regulations because

around 3 to 4 parts of DMF per part of end product are consumed / and are thus incurred as waste. The poor solubility of dimaleamic acid complicates this problem in that large amounts of solvent are required. Furthermore, the extreme temperature values in the ring closure step must be avoided (below 40 ⁰ C or above 65 ° C) to increase the reaction rate and the solubility of Dimaleinaminsäure without destroying significant amounts of Dimaleinaminsäure by side reactions that are strongly at higher temperatures, . One of the desired products, N, N - (4-methyl-m-phenylene) dimaleinimide, cannot be easily isolated when DMF is used

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-Jg-

medium is used.

Attempts have been made to use other solvent systems. The use of formamide instead of DMF also led to the reaction of the solvent with the acetic acid formed, while inferior yields were obtained and increased amounts of sodium acetate were required. procedure using different solvents for the two different stages have been successful carried out in the laboratory, but proved to be at of production on a larger scale than inexpedient due to the cost and time involved in removal of the first solvent were connected prior to performing the ring closure. An example of one such method is the synthesis of the dimaleamic acid in aqueous solution, isolation of the acid and Carrying out the conversion to the dimaleinimide in a non-aqueous solvent. The latter reaction does not take place in an aqueous solvent.

The invention provides the Aufgate, e * Ln synthetic Process for producing maleimides and dimaleinimides at reduced cost and less to make ecological hazards available.

The invention relates to the production of maleimides and dimaleinimides in high yield a method, which is characterized in that one after the other

1) Maleic anhydride and a suitable primary amine or diprimary diamine at about 30 to 60 ° C in an organic solvent selected from the organic ketones, ethers, esters and chlorinated ones aromatic organic hydrocarbons existing group brings together and here the

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forms corresponding maleamic acid or dimaleamic acid,

2) without isolating the product of step (1), the reaction mixture of this step with (a) about 1 to 1.5 mol of an anhydride of a C ₂ -C 6 fatty acid per -NH ₂ group equivalent in the primary amine or diprimary diamine and (b) a hydrated or non-hydrated magnesium, lithium, manganese (II) or cobalt (II) salt soluble in the liquid reaction medium at the reaction temperature in an amount of at least 0.2% by weight and the mixture is kept at about 45 to 60 ^° C. with suitable agitation and

3) the maleimide or dimaleinimide formed as product is isolated with the proviso that a tertiary amine with a pK _a value of at least 10 determined in aqueous solution at 25 ° C. is also present in stage (1) or (2).

For the purposes of the invention, the term "liquid reaction medium" is used as a combination of a) the selected organic solvent,

b) the tertiary amine and

c) the fatty acid anhydride introduced in step (2) of the process

Are defined.

The main advantage of the invention lies in the use of cheap organic solvents, which according to the Reaction can be eliminated or fully recovered without posing serious environmental threats develop. The tertiary amine can also be recovered. As solvents are suitable for the reaction, for example, acetone, cyclohexanone, dioxane, tetrahydrofuran, methyl ethyl ketone, ethyl acetate and o-dichlorobenzene. It is convenient to use a solvent to use the maleic anhydride acceptable

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well solves. Acetone is particularly preferred as the solvent.

• As primary amines or diprimary diamines used in the first stage of the process, any alkylamines, cycloalkylamines, arylamines and aralkylamines with preferably no more than 12 carbon atoms, any alkylenediamines with preferably 2 to 12 carbon atoms, are suitable .-C ^ p -cycloalkylenediamines, arylenediamines and alkylene-bis (arylamines). The aryl or cycloalkyl rings can be further substituted by C 1 -C 6 alkyl radicals or alkoxy radicals or chlorine, bromine or fluorine atoms. Possible aromatic and cycloaliphatic diamines are o-, m- and p-diamines. Of particular interest are m-phenylenediamine, 4-methyl-m-phenylenediamine, methylene-ρ, ρ ¹ -dianiline, 1,4-di (aminomethyl) cyclohexane and 1,4-di (ß-aminoethyl-cyclohexane, preferred as aromatic Monoamine becomes aniline.

