JPS6366164A - Production of bismaleimides - Google Patents

Abstract

PURPOSE:To easily produce the titled compound useful as a raw material for imide resin, by using specific amounts of a ketone solvent and a tert-amine in the dehydrative cyclization reaction of an amidic acid produced by the addition reaction of diphenylamine and maleic anhydride and carrying out the cyclization reaction under a specific condition. CONSTITUTION:A diamine of formula I (X is lower alkylene, -O-, -SO2- or -CO-) is made to react with maleic anhydride in a ketone solvent, preferably in acetone and the produced bismaleamidic acid is, without separating from the system, subjected to the dehydrative cyclization reaction in the ketone solvent in the presence of a catalyst, a tert-amine (preferably triethylamine) and a dehydration agent to obtain the objective compound of formula II. The above reaction is carried out by using 3-7pts.wt., preferably 4-6pts.wt. of the ketone solvent based on 1pt.wt. of the diamine, heating the reaction system at >=40 deg.C, preferably at 50-60 deg.C and dripping 0.05-0.5mol of the tert-amine to the system based on 1mol of the diamine.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a compound of formula (Il) (wherein, X is a lower alkylene group, -O-, -SO□-1
-CO-. ) The present invention relates to a method for producing diphenyl bismaleimides represented by

The above compound of formula (I1) is widely used as a thermosetting resin that requires heat resistance and dimensional stability, such as in impregnated laminate molded products in the electrical and mechanical fields, either alone or in combination with other materials. It is useful as a raw material for imide-based resins.

[Conventional technology]

The method for producing bismaleimides has been known for a long time.
The typical bismaleimide is N,N'-(4,4'
-diphenylmethane) bismaleimide, and currently bismaleimides are obtained by a method that uses 4 tons of this method.

That is, an example of a method for producing N,N'-(4,4''-diphenylmethane)bismaleimide is as follows: Using the formula % and 2 moles or more of maleic anhydride, ketones such as acetone, methyl ethyl ketone, N, A ring-opening addition reaction in a polar organic solvent such as N-dimethylformamide yields N,N"-(4,4"-diphenylmethane)bismaleamic acid, followed by a soluble metal salt catalyst such as i11 cobalt or nickel acetate. After the cyclodehydration reaction is carried out by adding a tertiary amine such as triethylamine as a cocatalyst and heating with a dehydrating agent such as acetic anhydride, a large amount of precipitant is added to the reaction mass. The desired product was obtained by injecting water to precipitate crystals.

As described above, the method for producing bismaleimides not only requires complicated operations but also does not necessarily provide a sufficient yield. Furthermore, the cost is high because expensive reagents are used. In particular, dimethylformamides are expensive, and acetones, which are poorer solvents, are cheaper but need to be used in large quantities.
As mentioned above, after the completion of the reaction, a large amount of water is added to obtain the desired product as a precipitate, so it is difficult to recover these solvents.

Therefore, JP-A-52-125161 discloses that after the intermediate maleamic acid is taken out of the system, a relatively large amount of a dehydrating agent such as acetic anhydride and a third agent such as triethylamine are used without necessarily using a solvent. A method is described in which a class amine is used to form a uniform solution, the reaction is heated, and after completion of the reaction, water is added and the precipitated product is filtered off.

In this method, although the solvent used in the first stage can be recovered, a relatively large amount of expensive acetic anhydride and acetic anhydride used in the second stage cyclization reaction are recovered.
Recovery of triethylamine and the like still has problems and cannot be called an advantageous method.

Furthermore, the precipitation method, in which water is injected into the reaction mass after the reaction is completed, remains the same, and as a result, impurities are removed from lFf.

The purity and yield are reduced.

Apart from these precipitation methods, there is also known a method in which the reaction is carried out in a slurry state, and after the reaction is completed, the desired product is directly separated into solid and liquid.

