JPH02229145A - Production of dimethylaminoethyl acrylate - Google Patents

Abstract

PURPOSE:To obtain the subject compound in high purity and high yield by reacting n-butyl acrylate with dimethylaminoethyl alcohol in the presence of tetra-n-butyltitanate catalyst and inhibiting side reaction with keeping activity of catalyst. CONSTITUTION:Dimethylaminoethyl alcohol (DMAE) is reacted with n-butyl acrylate (BA) using tetra-n-butyltitanate (TBT) as catalyst with distilling out n-butanol generated by side reaction from reacted solution in reduced pressure at a temperature of 70-130 deg.C to afford the aimed compound. Reaction molar ratio of BA and DMAE is 1.0-10.0 and TBT is used as 0.1-10mol% of DMAE. The aimed substance is used as improving agent of dyeability of fiber, antistatic agent of plastic, pigment-dispersing agent in paint or ultraviolet adjuvant, and further useful as raw material of fiber-treating agent, toner binder, paint or additive for lubricant, etc.

Description

Detailed Description of the Invention A. Object of the Invention [Industrial Application Field] The present invention relates to a transesterification reaction between n-butyl acrylate (hereinafter abbreviated as BA) and dimethylaminoethyl alcohol (hereinafter abbreviated as DMAE). The present invention relates to a method for producing dimethylaminoethyl acrylate (hereinafter abbreviated as 11qDA).

Dialkylaminoalkyl such as DA, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate (methane acrylemad, as it is, or with the amino group as a 6th or quaternary ammonium salt,
Polymers produced by homopolymerization or copolymerization with other unsaturated compounds can be used as dyeability improvers for fibers, antistatic agents for plastics, pigment dispersants in paints, and ultraviolet curing aids, or as fiber treatment agents and toner binders. It is used in a wide range of fields, including paints, lubricating oil additives, paper strength enhancers, adhesives, ion exchange resins, and polymer flocculants. Therefore, the present invention can be effectively utilized in fields where such drugs are used.

[Conventional technology]

A method for producing dialkylaminoalkyl acrylate by transesterification reaction between an alkyl acrylate and a dialkylaminoalkyl alcohol is already known. compounds, acetylacetone metal compounds such as iron acetylacetone, and the like are used.

The obtained dialkylaminoalkyl acrylate is generally purified by a distillation operation, and vacuum distillation in an atmosphere of air or 5% ON (oxygen/nitrogen) is widely employed.

[Problem to be solved by the invention]

However, when an alkali metal alcoholade such as sodium methylate is used as a catalyst, the dialkylaminoalkyl alcohol as a raw material and the alcohol by-produced in the reaction add to the double bonds of the raw material alkyl acrylate or dialkylaminoalkyl acrylate. Addition reactions are likely to occur, significantly reducing the yield and purity of the target dialkylaminoalkyl acrylate, and furthermore, undesirable side reactions such as alkali metal salt by-products and anionic polymerization occur. In addition, since the catalyst deactivates over time, it is necessary to add it continuously, and the catalyst deactivates by reacting with trace amounts of water in the reaction system, so it is complicated to perform sufficient dehydration in advance. Requires manual operation. Furthermore, before distilling the product from the resulting reaction solution, the catalyst must be removed by washing with water to prevent polymerization, which complicates the process and also requires a wastewater treatment process. It also has

Furthermore, when organic tin compounds such as magnesium alcolade, aluminum alcolade, titanium alcolade, and dibutyltin oxide are used as catalysts, deactivation occurs over time in the same way as alkali metal alcolades, and trace amounts of moisture in the reaction system occur. In addition to the disadvantage of deactivation due to the influence of alkali metals, they also have lower catalytic activity than alkali metal-based alcolades, requiring a larger amount of catalyst or requiring a longer reaction time. In particular, in the case of magnesium alcoholade, the above-mentioned Michael addition reaction is likely to occur, which significantly reduces the yield of DA.Several acetylacetone metal compounds have been proposed, but the activity varies depending on the type of metal. iron acetylacetonate has the drawbacks of low catalytic activity and low yield.

