JPS5938935B2 - Method for producing acrylic ester or methacrylic ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing higher acrylates or higher methacrylates by transesterification of lower alkyl esters of acrylic acid or methacryno I with higher alcohols.

It is known to produce higher acrylates or higher methacrylates by transesterification.

Catalysts commonly used in this case include acids such as sulfuric acid and para-toluenesulfonic acid (however, they cannot be used in the case of >N(CH2)n0H), and alcolades such as alkali metal alcolades, aluminum alcolades, and titanium alcolades. It has been known.

However, these catalysts have various problems.

That is, when an acid catalyst such as sulfuric acid is used, the reaction rate is slow and the production of polymers increases. Further, when a primary alcohol is used as a raw material, ether is produced, and when a secondary alcohol is used as a raw material, it is partially dehydrated to produce an olefin. Furthermore, some alcohols have drawbacks such as not only not allowing the reaction to proceed but also causing corrosion of the equipment. On the other hand, when an alkali metal alcoholade such as sodium methylate is used as a catalyst, it has the drawback of causing undesirable side reactions such as addition reaction product by-products, alkali metal salt by-products, and anionic polymerization. In addition, the catalyst deactivates over time, so it must be added continuously, and the catalyst deactivates by reacting with moisture in the reaction system, so complicated operations are required, such as sufficient dehydration in advance. shall be.

Furthermore, in order to prevent polymerization before taking out the obtained product by distillation or the like, the catalyst must be removed by washing with water, which makes the process complicated and further requires a wastewater treatment process. In addition, in the case of aluminum and titanium alcolades, in addition to the drawbacks of deactivation over time like alkali metal alcolades and deactivation due to the influence of moisture, their catalytic activity is lower than that of alkali metal alcolade catalysts. is low, and the amount of catalyst must be increased or the reaction time must be lengthened.

Therefore, no matter which catalyst is used, there are various industrial problems. The present inventors have fully considered these various problems and conducted intensive research to find a completely new catalyst. As a result, the present inventors have found that a catalyst for transesterifying lower alkyl esters of acrylic acid or methacrylic acid with higher alcohols has been developed. As a result, the inventors discovered that a β-diketone chelate compound of zirconium has a catalytic effect in this reaction and also achieves good results, leading to the completion of the present invention.

That is, the present invention relates to lower alkyl esters of acrylic acid or methacrylic acid and the general formula ROH (where R is a C3 to C2O alkyl group or cycloalkyl group) R1 or the general formula 〉N
(CH2)NOH (However, R1, R2R2 are C, ~Cl2
alkyl group, n is an integer of 2 to 6) to produce higher acrylates or higher methacrylates by transesterification with higher alcohols, wherein a zirconium β-diketone chelate compound is used as a catalyst. This is a method for producing acrylate or higher methacrylate.

The raw material lower alkyl ester of acrylic acid or methacrylic acid used in the present invention is generally a lower alkyl ester having fewer carbon atoms than the raw material alcohol,
Preferably it is methyl or ethyl ester.

The raw material higher alcohol used in the present invention has the general formula RO
H (however, R is a C3 to C2O alkyl group or cycloalkyl group), or the general formula R1>N-(CH2)NOH (however, R1 and R2 are C1 to R2
It is a higher alcohol represented by an alkyl group of Cl2 (n is an integer of 2 to 6), specifically n-, 1t-butanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, cyclohexyl alcohol, dimethylaminoethanol, Examples include diethylaminoethanol, dipropylaminoethanol, N-methyl, N-ethylaminoethanol, dimethylaminopropanol, and diethylaminopropanol.

These alcohols can be used as they are without dehydration.
Further, as the zirconium β-diketone chelate compound used in the present invention, zirconium acetylacetonate, 3-phenylacetylacetonate, 4-4-4
-trifluorotophenyl, 1,3-butanedionate, 2,2,6,6tetramethyl 3,5-hebutanedionate, 1,1,1-trifluoro5,5-dimethyl 2
-4-hexanedionate, 1,1,1-trifluoro2,4-pentanedionate, etc., but according to the present invention, when taking into consideration not only catalytic activity but also price,
Most preferred is zirconium acetylacetonate. In this reaction, an inert solvent can be used to form an azeotrope with the alcohol produced in the transesterification reaction.

Examples include hexane, benzene, and cyclohexane. This reaction is preferably carried out in the presence of a polymerization inhibitor since it involves handling substances that are generally prone to polymerization.

Therefore, hydroquinone, hydroquinone monomethyl ether, di-t-butylcatechol, phenothiazine, P
- Phenylene diamine, methylene blue, etc. are typically used. In the present invention, the molar ratio of the raw material lower alkyl ester of acrylic acid or methacrylic acid to the higher alcohol is 1.0 to 10 to the higher alcohol.
used in molar proportions, preferably 1.1 to 5.0
Moles are appropriate.

