JPS58192851A - Preparation of higher alcoholic ester from acrylic or methacrylic acid - Google Patents

Abstract

PURPOSE:To recover a raw material accompanied by a higher alcoholic ester from acrylic acid or methacrylic acid in obtaining the higher alcoholic ester therefrom in the presence of a strongly acidic cation exchange resin as a catalyst, by bringing the raw material alcohol into contact with a vapor consisting essentially of the water formed by the reaction. CONSTITUTION:Acrylic acid or methacrylic acid is reacted with a 6-10C alcohol, e.g. 2-ethylhexyl alcohol, at 1:(0.5-1)molar ratio in the presence of a strongly acidic cation exchange resin as a catalyst at 70-100 deg.C, and the raw material alcohol is brought into contact with a vapor consisting essentially of the water formed by the reaction and refluxed to separate and recover the acrylic or methacrylic acid and the alcohol distilled and accompanied by the formed water therefrom. The strongly acidic cation exchange resin has 2-10% crosslinking degree, 0.1-5m<2>/g specific surface area and <=10vol% porosity. The amount of the refluxing alcohol is at least 10% alcohol fed to the reaction. EFFECT:The apparatus can be remarkably simplified, and the aimed substance is obtained in high selectivity and yield.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing higher alkyl esters of methacrylic acid. To be more specific, the present invention uses a strongly acidic cation exchange resin as a catalyst to react with acrylic acid or methacrylic acid to a carbon number of 6.
This invention relates to an industrially advantageous method for producing corresponding esters by reacting them with higher alcohols. More specifically, when esterifying acrylic acid or methacrylic acid with an alcohol, the raw material alcohol is refluxed in contact with the vapor mainly composed of esterification reaction product water distilled from the reaction system, and the resulting water is Acrylic acid or methacrylic acid, which is entrained and distilled, provides a method for producing higher alkyl esters of acrylic acid or methacrylic acid, which is characterized by efficiently separating and recovering methacrylic acid and alcohol from produced water. [
In the method for producing corresponding esters from (hereinafter referred to as (meth)acrylic acid) and higher alcohols, the produced water must be removed from the system using a solvent because the esterification reaction is an equilibrium reaction. At present, the reaction has to proceed by oxidation, and acid catalysts such as sulfuric acid, phosphoric acid, and benzene sulfo/acid are generally used as catalysts. This work 8N1k)! always in need,
Not only is the operation and wastewater treatment expensive, but it also has the disadvantage of causing a loss in yield of the desired (meth)acrylic ester.

In recent years, solid acid catalysts and \'1 have been introduced as alternatives to these acid catalysts.
The use of this cation/exchange resin has been proposed.Since this catalyst maintains a solid state in the reaction system, it can be fixed as a catalyst layer and is easily separated from the reaction liquid, but it does not have sufficient heat resistance. However, it has been pointed out that the reaction temperature is limited and the reaction rate is slower than that of conventional acid catalysts. Various methods have been proposed for carrying out the esterification reaction. For example, according to the specification of Japanese Publication No. 46-3041, a cation exchange resin for esterification reaction is filled in the liquid inlet and outlet of a tray type column. A method of separating acrylic acid from penol and ester while boiling under reduced pressure by combining reactors is disclosed, and also disclosed in JP-A-49-54326.
In the specification of the publication, in order to flow cation exchange resin particles into a varnish/chilling reactor, an esterification reaction is carried out under reduced pressure while supplying an inert gas in the form of bubbles, and the resulting water is converted into alcohol.
A method for producing an ester from acrylic acid and an alcohol having 4 to 6 carbon atoms is provided, which is distilled off together with the alcohol or the ester. However, these methods have drawbacks as described below. In other words, there is a tendency for alcohol and even (meth)acrylic acid to be distilled out along with the ester and water produced, and this (meth)acrylic acid in particular is difficult to easily and effectively separate and recover from the distillate. In most cases, it has to be discarded, resulting in a loss of yield.