JP-A-61-83158 discloses that in producing N,N'-m-phenylene bismaleimide from meta-phenylene diamine and maleic anhydride, a ketone solvent is
- Using a specific amount of 3 to 6 times the weight of phenylene diamine, the slurry state is consistently maintained from the production of amic acid in the first stage to the dehydration and cyclization reaction of the dehydrating agent, catalyst, and meta-phenylene diamine. A method is disclosed in which a tertiary amine is added in a molar ratio of 0.05 to 0.2 to the tertiary amine, the reaction is heated, and immediately after the reaction is completed, the desired product is obtained by filtration.

[Problem that the invention seeks to solve]

The present inventors used a method similar to the method described in JP-A No. 61-83158, prior to investigating a production method in which the solvent is used as little as possible and the reaction-completed liquid can be obtained in the form of a slurry for direct solid-liquid separation. An additional attempt was made to produce the diphenyl bismaleimide represented by formula (If), but the desired results could not be achieved.

That is, according to the method described in Examples, 4.4''-diaminobenzenesulfone was used as the compound of formula (I) in place of metaphenylenediamine, and maleic anhydride was added using about 5 times the mole of acetone as a solvent. When we tried the reaction with amic acid, there was no problem up to the addition reaction to amic acid, but during the dehydration cyclization reaction, about 0.12 mole amount of triethylamine was added to the predetermined amount of diamine. When the reaction was heated at around °C, stirring gradually became difficult, and even if triethylamine was further added, stirring was difficult and the desired product could not be obtained.

In addition, when 4,4''-diaminodiphenylmethane was used as the compound of formula (I), it became difficult to stir during the addition reaction in the first stage with only about 6 times the weight of acetone solvent, resulting in a subsequent heterogeneous reaction. .

Tertiary amines such as triethylamine, which have traditionally been used in the cyclodehydration reaction of maleamic acid, activate the dehydration action and function as a cocatalyst to suppress isoimide formation, while at the same time solubilizing the amic acid. It is known that it has this function.

Therefore, if a small amount of poor solvent such as acetone is used, it may be possible to use a large amount of all the tertiary amines, but if a large amount of tertiary amine is used, it becomes difficult to control the reaction rate, and tar etc. An increase in by-products is inevitable.

[Means to solve the problem]

In view of these problems, the present inventors have determined that the formula <r>
In the cyclodehydration reaction of the amic acid obtained from the addition reaction of diphenylamine with maleic anhydride, the amount of ketone solvent is reduced, and the tertiary amine is contained within a limited range that does not affect the target product. We have intensively investigated a method for obtaining the desired product in the form of slurry crystals.

In addition to these results, it was found that the cause of non-uniform stirring during cyclodehydration was due to the tertiary amine added.

That is, diphenyl bismaleamic acid, especially S0 in the molecule.
Diphenylbisamidic acid having two groups immediately reacts with the tertiary amine, resulting in the formation of a gel-like substance.

This gelled product gradually becomes unable to be stirred using a normal stirrer, and if stronger stirring is performed, local stirring occurs only around the stirrer, making it impossible to obtain a uniform slurry solution. On the other hand, if a tertiary amine is not added during dehydration and cyclization, or if the amount used is less than the commonly used amount, problems may occur such as a low reaction rate or a long reaction time. I also understood.

Therefore, in order to obtain bismaleimide in the form of a slurry, it is necessary to use a certain amount of tertiary amine during the dehydration cyclization reaction, but the tertiary amine used must be used in a mild reaction system. With this understanding, the present invention has been completed.

That is, the present invention provides compounds of the formula (I) (wherein, X is a lower alkylene group, -O-, -SO, -1
-CO-. ) and maleic anhydride are reacted in a ketone solvent, and the obtained bismaleamic acid is reacted in a ketone solvent in the presence of a catalyst, a tertiary amine, and a dehydrating agent without subsequent isolation. When carrying out the cyclization reaction, the ketone solvent is heated at 40°C or higher in a state where the weight of the diamine is 3 to 7 times that of the diamine in the compound of formula (I). This is a method for producing diphenyl bismaleimide, which is characterized in that the reaction is carried out while dropping 0.5 times the amount by mole.

