JPS603294B2 - 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 a lower alkyl ester of acrylic acid or methacrylic acid with a higher alcohol.

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, (CH2)nOH cannot be used).

) and alcoholates such as alkali metal alcoholates, aluminum alcoholates, and titanium alcoholates are 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. Furthermore, when a primary alcohol is used as a raw material, ether is created, and when a secondary alcohol is used as a raw material, it is partially dehydrated to create an olefin. In addition, there are other drawbacks such as corrosion of the equipment.
On the other hand, when an alkali metal alcoholate such as sodium methylate is used as a catalyst, the addition reaction product L
In addition to the disadvantage that undesirable side reactions such as creation of alkali metal salts and anionic polymerization occur simultaneously, the catalyst deactivates over time, so it is necessary to add it continuously, and the catalyst may not react properly. Since it reacts with moisture in the system and is deactivated, it requires complicated operations such as sufficient dehydration in advance. Furthermore, the catalyst must be removed by washing with water to prevent polymerization before the obtained product is taken out by distillation or the like, which makes the process complicated and also requires a wastewater treatment process. In addition, in the case of aluminum alcoholate and titanium alcoholate, in addition to the disadvantage that they deactivate over time like alkali metal alcoholates and are also deactivated due to the influence of moisture, they also have lower catalytic activity than alkali metal alcoholate catalysts. If the reaction time is low, 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 took these various problems into full consideration and conducted intensive research to find a completely new catalyst. As a result, when transesterifying a lower alkyl ester of acrylic acid or methacrylic acid with a higher alcohol, The present inventors have discovered that a barium 8-diketone chelate compound has a catalytic effect on this reaction as a catalyst and can also achieve good results, leading to the completion of the present invention.

That is, the present invention provides an ester characterized in that an 8-diketone chelate compound of barium is used as a catalyst when producing a higher acrylate or a higher methacrylate by a transesterification reaction between a lower alkyl ester of acrylic acid or methacrylic acid and a higher alcohol. It is an exchange method.

The lower alkyl ester of acrylic acid or methacrylic acid as a raw material used in the present invention is generally a lower alkyl ester having fewer carbon atoms than the raw material alcohol, and is preferably a methyl or ethyl ester. As the raw material higher alcohol used in the present invention, any alcohol having a boiling point higher than that of the alcohol produced by the transesterification reaction can be used.

Suitable alcohols include alkanols, alkoxyalkanols, alkenoxyalkanols, alkenols, alkynols, alkylaminoalcohols, glycols, triols and polyhydric alcohols of 4 or more hydric, phenoxyalkanols, alkylphenoxyalkanols, cycloalkanols. , alkylcycloalkanol, phenylalkanol, alkylphenylalkanol, alkylmorpholinoalkanol, alkylpiberidinoalkanol, pyridylalkanol, halogenated alkanol, cyanoalkanol, alkylthioalkanol, etc., especially in terms of carbon number. Alcohols of 4 or more are preferred.

More specifically, n-, 1-, t-butanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, cyclohexyl alcohol, dimethylaminoethanol, diethylaminoethanol, glycidyl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, triethylene glycol, These include tetraethylene glycol, 1,3-butanediol, furyl alcohol, and trimethylolpropane.

These alcohols can be used as they are without dehydration.
In addition, barium 8-diketone chelate compounds used in the present invention include barium acetylacetonate, 2
・4-hexanedionate, 3.5-hebutanedionate, 3-phenylacetylacetonate, 2.2.6.
6-tetramethyl 3,5-hebutanedionate, 1,1
-1-trifluoro2,4-bentanedionate, etc., but according to the present invention, barium acetylacetonate is the most preferred when considering not only catalytic activity but also price.

In this reaction, an inert solvent is used in the reaction to form a co-brood mixture 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 mol, preferably 1.1 to 5.0 mol, relative to the alcohol. 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 from 0.0001 to 1.0 mol, preferably from 0.0005 to 0.05 mol, based on the raw material higher alcohol.

