JP2639029B2 - Method for producing cyano group-containing (meth) acrylic acid ester - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a cyano group-containing (meth) acrylate. The cyano group-containing (meth) acrylic acid ester is homopolymerized or copolymerized with another monomer to provide oil resistance, fuel oil resistance due to cyano group or flexibility due to ε-caprolactone ring opening,
An excellent polymer having characteristics such as chemical resistance is obtained.

[Prior Art] In general, when synthesizing a (meth) acrylate from (meth) acrylic acid and an alcohol, a dehydration esterification reaction using a dehydration catalyst is used. However, when the alcohol structure contains a functional group such as an ester bond or a cyano group, various side reactions occur during such a dehydration esterification reaction. The present inventors previously synthesized a cyano group-containing (meth) acrylate ester by a method using sulfuric acid as a dehydration esterification catalyst (see Japanese Patent Application No. 62-282177). However, this method requires prolonged dehydration esterification at a high temperature, so that side reactions such as transesterification and hydrolysis of cyano groups occur during the reaction, and the molecular weight and acid value of the resulting acrylate ester increase. There was a problem of doing.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a cyano group-containing (meth) acrylate ester by de-esterification, whereby the esterification reaction time can be shortened, and the side reaction occurring during the esterification can be reduced. It is to provide a catalyst system that can be suppressed.

[Means for Solving the Problems] The present invention provides a compound represented by the following formula (II) obtained by dehydration esterification of an ε-caprolactone ring-opened adduct of a cyano-substituted alkyl alcohol represented by the following formula (I) with (meth) acrylic acid: The present invention relates to a method for producing a cyano group-containing (meth) acrylate represented by the formula (1):

(Where R ¹ is a cyano-substituted alkyl group, R ² is a hydrogen or methyl group, n is an integer, and the number average value is 1 to 10.) In conducting the dehydration esterification reaction of the compound represented by (I), various dehydration catalysts were examined.
When a porous or high-porous strongly acidic ion-exchange resin was used, compared with the case of using conventional sulfuric acid,
Short-time dehydration esterification yields a cyano group-containing (meth) acrylate represented by the formula (II), and suppresses side reactions such as transesterification and hydrolysis of the cyano group during dehydration esterification. I found that.

The compound represented by the formula (I) used in the present invention is
It is synthesized by a known method of ring-opening addition of ε-caprolactone to a cyano-substituted alcohol in the presence of a catalyst such as an organic titanium compound, an organic tin compound, a tin halide compound, and perchloric acid.

The cyano-substituted alcohols used here include:
Ethylene cyanohydrin, 1-cyanoethyl alcohol, 1
-Cyanopropanol, 2-cyanopropanol, 3-cyanopropanol, 4-cyanobutanol, 6-cyanohexanol, etc., and ethylene cyanohydrin is particularly preferred.

The amount of the compound represented by the formula (I) used in the present invention is 0.05 to 2.
It is 0 equivalent.

Examples of the strongly acidic ion exchange resin used as a catalyst in the present invention include porous or heat-resistant high-porous resins such as Amberlyst 15, Amberlyst 15E manufactured by Rohm and Haas, and Levatit manufactured by Bayer. SPC-108, SPC-118 and the like are used. The amount of the resin catalyst used is 0.001 to 1 g equivalent, preferably 0.1 to 0.5 g equivalent, per 1 mol of the compound represented by the formula (1).
If the amount of the catalyst is too small, the required yield of the acrylate ester decreases, and if the amount of the catalyst is too large, side reactions during esterification increase.

The reaction is performed in a solvent used in a general dehydration esterification reaction, and for example, n-hexane, cyclohexane, benzene, toluene or the like is used. The amount used is not particularly limited.

In the present invention, in order to prevent acrylic acid or methacrylic acid from being polymerized during dehydration esterification, it is necessary to blow air into the polymerization inhibitor or the reaction solution. As the polymerization inhibitor, for example, hydroquinone, hydroquinone monomethyl ether, catechol and the like are used.

The reaction temperature is lower than the use limit temperature of the strongly acidic ion exchange resin, and is preferably 70 to 120 ° C.

By the method of the present invention, a side reaction during dehydration esterification can be suppressed in the synthesis of a cyano group-containing (meth) acrylate represented by the formula (II).

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the scope of the present invention is not limited thereto.

Example of synthesis of ring-opened ε-caprolactone of cyano-substituted alkyl alcohol of formula (I) 533.1 g (7.5 mol) of ethylene cyanohydrin and 171.2 g of ε-caprolactone in a 1,000 ml three-necked flask equipped with a stirrer and a condenser. (1.5 mol), and the temperature was raised while stirring. When the temperature reached 120 ° C, 0.5 g of stannous chloride was added, and the temperature was maintained at 120 ° C under a nitrogen atmosphere.
The reaction was performed for 1.5 hours. The conversion of ethylene cyanohydrin and ε-caprolactone after the reaction was 9.8%, respectively.
90.1%. Further, unreacted ethylene cyanohydrin and ε-caprolactone were removed from the reaction product by heating under reduced pressure to obtain a compound of the formula (I). The molecular weight of the obtained compound was 202.3. In the formula (I), R ¹ is a cyanoethyl group, and the number average value of n is
This corresponds to the compound of 1.15. Here, the conversion of ethylene cyanohydrin and ε-caprolactone can be determined by gas chromatography, and the molecular weight of the ring-opened adduct of ε-caprolactone can be determined by the acetyl chloride-pyridine method (DM method).
Smith and WMDBryant, J. Am. Chem. Soc., Vol. 57, 61 (1
935))).

