JPS603292B2 - 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.

Known catalysts commonly used in this case include acids such as sulfuric acid and valatoluenesulfonic acid, and alcoholates such as alkali metal alcoholates, aluminum alcoholates, and titanium alcoholates.

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 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, it has the drawback of causing undesirable side reactions such as the creation of addition reactants, the creation of alkali metal salts, 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, 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 alcoholates and titanium alcoholates, in addition to the drawbacks of deactivation over time like alkali metal alcoholates and deactivation due to the influence of moisture, they also have lower catalytic activity than alkali metal alcoholates, Either 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. Regarding the transesterification method using a zinc compound as a catalyst, JP-A-48-91008 describes a method for producing alkylaminoalkyl (meth)acrylates.

A very large number of zinc compounds are described here, but the inventors have found that surprisingly, most of them have no catalytic effect in the production process of higher (cyclo)alkyl (meth)acrylates by transesterification. It was found that the reaction rate was extremely slow, making industrial use impossible. The present inventors have fully considered the problems of these various known catalysts and the differences in reactivity between aminoalcohols and alcohols that do not have an amino group, and have found a catalyst that can produce the desired higher methacrylate in good yield. As a result of intensive research, it was discovered that only a specific zinc compound has a specific catalytic action and produces good results when transesterifying lower esters of acrylic acid or methacrylic acid with higher alcohols, and the present invention has been made. I have come to complete it.

That is, the present invention relates to a lower alkyl ester of acrylic acid or methacrylic acid, a higher alcohol represented by the general formula ROH (where R is a C3 to C2o alkyl group or a cycloalkyl group), or a polyhydric alcohol containing two or more hydroxyl groups. This is a method for producing higher acrylates or higher methacrylates, which is characterized in that a zinc 8-diketosochelate compound is used as a catalyst when producing higher acrylates or higher methacrylates by transesterification with zinc.

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 higher alcohol, and is preferably methyl or ethyl ester.
The raw material higher alcohol used in the present invention has the general formula R
It is a higher alcohol represented by OH (where R is a C3-C alkyl group or a cycloalkyl group) or a polyhydric alcohol containing two or more hydroxyl groups, specifically n-, 1-
, t-butanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, cyclohexyl alcohol, ethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-butanediol, trimethylolpropane, and the like.

These alcohols can be used as they are without dehydration.
Further, as the zinc P-diketone chelate compound used in the present invention, zinc acetylacetonate, 3-phenylacetylacetonate, 41404-trifluoro-
1-phenyl 1,3-phthanedionate, 2,2,6,
6-tetramethyl 3,5-heptanedionate, 1,1
・1-trifluoro5,5-dimethyl 2,4-hexanedionate, 1,1,1-trifluoro2,4-pentanedionate, etc., but according to the present invention, in addition to catalytic activity, price is also important. In consideration, zinc acetylacetonate is most preferred.

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 fluoride, 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 moles per hydroxyl group of the higher alcohol, preferably 1.
．． 1 to 5.0 mol is suitable.

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.

The transesterification reaction temperature is desirably carried out in a temperature range of 30 o'clock to 150 qo, preferably 60 o'clock to 1400 qo. 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 are determined by gas chromatography, and the conversion rate of raw material higher alcohol and the yield of the target higher ester are expressed based on the raw material higher alcohol. did.

That is, it was calculated using the formulas (1' and 2). Alcohol conversion rate = charged alcohol (mol) - unreacted alcohol (mol) XI.

〇、． ．． ．． ．． ．． '1, Prepared alcohol (mol)■Estel yield=Prepared alcohol (mol)=Prepared alcohol ≦Takutaishi X・〇.

‐‐‐■Example 1 N-butanol 74.1 hours (1
．． 0 mole), 'methyl methacrylate 250.2 mole (2
．． 5 moles), zinc acetylacetonate 5.27 moles (0
．． 02 mol), hydroquinone monomethyl ether 0.
On the 28th, heated defense 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 4
Time went. During this time, the tower top temperature was 660 to 70 qo, and the pot temperature was 104 to 129°C. The reaction results obtained are n
The conversion rate of -butyl/-al was 99.0%, and the yield of n-butyl methacrylate was 98.5%. When this reaction solution was directly distilled, 139.5 fractions of 93 to 94° C. at 8 yards of Hg were obtained.

