JP2001122858A - Production of phthalimide compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for a phthalimide compound by allowing a finely divided phthalic anhydride compound to react with ammonia under the reaction conditions where they are not melted and subjecting the resultant phthalamic acid compound to the dehydration reaction. SOLUTION: This reaction process can be carried out at a relatively low temperature and the reaction mixture can be maintained in a solid state. Thus, the product can be prevented from sticking and is easy to handle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Phthalimide compounds such as phthalimide are important as synthetic intermediates for dyes and pigments. For example, phthalimide is also a raw material for anthranilic acid, which is an intermediate raw material for pharmaceuticals, agricultural chemicals, fragrances and the like.

[0002]

2. Description of the Related Art Heretofore, phthalimide compounds, for example, phthalimide, have been prepared by (1) a method of producing phthalic anhydride dissolved in a solvent by the reaction of ammonia, and (2) a method of producing phthalic anhydride at a temperature not lower than its melting point without using a solvent. It has been manufactured by a method of reacting with ammonia or urea at a temperature and finally raising the temperature to a temperature equal to or higher than the melting point of the phthalimide compound to complete the reaction. Other examples include the reaction between ammonium carbonate and phthalic anhydride, and the reaction between formamide and phthalic anhydride. In these production methods, phthalic anhydride is reacted in a liquid phase state, for example, by melting phthalic anhydride at a high temperature or dissolving in a solvent in order to increase the reaction yield.

[0003]

However, (1)
The method of (1) inevitably raises the danger of using a flammable solvent, increases the cost due to solvent separation and post-treatment of the used solvent, and reduces process difficulties such as the reaction products sticking to the inner wall of the reactor. There was a problem such as accompanying. Also, (2)
Is difficult to recover the product due to the increase of sublimates, the imide compound is heated to the melting point or more, and the quality problem such as coloring due to the increase of by-products, and the energy cost increase by handling at high temperature There was a problem. An object of the present invention is to provide a low-cost, industrially excellent method for producing a phthalimide compound which has a simplified production process, and a phthalimide compound having a high product purity.

[0004]

The present inventors have conducted intensive studies and have found that (1) a finely divided phthalic anhydride compound is reacted with ammonia while maintaining a substantially solid phase to form an anhydrous phthalic anhydride compound. A two-step reaction consisting of a first step of converting at least a part of the phthalic acid compound into a phthalamic acid compound and (2) a second step of dehydrating the phthalamic acid compound obtained in the first step to form an imide compound The inventors have found that a phthalimide compound can be easily obtained with high purity from a phthalic anhydride compound and ammonia without passing through a molten state, and the present invention has been completed. That is, when a finely divided phthalic anhydride compound is reacted with ammonia to obtain a phthalimide compound in a one-step reaction, the phthalimide compound is melted during the reaction, whereas the reaction is divided into two steps as described above. This not only prevents melting but also improves the purity of the resulting phthalimide compound.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of phthalic anhydride compounds include phthalic anhydride and its derivatives represented by the following general formula (1).

The general formula (1)

Embedded image [In the formula, the substituent R is a hydrogen atom, a halogen atom, a nitro group, a substituted or unsubstituted alkyl group (1 to 3 carbon atoms, preferably 1 to 2 carbon atoms), a substituted or unsubstituted alkoxy group (carbon number 1 to 3, preferably 1 to 2 carbon atoms, and represents a substituted or unsubstituted amino group. n is the number of substituents R and is 0
Represents an integer from 4 to 4]

That is, an object of the present invention is to provide an industrially advantageous method for producing a phthalimide compound represented by the general formula (2).

General formula (2)

Embedded image [In the formula, the substituent R is a hydrogen atom, a halogen atom, a nitro group, a substituted or unsubstituted alkyl group (1 to 3 carbon atoms, preferably 1 to 2 carbon atoms), a substituted or unsubstituted alkoxy group (carbon number 1 to 3, preferably 1 to 2 carbon atoms, and represents a substituted or unsubstituted amino group. n is the number of substituents R and is 0
Represents an integer from 4 to 4]

Specific examples of the phthalic anhydride compound include phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, 3-ethylphthalic anhydride, 4-ethylphthalic anhydride, and 3-chlorophthalic anhydride. Acid, 4-chlorophthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride and the like.