Of course, it may be outside this range, but it will be disadvantageous when economic efficiency is considered from an industrial standpoint. The catalyst may be added in its entirety from the beginning, added at regular intervals, or completely continuously; however, from an operational point of view, it is preferable to charge the entire amount from the beginning.

Although the amount used can vary considerably, it is generally 0.0001 to 1.0 mol, preferably 0.001 to 0.05 mol, based on the raw material higher alcohol.

It is desirable that the transesterification reaction be carried out at a temperature of 30°C to 150°C, preferably 60°C to 140°C. Moreover, it can also be carried out under reduced pressure if necessary. The present invention will be specifically explained below with reference to Examples and Reference Examples. However, in Examples and Reference Examples, unreacted raw materials and reaction products were determined by gas chromatography, and the conversion rate of raw alcohol and the yield of ester were expressed based on the higher alcohol raw material. That is, (1) and 0 (calculated using formula (2).Example 1 74.IV (1.0 mol) of n-butanol was added to a flask with a content of 11 equipped with a stirrer, a thermometer, and a fractionating column. Methyl methacrylate 250.2V (2.5 mol), zirconium acetylacetonate 0.488y (0.00
1 mol), hydroquinone monomethyl ether 0.28
y was added, and the mixture was heated and stirred.

A mixture of methanol and methyl methacrylate is obtained azeotropically from the upper part of the fractionation column, and this is refluxed at a reflux ratio of 5 to 1.
The reaction proceeded continuously by taking out the solution at zero. The reaction is 1
．． I went there for 5 hours. During this period, the tower top temperature was 65-70°C, and the pot temperature was 104-130°C. The obtained reaction result is n
The conversion rate of -butanol was 99.5%, and the yield of n-butyl methacrylate was 99.2%. When this reaction solution was directly distilled, 140y of a fraction having a temperature of 93 to 94°C at 80 mmHg was obtained.

This was determined to be n-butyl methacrylate by gas chromatography, and the yield was 98.5%. Therefore, it is clear that distillation can be carried out as is without undergoing processes such as washing with water. Example 2 Using the apparatus described in Example 1, 74.1y (1.0 mol) of n-butyl alcohol and 17% of methyl acrylate were prepared.
Example 1 by adding 2.2 V (2.0 mol), 0.488 V (0.001 mol) of zirconium acetylacetonate, and 0.28 V of hydroquinone monomethyl ether.
The reaction proceeded in the same manner.

The reaction took place for 2 hours. The results obtained were a conversion rate of n-butyl alcohol of 98.4% and a yield of n-butyl acrylate of 97.6%. Further, when this ester was distilled in the same manner as in Example 1, it was recovered with a yield of 96.6%. Examples 3 to 5 One portion of the alcohol shown in Table 1 was added to the apparatus described in Example 1.
．． Add 0 mol and 2.0 mol of methyl methacrylate, and add 0.48 mol of zirconium acetylacetonate as a catalyst.
8y (0.001 mol) and 0.3v of hydroquinone monomethyl ether as a polymerization inhibitor were added, and the reaction proceeded in the same manner as in Example 1.

The reaction results are shown in Table-1. Example 6 In an 11-content flask equipped with a stirrer, thermometer, and fractionator, 89.1 y (1.0 mol) of dimethylaminoethanol, 250.2 y (2.5 mol) methyl methacrylate, and 0.4 V (phenothiazine) catalyst were added. as zirconium acetylacetonate 2.44y (0.005 mol)
was added and heated and stirred.

A mixture of methanol and methyl methacrylate is obtained azeotropically from the upper part of the fractionation column, and this is refluxed at a reflux ratio of 2 to 1.
The reaction proceeded continuously by taking out the solution at zero. The reaction is 3
Time passed. During this time, the tower top temperature was 65°C to 75°C, and the pot temperature was 104°C to 127°C. The reaction results obtained were that the conversion rate of dimethylaminoethanol was 99.9% and the yield of dimethylamino methacrylate was 99.3%. When this reaction solution was distilled as it was, 67
155y of fractions at ~68°C were obtained.

This was determined to be dimethylamino methacrylate by gas chromatography, and the yield was 98.7%. Therefore, it can be seen that the reaction solution can be directly distilled without going through steps such as washing with water. In all of the reactions described in Examples 1 to 6, no dehydration operation was performed before the reaction, and 0.005 to 0.007 mol of water was mixed in with respect to the raw material higher alcohol.
It did not affect the reaction, and all achieved sufficiently high results.

Therefore, it is clear that the dehydration operation before the reaction can be omitted.
Moreover, there is no by-product of methacrylic acid or acrylic acid due to hydrolysis, which brings about a remarkable effect in simplifying the reaction process. Reference Example 1 In the apparatus described in Example 1, n-butanol 74.17 (1
．． 0 mol), methyl methacrylate 250.27 (2.
5 molar hydroquinone monomethyl ether 0.257
, add 2.45y (0,025 mol) of concentrated sulfuric acid to it,
The reaction proceeded in the same manner as in Example 1.