The transesterification reaction temperature is desirably carried out in a temperature range of 30qo to 150qo, preferably 60qo to 140qo. 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 the target ester were expressed based on the higher alcohol raw material.

That is, it is calculated using equations '1} and '2). Higher alcohol conversion rate = fed alcohol (mol) - unreacted alcohol (mol) xl. 〇、． ．． 、． E-Prepared alcohol (mol) Ester yield = Preparation box F Keigo Kotenilla Miyoshi obihana) Into a flask were 74.1 moles (1.0 mole) of n-butyl alcohol, 250.2 moles (2.5 moles) of methyl methacrylate, 0.67 moles (0.002 mole) of barium acetylacetonate, and 1 mole of hydroquinone monomethyl. After adding 0.28 liters of water, heating waso-azusa was carried out.

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 went. During this period, the tower top temperature was 6yo to 70℃, and the pot temperature was 104 to 130℃. The reaction results obtained are n
- Butanol conversion rate sea bream. 3%, and the yield of n-butyl methacrylate was 97.3%. When this reaction solution was distilled as it was, 137 tons of crab with 8 tons of pork Hg and 93 to 94 oo was obtained. This was determined by gas chromatography to be n-butyl methacrylate, and the yield was 96.8.
%Met. Therefore, it is clear that it can be distilled as is without going through processes such as washing with water. - Example 2 Using the apparatus described in Example 1, n-butanol was heated to 74%.
1 day (1.0 mol), methyl acrylate 172.2 days (2.0 mol), barium acetylacetonate 0.0
The reaction was carried out in the same manner as in Example 1 by adding 0.8 moles (0.003 mol) and 0.2 moles of hydroquinone monomethyl ether.

The reaction was carried out for 3 hours. The results obtained were a conversion rate of n-butanol of 99.1% and a yield of n-butyl acrylate of 98%.
．． It was 4%. Further, when this ester was distilled in the same manner as in Example 1, it was recovered with a yield of 97.4%. Example 3
~9 Add 1 portion of the alcohol shown in Table 1 to the apparatus described in Example 1.
．． Example 1
The reaction proceeded in the same manner.

The reaction results at that time were as shown in Table 11. (Table −
1) In all of the reactions described in Examples 1 to 9, no dehydration operation was performed before the reaction, and 0%
．． Although 0.005 to 0.007 moles of water is mixed in, it does not affect the reaction and all of them have a sufficiently high level of prestige.

Therefore, it is clear that the dehydration operation before the reaction can be omitted.
Moreover, there is no by-product of acrylic acid or methacrylic 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, 74.1 hours of n-butanol (1
．． 0 mole), 250.2 moles of methyl methacrylate (2.
5 mol), hydroquinone monomethyl ether 0.25
In the evening, 2.45 mmol (0.025 mol) of concentrated sulfuric acid was added thereto, and the reaction was carried out in the same manner as in Example 1.

The reaction was carried out 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, gas chromatography revealed that high-boiling by-products were present, and methacrylic acid was 0.004 mol (2 mol based on n-butyl methacrylate).
66■m) was produced as a by-product. When this reaction solution was directly distilled in the same manner as in Example 1, the methyl methacrylate fraction was polymerized after it had been removed, and butyl methacrylate could not be recovered.

After the reaction was completed, the reaction solution was washed with 10% caustic soda water for 50 minutes, and this process was repeated twice.

Thereafter, distillation was performed in the same manner as in Example 1, yielding 122 butyl methacrylate fractions. Therefore, the yield is 8
It remained at 5.8%. Reference Example 2 Into a 1-quarium flask equipped with a hawker, a thermometer, and a fractionator, 74.1 mols of n-butanol (1.0 mol), 250.2 mols of methyl methacrylate, and 18 ml of n-hexane were added.
79 (2.18 mol) and 0.17 mol of hydroquinone monomethyl ether were added, and the mixture was heated under total reflux for one hour 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 heating was performed.