As metal salts that complete the dehydration and cyclization stages catalyze, for example magnesium nitrate, chloride, bromide and sulfate are suitable and acetate, lithium nitrate, chloride, bromide and acetate, manganese nitrate, chloride and acetate and Cobalt dl) nitrate, chloride, bromide, sulfate and -acetate.

The dehydration (cyclization) is carried out in the same reaction mixture, without the intermediate product to isolate. This is one of the advantages of the method according to the invention. The cyclization in Presence of a tertiary amine and a lower fatty acid anhydride is known, but leads Presence of a selected metal salt in the process according to the invention leads to much higher yields of the desired product. It is believed that both the tertiary AmJ.η and the metal salt as

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Cocatalysts are effective at this stage, producing a synergistic effect. as Anhydrides of C ^ -C ^ -fatty acids are acetic acid anhydride, Propionic anhydride and all isomeric forms of butyric and valeric anhydride.

Acetic anhydride, which is the most readily available, is preferred. Optimal yields are achieved when about 1.2 to 1.4 moles of anhydride per equivalent of -NHp groups in the primary amine or diprimary diamine be used. It would not be advantageous to keep the amount of the anhydride above 1.5 moles per -NH ^ group equivalent to increase. Any tertiary amines with a sufficiently high pK value are suitable for this

Method according to the invention. Typical examples are triethylamine, tributylamine, Ν, Ν-diethylcyclohexylamine, N-methylpiperidine and 1,4-diazabicyclo- Γ2..2 . ^ / Octane.

It is theoretically sufficient if only a catalytic amount of the tertiary amine is present in the reaction mixture is, however, it has been found advantageous to use a fairly large amount of this amine in order to obtain the To improve the solubility of the maleamic acid or dimaleamic acid formed as an intermediate. Of the The tertiary amine content can be up to 60 mole percent primary amine and even higher, but is common an amount of about 30 mole percent is sufficient. It is not recommended to use less than about 15 mole percent.

For the first stage of the process, a temperature range of about 35 to 45 ° C is preferred. This temperature is maintained for about 30 minutes. Temperatures below those in the invention paragraph for each Step of the process mentioned temperatures are due to the low reaction rates and the low solubility of the starting materials

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and / or reaction products inconvenient. Temperatures that are above the upper limits of the ranges, usually result in lower quality products. Under the preferred temperature conditions Both stages take place at reasonable reaction rates and become high quality products generated.

Isolation of the maleimide or dimaleinimide formed as the product is straightforward, since a greater part of this product is usually precipitated when the reaction mixture is cooled to room temperature. In the case of solvents that are miscible with water, additional product can be isolated by diluting the mixture with water prior to filtration. If the solvent is not miscible with water, the yield of isolated maleimide or dimaleinimide can often be increased by cooling the reaction mixture to about ⁰ ° C. prior to filtration.

The amount of solvent which is required to carry out the process according to the invention in large-scale equipment cannot be precisely stated, since it depends on the particular solvent and the maleimide or dimaleinimide to be produced and on factors such as temperature and concentration of the tertiary alkylamine. In general, however, from 2 to 12 parts by weight of solvent per part of the expected maleimide or dimaleinimide product are sufficient to form a reaction mixture or reaction medium which is easy to handle during both stages of the synthesis. In the case of N, N ¹ -m-phenylene- and N, N '- (4-methylm-phenylene) dimaleinimides, a process in which about 3 parts of acetone are used per part of the expected dimaleinimide, good feasibility and process management, high productivity and good

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Product quality achieved. The molar ratio of tertiary alkylamine to the primary amine used or Diamine is usually from 0.05 to 0.8. The molar ratio of metal salt to the primary used The amine or diamine is usually from 0.01 to 0.20.