In the present invention, since the above-mentioned phthalic anhydride compound is reacted with ammonia while substantially maintaining a solid phase, it is preferable to carry out the reaction in a finely divided state in order to promptly proceed the reaction. Specifically, a state divided into a powder, a flake, a needle, or the like is preferable.
If the size of these finely divided phthalic anhydride compounds is too large, unreacted phthalic anhydride compounds increase, so that finer ones are desirable, but as described later, the reaction with ammonia is practical. The size may be such that the unreacted phthalic anhydride compound is 10% by weight or less. Specifically, if it is a powder, the particle diameter is 200 μm or less, the average particle diameter is 45 μm or less, preferably the particle diameter is 80 μm.
m and an average particle diameter of 20 μm or less, and if it is flaky, its thickness is 26 μm or less, preferably 20 μm or less. If it is needle-shaped, the thickness is preferably 25 μm or less, and more preferably 20 μm or less. If it is larger than this, the unreacted phthalic anhydride compound in the reaction with ammonia becomes too large, and as described later, it is melted in the dehydration reaction in the second step and adheres to the inner wall of the reactor, or the phthalimide compound Is not preferred because the purity of

The reaction between the phthalic anhydride compound and ammonia can be carried out by a method in which phthalic anhydride is finely divided in advance and reacted with ammonia, or a method in which finely divided phthalic acid is reacted with ammonia.

The first step of the method for producing a phthalimide compound according to the present invention comprises the step of:
In this reaction, ammonia is reacted with ammonia while maintaining a substantially solid phase to convert at least a part of the phthalic anhydride compound into a phthalamic acid compound. Here, substantially maintaining the solid phase means that the reaction products such as the phthalic anhydride compound and the phthalamic acid compound are reacted while maintaining a finely divided state without substantially melting or fusing. That is, the heating reaction is performed at a temperature equal to or lower than the melting point. For example, when phthalic anhydride is used as a raw material, the phthalic anhydride is reacted with ammonia at a temperature in the range of room temperature to 125 ° C. In this case, the reaction may be performed at a constant temperature, or the temperature may be changed as the reaction proceeds.

As the ammonia used for the reaction, it is convenient and preferable to use ammonia gas. The supply of the ammonia gas may be normal pressure or pressurized, and may be diluted with air, nitrogen, or the like. As another ammonia source, a compound such as aqueous ammonia, liquid ammonia, or urea may be used as the ammonia source.

In the reaction of the first step, the phthalic anhydride compound becomes a corresponding phthalamic acid compound, but a partially unreacted phthalic anhydride compound may remain. In this case, if the unreacted phthalic anhydride compound is 10% by weight or less, it can be converted into a phthalimide compound without substantially melting or fusing in the subsequent dehydration reaction.
Unreacted phthalic anhydride compounds are also preferred because they can all be converted into imide compounds. Conversely, the content of the unreacted phthalic anhydride compound in the reaction of the first step is 10% by weight.
Exceeding the melting point is undesirable because the powder is melted and solidified in the second step of the dehydration reaction.

[0015] A reactor suitable for the first step is as follows.
A vertical or horizontal reactor having a stirring device for flowing the finely divided phthalic acid compound or a device for pulverizing the phthalic anhydride compound may be used. The reactor is supplied with a phthalic anhydride compound and ammonia, and while the phthalic anhydride compound finely divided is allowed to flow as it is or while flowing, while the phthalic anhydride compound before finely dividing is pulverized, And react with. The supply of the ammonia gas may be normal pressure or pressurized.

Next, as a second step, the phthalamic acid compound obtained in the first step is dehydrated to an imide compound. When a phthalamic acid compound is used as a raw material instead of a phthalic anhydride compound, the first step can be omitted and the present step can be started. The dehydration reaction is carried out by heating the phthalamic acid compound, but may be carried out under reduced pressure in order to keep the heating temperature low. Further, in order to accelerate the dehydration reaction, the reaction may be performed under a flow of an inert gas such as air or nitrogen.