This was determined to be n-butyl methacrylate by gas chromatography, and the yield was 98.1%. Therefore, it is clear that distillation can be carried out as is without any steps such as washing with water. Example 2 Using the apparatus described in Example 1, 74.1 moles (1.0 mol) of n-butyl alcohol and 172 moles of methyl acrylate were prepared.
．． 2 (2.0 mol), zinc acetylacetonate 5.
27 moles (0.02 mol) and 0.25 moles of hydroquinone monomethyl ether were added, and the reaction was proceeded in the same manner as in Example 1.

The reaction was carried out for 4 hours. The obtained composition. Shirashige had a conversion rate of n-butyl alcohol of 98.0% and a yield of n-butyl acrylate of 97.5%. When this ester was distilled in the same manner as in Example 1, it was recovered with a yield of 96.5%. Example 3 The apparatus described in Example 1 was charged with 62.1 moles (1.0 mole) of ethylene glycol and 450.5 moles (1.0 mole) of methyl methacrylate.
4.5 moles), zinc acetylacetonate 5.27 moles (
0.02 mol), hydroquinone monomethyl ether 1
．． The reaction was carried out in the same manner as in Example 1, with the addition of 0.0 ml.

The reaction was carried out for 7 hours. The top temperature during this period was 66-720
The pot temperature was 10yo to 1220℃. The reaction results showed that the conversion rate of ethylene glycol was 100% and the yield of ethylene dimethacrylate was 97.8%. When this reaction solution was distilled as it was, it was found to be 90-91℃ with Hg on the 3rd side.
190.7 ta of crab was obtained.

This was determined to be ethylene dimethacrylate by gas chromatography, and the yield was 96.3%. Therefore, it is clear that in this case as well, distillation can be carried out as is without going through steps such as washing with water. Examples 4 to 6 To the apparatus described in Example 1, 1.0 mol of the alcohol shown in Table 1 and 2.0 mol of methyl methacrylate were added, and 5.27 mol of zinc acetylacetonate (0 mol) was added as a catalyst.
．． 02 mol) and 0.3 mol 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 at that time were as shown in Table 11. Table 1 Examples 7 to 9 The alcohol shown in Table 2 was added to the apparatus described in Example 1 for 1 hour.
．． Add 0 mol and 2.0 mol of methyl methacrylate to each hydroxyl group of the alcohol in Table 1, and add 5.27 mol of zinc acetylacetonate (o.o 2 mol) as a catalyst.
Hydroquinone monomethyl ether 1 as a polymerization inhibitor
．． The reaction was carried out in the same manner as in Example 1, with the addition of 0.0 ml.

The reaction results at that time were as shown in Table 2. Table 2 In all of the reactions described in Examples 1 to 9, no dehydration operation was performed before the reaction, and 0.00%
Although 5 to 0.007 moles of water was mixed in, 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, and there is no generation of methacrylic acid or acrylic acid by 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 mol), methyl methacrylate 250.3 mol (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 side skin) There was a by-growth. When this reaction solution was directly distilled in the same manner as in Example 1, the methyl methacrylate fraction was polymerized after distillation, 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 In a flask with a 100% capacity equipped with a thermometer, a thermometer, and a fractionator, 74.1 moles of n-butyl alcohol (1.0 moles), 250.3 moles of methyl methacrylate (2.5 moles), 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 one hour to remove water from the reaction system.

As a result, the amount of water in the reaction solution was 0.001 mol. Then add sodium methylate as a catalyst. 0035 mol was added and a heating ritual was performed.