In general, acetylacetone metal compounds are not affected by moisture and are convenient to handle, but they have drawbacks such as poor solubility in reaction solutions and polymerization depending on the type of metal, and are also expensive. The problem is that it is difficult to adopt industrially.

Furthermore, dialkylaminoalkyl acrylate is much easier to polymerize than dialkylaminoalkyl methacrylate, and particularly when purified by distillation, it has the property of being easily polymerized throughout the distillation process. Therefore, in the conventional method of vacuum distillation in air or 5% ON atmosphere, polymerization occurs intensely in the distillation column, condenser (distillation system), and steam column bottom liquid, so a large amount of polymerization inhibitor is added to the bottom liquid. Measures to prevent polymerization have been adopted, such as injection of polymerization inhibitors into the distillate, spraying polymerization inhibitors from the top of the distillation column, and injection of polymerization inhibitors into the distillate, but these are by no means satisfactory, and the distillation temperature is generally 100°C. Because of the high temperatures above, not only is there no polymerization inhibitor that can satisfactorily prevent polymerization at such high temperatures, but there is also no polymerization inhibitor that can satisfactorily prevent polymerization at such high temperatures. Problems arise in the vapor pressure, sublimation property, stability, etc. of the agent, and furthermore, these polymerization inhibitors may be mixed into the distilled product, reducing the product value.

The inventors of the present invention conducted extensive studies in order to find a method for producing dialkylaminoalkyl acrylate that does not have the above-mentioned problems.

Summary of the Invention [Means for Solving the Problems] The present inventors have proposed a method for producing dialkylaminoalkyl acrylates, in particular, using titanium alcoholade as a catalyst and combining various alkyl acrylates with dialkylaminoalkyl alcohols. As a result of studying the transesterification reaction, it was found that tetra n-butyl titanate (hereinafter abbreviated as IllTBT) was used as the titanium alcoholade, BA as the alkyl acrylate, and I) MAE as the dialkylaminoalkyl alcohol, and the by-produced butanol was used. If the reaction proceeds while distilling off from the reaction solution under reduced pressure, the catalyst will not be deactivated over time even if a dehydration operation is not performed before the reaction using a normal catalyst lid.
The catalyst activity was maintained, and DA, a type of dialkylaminoalkyl acrylate, was obtained in an extremely high yield of 90 times or more in a reaction time of 4 to 5 hours, and the obtained J and IA were thought to be Michael adducts. The present inventors have completed the present invention by discovering that DA is of high purity, containing only 1% or less of machining impurities, and that DA can be easily purified by steaming the reaction solution as it is in a nitrogen atmosphere. It is.

That is, the present invention is characterized in that n-butyl acrylate and dimethylaminoethyl alcohol are reacted using tetra n-butyl titanate as a catalyst while distilling by-produced n-butanol under reduced pressure. The present invention relates to a method for producing acrylate.

The reaction molar ratio of BA and IIIAE in the production method of the present invention is preferably 10 to 100, more preferably 1.1
~5.0. When the molar ratio is less than 1.0, a small amount of BA and DA polymerization will occur during the reaction, and when it exceeds 100, a large reaction will occur. It becomes necessary,
Furthermore, recycling of excess BA requires a large amount of energy, which is desirable to avoid.

Commercially available TBT as a catalyst used in the present invention can be used as is. The amount of TBT used is the raw material D
It is preferably in the range of 0.1 to 10 mol, more preferably 0.5 to 5 mol, based on MAH.

If the amount of the catalyst used is less than 0.1 mol%, the reaction rate is too slow to be practical, and if it exceeds 10 mol%, Michael adducts, which are by-products, tend to increase.

As for the method of preparing TBT, any of the methods of charging all at once, continuous or divided charging can be adopted, but the method of charging all at once at the time of charging the raw materials is advantageous and preferable.

