JP2003300956A - Method for producing n-substituted maleimides - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing adhesion of a solid material to the inner surfaces of a condenser and a pipe when N-substituted maleimides are produced from maleamic acid or maleic anhydride and a primary amine in an inert organic solvent by using an apparatus equipped with a reactor, the condenser and the pipe connecting the reactor to the condenser. <P>SOLUTION: At least a part of the inner surfaces of the condenser and the pipe are regulated to (A) the smoothness of ≤6.3 S surface roughness and wetted with (B) an inert organic solvent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing N-substituted maleimides, and more specifically, to prevent solids from adhering to the inner surfaces of condensers and pipes, and to stabilize N-substituted maleimides for a long period of time. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art A process for producing N-substituted maleimides from maleic anhydride and a primary amine in one step in the presence of an acid catalyst in an inert organic solvent, and maleic anhydride and a primary amine to give maleic acid. The method for producing N-substituted maleimides by dehydration ring closure reaction of this maleamic acid is known well. This reaction is carried out while removing the produced water by azeotropic distillation with an inert organic solvent, but at this time, the inner surface of the condenser contacting with the steam or the inner surface of the pipe connecting the reactor and the condenser. Solid matter may adhere to the tube and, in extreme cases, may cause tube blockage. The adhesion of the solid matter is caused by a compound which is insoluble in an inert organic solvent such as maleic acid, fumaric acid, N-substituted maleamic acid, or N-substituted fumaramic acid, which is produced during the reaction, and which is anhydrous in the gas phase. It is believed that the maleamic acid formed by the reaction of maleic acid with the vapor of primary amines will also attach.

As a method for preventing the above-mentioned tube clogging, for example, in JP-A-4-139166, when maleic anhydride and a primary amine are continuously added and reacted,
A method of coexisting a specific stabilizer of a copper compound and / or a phosphorus compound to suppress the production of fumaric acid and N-substituted monofumaramic acid and to prevent clogging of a condenser and a pipe is described.

Further, Japanese Patent Laid-Open No. 10-59935 discloses a method of adding a protic polar solvent such as formic acid, acetic acid and propionic acid into the reaction system to prevent clogging of condensers and pipes and side reactions. Have been described.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to the production of N-substituted maleimides from maleamic acid or maleic anhydride and a primary amine in an inert organic solvent.
It is an object of the present invention to provide a method for simply and effectively preventing solid substances from adhering to the inner surfaces of a condenser and a pipe by using a completely different means from the above-mentioned conventional method.

[0006]

According to the research conducted by the present inventors, regarding the inner surface of the condenser and the inner surface of the pipe, at least a part of the inner surface has a surface roughness of 6.3 S or less, and is not smooth. It has been found that the above objectives can be achieved by wetting with an active organic solvent.

The present invention uses an apparatus comprising a reactor, a condenser, and a pipe connecting the reactor and the condenser, and uses maleic acid or maleic anhydride and a primary amine in an inert organic solvent. In the method for producing N-substituted maleimides from the above, regarding the inner surface of the condenser and the inner surface of the pipe, at least a part of the entire inner surface thereof has (A) a surface roughness of 6.3S or less, and (B) A method for producing N-substituted maleimides, which comprises wetting with an inert organic solvent.

In the present invention, "(A) surface roughness 6.3"
The term "smoothness of S or less and wetting with (B) an inert organic solvent" includes the following aspects, for example, when this treatment is performed on the entire inner surface. (A) The entire inner surface is made smooth with a surface roughness of 6.3 S or less, and a part thereof is wet with an inert organic solvent. (B) The entire inner surface is wetted with an inert organic solvent, and a part thereof has a surface roughness of 6.3 S or less. (C) The entire inner surface is made to have a surface roughness of 6.3 S or less and wet with an inert organic solvent.

The above-mentioned treatment in the present invention does not necessarily have to be carried out on all the inner surfaces of the condenser and the inner surface of the pipe, and unless the adhesion of solid matter occurs to an undesired degree, all the inner surfaces thereof. You may go to a part of. Among them, the above (a) to
It is preferable to perform any of (c).

Further, the present invention "wet with an inert organic solvent"
Means, for example, to form a liquid film of an inert organic solvent to the extent that the contact between the inner surface of the pipe and the vapor from the reactor can be sufficiently prevented, and as one of its concrete means, a spray nozzle. Can be used to spray an inert organic solvent onto the inner surface.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, N-substituted maleimides are produced in one step from maleic anhydride and primary amine as raw materials in the presence of an acid catalyst in an inert organic solvent. And a method for producing N-substituted maleimides from a maleamic acid produced from maleic anhydride and a primary amine using this maleic acid as a raw material. The present invention does not have a characteristic in the reaction itself, and can produce a corresponding N-substituted maleimide from maleic acid or maleic anhydride and a primary amine under conventionally known reaction conditions. .