A mixture of n-hexane and methanol is obtained from the upper part of the fractionating column (tower top), which is then azeotroped. This is then stabilized in a decanter, the n-hexane layer is returned to the column, and the methanol layer is taken out to allow continuous reaction. advanced. During this period, the tower top temperature was 56-59.800°C, and the pot temperature was 83-90°C.
The result obtained was 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, if the reaction occurs without dehydration, it will stop immediately and 5
Conversion rate of n-butyl alcohol 32.1 even after time reaction
%, the yield of n-butyl methacrylate remained at 25.9%.

Reference Example 3 Ethylene glycol 62.07 was added to the equipment described in Example 1.
Add 450.5 moles (4.5 moles) of methyl methacrylate, 129.3 moles (1.5 moles) of n-hexane, and 1.0 moles of hydroquinone monomethyl ether to remove water from the reaction system. In order to do this, I heated it in a candle for an hour with total reflux.

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 performed.

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
-5900, and the pot stripe was 80-90°C. The reaction was carried out for 3 hours. The results obtained were a conversion rate of ethylene glycol of 100% and a yield of ethylene dimethacrylate of 85.7%.
Met. However, gas chromatography showed that many adducts of methyl methacrylate to single bonds were produced as by-products, and when this reaction solution was distilled as it was, polymerization occurred immediately. When the reaction was carried out without dehydration, the reaction stopped immediately, and even after 8 hours of reaction, the conversion of ethylene glycol was 51.4% and the yield of ethylene dimethacrylate was 6.2%.

Reference Example 4 90% of 1,3-butanediol was added to the apparatus described in Example 1.
1 night (1.0 mol), methyl methacrylate 300.4
(3.0 mol), n-hexane 129.3 mol (1.5 mol)
mol) and 1.0 mol of hydroquinone monomethyl ether were added, and the reaction proceeded in the same manner as in Reference Example 1.

The tower top temperature was 56 to 60 degrees Celsius, and the pot overflow was 80 to 920 degrees Celsius. The reaction was also carried out for 4 hours. The results obtained were a conversion rate of 1,3-butanediol of 100% and a yield of 1,3-butane dimethacrylate of 84.6%. However, as in Reference Example 1, there was a large amount of adducts of methyl methacrylate, and when this reaction solution was distilled as it was, polymerization occurred immediately. Reference Examples 5 to 12 1.0 mol of n-butanol, 2.0 mol of methyl methacrylate, and 0.3 mol of hydroquinone monomethyl ether as a polymerization inhibitor were added to the apparatus described in Example 1, and Table 3
0.02 mol of the catalyst shown in Example 1 was added, and the reaction was carried out in the same manner as in Example 1.

The reaction results at that time were as shown in Table 3. It can be seen that both have low catalytic activity and are not of practical use. Table 3 In addition, zinc halides, various inorganic acid salts, hydroxides, etc. other than those listed above showed reaction results similar to those in Table 3, and were found to have no practical value in the present invention. .

Reference Examples 13-20 In the apparatus described in Example 1, 1.0 mol of ethylene glycol and 4.0 mol of methyl methacrylate were added to inhibit polymerization. Hydroquinone monomethyl ether as R stopper1. M was added, 0.02 mol of the catalyst shown in Table 4 was added, and the reaction was proceeded in the same manner as in Example 1.

The reaction results at that time were as shown in Table 4. From this table, it can be seen that, like Taiichi 3, all of them have low catalytic activity and are not worthy of practical use. Table 4 Reference Examples 21 to 24 The same reaction as in Example 2 was carried out in the same manner as in Example 1 except that the type of catalyst was changed to the compound shown in Table 5 and 0.02 mol was added.

The results are shown in Table-5. Table 5 From these results, it was found that even a chelate compound with 8-diketone cannot be put to practical use when magnesium or cobalt is used.

Claims (1)

[Claims] 1 Transesterification of a lower alkyl ester of acrylic acid or methacrylic acid with a higher alcohol represented by the general formula ROH (where R is an alkyl group or a cycloalkyl group of C_3 to C_2_0) or a polyhydric alcohol containing two or more hydroxyl groups. A method for producing higher acrylates or higher methacrylates, which comprises using a β-diketone chelate compound of zinc as a catalyst and reacting at a temperature of 30 to 150°C.