Compared to the previous syntheses, in particular those in which DMF is used as solvent, the process according to the invention leads to a much higher yield of dimaleinimide and a product of high purity. For example, an N, N • -m-phenylenedimaleinimide which is produced according to the process according to the invention shows a lighter yellow color than a product produced according to the known process using DMF, a sign of higher purity, which is indicated by a melting point of the Product of at least 200 ° C, usually 202 to 205 ° C, is further confirmed. In contrast, products are obtained with a melting point of less than 200 ⁰ C or higher than 210 ° C in the known method often, both of which were found to be unsatisfactory in technical applications.

In the following examples, all quantitative data relate to parts, proportions and percentages based on weight, unless otherwise stated. All melting points are uncorrected.

example 1

This example illustrates various metal salt cocatalysts that which can be used for the production of Ν, Ν'-m-phenylenedimaleinimide.

A glass flask was fitted with a thermometer, a mechanical paddle stirrer, and a water-cooled Cooler provided. Crushed maleic anhydride (1.92 parts) was added to a solution of 1 part of m-pheny-

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Lenediamine and 13 parts of acetone are added within 15 minutes. The heterogeneous reaction mixture was ^{stirred at 40 °} C. for 1 hour. 2.44 parts acetic anhydride, 0.32 parts triethylamine and 0.04 parts magnesium acetate tetrahydrate were added all at once. The temperature was raised using a heating mantle to 60 ⁰ C and held for 4 hours at 60 ⁰ C. The reaction mixture was cooled and 20 parts of water were added, whereupon the precipitated product was filtered off with a suction filter. The filter cake was washed with water and ^{dried for 24 hours at 60 to 70 °} C. in a vacuum heating cabinet. N, N ¹ -m-phenylenedimaleimide of melting point 203-204 ⁰ C was obtained in a yield of 74%.

The experiment was repeated, except that 0.04 part of lithium acetate dihydrate was used as the catalyst instead of magnesium acetate tetrahydrate. Here, N, N'-m-phenylenedimaleinimide with a melting point of 208 ^° C. was obtained in a yield of 84%.

The experiment was repeated again, but 0.04 parts of manganese D-acetate tetrahydrate instead of Magnesium acetate tetrahydrate used as a catalyst

en was. Here, N, N · -m-phenyldimaleinimide with a melting point of 203 to 204 ^° C. was obtained in a yield of 80%.

When the same experiment was repeated, but using 0.02 part of lithium chloride instead of magnesium acetate tetrahydrate as a catalyst, N, N'-m-phenylenedimaleinimide with a melting point of 199 ^° C. was obtained in a yield of 84%.

Example 2

This example illustrates various metal salts and amines serving as cocatalysts that are used in preparation used by N, N'-m-phenylenedimalinimide

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can be.

A flask was equipped in the manner described in Example 1. To a solution of 1.92 parts Maleic anhydride in 4.8 parts of acetone was a solution of 1 part of m-phenylenediamine and 0.32 parts of triethylamine and 1.6 parts of acetone added within 15 minutes. During this time one formed Precipitation. The heterogeneous reaction mixture was held at 40 ° C. for 30 minutes. 0.08 part of magnesium chloride hexahydrate and 2.44 parts of acetic anhydride were added all at once. The temperature was increased to 50 ° C and held at 50 ° C for 3 hours. After 30 minutes the reaction mixture became homogeneous and took off Amber color. Precipitation of the product started 5 minutes later. After the end of the reaction time the mixture is cooled and treated with 12 parts of water. The precipitated product was suction filtered with water washed and dried for 24 hours at 60 ° C in a vacuum oven. Here, N, N · -m-phenylenedimaleinimide from melting point 2O4-2O5 ° C in a yield of 92% obtain.

The experiment was repeated, except that 0.1 part of magnesium sulfate heptahydrate was used instead of 0.08 part of magnesium chloride hexahydrate. Here, N, N ¹ -m-phenylenedimaleinimide with a melting point of 206 to 207 ^° C. was obtained in a yield of 89%.

When the experiment is repeated using 0.5 part of NjN-diethylcyclohexylamine instead of 0.32 parts of triethylamine was Ν, Ν'-m-phenylenedimaleinimide obtained from melting point 2O2-2O3 ° C in a yield of 92%.