Typical examples of primary amines used as raw materials are methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-
Butylamine, tert-butylamine, n-hexylamine, n-dodecylamine, allylamine, benzylamine, cyclohexylamine, aniline, nitroaniline, aminophenol, aminobenzoic acid, anisidine, ethoxyphenylamine, monochloroaniline, dichloroaniline, toluidine. , Xylidine, ethylaniline and the like.

The maleamic acid is obtained by reacting the above primary amine with maleic anhydride,
As a typical example thereof, N-phenylmaleamic acid,
Examples thereof include N-benzylmaleamic acid, N-cyclohexylmaleamic acid and N-tripromophenylmaleamic acid.

Typical examples of the acid catalyst include inorganic or organic monobasic acids and polybasic acids such as sulfuric acid, paratoluenesulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, benzenesulfonic acid, methanesulfonic acid and trichloroacetic acid. Amine salts obtained by neutralizing these basic acids with amines, which are the raw materials for the production of maleimides; acidic ion exchange resins and the like.

Typical examples of the inert organic solvent are benzene, toluene, petroleum fraction having a boiling point of 50 to 120 ° C., xylenes, ethylbenzene, isopropylbenzene, cumene, mesitylene, tert-butylbenzene, pseudocumene, trimethylhexane, octane. , Tetrachloroethane, nonane, chlorobenzene, ethylcyclohexane, petroleum fraction having a boiling point of 120 to 170 ° C., m-dichlorobenzene, sec-butylbenzene, p-dichlorobenzene, decane, p-cymene, o-dichloro Examples thereof include benzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, naphthalene, cyclohexylbenzene, and a petroleum fraction having a boiling point of 170 to 250 ° C.

Various reaction conditions such as the ratio of maleic anhydride and primary amine, the amount of the acid catalyst used, the amount of the inert organic solvent used, and the reaction humidity can be appropriately selected from known condition ranges.

FIG. 1 is an explanatory view showing an embodiment of the present invention. As shown in FIG. 1, the method of the present invention comprises a reactor (jacketed reaction vessel 4), a condenser for condensing vapor (azeotropic mixture of produced water and an inert organic solvent) from the reactor. (Cooling condenser 6) and a device including a pipe (steam conduit 5) connecting the reactor and the condenser are used. Hereinafter, the present invention will be described in detail with reference to FIG.

As shown in FIG. 1, the raw material is supplied from a pipe having an opening in the gas phase, such as a maleic anhydride supply pipe 1 and a primary amine supply pipe 2.

A part of the inert organic solvent from the water separator 7 is circulated in the reaction tank 4, and the remaining inert organic solvent is introduced from the shower nozzle 15 into the vapor conduit 5 to wet the inner surface of the pipe. Alternatively, it is introduced into the cooling condenser 6 and the steam conduit 5 from the shower nozzles 14 and 15, respectively, to wet the inner surface of the pipe and the inner surface of the condenser with the inert organic solvent. For wetting with this inert organic solvent,
As long as direct contact between the inner surface of the condenser and the inner surface of the pipe and vapor can be prevented, a method other than the spraying of the inert organic solvent using the shower nozzle can be appropriately adopted. As the shower nozzle, for example, a circular whole surface water spray type nozzle (EX4 type, NIIKUR) is used.
A CORPORATION) or the like can be used. As the inert organic solvent, a new inert organic solvent may be used, but it is preferable to recover and circulate the inert organic solvent used for the cyclization dehydration reaction before use.

The inner surface of the pipe and / or the inner surface of the condenser has a surface roughness of 6.3 S or less. The surface roughness and S referred to in the present invention refer to JIS B0601-1.
It is based on the regulations of 982-3.4. In particular, it is preferable that the surface roughness is 1.6S or less.

The polishing means for achieving the above smoothness is not particularly limited, and a mechanical polishing method, an electrolytic polishing method or the like can be used. For example, # 200 or more, preferably # 3
The puff polishing may be performed to 00 or more, and more preferably to # 400 or more.

In order to perform the above-mentioned treatment on the inner surface of the condenser, it may be performed on the entire inner surface of the condenser, or at least on the inner surface in contact with the steam from the pipe. The same applies to wetting with an inert organic solvent.

Further, in the present invention, at least a part of the inner surface of the condenser and the inner surface of the pipe which come into contact with the gas phase portion in the reactor are (A) surface roughness 6.3S or less. And / or (B) wet with an inert organic solvent.

[0024]

EFFECTS OF THE INVENTION According to the method of the present invention, since solid substances can be easily and effectively prevented from adhering to the inside of the condenser and the pipe, N-substituted maleimides can be stably produced over a long period of time.

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, the shower nozzle used here is a circular whole surface water spray type nozzle (EX470 type, NIIKURA).
(Corporation). Comparative Example 1 200 kg of orthoxylene and 30 k of orthophosphoric acid (85%) were placed in a preparation tank of 500 liter capacity equipped with a stirrer.
After supplying g, granular silica gel (trade name: Microbeads silica MB-4B, manufactured by Fuji Silysia Chemical Ltd.) 1
00 kg was added to support the orthophosphoric acid on the silica gel. Next, by adding 8 kg of aniline, a catalyst having a part of the supported acid as an amine group was prepared.