Thus, in order to overcome these drawbacks, the present inventors
After conducting various researches, we discovered a method to effectively and easily recover the (meth)acrylic acid that is distilled out along with the entrainment, and after gaining some knowledge, we developed a device that uses a strongly acidic cation exchange resin as a catalyst. We have developed a method for producing Nisdel compounds of (meth)acrylic acid and higher alcohols with high selectivity and high yield by greatly simplifying the process.In other words, the present invention can be specified as follows. ) Medium Using a strongly acidic cation exchange resin as a catalyst, acrylic lI! Maku produces the corresponding esters by reacting methacrylic acid with higher alcohols having 6 to 10 carbon atoms. A method for producing esters of acrylic acid or methacrylic acid and higher alcohols, characterized by catalytically refluxing the alcohol and separating and recovering the acrylic acid or methacrylic acid and the alcohol distilled out together with the distilled water; 21 The molar ratio of acrylic acid or methacrylic acid and the alcohol in the esterification reaction system is 1:0.
The reaction mixture was supplied to the esterification reaction system at a ratio of 5 to 1:1, reacted at a reaction temperature of 70 to 00°C, and the reaction mixture was adjusted to a ratio of 60 to 85 moles. The above (
11. The method described in 11.

(31 strongly acidic cation exchange resin has a crosslinking degree of 2 to 10,
The above (1) or (1) having a specific surface area of 0.1 to 5 m2/11 and a porosity of 10 or less
2) The method described.

(4) The alcohol is 2 ethylhexyl alcohol as % mold (1) above, 121 tons (3)
Method described.

(5) The method described in (1), (12+), (31) or (4) above, wherein the amount of alcohol provided for reflux is at least 10 times the amount of alcohol supplied to the esterification reaction.

Next, the present invention will be explained in detail.

A feature of the present invention is that the water produced by the esterification reaction can be removed extremely simply and efficiently in order to carry out the method of the present invention industrially advantageously. In other words, (meth)acrylic acid, alcohol, and ester distilled out together with the produced water are brought into countercurrent contact with the raw material alcohol, so that they are efficiently extracted and recovered from the water to the alcohol side, and then recycled to the esterification reaction system. Features. The product water condensed and separated in this way contains virtually no (meth)acrylic acid and is completely separated and recovered, so even if this product water is disposed of as is, the loss is extremely small. Understood.

In the recovery of active ingredients, especially (meth)acrylic acid, using raw alcohol, the amount of raw alcohol used that is refluxed for countercurrent contact is between 0 and 30% by weight relative to the alcohol supplied for the esterification reaction. is sufficient. If the amount is less than this, there is a risk that Fi(meth)acrylic acid may not be completely recovered, and if it is too much, it will be economically disadvantageous, so it is not recommended.

Now, when using a strongly acidic cation exchange resin for the esterification reaction targeted by the present invention, the reaction temperature is 70 to 1
00°C, preferably in the range of 80 to 90'C. This is because it has been found that if the heat resistance of the skeleton ion exchange resin exceeds 100° C., it is not preferable and the impurity generation reaction in the esterification reaction becomes too large to be ignored. For example, when 2-ethylhexyl alcohol is selected as the alcohol source, an intramolecular dehydration reaction occurs and the production of olefins such as isooctene cannot be ignored, and when acrylic acid is used as the acid, dimerization produces dimer acid. It became clear that the selectivity for ester formation decreased. On the other hand, it is not preferable to employ a reaction temperature of less than 70° C. because the reaction rate may become extremely low.

Furthermore, according to the findings of the present inventors, it has become clear that when using a strongly acidic cation exchange resin, the reaction rate can be further improved and impurity generation can be suppressed by specifying its physical properties.

For example, if we take a commercially available polystyrene-sulfonic acid type resin, in the dehydration reaction of 2-ethylhexyl alcohol mentioned above, a resin with a high degree of crosslinking, a large specific surface area, and a large porosity [for example, "Amberlyst J" A
mberlyst) -15, (manufactured by O-M&Haas), Diaion HPK40 (manufactured by Mitsubishi Chemical Industries)
] Resins with a lower degree of crosslinking, smaller specific surface area, and smaller porosity [e.g., Diaion PK-208 (manufactured by Mitsubishi Chemical Industries) and DOWEX 50Wx4 (manufactured by Dow Chemical)]
It was found that the dehydration reaction was significantly suppressed, and it became clear that it is advantageous for the strongly acidic cation exchange resin to have physical properties such as a low degree of crosslinking and porous properties in carrying out the method of the present invention. In other words, it has been found that resins that are particularly recommended in the present invention have physical properties such as a degree of crosslinking of 2 to +0 qb, a specific surface area of 0.1 to 5 m2/f, and a porosity of 10 m2/f or less. be.

In the method of the present invention, the molar ratio of (meth)acrylic acid and higher alcohol in the reaction system is preferably i: o, s to l: 1, preferably 1: 0.7 to 1: 1, which is a slightly acidic side. It is done. It has been found that, in both cases of excess acid and excess alcohol, not only does the recovery step lead to increased costs, but also the esterification reaction cannot be carried out advantageously.

