JPS6178751A - Production of unsaturated esters - Google Patents

Abstract

PURPOSE:The reaction of a 1,2,3,6-tetrahydrobenzyl alcohol derivative with a carboxylic acid is effected with heat in the absence of a catalyst to enable high-productivity production of the titled compound with reduced discoloration, which is used in the production of epoxy resins and unsaturated polyester resins. CONSTITUTION:A compound of the formula (R1-R9 are H, alkyl, alkene, alkylene of 5 or less carbon atoms) and a carboxyl compound, preferably a polycarboxylic compound are used so that the amount of the alcohol is more than equimolar than the carboxyl groups, preferably less than 3 time moles of the carboxyls, to effect the reaction with heat at 150-200 deg.C to give the objective unsaturated ester. In order to avoid the discoloration of the product, it is preferred that the reaction system is kept in a nitrogen atmosphere and nitrogen gas is bubbled in the reaction mixture.

Description

[Detailed description of the invention] (Technical background) The present invention relates to a method for producing unsaturated ester compounds.

The dehydration esterification reaction between organic acids and alcohols is highly yielding and versatile, and is widely used in the industrial production of ester compounds.

(Prior art) A catalyst is usually used in the dehydration esterification reaction of a carboxylic acid and an alcohol, and a catalyst is also used in the conventional technology of condensing a 1.2.3.6-titrahydropenzyl alcohol derivative with a carboxylic acid. It is being

For example, in US Pat. No. 2,750,395, sulfuric acid and para-toluenesulfonic acid are used as catalysts for the condensation of a divalent carboxylic acid compound and 1,2,3,6-tetrahydrobenzyl alcohol.

Furthermore, in U.S. Patent No. 3,565.922, trifluoroacetic acid is used in the reaction between tetrahydrophthalic anhydride and 1,2,3,6-tetrahydrobenzyl alcohol, and for the same reaction, British Patent No. 1.527,927 uses trifluoroacetic acid. Nato 2 isopropoxy titanium is used.

(Problems to be Solved by the Invention) However, upon examination by the present inventors, it was found that the conventional technology using a catalyst may lead to coloration of the condensation reaction product, and that the physical properties and stability of the product may be affected by the catalyst. It has been found that there are disadvantages such as the need for complex purification processes such as neutralization, washing with water, and drying if attempts are made to remove it without adversely affecting performance.

In view of this situation, the present inventors conducted extensive studies and arrived at the present invention.

(Structure of the present invention) That is, the present invention provides a method for obtaining an unsaturated ester compound by reacting a 1, 2, 3, 6-tetrahydrobenzyl alcohol derivative represented by the following formula with an ocalphonic acid compound, which comprises heating without a catalyst. This is a method J for producing an unsaturated compound, characterized by:

(R, to R, qH, lower alkyl groups, alkene groups, and alkylene groups of C5 or less are excluded.) The 1, 2, 3, 6-tetrahydrobenzyl alcohol rust conductor used in the present invention is a butadiene spinneret and an allyl alcohol derivative. It can be synthesized by Diels-Alder reaction. Furthermore, the product is not limited to this method, but can also be produced by a method in which a Diels-Alder reaction is performed using an acrolein derivative instead of an allyl alcohol derivative, and then an aldehyde group is reduced to alcohol.

Examples of compounds that can be used include compounds shown in Table 1.

Table 1 Note: (1) Items in the same frame are in no particular order (2) Two locations marked with * indicate that they are connected by -CH2-.

Among the compound examples shown in Table IK, the product synthesized from 1,2,3,6-tetrahydrobenzyl alcohol (1) has a lower viscosity and is easier to handle than those made from other alcohols. preferable.

The carboxylic acid compound used in the present invention is preferably a polyhydric carboxylic acid. The carboxyl group of the carboxylic acid compound may be in the form of an acid anhydride. Also,
The carboxylic acid compound may have other functional groups in its structure.