The reaction lasted for 6 hours. The reaction results obtained were a conversion rate of n-butanol of 96.5% and a yield of n-butyl methacrylate of 91.2%. However, as a result of analysis by gas chromatography, it was found that high boiling point products were present and 0.004 mol of methacrylic acid (2660 ppm based on n-butyl methacrylate) was produced as a by-product. When this reaction solution was directly distilled in the same manner as in Example 1,
After the methyl methacrylate fraction was distilled off, polymerization occurred, and butyl methacrylate could not be recovered.

After the reaction was completed, the reaction solution was washed with 507 10% caustic soda water, and this process was repeated twice.

Thereafter, distillation was performed in the same manner as in Example 1, and 1227 butyl methacrylate fractions were obtained. Therefore, the yield is 8
It remained at 5.8%. Reference example 2 11? equipped with a stirrer, thermometer, and fractionating column. The contents of the flask were 74.17 (1.0 mol) of n-butyl alcohol, 250.2 y (2.5 mol) of methyl methacrylate, and 74.17 (1.0 mol) of n-butyl alcohol.
Hexane 1877 (2.18 mol) and hydroquinone monomethyl ether 0.17 y were added, and the mixture was heated and stirred for one hour under total reflux to remove water from the reaction system.

As a result, the amount of water in the reaction solution was 0.001 mol. Thereafter, 0.0035 mol of sodium methylate was added as a catalyst, and the mixture was heated and stirred.

A mixture of n-hexane and methanol is obtained from the top of the fractionating column (tower top), which is azeotroped. This is left to stand in a decanter, the n-hexane layer is returned to the column, and the methanol layer is taken out. Therefore, the reaction proceeded continuously. During this period, the tower top temperature was 56-59.8°C and the pot temperature was 83-90°C. The results obtained were a conversion rate of n-butyl alcohol of 99.4%,
The yield of n-butyl methacrylate was 87.3%.
However, gas chromatography revealed that many methyl methacrylate adducts were produced as by-products, and polymers were also present. When this reaction solution was directly distilled, polymerization occurred immediately. In addition, when the reaction was performed without dehydration, the reaction stopped immediately, and even after 5 hours of reaction, the conversion rate of n-butyl alcohol was 32.1%,
The yield of n-butyl methacrylate remained at 25.9%.

Reference Example 3 Dimethylaminoethanol 89.1y (1.0 mol) and methyl methacrylate 250.2f (2.5 mol) were added to a 11-content flask equipped with a stirrer, a thermometer, and a fractionator.
, n-hexane 1877 (2.18 mol), and hydroquinone monomethyl ether 0.177 were added, and the mixture was heated and stirred for 1 hour under total reflux to remove water in the reaction system.

As a result, the water content in the reaction solution was 60 ppm. This amount has a molar ratio of 0.0018 to the raw material alcohol.
Thereafter, 0.0035 mol of sodium methylate was added to the starting alcohol as a catalyst to start the reaction.

A mixture of n-hexane and methanol is obtained from the top of the fractionating column (tower top), which is azeotropically produced. This is allowed to stand in a decanter, the n-hexane layer is returned to the column, and the methanol layer is taken out. The reaction proceeded continuously. During this period, the tower top temperature was 55 to 59°C, and the pot temperature was 84 to 90°C. The reaction lasted for 3 hours. The results obtained were a conversion rate of dimethylaminoethyl alcohol of 99.0% and a yield of dimethylaminoethyl methacrylate of 83.4%. However, analysis by gas chromatography revealed that there were many by-products of adducts of methyl methacrylate to double bonds, and polymers were also present. When this reaction solution was directly distilled, polymerization occurred immediately.

When the reaction was performed without dehydration, the reaction stopped immediately, and even after 5 hours of reaction, the conversion of dimethylaminoethanol remained at 35.3% and the yield of dimethylaminoethyl methacrylate remained at 28.5%.

Claims (1)

[Scope of Claims] 1 A lower alkyl ester of acrylic acid or methacrylic acid and the general formula ROH (where R is an alkyl group of C_3 to C_2_0 or a cycloalkyl group), or the general formula ▲ mathematical formula,
There are chemical formulas, tables, etc.▼ (However, R_1 and R_2 are C_
When producing a higher acrylate or higher methacrylate by transesterification reaction with a higher alcohol represented by an alkyl group of 1 to C_1_2, n is an integer of 2 to 6,
A method for producing higher acrylates or higher methacrylates, characterized in that a β-diketone chelate compound of zirconium is used as a catalyst. 2. The method according to claim 1, wherein zirconium acetylacetonate is used as the β-diketone chelate compound of zirconium. 3. The method according to claim 1, in which the β-diketone chelate compound of zirconium is used in an amount of 0.0001 to 1.0 mol based on the higher alcohol.