As a reaction solvent, it is also possible to use a co-solvent for the by-product n-butanol, such as xylene, toluene, hexane, etc., but the production method of the present invention can be carried out without using a reaction solvent. This point is also one of the features of the present invention.

Although the reaction temperature is influenced by the composition of the raw materials, it is mostly determined by the degree of vacuum.9 In the present invention, the preferred reaction temperature is 7.
The temperature is preferably 90 to 120°C, more preferably 90 to 120°C, and this temperature is controlled by adjusting the degree of vacuum. The corresponding degree of decompression is 20
It is 0 to 500 Torr.

If the reaction temperature is less than 70°C, the reaction rate will be slow;
This is because polymerization tends to occur at high temperatures exceeding 30"C. The reaction time depends on the temperature and the amount of catalyst, but is usually 6 to 7 hours.

In the present invention, it is preferable to add a polymerization inhibitor to the reaction system for the purpose of suppressing the thermal polymerization reaction during the reaction and distillation. The polymerization inhibitor used in this case may be any known one, such as hydroquinone monomethyl ether, phenothiazine, etc., and one or more of these may be used. These polymerization inhibitors are used in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight based on the total amount charged. Note that, if hydroquinone is used in the reaction system, TBT will precipitate as red crystals and the reaction will almost stop, so it is not preferable to use hydroquinone in the reaction system.

After the reaction is completed, the reaction solution is directly distilled in a nitrogen atmosphere according to a conventional method to obtain Inn-butanol, DMAE, and B.
The low-boiling components such as 'A' are cut off, and the desired DA is obtained in a purified state by steaming in a nitrogen atmosphere. In addition, when distilled with 5% ON or in the presence of air, DA is extremely susceptible to coloring and polymerization, and this tendency is even more pronounced at high temperatures, so such a method cannot be adopted.

The n-butanol distilled in the reaction process of the present invention includes n
- Since only a small amount of BA, which is azeotropic with butanol, is contained, BA can be easily obtained by reacting the distillate containing n-butanol as a main component with, for example, acrylic acid. One of the features of the present invention is that it can be recycled into a raw material, and the by-product alcohol can be effectively used.

[For production]

Conventionally, there has been no report on the technology of transesterifying BA and DMAE using a TBT catalyst under reduced pressure to obtain DA while distilling off the by-product butanol. Although it is unclear whether the TBT catalyst, which is known in U.S. Pat. Inactivation due to
It has disadvantages such as low catalytic activity and long reaction time, and considering the current situation where catalysts without these problems are being investigated, the effect of the present invention is completely unpredictable. .

For example, in the DA manufacturing method, methyl acrylate (hereinafter abbreviated as MA) is used as the alkyl acrylate, and by-product butanol is extracted under normal pressure by azeotropic distillation with MA.
Even if a TBT catalyst is used in the same manner as in the present invention, the reaction rate is extremely slow and the yield of DA is about 60% even after 6 hours of reaction, and by-products that are thought to be Michael adducts are present in the reaction solution.
The selectivity of DA is 80 to 90%.

In addition, ethyl acrylate (
When reacting using the same procedure using EA (hereinafter abbreviated as EA),
After 7 hours of reaction, the yield of DA was about 70%, and 6 to 5 by-products, which were thought to be Michael adducts, were produced in the reaction solution.
The selection rate of DA is also 85-95%.

In addition, if the reaction is allowed to proceed while distilling off the by-product n-butanol under normal pressure without maintaining the decompressor state (hereinafter referred to as the normal pressure method), Although the cause is unknown, it has been observed that the reaction solution becomes cloudy during the reaction, the reaction rate becomes extremely slow, and TBT is deactivated over time. In addition, like the reduced pressure method, the normal pressure method requires the reaction solution temperature to be 130 to 150'C in order to extract byproducts at a high rate, and as a result, polymerization of BA and DA occurs.
Since the yield of DA is lowered, the normal pressure method does not have any superior effects in the present invention in any respect.