A mixture of n-hexane and methanol is obtained from the top of the fractionation column (tower top), which is azeotroped. This is left to stand still in a decanter, the n-hexane layer is returned to the column, and the methanol layer is taken out. The reaction proceeded continuously. The peak temperature during this period was 56-59. However, the pot temperature was 83 to 90 oo. The results obtained were a conversion rate of n-butanol of 99.4% and an n-butanol conversion rate of 99.4%.
The yield of butyl methacrylate was 87.3%. However, gas chromatography revealed that many adducts of methyl methacrylate were formed, and polymers were also present. When this reaction solution was directly distilled, polymerization occurred immediately. When the reaction was carried out without dehydration, the reaction stopped immediately, and even after 5 hours of reaction, the conversion of n-butanol remained at 32.1% and the yield of n-butyl methacrylate remained at 25.9%.

Reference Example 3 Into a flask with a 100% capacity equipped with a hawker, a thermometer, and a fractionator, dimethylaminoethanol 89.1 mol (1.0 mol) and methyl methacrylate 250.2 mol (2.5 mol) were added.
, 187 moles (2.18 moles) of n-hexane, and 0.17 moles of hydroquinone monomethyl ether were added, and the mixture was heated under total reflux for 1 hour to remove water in the reaction system.

As a result, the amount of water in the reaction solution was 60. 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 fractionation column (tower top), which is azeotropically distilled. This is left to stand still 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 84:00 to 9,000. The reaction was carried out 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, gas chromatography revealed that many adducts of methyl methacrylate to double bonds were produced as by-products, and polymers were also present. When this reaction solution was directly distilled, polymerization occurred immediately. Note that when the reaction was performed without dehydration, the reaction stopped immediately, and even after 5 hours of reaction, the conversion rate of dimethylaminoethanol remained at 35.3% and the yield of dimethylaminoethyl methacrylate remained at 28.5%.

Reference Example 4 Into the apparatus described in Example 1, 62.07 moles of ethylene glycol (1.0 mol) and 4 moles of methyl methacrylate were added.
50.5 moles (4.5 moles), n-hexane 129.3 moles (1.5 moles), hydroquinone monomethyl ether 1
．． The mixture was heated under total reflux for 1 hour to remove water from the reaction system.

As a result, the water content in the reaction solution was 0.001 mol. Thereafter, 0.0035 mol of sodium methylate was added as a catalyst and heating was carried out.

A mixture of n-hexane and methanol is obtained from the upper part of the fractionating column, which is left still in a decanter.
The reaction proceeded continuously by returning the n-hexane layer to the column and taking out the methanol layer. The temperature at the top of the tower during this period was 56
~593○, the pot temperature was 80-90'0. The reaction is 3
Time went. The results obtained were a conversion rate of ethylene glycol of 99.9% and a yield of ethylene dimethacrylate of 85.
It was 7%. However, gas chromatography showed that many adducts were formed on the double bond of methyl methacrylate, and when this reaction solution was distilled as it was, polymerization occurred immediately.

In addition, when the reaction was performed without dehydration, the reaction stopped immediately, and even after 8 hours of reaction, the conversion rate of ethylene glycol was 51.4%.
The yield of ethylene dimethacrylate remained at 6.2%.

Reference Examples 5-6 The same reaction as in Example 2, but the types of catalysts are listed below.
0.02 mol was added instead of the compound shown in 1 and the reaction time was 5.
The procedure was carried out in the same manner as in Example 1 except for the time.

The results are shown in Table-1. Table I

Claims (1)

[Scope of Claims] 1. A process characterized by using a β-diketone chelate compound of barium as a catalyst when producing a higher acrylate or higher methacrylate by a transesterification reaction between a lower alkyl ester of acrylic acid or methacrylic acid and a higher alcohol. transesterification method. 2. The transesterification method according to claim 1, which uses barium acetylacetonate as a catalyst.