JPH0560454B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing an acrylic monomer, and more particularly to a method for obtaining a high-grade acrylic monomer in high yield. The acrylic monomer obtained by the present invention can be used as a cationic polymer flocculant used in the treatment of industrial wastewater and domestic wastewater, as a retention aid for neutral papermaking, as an antistatic agent, as a dye improver, as a soil improver, and as a paper strength agent. Used as a raw material for enhancers, etc. (Prior Art) Regarding the method for producing the acrylic monomer of the present invention, there is a method described in JP-A-57-82350, for example, as a prior art. This method uses bicyclo[2,2,
1] Heptene-5-carboxylic acid ester-2 is amidated by reacting with ammonia, a primary amine, or a secondary amine in the presence of an alkali metal alcoholate to which an alcoholic solution is added. After deactivating the alcoholate with a mineral acid or the like, an acrylic monomer can be obtained through thermal decomposition and rectification. (Problems to be Solved by the Invention) However, bicyclo[2,2,1]heptene-5-carboxylic acid ester-2 (hereinafter simply referred to as ester adduct) used in the above method.
is hygroscopic, and when bicyclo[2,2,1]heptene-5-carboxylic acid amide-2 is produced by reacting a water-containing substance with an amine compound, the catalyst is hydrolyzed and deactivated. It is pointed out that it is desirable that the raw materials used in the reaction, such as the esters, ammonia, amines, solvents, etc., be thoroughly dehydrated before use and kept so that moisture does not enter. However, the ester adduct absorbs moisture from the air and easily becomes more than 0.3% moisture, so even if well-dehydrated raw materials are used, the amount of moisture absorbed during charging into the reaction vessel may be insufficient. It was also found that the method also has the following drawbacks. That is, 1. When reacting with an amine compound, if moisture is present in the system, the ester adduct is easily hydrolyzed by the moisture to form bicyclo[2,2,
1] Heptene-5-carboxylic acid (hereinafter simply referred to as acrylic acid adduct) is produced as a by-product. This acrylic acid adduct is converted into acrylic acid in the next thermal decomposition step, but this acrylic acid is anionic and inhibits the polymerization of the anionic acrylic monomer produced by the method of the present invention, resulting in a high degree of polymerization. It becomes a hindrance to obtain the polymer. However, since acrylic monomers and acrylic acid have similar physical properties such as boiling point and volatility,
It is extremely difficult to separate by rectification, and in order to obtain a polymer of a practical quality level, it is necessary to suppress the permissible limit of acrylic acid in the monomer to 0.05% or less, which requires repeated rectification many times. Moreover, as the process is repeated, polymers and other substances are generated, resulting in loss, resulting in a significant decrease in yield. 2 In addition, as shown in 1 above, if the reaction starts in a state that contains water, the catalyst used in conjunction with this reaction will be deactivated in an amount equivalent to the water content, so in order to proceed with the reaction, a catalyst equivalent to the water content must be used. However, if the amount of catalyst is large, more salts will be produced when neutralized with mineral acid after the reaction, and these salts will cause problems in the subsequent thermal decomposition step. That is,
The liquid pump that sends the reacted liquid to the evaporator for thermal decomposition is likely to clog, the evaporator becomes more dirty and the thermal efficiency deteriorates, and the oversupply of heat causes a large amount of polymer to be produced, reducing the yield. arise. 3. Furthermore, if a large amount of water is present in the reaction system, the reaction system tends to become asbestos-like and heterogeneous, which significantly hinders the progress of the reaction, although the reason is not clear. As described above, since the ester adduct is hygroscopic, even if a sufficiently dehydrated product is used, it absorbs moisture during operation, and defects due to the presence of moisture cannot be prevented. (Means for Solving the Problems) In order to solve the above-mentioned drawbacks, the inventors of the present invention made extensive studies and found that the ester adduct and the amino compound were heated and refluxed under reduced pressure before the reaction to remove the water content of the ester adduct. It was discovered that by adding an amino compound and reacting after reducing the amount to 0.08% by weight, the content of acrylic acid adduct was significantly reduced, and as a result, the amount of acrylic acid as an impurity was reduced, and acrylic monomers could be obtained in good yield. , the present invention has been achieved. That is, the present invention provides (a) reacting an ester adduct represented by the general formula [] with an amino compound represented by the general formula [] or ['] to obtain the compound represented by the general formula [] or ('). When producing an acrylic monomer represented by the general formula [] or ['] by thermally decomposing and rectifying the acrylic adduct, the ester adduct [] and amino Moisture content of compound [] or [′] is 0.08% by weight
High quality, characterized by the following: After dehydration, a catalyst is added, and the reaction is further carried out under reflux.