Furthermore, in the present invention, as described above, the effect of the present invention is exhibited even without using a reaction solvent, and the process without using a reaction solvent is extremely simple, so that the present invention can be used more effectively industrially. . That is, the transesterification reaction is an equilibrium reaction, and in order to advance the reaction beyond the equilibrium state, it is necessary to remove the by-product alcohol. To accomplish this purpose efficiently, an azeotropic solvent with the by-product alcohol is usually used (in some cases, the raw material alkyl acrylate is used as an azeotropic solvent). In industrial operations, a considerable amount of consideration is required for effective use of the mixture of solvent and by-product alcohol, and means for separating this mixture, and the operational method becomes quite complicated.
In addition, equipment for this purpose is also required, and the plant is usually expensive.

For example, when MA or EA is used as the alkyl acrylate, the reaction proceeds smoothly unless the amount of by-product alcohol in the reaction solution is minimized, so efficiency cannot be improved unless an azeotropic solvent is used.

However, in the present invention, when n-butanol is selected as the alkyl acrylate, the reaction proceeds smoothly by simply distilling it off under reduced pressure. It is also recognized to have an excellent effect in that it does not need to be removed externally.

Furthermore, as mentioned above, with conventional catalysts, if the reaction solution obtained is subjected to distillation as it is, polymerization and gelation tend to occur extremely easily, and to prevent such troubles, it is usually necessary to carry out multi-leaf polymerization in the distillation process. Adding inhibitors, blowing air,
However, the method of the present invention allows easy distillation without these troubles, and this method is suitable for TB'T among titanium alcoholades.
It is recognized only by

In addition to TBT, tetra-isopropyl titanate, tetra-stearyl titanate, etc. are known as titanium alcoholades, but these compounds do not exhibit any of the effects recognized in the present invention, and the effects of the present invention are limited to TBT only. It is a unique thing recognized by.

〔Example〕

EXAMPLES Hereinafter, in order to explain the present invention more specifically, the present invention will be described in detail by giving Examples and Comparative Examples.

In addition, the definitions of conversion rate, selectivity, and yield used in this specification are as follows.

Yield [C] Diconversion rate [C] × Selectivity [C]/100 Total yield [%] Bisynthesis yield [C] Distillation yield [% V100 Example 1 Stirrer, thermometer, cooler and Number of theoretical plates with fractionator: 1
691 g of BA (
5.4 mol, water 0.01%), DMAE 160g (1
, 8 mol, moisture 0.01%), TBTl 2.2.9
(0,036 mol) and fetchazidiy O,1,! as a polymerization inhibitor. i' (1000 ppm vs. total amount) was added, and heating was started under reduced pressure of 30 D Torr with stirring. The reaction was carried out for 5 hours while maintaining the reaction solution temperature at 110 to 120°C and the rectification column top temperature at 96 to 98°C and extracting the produced n-butanol at a reflux ratio of 60 to 50.

When the reaction solution was analyzed by gas chromatography, the conversion rate of I) MAE was 97%, and the selectivity of DA was 1d9.
8%, the yield to J) was 95%. In the n-butanol distilled during the reaction, n-butanol DMAE
, After distilling off BA, without bubbling nitrogen, 3
232 g of DA was obtained at a reduced pressure of 0 Torr and a temperature of 80°C.

The distillation yield of DA was 95%, and the overall yield was 90%.

The distillation residue was a pale yellow liquid with a viscosity of 1 [1 cps (25°C)].

Note that the same distillation operation as above was performed except that air bubbling was performed on the reaction solution obtained above to obtain 1) A215I.

The distillation yield of DA was 88, and the overall yield was 84%.

The distillation pot residue has a black viscosity of 4 () OCpS (25℃)
It was a liquid.

If distillation is carried out in an air atmosphere, the distillation yield of DA will be poor, and the residue in the distillation pot will turn black, have a high viscosity, and contain a small amount of methanol-insoluble matter, causing problems in cleaning the residue in the stillage pot. Ta.