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Example 3

This example illustrates the use of 4-methyl- and 2-methyl-m-phenylenediamine in the manufacture of aryldimaleinimides.

A flask was equipped in the manner described in Example 1. A solution of 1 part of 4-methyl-m-phenylenediamine, 0.28 part of triethylamine and 2.5 parts of acetone was added to a solution of 1.7 parts of maleic anhydride in 3.9 parts of acetone. The heterogeneous reaction mixture was stirred at 40 ° C. for 30 minutes. Then 0.071 parts of magnesium chloride hexahydrate and 2.16 parts of acetic anhydride were added simultaneously all at once. The reaction temperature was increased to 50 ° C and held at 50 ° C for 2.5 hours. 30 minutes after the addition, the mixture became homogeneous and remained homogeneous. The solution was cooled and 16 parts of water were added. The precipitated product was suction filtered, washed with water, and 24 hours in a vacuum oven at 60 ⁰ C dried. This gave N, N '- (4-methyl-m-phenylene) dimaleinimide with a melting point of 168-172 ° C. in a yield of 85%.

The experiment was repeated, except that 1 part of 2-methyl-m-phenylenediamine was used in place of 1 part of 4-methylm-phenylenediamine. The diamine was added to the jar as a solution containing 0.28 parts triethylamine and 3.2 parts acetone. This gave N, N ¹ - (2-methyl-m-phenylene) dimaleinimide with a melting point of 210-212 ° C. in a yield of 85%.

Example 4

This example illustrates the use of various alkyl amines and aromatic mono- and difunctional amines for the production of maleimides.

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A flask was equipped in the manner described in Example 1. To a solution of 1.06 parts Maleic anhydride in 3.5 parts of acetone became a mixture of 1 part of methylenedianiline, 0.35 part Triethylamine and 1.0 part of acetone were added within 30 minutes. During this time one formed Precipitation. The heterogeneous reaction mixture was held at 40 ° C. for 30 minutes. Then 0.044 part of magnesium chloride hexahydrate was added and 1.34 parts of acetic anhydride were added all at once. The reaction mixture was stirred at 45 ° C. for 5 to 6 hours. Fifteen minutes after the addition, the mixture became homogeneous and remained homogeneous. The solution was cooled and with 5.5 parts of water are added. The precipitated product was filtered off with suction, washed with water and dried. Here, N, N - (methylenedi-p-phenylene) dimaleinimide with a melting point of 154-155 ° C in a yield of 89% obtain.

A flask was equipped in the manner described in Example 1. To a solution of 3.64 parts Maleic anhydride in 10.6 parts of acetone was a solution of 1 part of ethylenediamine and 0.61 parts of triethylamine and 1.5 parts of acetone were added over the course of 25 minutes. The resulting reaction mixture contained white Solids and was held at 40 ° C for 30 minutes. Then 0.15 parts of magnesium chloride hexahydrate and 4.6 parts of acetic anhydride were added all at once. The reaction temperature was increased to 50 ° C and held at 50 ° C for 2.5 hours. The homogeneous reaction mixture was cooled and washed with 25 parts of water offset. The precipitated product was filtered off with suction, washed with water and dried in a vacuum oven. Here was N, N'-Ethylenedimaleinimid from Melting point 193-194 ° C obtained in a yield of 27%.

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A flask was equipped in the manner described in Example 1. To a solution of 1.8 parts Maleic anhydride in 5.2 parts of acetone was a solution of 1 part of hexamethylenediamine and 0.3 part of triethylamine and 1.5 parts of acetone added within 30 minutes. The heterogeneous reaction mixture obtained was held at 40-5O ° C for 30 minutes. Then there were 0.075 parts of magnesium chloride hexahydrate and 2.3 parts Acetic anhydride added all at once.

The reaction mixture was kept at 50 ° C. for 3 hours. After adding 11 parts of water to the cooled mixture the precipitated product was filtered off with suction. The filter cake was washed with water and placed in a vacuum oven dried. This resulted in N, N'-hexamethylene dimaleinimide obtained from the melting point 136-139 ° C in a yield of 22%.

