JPH04282361A - Production of succinic imide - Google Patents

Abstract

PURPOSE:To produce the subject compound useful as an intermediate for synthesizing drugs, further as a metal surface-treating agent, a plant growth-regulating agent, etc., at a low cost in high purity and high yield by reacting succinic acid with ammonia and subsequently dehydration-cyclizing the reaction product in the presence of a phosphite ester. CONSTITUTION:1 mole of succinic acid is reacted with 1.05-1.3moles of ammonia in an aqueous medium at ordinary temperature to 100 deg.C for 0.5-5hr to produce succinic acid monoammonium salt. The product is subjected to a dehydration- cyclization reaction in the presence of a phosphite ester in an amount of 0.1-5wt.% based on the succinic acid as a catalyst at 180-230 deg.C for 2-7hr, and the produced crude succinic imide is recrystallized from water to provide pure succinic imide. The method permits to perform the reaction at a temperature 50-80 deg.C lower than that in conventional methods, to reduce the requirement of ammonia and to save the resources without by-producing ammonia, without causing pollution problems and further without requiring the recovery and purification of an alcohol.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a method for producing succinimide.

0002

[Prior art] Succinimide is used as a pharmaceutical synthesis intermediate,
It is useful as a metal surface treatment agent, plant growth regulator, etc. The general synthesis method is to react 1 mole of succinic acid with 2 moles of ammonia to produce succinic acid diammonium salt, and then raise the reaction temperature to a maximum of 290°C to perform a dehydration reaction, and then remove the produced succinimide. While distilling
After obtaining crude succinimide, the crude product is recrystallized with alcohol to obtain colorless succinimide (
(See Organic Synthesis Collective Volume 2, p. 592). The melting point of the product obtained is 12
It is 7℃. This method requires a high reaction temperature of nearly 300° C., which poses an economical problem. Also, the melting point of the product is 12
Because the temperature is as high as 7°C, there is a problem in that the succinimide product crystallizes during distillation and adheres to piping and condensation towers, clogging them. Furthermore, there may be a problem of pollution due to the generation of ammonia. On the other hand, West German Published Patent No. 231
According to No. 3386 (1974), it is shown that the reaction is completed at 260° C. by using triammonium phosphate as a reaction aid, but this is insufficient from an economic point of view. Also, a distillation step is still required as in the organic synthesis method described above.

0003

As described above, the conventional method for producing succinimide has high reaction temperatures and is therefore uneconomical, and there is a great risk of clogging of piping during distillation, resulting in safety problems. There is also the possibility of pollution caused by ammonia. Furthermore, there were other problems, such as the purity of the obtained succinimide being poor, and the use of an organic solvent such as alcohol as a recrystallization solvent, which required recovery and purification of the alcohol. This invention provides a method to solve these problems.

0004

[Means for solving the problem] The inventors of this invention,
As a result of intensive research to solve the above problems, the manufacturing method of the present invention was discovered. That is, the method of the present invention involves reacting succinic acid and aqueous ammonia to produce a succinic acid monoammonium salt, and subjecting this to a dehydration ring closure reaction at a temperature of about 180 to 220°C in the presence of a phosphorous ester.
By recrystallizing the obtained crude succinimide from water, pure succinimide can be obtained in high yield.

[0005] This reaction formula is shown as follows.

[0006]

[Chemical formula 1]

In the process of this invention, ammonia is used in a chemical equivalent amount or in slight excess to form the monoammonium succinate salt. That is, it is generally 1 to 1.4 mol, preferably 1.05 mol per mol of succinic acid.
~1.3 mol. As the ammonia, it is convenient to use approximately 28% industrial ammonia water, which also serves as the aqueous medium. However, its concentration is not particularly limited.

[0008] Both the first stage reaction and the second stage reaction are carried out in a nitrogen stream.

[0009] Furthermore, phosphorous acid esters are used as catalysts when succinic acid monoammonium salts are dehydrated and ring-closed. Phosphite esters are represented by the general formula: (R1O)3P and/or (R2O)2P(O)H [wherein R1 and R2 are hydrogen atoms or organic residues].

[0010] The organic residues represented by R1 and R2 are the same or different, linear or branched, and having 1 to 1 carbon atoms.
12 alkyl group, or an aryl group having 6 to 12 carbon atoms, such as hydrogen, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, hexyl group, octyl group, isooctyl group. group, 2-
Examples include ethylhexyl group, decyl group, isodecyl group, phenyl group, cresyl group, xylenyl group, isopropylphenyl group, butylphenyl group, nonylphenyl group. Specifically, phosphorous acid, dimethyl phosphite, trioctyl phosphite, triphenyl phosphite, tributyl phosphite, tri(butylphenyl) phosphite, etc. are used, with phosphorous acid being particularly preferred.

The amount of phosphorous acid ester used is 0.05 to 5% by weight, preferably 0.1 to 2% by weight of succinic acid.

[0012] The reaction temperature in the first stage is room temperature to about 10
At 0°C, the second stage reaction is at 180-230°C, preferably 190-210°C. In particular, if the reaction temperature in the second stage is raised to 250°C or higher, the succinimide product will begin to evaporate, and there is a risk of clogging pipes such as the condenser and distillation column. Undesirable.