Moreover, it is a method for producing acrylic monomers in high yield. However, X is -CH ₂ - group or oxygen atom Y is -OH or -NH ₂ group Z is oxygen atom or -NH ₂ - group n is a natural number R ₁ of 1 to 4, R ₂ is C ₁ to _{C 3} alkyl Group or hydrogen atom Examples of the above ester adduct [] include bicyclo[2,2,1]heptene-5-carboxylic acid methyl-2,7-epoxybicyclo[2,2,
1] Methyl-2 heptene-5-carboxylate, but is not limited thereto. In addition, examples of the above amino compound [] or ['] include monomethylamine, dimethylamine, dimethylaminomethylamine, dimethylaminoethanol, dimethylaminopropylamine,
Examples include, but are not limited to, diethylamine, monopropylamine, and monomethylaminobutylamine. As the reaction vessel used in the present invention, a vessel equipped with a rectification device is used. Before the reaction, the ester adduct [] is rectified in the reaction vessel by heating appropriately to a vacuum degree of 300 to 10 Torr and a reflux ratio of 5/1 to 20/1 until the water content is 0.08% by weight or less. Dehydrated. Furthermore, after this dehydration, a predetermined amount of the amino compound [] or ['] was added, and the moisture in the reaction vessel was removed in the same manner as above.
Perform rectification dehydration until it becomes 0.08% or less. At this time, the ester adduct [] and the amino compound []
Alternatively, ['] may be charged at the same time and dehydrated by rectification. After rectifying and dehydrating these main raw materials, an alkali metal alcoholate such as sodium methylate is added as a reaction catalyst by vacuum suction or the like to start the reaction so as to prevent moisture from entering the reaction vessel. The reaction catalyst is usually an anhydrous alcohol solution, and the amount added is based on the ester adduct.
0.5-20 mol% is preferred. The reaction differs slightly depending on the type of ester adduct [], amino compound [] or [′].
The temperature is 10 to 150°C, the temperature is 10 to 300 Torr, and the reflux ratio is appropriately adjusted so that the alcohol by-produced during the reaction can be removed from the system. The acrylic adduct [] or ['] obtained by the reaction is bicyclo[2,2,1]heptene-5-N,N-dimethylcarboxylic acid amide-2,7-epoxybicyclo[2,2,1] ]Heptene-5-N,N-dimethylcarboxylic acid amide-2, bicyclo[2,2,
1] Heptene-5-N-monomethylcarboxylic acid amide-2, bicyclo[2,2,1]heptene-5
-N-(N',N'-dimethylaminomethyl)carboxylic acid amide-2, bicyclo[2,2,1]heptene-5-N,N-dimethylaminoethylcarboxylic acid ester-2, bicyclo[2,2 , 1] heptene-5-N-(N',N'-dimethylaminopropyl)carboxylic acid amide-2, bicyclo[2,2,
1] Heptene-5-N,N-diethylcarboxylic acid amide-2, bicyclo[2,2,1]heptene-
5-N-monopropylcarboxylic acid amide-2, bicyclo[2,2,1]heptene-5-N-(N'-
Monomethylaminobutyl)carboxylic acid amide-2
etc. can be obtained. After the reaction, the acrylic adduct [] or [′] can be purified and extracted by direct distillation of the reaction product, but it is preferable to neutralize the remaining catalyst with a mineral acid such as sulfuric acid or an organic acid such as acetic acid. It is better to perform a purification extraction operation such as distillation after removal with an ion exchange resin. Obtained acrylic adduct [] or [′]
is thermally decomposed at a temperature of about 200 to 500℃,
Acrylic monomer [] or [′] is obtained.
