JPS61293964A - Production of n,n'-m-phenylenebismaleimide - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a vulcanization accelerator, etc., in high yield, by reacting N,N'-m-phenylenebism aleamidic acid with an acid anhydride in the coexistence of a specific amount of water and aliphatic ketone within a specific temperature range in the presence of a tertiary amine and a metal salt. CONSTITUTION:N-N'-m-Phenylenebismaleamidic acid is reacted with an acid anhydride (acetic anhydride is preferred) in the presence of a tertiary amine such as triethylamine and a metal salt such as cobalt acetate to obtain N,N'-m- phenylenebismaleimide expressed by the formula; wherein the reaction is carried out in the coexistence of 1-6wt% preferably 1.5-4.5wt% water aliphatic ketone (preferably acetone) in an amount of 1-2 times, preferably 1.4-2 times based on the weight of N, N'-m-phenylenebismaleamidic acid at 30-40 deg.C, preferably 32-38 deg.C. EFFECT:The titled compound of high quality is stably obtained. USE:A raw material for heat-resistant polymers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing N,N'-m-phenylene bismaleimide.

N,N'-m-phenylenebismaleimide represented by the formula is a very important compound as a vulcanization accelerator for rubbers or as a raw material for heat-resistant polymers.

Conventionally, as a method for producing such N,N'-m-phenylenebismaleimide, N,N'-m-phenylenebismaleamide acid is used. A method of reacting with an aliphatic acid anhydride at 40 to 60°C in the presence of an 8th class amine and a metal salt in a medium (JP-A-58-58648, JP-A-58-52-
126161, 5B-28896, etc.)
It has been known.

However, these known methods generally have problems such as a large amount of organic solvent used, a long reaction time, a low yield and instability, and furthermore, in order to improve the yield, it is necessary to add water after the reaction is completed. If the desired product is forcibly precipitated by addition, it will contain a large amount of polymerization activity inhibitors, causing problems such as difficulty in purification.

In a similar method, bis-maleamic acid is heated in a lower carboxylic anhydride and acetone in the presence of a tertiary amine, a soluble nickel derivative, and water, and the bis-maleimide formed is precipitated by adding water. A method (Japanese Unexamined Patent Publication No. 49-92054) is also known.

However, in this method, the reaction temperature is as high as 50 to 80°C, and a large amount of acetone is used, about 8 times the weight of the raw materials.
In addition to having the same problems as the conventional method described above, in which water as much as twice the volume is added,
The problem is that recovery of the solvent becomes more difficult.

Therefore, the present inventors solved these problems and produced N,N1-m-phenylene bismaleimide with industrial advantage; We discovered that when conditions are selectively combined, the selectivity of the reaction is improved, the yield is improved, and a product of high purity and quality can be obtained, which is an excellent effect. This led to the invention.

That is, the present invention produces N by reacting N,N'-m-7 22lene bismaleamic acid with an acid anhydride in the presence of an 8th class amine and a metal salt.

In producing N'-m-phenylenebismaleimide, [~6% of water and 1 to 2 times the weight of aliphatic ketone] are added to N,N'-m-7enylenebismaleamic acid. The present invention provides a method for producing N,N'-m-7 enylene bismaleimide, characterized in that the reaction is carried out at a reaction temperature of 80 to 40° C.

The present invention will be explained in detail below.

In the present invention, various acid anhydrides conventionally used in this reaction are used as the acid anhydride to be reacted with N,N1-m-phenylenebismaleimide acid, but in particular, acetic anhydride, propionic anhydride Aliphatic acid anhydrides such as acetic acid anhydrides are preferred, and acetic anhydride is particularly preferably used.

The amount of such acid anhydride used is usually 2.1 to 2.8 times the mole of N,N1-m-phenylene bismaleamic acid.

Furthermore, the 8th class amine and metal salt used in this reaction are those conventionally used in this reaction, and are not particularly limited.

For example, the v18-class amine includes trialkylamines such as trimethylamine, triethylamine, tri-n-butylamine, and N.

Examples include N,N-dialkylbenzylamines such as N-dimethylbenzylamine, but trialkylamines are preferred, and triethylamine is particularly preferred.

In addition, metal salts include hydrated or non-hydrated salts of lithium, magnesium, manganese, nickel, and cobalt nanometals, such as halides, carbonates, acetates, propionates, stearates, and naphthenates. Examples thereof include cobalt acetate (divalent).