Example 1 313 g of the obtained compound of the formula (I), 122 g of acrylic acid, 315 g of toluene, 10 g of hydroquinone, and 90 g (0.40 g equivalent) of a dry resin of Amberlyst 15 manufactured by Rohm and Haas Co. were added to a stirrer and a condenser. Then, the mixture was charged into a 1,000 ml three-necked flask equipped with a separator, and an esterification reaction was performed. The water produced by the reaction was distilled and condensed with toluene, removed outside the system by a separator, and only toluene was returned to the reaction system. Five hours after the start of the reaction, no water was generated, and the reaction was terminated by cooling. After completion of the reaction, the catalyst was removed by decantation, and the reaction solution was diluted with 5% aqueous sodium hydroxide and 20%
The unreacted acrylic acid, polymerization inhibitor and unreacted ε-caprolactone ring-opening adduct are removed by washing several times with an aqueous sodium chloride solution, and toluene is removed under reduced pressure to obtain the desired pale compound of the formula (II). A yellow cyano group-containing acrylate was obtained. The yield was 399 g. The acid value of the obtained acrylate was 2.0 × 10 ⁻⁵ eq / g. The molecular weight of the acrylic ester calculated from the quantitative determination of the terminal unsaturated group of the obtained acrylic ester was 279.2. This corresponds to a compound of the formula (II) in which R ¹ is a cyanoethyl group, R ² is hydrogen, and the number average value of n is 1.35. Here, the acid value is the number of equivalents of alkali required to neutralize the acid contained in 1 g of the sample, and is measured by neutralization titration. The quantitative determination of the terminal unsaturated group was measured by the morpholine method (for example, the method described in Polymer Experiments, Vol. 2, “Monomer”, paragraph 225, edited by the Society of Polymer Science, Japan Society of Polymer Science).

Example 2 As a catalyst, 104 g (0.2 g of Levatit 108 manufactured by Bayer AG) was used.
g equivalent) and esterification was carried out in the same manner as in Example 1. The reaction time was 5 hours. The yield of the obtained acrylate was 395 g. The acid value of the obtained acrylate was 1.5 × 10 ⁻⁵ eq / g, and the molecular weight was 274.9. This corresponds to the compound of formula (II) in which R ¹ is a cyanoethyl group, R ² is hydrogen, and the number average value of n is 1.30.

Example 3 The same operation as in Example 1 was performed except that 146 g of methacrylic acid was used instead of acrylic acid. The reaction time was 5 hours. The yield of the obtained methacrylate was 41.
It was 0. The resulting methacrylic acid ester has an acid value of 3.1.
× 10 ^-5 equivalents / g, and the molecular weight was 293.3. This corresponds to the compound of formula (II) in which R ¹ is a cyanoethyl group, R ² is a methyl group, and the number average value of n is 1.35.

Comparative Example 1 The same operation as in Example 1 was performed except that 10 g of sulfuric acid was used as a catalyst. Reaction time H was 7 hours. The resulting reaction solution is neutralized with a 20% aqueous sodium hydroxide solution, and then washed several times with a 20% aqueous sodium chloride solution to remove the catalyst, polymerization inhibitor and unreacted ε-caprolactone ring-opened adduct. Toluene is removed under reduced pressure to obtain formula (II)
The target acrylic acid ester was obtained. The yield of the obtained acrylate was 450 g. The acid value of the obtained acrylate was 3.6 × 10 ⁻⁴ eq / g, and the molecular weight was 307.8. This corresponds to a compound of the formula (II) in which R ¹ is a cyanoethyl group, R ² is hydrogen, and the number average value of n is 1.6.

Comparative Example 2 The same operation as in Comparative Example 1 was performed except that 9.5 g of sulfuric acid was used as a catalyst. The reaction time was 7 hours. The yield of the obtained acrylate was 441 g. The acid value of the obtained acrylate was 2.7 × 10 ⁻⁴ eq / g, and the molecular weight was 302. This corresponds to a compound of the formula (II) in which R ¹ is a cyanoethyl group, R ² is hydrogen, and the number average value of n is 1.55.

[Effects of the Invention] From the above results, it is clear that the method of the present invention can suppress an increase in the acid value due to a side reaction and an increase in n in the formula (II).

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the cyano-substituted alkyl alcohol represented by the following formula (I) is used in the presence of a strongly acidic ion exchange resin.
A method for producing a cyano group-containing (meth) acrylate represented by the following formula (II), wherein a dehydration esterification reaction between a caprolactone ring-opened adduct and acrylic acid or methacrylic acid is carried out. (Where R ¹ is a cyano-substituted alkyl, R ² is a hydrogen or methyl group, n is an integer, and the average value is 1 to 10.) 2. The method according to claim 1, wherein the strongly acidic ion exchange resin is a porous resin or a heat-resistant high porous resin.