The heat exchange method is not particularly limited, but
For example, there is a method in which the vapor of heated and vaporized acrylic adduct [] or ['] is directly passed through a heating tube filled with a Raschig ring made of glass, stainless steel, porcelain, etc. as necessary. Then, in a rectification process, pure acrylic monomer []
Or get [′]. The obtained acrylic monomers include N,N-dimethylacrylamide, N
-Methylacrylamide, N,N-dimethylaminomethylacrylamide, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropylacrylamide, N,N-diethylacrylamide, N-propylacrylamide, N-
Examples include methylaminobutylacrylamide. (Operations and Effects) According to the method of the present invention, by reducing the water content of the raw materials in the reaction vessel before the reaction to 0.08% by weight or less, which cannot be achieved with conventional methods, the acrylic intermediate product Since we were able to significantly reduce the amount of impurity acrylic acid adduct contained in the adduct, the content of acrylic acid contained in the acrylic monomer obtained by thermally decomposing it was also reduced, achieving a purity level of 99.5, which is desired for industrial use in the purification process. % or higher quality can be achieved by reducing the number of rectifications, and this reduces the yield drop. Furthermore, since there is little moisture in the raw materials, there is almost no asbestos-like material in the reaction system, and the reaction proceeds smoothly.In addition, the amount of catalyst required is small, so the production of salts after the reaction is reduced, making the process easier. The liquid inside is transferred smoothly. (Examples) The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples. (Example 1) 1530.5 kg of methyl bicyclo[2,2,1]heptene-5-carboxylate-2 was charged into a reaction vessel (5 m ³ ) equipped with a rectification device, the pot temperature was 82 to 95°C, and the degree of vacuum was
Dehydrate under conditions of 113 to 24 Torr and reflux ratio of 9/1.
Dehydrated for 24 hours, then added 1120 kg of dimethylaminopropylamine and further dehydrated under the same conditions.
I did it for 15 hours. Water content in the reaction system after dehydration is 0.02
It was %. Thereafter, 35 kg of a 28% methanol solution of sodium methylate (1.8 mol % based on the ester adduct) was charged as a catalyst, and the reaction was started. The reaction was carried out at a pot temperature of 75 to 100℃ and a vacuum of 200Torr.
The reaction was carried out for 24 hours at a reflux ratio of 3/1 (reaction rate 100%).
After the reaction, the mixture was cooled to 70°C, and 18.2 kg of 50% sulfuric acid was added to neutralize the catalyst. After that, the pot temperature is 80-100℃,
The remaining dimethylaminopropylamine is distilled off and purified at a vacuum degree of 200 to 6 Torr and a reflux ratio of 3/1 to 9/1 to obtain bicyclo[2,2,1]heptene-5-N-
2210 kg (yield 99%) of (N', N'-dimethylaminopropyl)carboxylic acid amide-2 was obtained. The content of acrylic acid adduct in the product was 0.1%. The obtained bicyclo[2,2,1]heptene-5
-N-(N',N'-dimethylaminopropyl)carboxylic acid amide-2 and polymerization inhibitor phenothiazine
A solution containing 1000ppm was supplied to the evaporator at a supply rate of 26Kg/Hr, and heated to 230-240℃ at a vacuum level of 60Torr.
The acrylic adduct, which had been evaporated by heating to , was thermally decomposed by passing it through a 90-volume pyrolysis tower filled with a Raschig ring and heated to 370-390°C. As a result, 1574 kg of crude N,N-dimethylaminopropylacrylamide (purity 95.7%, thermal decomposition efficiency 97%) was obtained, with an acrylic acid content of 0.08%.
It was hot. Subsequently, 5000 ppm of the polymerization inhibitor phenothiazine was added to the obtained crude N,N-dimethylaminopropylacrylamide and charged into a 500 evaporator.
Rectification was carried out at a reduced pressure of 5 Torr using a rectification column packed with Pall rings to produce 1400 kg of N,N-dimethylaminopropylacrylamide (purity 99.7%, rectification yield
89%). The content of acrylic acid was 0.02%. (Example 2) 1850 kg of methyl bicyclo[2,2,1]heptene-5-carboxylate-2 and 1410 kg of dimethylaminoethanol were placed in a reaction vessel (5 m ³ ) equipped with a rectification device.
Prepare the pot temperature at 85-90℃, vacuum level at 200-40Torr,
Dehydration was carried out for 24 hours at a reflux ratio of 9/1. The water content in the reaction system after dehydration was 0.02%. Thereafter, 34 kg of a methanol solution of 28% sodium methylate (relative to the ester adduct) was added as a catalyst.