A reaction flask was equipped in the manner described in Example 1. To a solution of 1.12 parts of maleic anhydride in 5.6 parts of acetone, a solution of 1 part of aniline and 0.375 part of triethylamine in 1.9 parts of acetone was added over the course of 30 minutes. The resulting heterogeneous mixture was kept at 40 ° C. for 30 minutes. Then 0.093 parts of magnesium chloride hexahydrate and 1.4 parts of acetic anhydride were added all at once. The temperature was raised to 50 ° C and held for 3 hours at 50 ⁰ C. The homogeneous mixture was cooled and 14 parts of water were added. The precipitated product was suction filtered, washed with water and air dried. The crude product was recrystallized from ethanol / water (volume ratio 90:10), with 0.89 parts of N-phenylene maleimide having a melting point of 84 ° -86 ° C. being obtained.

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Example 5

This example illustrates the use of a different solvent.

A flask was equipped in the manner described in Example 1. To a solution of 1.92 parts Maleic anhydride in 13 parts of ethyl acetate was a mixture of 1 part of m-phenylenediamine, 0.32 parts Triethylamine and 2.3 parts of ethyl acetate are added over the course of 40 minutes. The heterogeneous mixture obtained was held at 40 ° C for 50 minutes. Then there were 0.08 parts of magnesium chloride hexahydrate and 2.44 parts Acetic anhydride added all at once. The temperature was increased to 50 ° C and 3 hours at Maintained 50 ° C. The precipitated product was filtered off with suction. The filter cake was washed with water and dried. This became N, N'-m-phenylenedimaleinimide obtained from melting point 2O2-2O3 ° C in a yield of 70%.

Examples 6 to 27

In the experiments described below, the synthesis of N, N'-m-phenylenedimaleinimide was carried out among the The same general conditions, but carried out in the presence of various metal salts, of which some do not fall within the scope of the invention. In each case the overall yield was solid product and the melting point of the product and the yield of pure dimerimide determined from liquid chromatography data calculated. It should be noted that the industrial goal is to use maleimide in The highest possible raw yield and the highest possible purity to meet the need for purification of the raw product before use in vulcanization formulations for elastomers.

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General procedure

A glass flask was fitted with a thermometer, a mechanical paddle stirrer, and a water-cooled Equipped with a cooler. A solution of 0.46 mol of m-phenylenediamine, 0.16 mol of triethylamine (except in example 7) and 100 ml of acetone became a solution of 0.98 mol of maleic anhydride within 15 to 30 minutes given in 300 ml of acetone. During this time a precipitate formed. The heterogeneous reaction mixture was kept at 40 ° C for 30 minutes. Then 0.1 and 0.01 moles of metal salt per mole of diamine and 1.2 moles of acetic anhydride were added simultaneously at once, whereupon the temperature increased to 50 ° C and Was held at 50 ° C for 3 hours. 300 ml of water was then added and the mixture was cooled.

The precipitated product was suction filtered, washed with water and dried for 12 hours at 60 ⁰ C in a vacuum heating oven. The yields of isolated solids and N, N · m-phenylenedimaleinimide based on m-phenylenediamine are given in the table below. The yields of the dimaleinimide calculated by liquid chromatography are given with an accuracy of ± 4%. The results are given in Table 1.

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- Y5

Tabel

Example metal salt and salt / diamine molar ratio product

Melting point, ⁰ C

Yield Yield of solids and distaffs, male- % imid.%

7 8

10 11 12 13

14th

15th

16 17

18th

19 20

(b)

no

LiOAc-2H ₂ O (0.10) LiOAc-2H ₂ O (0.10)

NaOAc (0.10) (c)

KOAc (0.10) (c)

Mn (OAc) ₂ MH ₂ O ID-

Cu (OAc) ₂ H ₂ O (0.10) (c)

Zn (OAc) ₂ 2H ₂ O (0.10) (c)

Fe (OAc) ₂ (0.10) (c) Co (OAc) ₂ MH ₂ O (0.10)