Examples of polyvalent carboxylic acids that can be used include divalent ones such as oxalic acid, malonic acid, succinic acid, succinic anhydride, fumaric acid, maleic acid, m-hydric maleic acid, glutaric acid, methylmaleic acid, Methyl maleic anhydride, itaconic acid, itaconic anhydride, adipic acid, 2-butene-1,4
-dicarboxylic acid, azelaic acid, cepatic acid, 1,12
-tetrahydrophthalic anhydride, 1,2,3,6-titrahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6- Tetrahydrophthalic anhydride, 1,2,3.4-tetrahydrophthalic anhydride, 1,415.6-tetrahydrophthalic anhydride, 3,4,5.6-tetrahydrophthalic anhydride, 5-
Norbornene-2゜3-dicarboxylic anhydride, chlorendic acid, chlorendoic anhydride, terephthalic acid, isophthalic acid, O-phthalic acid, 7-thalic anhydride, tetrabromo-terephthalic acid, tetrabromo-O-phthalic acid, tetrabromo 7-talic anhydride etc. can be raised.

Trivalent examples include trimellitic acid, trimellitic anhydride, citric acid, and the like.

Examples of tetravalent acids include pyromellitic acid, pyromellitic anhydride, butane-1,2,3,4-tetracarboxylic acid, 3.
3',4.4'-benzophenonetetracarboxylic acid, 3
．． Examples include 3',4,4'-bensibuenonetetracarboxylic anhydride.

Further examples of polyhydric acids include polyacrylic acid and polymethacrylic acid.

In the reaction between the carboxylic acid compound and the 1.2.3.6-tetrahydrobenzyl alcohol derivative, it is necessary to charge the alcohol in an amount equal to or more than the equimolar amount to the carboxyl group in order to complete the reaction.

On the other hand, if too much alcohol is charged, there are disadvantages such as it takes time to recover the excess alcohol, the product concentration decreases, and productivity deteriorates, so the amount of alcohol is three times the amount of carboxyl groups. It is preferable to keep it below mol.

The higher the reaction temperature, the faster the reaction progresses, but if it exceeds 300°C, the raw materials will decompose, so a temperature of 300'C or less is preferred. At the same time, the reaction is slow at temperatures as low as 150℃ (
Since this is economically disadvantageous, a temperature of 150° C. or higher is preferable. However, at the beginning of the condensation reaction, the reaction temperature may not rise because a large amount of water is generated, but in this case, the above conditions should be applied after less water is generated. When using as a raw material, the addition reaction of alcohol occurs easily and proceeds rapidly even at 150° C. or lower, so the above-mentioned conditions may be applied after reaching the condensation reaction stage.

In particular, in order to complete the reaction quickly, it is preferable to raise the reaction temperature to 200° C. or higher.

Water generated during the reaction can be removed by providing a water separator at the top of the reactor to promote the condensation reaction.

A solvent such as toluene or xylene may be added to facilitate the removal of water from the reaction system, but when using 1,2°3,6-tetrahydrobenzyl alcohol as a raw material,
Water can also be removed using unreacted alcohol.

Furthermore, for the purpose of preventing coloration of the product, it is preferable to maintain the reaction system in a nitrogen atmosphere and to bubble nitrogen gas into the reaction solution.

c) Effects of the present invention) According to the present invention, an unsaturated ester compound with little coloring and containing no catalyst can now be produced with good productivity.

The unsaturated ester compound according to the present invention can be made into an epoxy resin by epoxidizing it by a known method using a peroxide such as an organic peracid, hydrogen peroxide, or hydrocarbon oxide.

The above epoxy resin is mixed with a hardening agent and a filler, and molded.
By curing, mechanical properties such as tensile strength and hardness,
It is possible to obtain a cured product that has excellent electrical properties such as tracking resistance and arc resistance, and heat distortion temperature, and is less corrosive. That is, the present invention can be applied to insulating varnishes and UV-curing paints for molded products, cast products, motors, transformers, etc., semiconductor encapsulation, light emitting diode encapsulation, coil impregnation, fiber-reinforced plastics, other paints, electrical and It has become possible to easily produce alicyclic epoxy resin suitable for electronic component applications.

Furthermore, the present invention has made it easier to supply unsaturated polyester resins that do not contain metal or acid content.

The present invention will be explained in more detail by way of examples below.

Example-1 After replacing the reactor with a stirring device, condenser, and water separation device with nitrogen, adipic acid 1001/(0,6
8 mol) and 1.2.3.6-tetrahydrobenzyl alcohol (hereinafter abbreviated as THBA) 23 (1 (2.05 mol)), and the temperature was raised while stirring.