1.4 mol%) and started the reaction. The reaction was carried out at a pot temperature of 60 to 100°C, a vacuum of 200 to 31 Torr, and a reflux ratio of 1/
The reaction was carried out for 24 hours at 1 to total reflux (reaction rate 87.7%). Thereafter, low-boiling substances such as residual dimethylaminoethanol were removed at a pot temperature of 112 to 120°C, a degree of vacuum of 20 to 4 Torr, and a reflux ratio of 1/1, followed by simple distillation at a pot temperature of 130°C and 5 Torr to obtain crude bicyclo[2 ,2,1]heptene-5-N,
N-dimethylaminoethylcarboxylic acid ester-
2,547 kg (yield 93%) of 2 were obtained. The content of acrylic acid adduct in the product was 0.05%. Thermal decomposition was carried out using the same equipment and method as in Example 1. Supply amount 30Kg/Hr, evaporator temperature 125~
130℃, degree of vacuum 60Torr, thermal decomposition tower temperature 300-350℃
1785Kg of crude N,N-dimethylaminoethyl acrylate (purity 93%, thermal decomposition efficiency 95%) under the following conditions.
was obtained, and the acrylic acid content was 0.04%. Subsequently, rectification was performed using the same equipment as in Example 1 to obtain N,N-dimethylaminoethyl acrylate.
1600Kg (purity 99.8%, rectification yield 90%) was obtained, and the acrylic acid content was 0.01%. (Example 3) 1486 kg of methyl bicyclo[2,2,1]heptene-5-carboxylate-2 was charged into a reaction vessel (5 m ³ ) equipped with a rectification device, the pot temperature was 85 to 90°C, and the degree of vacuum was 200.
Dehydration was carried out for 24 hours at ~40 Torr and a reflux ratio of 9/1. The water content in the reaction system after dehydration was 0.02%. Thereafter, 472 kg of liquefied dimethylamine was charged, and then 85 kg of a 28% methanol solution of sodium methylate (4.5 mol % based on the ester adduct) was charged as a catalyst to start the reaction.
The reaction was carried out for 24 hours at a pot temperature of 80 to 100°C, a vacuum degree of 200 Torr, and a reflux ratio of 1/3 (reaction rate 95.0%). After that, the pot temperature is 80 to 100℃, the vacuum is 200 to 4 Torr, and the reflux ratio is 1/
After removing low-boiling substances in step 1, simple distillation is performed at a pot temperature of 90 to 120°C and a vacuum of 3 to 4 Torr to obtain bicyclo[2, 2,
1] 920 kg (yield 95%) of heptene-5-N,N-dimethylcarboxylic acid amide-2 was obtained. The content of acrylic acid adduct in the product was 0.04%. Thermal decomposition was carried out using the same equipment and method as in Example 1. Supply amount 30Kg/Hr, evaporator temperature 80℃,
590 kg of crude N,N-dimethylacrylamide was produced under the conditions of vacuum degree of 60 Torr and thermal decomposition tower temperature of 300 to 360°C.
(purity: 84%, thermal decomposition efficiency: 90%), and the acrylic acid content was 0.02%. Subsequently, rectification was carried out using the same equipment as in Example 1 to obtain 442 kg of N,N-dimethylacrylamide (purity 99.8%, rectification yield 75%), with an acrylic acid content of 0.01%. (Comparative Example 1) An acrylic adduct-forming reaction was carried out using the same equipment as in Example 1 and the same charging amount without performing dehydration before the reaction. As a result, the water content in the system was 0.9%.
Since the catalyst is deactivated and does not react, add a catalyst to measure the
350 kg (18 mol % based on ethyl adduct, 10 times that of Example 1) was used. The reaction resulted in an asbestos-like heterogeneous solution in the system, and the outflow of methanol (progress of the reaction) was slow. The yield is 2100Kg (94% yield) and the content of acrylic acid adduct in the product is 1.3%.