Mn (OAc) ₂ 4H ₂ O (0.01) Cu (OAc) ₂ H ₂ O (0.01) (c)

Zn (OAc) ₂ -2H ₂ O 0.01) (c)

Fe (OAc) ₂ (0.01) (c) Co (OAc) ₂ -4H ₂ O (0.01)

184-200
190-205 68
69 29
30th 170-201 20th 9 200-2
201-3 86
87 85
85 195-202
197-203 72
72 63
68 181-195
180-197 59
62 34
40 203-5
202-4 88
88 84
(ö) 199-203
203-204 67
63 65
65 206-7
202-8 56
56 52
54 196-202 85 72 204-6
205-6 91
90 91
(d) 203-4 88 80 195-206
195-201 59
63 (d)
47 197-200 58 26th 190-210 74 30th 203-204 88 86

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product

Example metal salt and salt / Diamiη mol ratio

Melting yield Yield point, ° C of solids to distoffe, malein-

21 22 23 24 25 26 27

Co

(0.10)

CoS0 ₄ -7H ₂ 0 (0.10) CoCl ₂ -6H ₂ 0 (0.10)

(0.10)

^LiN0

Mg (NO ₃ J ₂ -6H ₂ O (0.10) Mn (NO ₃ ) ₂ -4H ₂ O (0.10)

202-3 89 89 202-4 89 89 202-3 88 87 202-4 87 84 200-3 85 81 200-3 84 81 201-2 84 81

(a): In cases in which double tests were carried out, two results are given in each case.

(b): No triethylamine was used in this experiment.

(c): Outside the scope of the invention, (d): Not determined.

The results of Examples 6 to 27 above show:

1) Both lithium acetate in the absence of triethylamine and triethylamine alone are poor catalysts. The combination of lithium acetate and triethylamine is an effective catalyst.

2) Lithium acetate is a much better catalyst than Sodium acetate or potassium acetate.

3) Manganese (II) acetate and cobalt (II) acetate are excellent Catalysts and much better than three

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other first-line transition metal acetates, namely zinc, copper (II) and iron (II) acetate.

4) the superiority of manganese (II) acetate and cobalt (II) acetate is particularly noticeable at a catalyst / diamine molar ratio of 0.01, with the zinc, copper (II) and iron (II) salts very poor results demonstrate.

Examples 28-36

The same procedure as in the case of Examples 6 bis was carried out, except that the molar ratio changed from metal salt to diamine within a moderately wide range. The results are below mentioned in table 2.

Table 2 ⁽ a) P r ο d u k t 84 85 yield
and I-
malein-
imid, t at Metal salt and salt / Melting yield
point, at fixed
⁰ C substances,
% 203-5 85
199-202 80 85
91 (b) game Diamine molar ratio 208 203-4 89
89 ^ 80
(b) 28 LiOAc'2H ₂ O (0.043) 200-3
202-4 90 76 29 LiCl (0.10)
(0.052) 203
206-7 92 (b)
86 30th LiBr (0.10) 201-3 79 (b)
88 31 Mg (OAc) ₂ 4ΗΟ (0.04)
(0.043) 202-3 84 90 32 MgSO -7H.0 (0.022)
(0.044) 2C3-4 77 33 MgCl ₂ -OH ₂ O (0.043) 204-6 (b) 34 MgBr ₂ -OH ₃ O (0.043) 80 35 Mn (OAc) ₂ -4H ₂ O (0.018) 36 MnCl ₂ (0.044)

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(a): If double tests are carried out, two results are given in each case.

(b): Not determined.

The above results of Examples 28 to 36 in conjunction with Examples 8 to 27 show that high yields of N, N ¹ -m-phenylenedimaleinimide are obtained with the catalysts according to the invention regardless of their molar ratio to diamine within the experimental range.