In the method of the present invention, applicable diamines represented by formula (I,) include 4.4'-diaminodiphenylmethane, 4.4'-diaminodiphenyl ether, 4.4'
-diaminodiphenylsulfone, 3,3°-diaminodiphenylsulfone, 3,3°-diaminodibenzophenone, 4,4′-diaminodibenzophenone, and the like. In particular, when the method of the present invention is applied to 4,4''-diaminodiphenylsulfone, very good results can be obtained.

In addition, the ketone solvent used in the present invention includes:
Examples include acetone, methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone, among which acetone is preferably used, and the amount used is 3 to 7 times, preferably 4 to 6 times the weight of the diamine.

In the present invention, the ketone solvents used in the production of diphenylamide acids obtained in the initial reaction are subsequently used in the dehydration cyclization reaction without being isolated. Sometimes it can be added all at once, but
During the latter stage of the cyclodehydration reaction, it may be added cumulatively to a predetermined amount as a solvent diluent for the tertiary amine. If the amount of the ketone solvent used is outside the specified range, a slurry-like reaction solution cannot be obtained with a satisfactory yield.

Further, as the dehydrating agent used in the present invention, commonly used lower aliphatic carboxylic anhydrides such as acetic anhydride and propionic anhydride are used, but acetic anhydride is preferably used, and the amount used is limited to diamine It is used in an amount of 2.0 to 3.0 times by mole, preferably 2.0 to 2.2 times by mole.

Examples of the catalyst used in the present invention include commonly used soluble metal salts such as calcium oxide, barium acetate, magnesium acetate, nickel acetate, cobalt acetate, and cobalt naphthenate. Preferably, cobalt acetate is used and the amount used is is 0.001 to 0.0 for diamines.
2, preferably used in an amount of o, ooi to 0.01 mole.

The tertiary amines added dropwise during the cyclodehydration reaction, which is a feature of the present invention, include trialkylamines such as triethylamine and tributylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, etc. −
Dialkylbenzylamine etc. are used, preferably triethylamine, and the amount used is 0.05 to 0.5 times the mole of diamines, preferably 0.2 to 0.5 times.
is good. If the tertiary amine neck added dropwise is less than 0.05, the reaction time will be long, the reaction rate will be low, and unreacted substances will remain. On the other hand, if the amount exceeds 0.5 mole times, not only the production of by-products increases and the yield decreases, but also subsequent purification becomes extremely difficult.

As for the addition conditions, it is necessary to drop it while heating at 40°C or higher, and it is usually better to drop it in about 10 to 60 minutes, preferably dropwise to add it in 20 to 30 minutes at 50 to 60°C.

Even if it is added dropwise over 30 minutes or more under heating, if the temperature is below 40°C, it will gel after a while after the dropwise addition has started, making it difficult to stir, for example, when about 0.1 to 0.2 times the amine is added by mole. become. On the other hand, even under heating (50 to 60℃)
), or even if it is added dropwise over a short period of 10 minutes or more, it will gel, making stirring difficult, which is unavoidable from an industrial standpoint.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 24.8 g (0.10 mol) of 4,4'-diaminobenzenesulfone was added to 160 ml of an acetone solution containing 19.6 g (0.20 mol) of maleic anhydride, and the mixture was stirred at room temperature for 1 hour to form a corresponding solution. A slurry liquid of maleamic acid was obtained. To this, 0.33 g (0,0013 mol) of cobalt acetate tetrahydrate
, 24.5 g (6.24 mol) of acetic anhydride was added, and the mixture was further heated until the reaction temperature reached 55° C., and then 4.5 g (0,044 mol) of triethylamine was added dropwise over about 30 minutes.

During this time, when the dropwise addition started, the amic acid began to dissolve, and when the dropwise addition was completed, most of the slurry was dissolved to become a transparent reaction liquid. After the dropwise addition was completed, further heating was carried out at 58 to 60°C for 1.
After continuing stirring for 5 hours, the reaction solution gradually became a slurry.