The amount of the 8th class amine used is usually 0405 to 0.2 times the amount of N,N'-m-phenylene bismaleamic acid, and the amount of the metal salt used is N,N'-m- The amount is 0.001 to 0.01 times, preferably 0.004 to 0.00 times, relative to 7-enylene bismaleamic acid.

The presence of water is essential in the reaction of the present invention, and the amount used is 1 to 6% by weight, preferably 1.5 to 4.5% by weight based on N,N'-m-phenylene bismaleamic acid. It is.

Examples of aliphatic ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Acetone is particularly preferably used, but the amount used is N, N'
-1 to 2 for m-phenylenebismaleamic acid.
It is 2 times by weight, preferably 1.4 to 2 times by weight.

The reaction temperature is 80-40°C, preferably 82-88°C.

In the present invention, the amount of water and aliphatic ketone used as well as the reaction temperature are very important requirements; for example, if the amount of water used exceeds this range, a large amount of acetone may be required, or the desired amount may be resulting in decreased yield and quality;
Furthermore, if any of these requirements are lacking, the desired effect cannot be obtained, such as the processing after the completion of the reaction becoming complicated.

As described above, the above three requirements specified in the present invention are closely related to each other, and excellent effects can only be obtained by selectively combining the selected requirements.

Thus, according to the method of the present invention, it is possible to stably obtain the target product in high yield and quality, and since the reaction proceeds in a slurry form, it is not necessary to further add water after the reaction is completed. Instead, the desired product can be easily taken out by separating the crystalline substance from the reaction slurry as it is or after cooling it to about 0° C. to room temperature as necessary.

The present invention will be explained below with reference to Examples.

In addition, "Example middle part" indicates parts by weight.

Example 1 0.08 parts of water in a mixture of 1 part of N,N'-m-phenylene bismaleamic acid and 1.6 parts of acetone,
cobal acetate) and 0.007 parts of triethylamine.
15 parts of acetic anhydride was added, and while stirring at 85°C, 0.0 parts of acetic anhydride was added.
Add 87 parts. It is then held at 82-87°C for 8 hours.

After the reaction is completed, the mixture is cooled to room temperature and the crystals are filtered off.

The obtained crystals were washed with water and dried to obtain 0.86 part (yield: 96.4%) of N,N'-m-y enylene bismaleimide having a melting point of 202 to 204°C.

The same manufacturing experiment as above was repeated four times, and the yield was stable at 95 to 97% in all cases.

Comparative Example 1 A reaction was started in the same manner as in Example 1 except that water was not added, but the viscosity of the reaction system immediately increased and stirring became impossible during the addition of acetic anhydride. When acetic anhydride was further forcibly added, the temperature of the system rose rapidly and the reaction mixture flowed out of the system.

Comparative Example 2 The reaction and post-treatment were carried out in the same manner as in Example 1 except that the amount of water added was 0.08 parts.
-m-Phenylene bismaleimide has a melting point of 182-19
6c, and the yield was low at 67%.

Comparative Example 8 The reaction was started in the same manner as in Example 1 except that the reaction temperature was 25°C, but the reaction did not proceed at all at the beginning of the addition of acetic anhydride, and when acetic anhydride was further added, a rapid reaction occurred. The reaction mixture will bump and the reaction will not be able to be controlled.

Comparative Example 4 The reaction and post-treatment were carried out in the same manner as in Example 1 except that the reaction temperature was 47°C, except that N.

The yield of N'-m-phenylene bismaleimide was 78%.

Comparative example 5

Claims (4)

[Claims] (1) In producing N,N'-m-phenylene bismaleimide by reacting N,N'-m-phenylene bismaleamic acid with an acid anhydride in the presence of a tertiary amine and a metal salt, , N'-m-phenylene bismaleamic acid in the presence of 1 to 6% by weight of water and 1 to 2.2 times the weight of aliphatic ketone at a reaction temperature of 80 to 40°C. Method for producing N,N'-m-phenylene bismaleimide (2) The production method according to claim 1, wherein the aliphatic ketone is acetone. (3) The manufacturing method according to claim 1, wherein the tertiary amine is triethylamine. (4) The manufacturing method according to claim 1, wherein the metal salt is a cobalt, nickel or magnesium salt.