It was hot. When this liquid was sent to pyrolysis, it was passed through a strainer, but at this time, a large amount of mirabilite clogged the strainer, making it difficult to pass the liquid, so after removing the mirabilite during the process, the liquid was fed again. Subsequently, thermal decomposition was carried out using the same equipment and method as in Example 1 to obtain 1500 kg of crude N,N-dimethylaminopropylacrylamide (purity 85%, thermal decomposition efficiency 90%), with an acrylic acid content of 1.0%. It was hot. After the pyrolysis was completed, a significant amount of mirabilite had accumulated in the evaporator. Subsequently, rectification was carried out using the same equipment and method as in Example 1 to obtain 1320 kg of N,N-dimethylaminopropylacrylamide (purity 95.5%, rectification yield 88
%) and the content of acrylic acid was 0.5%. As mentioned above, if the rectification yield is the same as in Example 1, the purity will be low and the acrylic acid content will be high. Purified under the above rectification conditions and purified
780 kg of N,N-dimethylaminopropylacrylamide with an acrylic acid content of 99.3% and 0.09% was obtained.
The obtained purified product was further purified in the same manner to obtain 620 kg of N,N-dimethylaminopropylacrylamide with a purity of 99.5% and 0.03% of acrylic acid. Although the quality of this product was slightly inferior to that of Example 1, the total rectification yield after the above three rectifications was only 41%, which was significantly less practical than 89% in Example 1. It was something that was lacking. (Comparative Example 2) The amount of catalyst was reduced by dehydrating the moisture in the system to 0.2% before the reaction.
The reaction was carried out in exactly the same manner as in Example 1 except that the weight was 70 kg, and an acrylic adduct was obtained with a yield of 96%, and the content of acrylic acid adduct was 0.5%. Asbestos-like material was generated in the reaction solution, although the degree was lower than that in Comparative Example 1. Next, the strainer was clogged during the liquid transfer to the thermal decomposition process, and the liquid transfer did not proceed smoothly. Pyrolysis yields 1550Kg with 89% pure content and 93% pyrolysis efficiency.
The content of acrylic acid was 0.3%. In the next rectification, 1395Kg of N,N-dimethylaminopropylacrylamide (purity 96.1%, rectification yield 90%)
The content of acrylic acid was 0.2%. (Comparative Example 3) In Example 1, methyl-2 bicyclo[2,2,1]heptene-5-carboxylate and dimethylaminopropylamine were separately dehydrated to 0.08%,
They were stored separately in storage tanks and then charged. The moisture content after charging into the reaction vessel had increased to 0.3%. The reaction was carried out with a catalyst amount of 100 kg, yield 95
%, and the content of acrylic acid adduct was 0.9%. A considerable amount of asbestos-like material was generated in the reaction solution, although the degree was lower than that in the comparative example, which impeded uniformity and stirring of the solution. Then, while the liquid was being sent to the thermal decomposition step, the strainer was clogged considerably by mirabilite generated by neutralizing the catalyst, making it difficult to send the liquid. Pyrolysis yields 1500 kg with 87% pure content and 92% pyrolysis efficiency.
The content of acrylic acid was 0.5%. In the next rectification, 1335Kg of N,N-dimethylaminopropylacrylamide (purity 96.5%, rectification yield 89%)
The content of acrylic acid was 0.2%.

[Table] As shown above, as in the comparative example, if the moisture content of the raw material before reaction is 0.08% by weight or higher, the intermediate product will contain a large amount of moisture. By-products, ie, acrylic acid adducts, are produced as by-products and therefore contain a significant amount of acrylic acid after thermal decomposition. Therefore, when rectified with the same purification yield as in the example, the purity is low and the acrylic acid content is low. became high. It is clear that if rectification is repeated to obtain the same quality as Example 1, the yield will be significantly lower.

Claims (1)

[Scope of Claims] 1 (a) First, an ester adduct represented by the general formula [1] and an amino compound represented by the general formula [11] or [11'] are reacted to form a compound of the general formula [111] or [ In order to obtain an acrylic adduct represented by [111'] and (b) thermally decompose and rectify it to produce an acrylic monomer represented by compound [IV] or [IV'], A high-quality product characterized by dehydrating the ester adduct [1] and the amino compound [11] or [11'] to a moisture content of 0.08% by weight or less before the reaction, adding a catalyst, and further reacting under reflux. A method for producing acrylic monomers in high yield. (1) However, X is -CH ₂ - group or oxygen atom Y is -OH or -NH ₂ group Z is oxygen atom or -NH- group n is a natural number R ₁ of 1 to 4, R ₂ is C ₁ to C ₃ alkyl group or hydrogen atom