7098A7 / O8A7

Claims (13)

Claims 1) Process for the preparation of maleimides and dimalein- '' ■■ / imides, characterized in that one after the other A) bringing together maleic anhydride and a suitable primary amine or diprimary diamine at etv / a 3O to 6O ⁰ C in an organic solvent from the group consisting of ketones, ethers, esters and chlorinated aromatic organic hydrocarbons and thereby forming the corresponding maleic acid or dimaleamic acid, B) without isolating the product of stage (A), the reaction mixture of this stage with (a) etv / a 1 to 1.5 mol of an anhydride of a C ^ -Cr fatty acid per -NH - group equivalent in the primary used Amine or diprimary diamine and (b) a hydrated or non-hydrated magnesium, lithium, manganese (II) or cobalt (II) salt which is soluble in the liquid reaction medium at the reaction temperature in an amount of at least 0.2 wt .-% mixes and holds the Genisch under suitable agitation at about 45 to 6O ⁰ C and C) the maleimide or dimaleinimide formed as the product isolated with the proviso that (I) a tertiary amine with a pK value determined in aqueous solution at 25.degree. C. of at least 10 is also present in stage (A) or (B) and (II) an alkylamine as the primary amine, Cycloalkylamine, arylamine and / or aralkylamine and, as diprimary diamine, an alkylene diamine, cycloalkylene diamine, Arylenediamine and / or alkylenebis (arylamine) ends and the aryl and cycloalkyl rings of any of the above amines are either independently unsubstituted or with Cj-Cg-alkyl radicals or -alkoxy- 709847 / 08A7 ORIGINAL INSPECTED radicals or chlorine, bromine or fluorine atoms are substituted. 2) Process according to claim 1, characterized in that the metal salt used is magnesium nitrate, chloride, bromide, sulfate and / or acetate, lithium nitrate, chloride, bromide and / or acetate, manganese nitrate, chloride, and / or acetate and / or cobalt (II) nitrate, chloride, bromide, sulfate and / or acetate used. 3) Method according to claim 1 and 2, characterized in that the metal salt is a magnesium or cobalt (II) salt, magnesium sulfate is preferably used. 4) Process according to Claim 1 to 3, characterized in that the temperature in stage (A) is 35 to 45 ° C holds. 5) Process according to claim 1 to 4, characterized in that one has a molar ratio of tertiary amine to used primary amine or diamine of about 0.05 to 0.8 and a molar ratio of metal salt to the primary amine or diamine used as starting material works from about 0.01 to 0.20. 6) Method according to claim 1 to 5, characterized in that the primary amine and the diprimary diamine of the following subject to further limitation: the primary amine contains a maximum of 12 carbon atoms and that Diprimary diamine contains 2 to 12 carbon atoms when it is an alkylene diamine and when it is a cycloalkylene diamine is, 4 to 12 carbon atoms, any alkyl or alkoxy substituents on the aryl or cycloalkyl rings are not included. 709847/0847 7) Method according to claim 6, characterized in that the primary monoamine used as starting material Is aniline. 8) Method according to claim 6, characterized in that the primary diamine is m-phenylenediamine, 4-methyl-mphenylenediamine, methylene-ρ, ρ ¹ -dianiline, 1,4-di (aminomethyl) cyclohexane or 1,4-di ( ß-aminoethyl) cyclohexane is used. 9) Method according to claim 6, characterized in that The preferred solvent is acetone / in an amount of about 3 parts by weight per part by weight of the theoretically expected dimaleinimide used. 10) Method according to claim 1 to 9, characterized in that a water-miscible solvent, preferably Acetone used and the reaction mixture prior to isolating the maleimide or dimaleinimide with water diluted. 11) Process according to claim 1 to 10, characterized in that the tertiary amine is triethylamine, tributylamine, N, N-diethylcyclohexylamine, N-methylpiperidine and / or 1,4-diazabicyclo / 2.2.27octane used. 12) Method according to claim 1 to 11, characterized in that the acid anhydride in an amount of 1.2 to 1.4 mol per equivalent of the -NH ^ groups in the primary amine or diprimary diamine used used. 13) Process according to claim 1 to 12, characterized in that acetic anhydride is used as the acid anhydride used.