In particular, when the dehydration reaction is carried out in an ammonia atmosphere, the melting of the phthalamic acid compound can be prevented, so that the product does not adhere to the inner wall of the reaction vessel, handling can be facilitated, the apparatus can be simplified, and energy costs can be reduced. It is preferable in terms of reduction of the amount. The condition under the ammonia atmosphere can be achieved by supplying ammonia gas into the reactor, and may be appropriately diluted with an inert gas such as air or nitrogen gas. The ammonia atmosphere may be an ammonia atmosphere at the start of the dehydration reaction, and at least a dehydration rate of 30 to 50.
An ammonia atmosphere may be used up to the weight%. Conversely, if the ammonia atmosphere is excessively maintained even after the dehydration rate of 50% by weight or more, the dehydration rate decreases and the amount of by-products increases, which is not preferable.

Here, instead of performing the second step in an ammonia atmosphere, at least a part of the phthalamic acid compound may be converted to an ammonium salt in the first step. By using an ammonium salt of a phthalamic acid compound, it can be converted into a phthalimide compound without substantially melting or fusing in a subsequent dehydration reaction, and all unreacted phthalic anhydride compounds are also converted into imide compounds. It is preferable because it can be used.

For example, in the case of phthalamic acid, the content of ammonium salt is at least 53% by weight, preferably 5% by weight.
The content is desirably from 3% by weight to 60% by weight. When the content of the ammonium salt is less than 53% by weight, the product is melted. When the content is more than 60% by weight, the purity of the imide is reduced, which is not preferable. In the present invention, the first step and the second step may be performed in the same reactor or in separate reactors, and may be performed in any of a batch system and a continuous system.

When a separate reactor is used in the second step, for example, a vertical or horizontal reactor equipped with a stirrer for flowing the phthalamic acid compound or its ammonium salt can be used.

[0021]

EXAMPLES Examples are described below, but the present invention is by no means limited to these. Example 1 100 parts by weight of phthalic anhydride was reacted while pulverizing to a mean particle size of 44 μm at room temperature in a small pulverizer under a flow of ammonia. A powder of 103.9 parts by weight of a mixture of phthalamic acid and ammonium phthalamidate and 12.6 parts by weight of a mixture of phthalic anhydride and phthalic acid was obtained.
The phthalic anhydride content in this mixture was 7.8% by weight. The obtained powder was transferred to a test tube and heated in an oil bath at 185 ° C. for 5 hours to obtain phthalimide having a purity of 99.2% by weight as a powder.

Example 2 100 parts by weight of phthalic anhydride pulverized to an average particle size of 42 μm was placed in a flask, and the temperature was raised from room temperature to 124 ° C. in an oil bath with stirring while flowing ammonia to cause a reaction. A powder of 107.7 parts by weight of a mixture of phthalamic acid and ammonium phthalamidate, 0.1 part by weight of phthalimide, and 9.3 parts by weight of a mixture of phthalic anhydride and phthalic acid were obtained. The obtained powder was heated to 185 ° C. in an ammonia atmosphere and reacted at the same temperature for 4 hours while flowing air. Phthalimide having a purity of 99.5% by weight was obtained as a powder. The sublimated phthalimide was 4.8 parts by weight.

Comparative Example 1 The procedure of Example 2 was repeated except that 100 parts by weight of phthalic anhydride pulverized to an average particle size of 50 μm was used. As a result, 102 parts by weight of a mixture of phthalamic acid and ammonium phthalamidate were obtained. 0.
3 parts by weight and 16 parts by weight of a mixture of phthalic anhydride and phthalic acid were obtained as a powder. The phthalic anhydride content in this mixture is 1
0.8% by weight. The temperature of the obtained powder was raised to 185 ° C. in an ammonia atmosphere. However, the powder solidified around 130 ° C. on the way and could not be stirred.