When the reaction temperature reaches about 150℃, water and '1' H
B A mixed vapor reached the condenser and reflux began. Thereafter, the condensate from the condenser was introduced into a water separator, and the reaction was carried out while separating water. During the reaction, nitrogen gas was introduced into the reaction solution through a glass tube, and nitrogen gas was bubbled in an amount that would not cause reflux vapor to leak from the top of the condenser. The reaction temperature increased with the formation of high-boiling condensation compounds, and reached 235°C after 15 hours. At this point, the temperature inside the reactor was lowered to 120° C., and then the pressure of the reaction system was gradually reduced to 3 torr to distill off excess THBA.

After the distillation of THBA was no longer observed, the product was analyzed and an infrared absorption spectrum revealed that there was strong absorption due to ester at 1770 on-', and that the acid value was 0.6 KOHq15.
t, it was confirmed that the carboxylic acid in the raw material was esterified almost quantitatively.

The degree of coloration of the product was 50 on APHA.

Comparative Example-1゜Adipic acid 10010.68 mol), THBA 184 g
(1,64 mol), toluene (28 mol), and para-toluenesulfonic acid (1,6 I) were reacted in the same manner as in Example-1. Reflux starts at 125°C, and the temperature of the reaction system is 3
After an hour, the temperature reached 150°C. During the reaction, the development of color was observed.

After adding 180 mm of toluene to the crude reaction solution, the crude reaction solution was washed with an equal amount of water. It took four washings for the pH of the lower layer water to reach 5 or higher.

The organic layer was concentrated in the same manner as in Example-1 to obtain a product. In the infrared absorption spectrum, there is a strong absorption by ester at 1770 m, and the condensed water generated is at 24.4 m.
9, it was confirmed that ester was produced almost quantitatively.

The coloring degree of the product was 500 or higher on FiAPHA.

Example-2 1,2,3,6-titrahydro anhydrous 7tal r14569
(3.0 mol) and THBA9869 (8.8 mol) were reacted in the same manner as in Example-1. Reflux starts at 180°C, and after 24 hours the reaction temperature reaches #1230°C.
reached.

A product was obtained by #condensation in the same manner as in Example-1. There is strong absorption by 1770α-IVC ester in the infrared absorption spectrum, and the acid value is 1.1 (KOHtny/9)
Therefore, it was confirmed that ester was produced almost quantitatively.

The coloring degree of the product was 40 on ViAPHA.

Reference Example-1 In a reactor with a stirring device removed, 30% peracetic acid ethyl acetate solution 1849 was gradually added dropwise to 110 g of the product of Example-1 so as to maintain the reaction temperature at 30°C. After dripping,
The mixture was aged until the conversion of peracetic acid exceeded 93%.

The reaction crude liquid was desolvated in a continuous flash evaporator, and the bottom liquid that reached a steady state was collected and analyzed, and an epoxy resin with an oxygen content of 7.3%, an acid value of 3, and an APHA of 30 was obtained. It turned out that

Reference Example 2 The product of Comparative Example 1 was epoxidized in the same manner as in Reference Example 1, and the coloring degree of the obtained epoxy resin was 500 or more in AP) (A).

Reference example-3 Ethyl acetate 3002 to the product 1000.9 of Example-2
was added, and evaporation/conversion was carried out in the same manner as in Reference Example 1 using 2579 g of a 30-thioperacetic acid ethyl acetate solution. After washing the reaction crude liquid with water to remove acetic acid, the organic layer was concentrated using a rotary evaporator.

When the product was analyzed, the Okinran oxygen concentration was 10.4.
%, divalent 2, AP) (It was found that an epoxy resin of A25 was obtained.

patent face person Daicel Chemical Industries, Ltd.

Claims (1)

[Claims] A method for obtaining an unsaturated ester compound by reacting a 1,2,3,6-tetrahydrobenzyl alcohol derivative represented by the following formula with a carboxylic acid compound, characterized by heating without a catalyst. A method for producing an unsaturated ester compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_1 to R_9 are H, lower alkyl groups of C_5 or less,
Represents an alkene group or an alkylene group. )