JPS6138180B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing esters of acrylic acid or methacrylic acid by transesterification. Conventionally, it has been known to produce esters of acrylic acid or methacrylic acid by transesterification reaction between esters of acrylic acid or methacrylic acid and alcohols. Alkoxide, alkoxide such as titanium alkoxide,
tin compounds, lead metal, lead compounds, thallium metal,
Known examples include talum compounds and calcium hydroxide. Among these catalysts, acid catalysts such as sulfuric acid and paratoluenesulfonic acid have low activity and require a long time for reaction, so they tend to cause side reactions and polymerization.
Further, these acid catalysts do not exhibit any catalytic activity in the transesterification reaction of alcohols having amino groups, and furthermore, they have the disadvantage that the equipment is severely corroded. Since the catalytic activity of the alkali metal alkoxide decreases during the reaction, it is necessary to add it in portions. In addition, since the catalyst tends to cause ester hydrolysis, it is necessary to dehydrate the raw material before adding the catalyst. This makes the process complicated. Titanium alkoxides and tin compounds also require complete removal of water in the raw materials before the reaction, and are also expensive, like the catalysts described above. Although metallic lead, lead compounds, metallic thallium, and thallium compounds have activity as catalysts, they are also highly toxic and difficult to handle.
Furthermore, the spent catalyst may cause pollution.
Calcium hydroxide is inexpensive and has low toxicity, but has low catalytic activity. The inventors of the present invention conducted extensive research to solve the above-mentioned drawbacks, and as a result, discovered that strontium and its compounds are extremely excellent catalysts, and arrived at the present invention. That is, the present invention transesterifies a lower alkyl ester of acrylic acid or methacrylic acid with a higher alkyl alcohol or a higher alkylamino alcohol to produce a higher alkyl ester or a higher alkylamino ester of acrylic acid or methacrylic acid. This is a method for producing an alkyl ester or an alkylamino ester of acrylic acid or methacrylic acid, characterized in that metal strontium and/or a strontium compound are used as a catalyst. The raw material lower alkyl ester of acrylic acid or methacrylic acid used in the present invention is generally an alkyl ester having fewer carbon atoms than the raw material higher alcohol, and is preferably methyl acrylate, ethyl acrylate, methyl methacrylate,
Examples include ethyl methacrylate. The raw material higher alkyl alcohol used in the present invention is an alcohol that generally has a higher boiling point than the alcohol produced by transesterification. Suitable for this are linear or branched monohydric alcohols having 3 to 18 carbon atoms, examples being n-propanol, iso-propanol, n-propanol,
Examples include butanol, iso-butanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, and the like. In addition, as the higher alkylamino alcohol, general formula; (In the formula, R ₁ is a hydrogen atom or a straight chain or branched alkyl group having 1 to 8 carbon atoms, and R ₂ is a hydrogen atom or a straight chain or branched alkyl group having 1 to 8 carbon atoms.)
8 straight chain or branched alkyl group, X has 1 to 1 carbon atoms
4 straight chain or branched alkylene group. ) are used, and specific examples include methylaminoethanol, dimethylaminoethanol, ethylaminoethanol, methylethylaminoethanol, diisopropylaminoethanol, dibutylaminoethanol, and t-butylaminoethanol. Examples of the catalyst used in the present invention include strontium metal and strontium compounds selected from the group consisting of strontium oxide, strontium hydroxide, strontium salts of inorganic acids, strontium salts of organic acids, strontium halides, and strontium alkoxides. It will be done. Strontium metal is used in the form of foils, rods, plates, granules, etc. Examples of strontium compounds include strontium oxide, strontium hydroxide, strontium nitrate, strontium sulfate, strontium hydrogen phosphate, strontium cyanate, strontium thiocyanate, strontium carbonate, strontium chromate, strontium borate, strontium molybdate, Examples include strontium silicate, strontium formate, strotium acetate, strontium citrate, strontium stearate, strontium chloride, strontium bromide, strontium fluoride, and strontium dimethoxide. These metals and compounds can be used singly or in combination of two or more. In the present invention, the lower alkyl ester of acrylic acid or methacrylic acid as a raw material is used in an amount of 1.0 to 10.0 mol, preferably in a range of 1.1 to 5.0 mol, per 1 mol of higher alkyl alcohol or higher alkylamino alcohol as a raw material. used in The catalyst is 0.01 to 100% relative to the raw material higher alkyl alcohol or higher alkylamino alcohol.
It is used in the range of mol%, preferably 0.1 to
Advantageously, it is used in a range of 10.0 mol%. Although it is possible to add the catalyst all at once, continuously or in portions, the method of adding the catalyst all at once is advantageous in terms of operation. The catalyst can be reused, and if it is separated separately at the end of the transesterification reaction, it can be advantageously reused. A reaction solvent usually does not need to be used, but may be used. Examples of solvents used include benzene, toluene, and hexane. The present invention is preferably carried out in the presence of a polymerization inhibitor. Known polymerization inhibitors used in this case include hydroquinone, hydroquinone monomethyl ether, di-t-butylcatechol, phenothiazine, p-phenylenediamine, and methylene blue. A combination is used. The transesterification reaction temperature range is 40 to 150°C, but 60 to 130°C is more suitable in order to suppress polymerization and side reactions. Moreover, if necessary, it is also possible to proceed with the reaction under reduced pressure. In the present invention, since the catalyst has low toxicity, it is easy to handle during reaction preparation, and there is no risk of the waste catalyst causing pollution. Furthermore, it is possible to omit the step of dehydrating the raw materials before starting the reaction, which is necessary when using an alkali metal alkoxide catalyst. In the present invention, even if water is present in the raw material in an amount of up to 3 mol % based on the higher alkyl alcohol or higher alkylamino alcohol, it does not affect the transesterification reaction at all. Since the catalyst has high activity and selectivity, a high-yield, high-quality product can be obtained simply by treating the reaction solution after transesterification using a conventional distillation method. Furthermore, the catalyst of the present invention has many advantages such as not necessarily corroding equipment and is inexpensive, and can produce the product ester very advantageously compared to other catalysts. The alkyl ester of acrylic acid or methacrylic acid obtained in the present invention is a useful chemical substance that can be used as a raw material for producing polymers and copolymers that provide products such as paints, films, adhesives, lubricating oil additives, and coating materials. In addition, alkylamino esters having an alkylamino group can be used as antistatic agents, paper processing agents,
It is a useful chemical substance that can be used as a raw material for producing cationic polymers such as flocculants. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A thermometer, a stirrer,
A packed column filled with Raschig rings was installed, and a reflux distributor was installed at the top of the packed column so that the reflux ratio could be changed arbitrarily. 400 g of methyl methacrylate, 148 g of n-butanol were added to the reactor.
g, 7.8 g of strontium oxide as a catalyst, and 2.0 g of phenothiazine as a polymerization inhibitor, and heated while stirring. The reflux ratio was varied between 5:1 and 10:1 so that the top temperature was maintained at 66 to 68°C, and the methanol-methyl methacrylate azeotrope was distilled off under normal pressure. The reaction was completed in 4.0 hours. Next, methyl methacrylate and then n-butyl methacrylate were distilled off under reduced pressure. The obtained n-butyl methacrylate was 249g,
This was a yield of 91.6% based on the starting alcohol. Examples 2 to 14 Using the same reaction apparatus as in Example 1, and in the same manner as in Example 1, lower alkyl esters of raw material acrylic acid or methacrylic acid (raw material ester) and higher alkyl alcohols or higher alkylamino alcohols (raw material alcohol) were prepared. Table 1 shows examples in which the present invention was carried out by changing the type of catalyst) and the type of catalyst. In Examples 2 to 12 and 14, the raw alcohol was 2.0
mol, using 4.0 mol of raw material ester, Example 13
So, 2.0 mol of raw alcohol and 2.0 mol of raw material ester.
6.0 mol was used. Moreover, in Examples 2 to 14,
In each case, 2.0g of phenothiazine is used as a polymerization inhibitor.
was used. In Example 12, the reaction was conducted at 560 mmHg, and in other cases under normal pressure.