Thermometer 13, steam conduit (inner diameter 105 mm)
5, cooling condenser 6, water separation tank 7, shower nozzle 14,
15, and the agitator 3 with the placed device as shown in FIG. 1, the jacketed reaction vessel 4 volume 2m ^3, ortho-xylene 600 kg, dibutyl thiocarbamate copper 0.
02 kg and the above supported catalyst were charged, and the internal temperature was 130
The mixture was heated and stirred so that the temperature became ° C. Next, 110 kg of maleic anhydride and 100 kg of aniline were quantitatively added over 1 hour from the maleic anhydride supply pipe and the aniline supply pipe, respectively, which were opened in the gas phase portion in the reaction tank 4, to perform the reaction, and the addition was completed. After that, N-phenylmaleimide was produced by further reacting for 3 hours. Water produced along with the progress of the reaction was distilled off together with ortho-xylene, and the ortho-xylene was refluxed to the reaction vessel 4 while removing the water outside the system in the water separation vessel 7.

The steam conduit 5 and the cooling condenser 6 are made of stainless steel (SUS316), and all the inner surfaces are in conformity with JIS B0601-1982-3.4, and a surf test manufactured by Mitoyo Co., Ltd. is used. The surface roughness was measured by measuring the smoothness.

A portion of the orthoxylene refluxed in the reaction vessel 4 is sprayed through the shower nozzles 14 and 15 attached to the contact portion between the vapor conduit 5 and the upper part of the cooling condenser 6 with the gas phase portion to keep the wall surface wet. While reacting. At this time, the shower flow rate was 300 liters / hour sprayed on each of the steam conduit 5 and the cooling condenser 6. After the completion of the reaction, the steam conduit 5 and the cooling condenser 6 were disassembled, the solid substance adhering to the inner surface was recovered, and the weight after drying was measured and found to be 80 kg. Example 1 In Comparative Example 1, the entire inner surfaces of the steam conduit 5 and the cooling condenser 6 were mechanically polished using a grindstone # 200 manufactured by Tosa Emery Co., Ltd. to obtain a smoothness of surface roughness 6.3S. The reaction was performed in the same manner except for the above. After the completion of the reaction, the steam conduit 5 and the cooling condenser 6 were disassembled, and the solid matter adhering to the inner surface was recovered, dried and weighed to find 20 kg.

From this result, the solvent orthoxylene was sprayed on the inner surfaces of the condenser and the pipe to wet the surfaces,
Furthermore, the inner surface of the condenser and the pipe has a surface roughness of 6.3S.
It can be seen that the following smoothness can more effectively prevent the solid matter from adhering to the inner surfaces of the condenser and the pipe. Example 2 In Comparative Example 1, the entire inner surfaces of the steam conduit 5 and the cooling condenser 6 were mechanically polished using a grindstone # 400 manufactured by Tosa Emery Co., Ltd. to obtain a smoothness of surface roughness 1.6S. The reaction was performed in the same manner except for the above. After the completion of the reaction, the steam conduit 5 and the cooling condenser 6 were disassembled, the solid substance attached to the inner surface was recovered, and the weight after drying was measured and found to be 13 kg.

From these results, the solvent ortho-xylene was sprayed onto the inner surfaces of the condenser and piping to wet the surfaces,
Furthermore, the inner surface of the condenser and the pipe has a surface roughness of 1.6S.
It can be seen that the following smoothness can more effectively prevent the solid matter from adhering to the inner surfaces of the condenser and the pipe.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 Maleic anhydride supply pipe 2 Primary amine acid supply piping 3 stirrer 4 jacketed reaction tank 5 steam conduit 6 Cooling condenser 7 water separation tank 8 reflux liquid circulation pump 9 Steam entrance 10 steam exit 11 Cooling water inlet 12 Cooling water outlet 13 Thermometer 14, 15 Shower nozzle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taiji Kinoshita             Hyogo prefecture Himeji city             1 Within Nippon Shokubai Co., Ltd. F term (reference) 4C069 AD08 BA08 BC12 CC11 CC30

Claims (3)

[Claims] 1. A system comprising a reactor, a condenser, and a pipe connecting the reactor and the condenser is used, and maleic acid or maleic anhydride and a primary amine are converted to N in an inert organic solvent. -In the method for producing a substituted maleimide, regarding the inner surface of the condenser and the inner surface of the pipe, at least a part of the entire inner surface thereof is (A) surface roughness 6.
A method for producing N-substituted maleimides, which comprises making the smoothness 3 S or less and wetting with (B) an inert organic solvent. 2. Further, with respect to the inner surface in contact with the gas phase portion in the reactor, at least a part of the whole inner surface is
(A) A surface roughness of 6.3 S or less, and /
Alternatively, (B) the method for producing an N-substituted maleimide according to claim 1, which is wet with an inert organic solvent. 3. The method for producing N-substituted maleimides according to claim 1, wherein an inert organic solvent is introduced from a shower nozzle and wetted.