Example 3 4-Methylphthalic anhydride 10
0 parts by weight were reacted while pulverizing at room temperature with ammonia flow using a small pulverizer. 4-methylphthalamic acid and 3-
83.5 parts by weight of a mixture of methylphthalamic acid and their ammonium salts, 3-methylphthalic anhydride and 3
39.3 parts by weight of a mixture with -methylphthalic acid and its ammonium salt were obtained in powder form. The obtained powder was transferred to a test tube and heated in an oil bath at 185 ° C. for 2 hours. Purity 9
9.6% by weight of 4-methylphthalimide was obtained in powder form.

Example 4 4-Nitrophthalic anhydride 10
0 parts by weight were reacted while pulverizing at room temperature with ammonia flow using a small pulverizer. 95.0 parts by weight of a mixture of 4-nitrophthalamic acid and its ammonium salt and 19.8 parts by weight of a mixture of 4-nitrophthalic anhydride, 3-nitrophthalic acid and its ammonium salt were obtained. The obtained powder was transferred to a test tube and placed in an oil bath at 185 ° C. for 2 hours.
Heated for hours. 4-nitrophthalimide having a purity of 99.2% by weight was obtained as a powder.

"Comparative Example 2" Heat dehydration reaction was carried out under various conditions while changing the mixing ratio of phthalamic acid and ammonium phthalamidate, and the state of the product was observed.

[0027]

[Table 1]

[Comparative Example 3] Phthalic anhydride was dispersed in ortho-xylene, and the temperature was raised from room temperature to 130 ° C under a flow of ammonia to cause a reaction. Then, the temperature was raised to 140 ° C and ortho-xylene was distilled off. Consolidated. The consolidated product was taken out to obtain phthalimide having a purity of 97.1% by weight.

Comparative Example 4 100 parts by weight of phthalic anhydride was dispersed in Hisol P manufactured by Nisseki Chemical as a solvent, and the reaction was carried out by raising the temperature from room temperature to 210 ° C. under flowing ammonia. 210
The reaction was terminated when all the crystals were dissolved at
After cooling to 0 ° C. for crystallization, the mixture was filtered. The filter cake was dried under reduced pressure to obtain 85.6 parts by weight of phthalimide having a purity of 99.8% by weight. Phthalimide was colored light brown, and the filtrate was colored yellow

Comparative Example 5 100 parts by weight of phthalic anhydride was dissolved at 140.degree. C., and heated to 240.degree. C. under flowing ammonia to cause a reaction. After maintaining at 240 ° C. for 10 minutes, the solution was poured into an enamel vat and solidified by cooling to obtain 88.7 parts by weight of phthalimide having a purity of 96.7% by weight.

[0031]

According to the method of the present invention, a phthalimide compound can be obtained in a good yield despite the fact that the reaction is carried out at a relatively low temperature without melting, the solidification of the product is prevented, and the handling is facilitated. Easy. Further, since no solvent is used, there is no need for separation and post-treatment, so that the apparatus can be simplified and equipment costs can be reduced. Furthermore, since the treatment is carried out at a relatively low temperature, the energy cost can be reduced, and the reaction conditions can be selected in a mild and relatively wide range, so that the coloring of the product can be prevented, and the impurities can be reduced and the purity can be improved.

Claims (5)

[Claims] 1. A method for obtaining a phthalimide compound from a phthalic anhydride compound and ammonia, comprising the steps of: (1) reacting a finely divided phthalic anhydride compound with ammonia while maintaining substantially a solid phase to form an anhydride; A method for producing a phthalimide compound, comprising: a first step in which at least a part of the phthalamic acid compound is converted into a phthalamic acid compound; and (2) a second step in which the phthalamic acid compound obtained in the first step is dehydrated to form an imide compound. 2. The method according to claim 1, wherein the amount of the unreacted phthalic anhydride compound is 10% by weight or less in the first step. 3. The method according to claim 1, wherein in the second step, the dehydration reaction is started under an ammonia atmosphere. 4. The method according to claim 1, wherein at least a part of the phthalamic acid compound is an ammonium salt. 5. A method for producing phthalimide from phthalamide acid, wherein the finely divided phthalamide acid is dehydrated in an ammonia atmosphere.