【table】

[Table] Example 15 and Comparative Example 1 Using the same reaction apparatus as in Example 1 and in the same manner as in Example 1, 4.0 mol of methyl methacrylate and 2.0 mol of dimethylaminoethanol were used, and 2 g of phenothiazine was added as a polymerization inhibitor. The transesterification reaction was carried out under normal pressure by adding 1 g of water, and the catalytic performance of a metal strontium catalyst and a known catalyst, sodium methoxide, were compared in the presence of water in the reaction system. The results are shown in Table 2.

[Table] Examples 16 to 22 Using the same reaction apparatus as in Example 1, lower alkyl esters (raw material esters) of raw material acrylic acid or methacrylic acid and higher alkyl alcohols or higher alkylamino acids were prepared in the same manner as in Example 1. Table 3 shows examples where the present invention is carried out by changing the type of alcohol (raw alcohol) and the type of catalyst.
Shown below. In each example, 2.0 moles of raw material alcohol and 4.0 moles of raw material ester were used, and 2.0 g of phenothiazine was used as a polymerization inhibitor. All reactions were conducted under normal pressure.

【table】

Claims (1)

[Claims] 1 Transesterifying a lower alkyl ester of acrylic acid or methacrylic acid with a higher alkyl alcohol or higher alkylamino alcohol,
When producing higher alkyl esters or higher alkylamino esters of acrylic acid or methacrylic acid, metal strontium, strontium oxide, strontium hydroxide, strontium salts of inorganic acids, strontium salts of organic acids, strontium halides, and strontium are used as catalysts. 1. A method for producing an alkyl ester or alkylamino ester of acrylic acid or methacrylic acid, the method comprising using a strontium compound selected from the group consisting of alkoxides.