The reaction time varies depending on the reaction amount and temperature, but the first stage reaction is usually 0.5 to 3 hours, preferably 1 hour.
The second stage reaction is usually 2 to 7 hours, preferably 4 to 5 hours.

In the first stage reaction, succinic acid monoammonium salt is obtained almost quantitatively, but the reaction temperature is raised in the same reactor without separating it, and dehydration ring closure in the second stage reaction is carried out. is preferable.

The phosphorous ester may be added to the reaction system before the first stage reaction or during the second stage reaction.

After the first stage reaction is completed, water is distilled out of the reaction system and the temperature is raised. In this way, crude succinimide is produced. By recrystallizing this with water, colorless and highly pure succinimide can be obtained. Yield is 8
It is 5-95%.

Further, in the present invention, in order to stably obtain a succinimide with a good hue, a phenolic antioxidant can be used together with the phosphorous acid ester. As a phenolic antioxidant, 2,6-t-butyl-
p-cresol (BHT), butylated hydroxyanisole (BHA), 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylene-bis(4-methyl-
6-t-butylphenol), 4,4'-thiobis-(
3-methyl-6-t-butylphenol) and the like. Furthermore, it is desirable to carry out the first and second stage reactions in an inert gas (eg nitrogen gas).

By the method of the present invention, various problems such as generation of a large amount of ammonia gas during the reaction and clogging of the distillation tube due to adhesion of product crystals to the distillation tube, etc., which are disadvantages of the conventional method, can be solved. can.

[0019]

EXAMPLES The method for producing succinimide of the present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 118 g of succinic acid was placed in a three-necked flask equipped with a thermometer, stirring rod, and vapor tube (connected to a condenser).
(1 mol) 28% ammonia water 70g
(1.15 mol) phosphorous acid
0.2 g was charged, and the reaction temperature was gradually raised from room temperature to 100° C. over about 1 hour in a nitrogen stream. Further, the temperature was raised to 200°C while water was distilled off, and the reaction was then carried out at 200 to 210°C for 5 hours. The reaction product in the flask was recrystallized using 100 g of water. After standing overnight, separate the solid and liquid, and remove the crystal part under vacuum at 10 degrees.
After drying for 2 hours at 70° C., 92 g of colorless succinimide was obtained. The yield was 90% and the melting point was 127°C.

Example 2 The same procedure as in Example 1 was carried out except that 0.5 g of dimethyl phosphite was used instead of phosphorous acid. The yield of the colorless succinimide obtained was 91%, and the melting point was 127°C.

Example 3 The same procedure as in Example 1 was carried out except that 0.5 g of trioctyl phosphite was used instead of phosphorous acid. The yield of the colorless succinimide obtained was 87%, and the melting point was 127°C.

Example 4 The same procedure as in Example 1 was carried out except that 0.5 g of triphenyl phosphite was used instead of phosphorous acid. The yield of the colorless succinimide obtained was 88%, and the melting point was 127°C.

Example 5 The same procedure as in Example 1 was carried out except that 1 g of tri(butylphenyl)phosphite was used instead of phosphorous acid. The yield of the colorless succinimide obtained was 86%, and the melting point was 127.
It was ℃.

Comparative Example 1 Using the same apparatus as in Example 1, 118 g of succinic acid (
1 mole) 28% ammonia water 122g
(2 mol) was charged, and the reaction was completed at 275-290° C. while distilling off the succinimide according to the conditions described in Organic Synthesis Collective Volume 2, page 592. In order to prevent clogging of the condenser tube, it was necessary to heat the condenser to a temperature above the melting point of the succinimide. The obtained fraction contained some thermal decomposition products and had poor purity. The fraction was recrystallized with alcohol. The yield of the obtained succinimide was 83%, and the melting point was 127°C.

[0026]

[Effects of the Invention] The method of the present invention has the following advantages over conventional methods. 1) Compared to the conventional method, the reaction temperature of the method of the present invention is 50 to 80° C. lower, so it consumes less energy and is an industrially advantageous production method. 2) The amount of ammonia used as a raw material is reduced by 2 compared to the conventional method.
It is possible to provide inexpensive succinimide at a fraction of the cost. 3) The method of this invention does not produce ammonia as a by-product and causes no pollution problems. 4) High yield and high purity succinimide can be obtained. 5) Compared to conventional methods, there is no need to recover and purify alcohol, making it a resource-saving manufacturing method.

Claims (4)

[Claims] Claim 1: Succinic acid and ammonia are reacted in an aqueous medium to produce a succinic acid monoammonium salt, which is dehydrated and ring-closed at a temperature of about 180 to 220°C in the presence of a phosphorous ester. A method for producing succinimide, which comprises recrystallizing crude succinimide with water. [Claim 2] Ammonia is 1.0 per mole of succinic acid.
The manufacturing method according to claim 1, wherein 5 to 1.3 mol is used. Claim 3: The phosphorous ester has the general formula: (R1O)3P and/or (R2O)2P(O
)H [R1 and R2 are hydrogen atoms or organic residues]. 4. The method according to claim 1, wherein the amount of phosphorous ester used is 0.1 to 5% by weight of the succinic acid used.