Example 2゜Other than changing the TBT of the catalyst to 6.1.9 (0,018 mol), all operations were carried out in the same manner as in Example 1, and the reaction was carried out for 6 hours.

The conversion rate of DMAE is 96%, the selectivity of DA is 98%, D
The yield of A was 94%. The n-butanol distilled out during the reaction contained 6 units of BA.

Distillation was performed in the same manner as in Example 1 to obtain 224 g of DA.

The distillation yield of DA was 93%, and the overall yield was 87%.

In addition, the residue from the distillation pot is pale yellow and has a viscosity of 10 cps (at 25°C).
It was a liquid.

Comparative Example 1° The reaction operation was carried out in the same manner as in Example 1 except that the reaction was carried out at normal pressure. The reaction proceeded while removing n-butanol produced at a reaction liquid temperature of 162°C to 165°C and a rectification column top temperature of 115 to 120°C and a reflux ratio of 3.0 to 50. However, 4 hours after the start of the reaction, the reaction liquid became cloudy. As a result of gas chromatography analysis, the conversion rate of DMAE was 76% and the selectivity of DA was 85%. The reaction was further continued for 4 hours, but the conversion rate of DMAH was 78%, indicating that the reaction had hardly progressed. Moreover, the selectivity of DA was 84%.

As shown in this comparative example, in the normal pressure method, deactivation of the 'I' B T catalyst over time was observed, and the selectivity of DA was extremely poor, with as much as 15% of by-products, of which there was a high percentage of by-products that were thought to be polymers. The boiling point was about 7% (undetected by gas chromatography).

Comparative Example 2 The same procedure as in Example 1 was carried out except that tetrainglovir titanate was used as a catalyst.

The reaction was carried out for 5 hours, and the conversion rate of DMAH was 81%, and the selectivity of DA was 92%.

Comparative Example - 3° MA 516.616 mol, moisture 0.01%), DMA in a three-loaf flask equipped with a stirrer, thermometer, packed tower, and condenser
E214 g (2.4 mol, water 0.01%), TBT
8.16 & (0,024 mol) and 11,000 pp (total amount) of phenothiazine as a polymerization inhibitor were added and heated while stirring. The reaction was carried out for 5 hours while extracting the azeotrope of methanol and MA from the system. Ta.

The conversion rate of DMAE was 19%, and the selectivity of DA was 81%.

As shown in this comparative example, when MA was used, the conversion rate was extremely low, and the selectivity of DA was as low as 81%.

Comparative Example-4 Using the same apparatus as Comparative Example-9, DA6 D El, 9
(6 mol, moisture 0.01%) by the same operation as in Comparative Example-3, maintaining the reaction temperature at 103 to 122°C and the packed column top temperature at 76 to 80°C. The reaction was carried out for 7 hours while extracting the azeotrope from the system.

The conversion rate of DMAH is 73%, the selection rate of DA is 95%, D
The yield of A was 69%.

As shown in this comparative example, when EA was used, the conversion rate was low and the selectivity was also not satisfactory.

C1 Effects of the Invention According to the present invention, it can be used as a dyeability improver for fibers, an antistatic agent for plastics, a pigment dispersant in paints, an ultraviolet curing aid, and also as a fiber treatment agent, a toner binder, a paint,
Lubricating oil additives, paper strength agents, adhesives, ion exchange resins.

Dimethylaminoethyl acrylate, which is suitable as a raw material for the production of polymer flocculants, etc., is produced without any special dehydration operation before the reaction, without deactivation of the catalyst over time, and by keeping side reactions to an extremely low level while maintaining high catalyst activity. Moreover, even in purification operations by distillation, high purity and high yield can be obtained in a short time without worrying about thickening or gelation due to polymerization, and the effect of contributing to various industries is significant.

Claims (1)

[Claims] 1. A method for producing dimethylaminoethyl acrylate, which comprises reacting n-butyl acrylate and dimethylaminoethyl alcohol using tetra n-butyl titanate as a catalyst while distilling off by-produced n-butanol under reduced pressure. .