After the reaction was completed, the mixture was cooled to room temperature (30°C), and the precipitated crystals were filtered off, washed with acetone, water, and dried.

N,N”-(4,4°-diphenylsulfone)bismaleimide 34.91g (yield 85.5χ, HE, C purity 9
9.4χ) was obtained.

Example 2 Instead of 4.4”-diaminobenzenesulfone, 3.
The procedure was carried out in exactly the same manner as in Example 1 except that 3°-diaminobenzenesulfone was used.
N''-(3,3'-diphenylsulfone)bismaleimide 37.86g (yield 92.7χ, HLC purity 96.0
χ) was obtained.

Example 3 Instead of 4.4"-diaminobenzenesulfone, 4.
4”-diaminodiphenylmethane 19.8g (0,10
The procedure was carried out in the same manner as in Example 1 except that the amount of acetone was changed to 180 ml, and the target yellow solid N, N
”-(4,4'-diphenylmethane)bismaleimide 3
3.93g (yield 94.7χ, HLC purity 97.0χ)
Example 4 obtained 4. Instead of 4”-diaminobenzenesulfone, 3.
21.23 g of 3°-diaminobenzophenone (0,10
The procedure was carried out in the same manner as in Example 1, except that 110 ml of acetone was used, and the white solid N, N'', which was the target product, was
-(4,4°-diphenylketone)bismaleimide 34
．． 78g (yield 93.5χ, ILC purity 92.1χ)
I got it.

Example 5 Instead of 4.4'-diaminobenzenesulfone, 4.
4°-diaminodiphenyl ether 20.0g (0,1
A corresponding slurry of maleamic acid was obtained in the same manner as in Example 1 using 0.33 g (0,0013 mol) of cobalt acetate tetrahydrate and 24.0 g (0,0013 mol) of acetic anhydride.
Add 5g (0.24 mol) and heat until the reaction temperature reaches 55.
When the temperature reached ℃, 1.2 g of triethylamine (0,012
mol) was added dropwise over about 30 minutes, and the mixture was stirred at 58 to 60°C for 1.5 hours.

After the reaction was completed, the same procedure as in Example 1 was carried out to obtain 32.6 g of the target product, yellowish brown solid N,N'-(4,4"-diphenyl ether) bismaleimide (yield 90.5χ, 11 L).
A C purity of 88.9χ) was obtained.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the tertiary amine was added dropwise at room temperature (27°C). When approximately χ amount of triethylamine was added dropwise, stirring became difficult and the reaction was stopped.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the tertiary amine was added all at once under heating (55°C), but stirring became difficult, so about 80 ml of acetone was added to enable stirring, and the reaction was further accelerated. went. However, in this case, unlike in the example, almost no crystals were precipitated. After the reaction was completed, the mixture was allowed to cool, 160 ml of water was added, and the precipitated crystals were filtered and dried. , 1(
An LC purity of 91.6x) was obtained.

Claims (1)

[Claims] 1) Formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, X is a lower alkylene group, -O-, -SO_2-
, -CO-. ) and maleic anhydride are reacted in a ketone solvent, and the obtained bismaleamic acid is reacted in a ketone solvent in the presence of a catalyst, a tertiary amine, and a dehydrating agent without subsequent isolation. When carrying out the dehydration cyclization reaction, after heating to 40°C or higher in a state in which the ketone solvent is present in a proportion of 3 to 7 times the weight of the diamine in the compound of formula (I), the tertiary amine is added in an amount of 0.05 weight to the diamine. ~0.5
The formula (
II) ▲Mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, X is a lower alkylene group, -O-, -SO_2-
, -CO-. ) A method for producing bismaleimides shown in 2) The method according to claim 1, wherein the ketone solvent is acetone. 3) The method according to claim 1, wherein the tertiary amine is triethylamine. 4) Claim 1 in which the heating temperature is 50 to 60°C
The method described in section.