Furthermore, by carrying out the esterification reaction at a slightly excessive acid level as in the present invention, the by-product of alkoxylated ester, which is an impurity in which alcohol is added to the double bond of (meth)acrylic acid, can be suppressed. In particular, according to the findings of the present inventors, the conversion rate of alcohol is 60 to 85 molar, preferably 70 molar.
It has become clear that by withdrawing the reaction mixture from the reaction system at a level that is suppressed to ~80 mol, the generation of by-products can be reduced to #1, which can be almost ignored.

Next, the present invention will be explained in detail using examples.

Examples 1 to 3 A strongly acidic cation exchange resin (Diaion PK-208 manufactured by Mitsubishi Chemical Industries, Ltd.) was placed in the inner tube of a glass double-tube heat exchange type reaction tower with an inner diameter of 30 mm and a length of 550 mm. 1729 (dry) was filled, and silicone oil at 93°C was circulated through the outer jacket.

At the top of the reaction tower, there is an Ordasillo distillation tower (with an inner diameter of 32 m).
A 20-tier sheep tray (manufactured by Shipata Kagaku) was installed.

The raw materials are acrylic acid and 2-ethylhexanol in a molar ratio of 1.
: A pre-mixed product was used at a ratio of 0.64, and 100 ppm of fetch azide/acrylic acid was added to the mixed solution. The mixed raw materials were introduced from the bottom of the reaction tower by a metering pump through a back pressure valve at a rate of 143.33 t/hour.

On the other hand, 2 ethylhexanol was added from the top of the distillation column at 1 hourly.
It was refluxed at 6.95 t. At this time, the heating temperature of the reaction tower was 93°C, the reaction temperature was 80°C, and the degree of pressure reduction was somHf.

134.27 per hour from the top of the reaction tower? The ester product liquid was extracted, and an organic phase of 0.69 f/hour and an aqueous layer of 8.37 f/hour were distilled from the top of the distillation column.

Acrylic 1117.8012-ethylhexanol 15.3 was extracted from the upper part of the reaction tower.
09G, acrylic 1I2-ethylhexyl 65.591
1. It contained inoctene o, o2cm, octoxypropion Wl/2 ethylhexyl 0.6OL, and water 0.264. Further, the organic phase distilled from the top of the distillation column was a 2-ethylhexanol phase containing 8.09% isooctene and 2.13% water. The aqueous layer contained 0.014.2% of acrylic acid and 0.241% of ethylhexanol.

Table 1 shows the reaction results obtained by changing the ion exchange resin, the amount used, and other reaction conditions in the above.

Table 1 Comparative Example 1 The same equipment as used in Example 1 was used, and the raw materials were acrylic acid and 2-ethylhexanol in a molar ratio of 1:0.
A mixture of H and H was used.

However, 2-ethylhexanol was not refluxed from the top of the distillation column. The reaction conditions and results in this case are shown in Table 2.

Table 2 Procedural amendment (method) IO month 1980 l [l Director General of the Patent Office 1, Indication of the case Patent Application No. 73 '348 of 1981 2, Name of the invention Acrylic acid is still methacrylic acid and higher alcohol Process for producing esters of 3 Amendment applicant: 5-1 Takatakubashi, Higashi-ku, Osaka, Osaka Prefecture (+62) Nippon Shokubai Kagaku Kogyo Co., Ltd. Representative Director San Ishikawa Department 4, Agent: -1 () 0 1-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 5. Date of amendment order July 9, 1980 (shipped on July 27 of the same year) 6 Application and specification to be amended 76 Contents of amendment (11 Engraving (no change in content) (21 Engraving of specification (no change in content) 8 List of attached documents

Claims (1)

[Claims] (11) Esterification when producing corresponding esters by reacting acrylic acid or methacrylic acid with a higher alcohol having 6 to 10 carbon atoms using a strongly acidic cation exchange resin as a catalyst. The raw alcohol is refluxed in contact with the vapor mainly composed of esterification reaction product water distilled from the reaction system, and the acrylic acid or methacrylic acid and alcohol distilled out together with the product water are separated and recovered from the distillation product water. Characteristic method for producing esters of acrylic acid or methacrylic acid and higher alcohol. (2) Acrylic acid or methacrylic acid and alcohol are mixed in a molar ratio of 1:0.5 to 1 in the esterification reaction system. : 1 to the esterification reaction system and reacted at a reaction temperature of 70 to 100°C,
The method according to claim 1, characterized in that reaction conditions are adopted such that the reaction mixture is withdrawn so that the conversion rate of alcohol is in the range of 60 to 85 moles. (31 strongly acidic cation exchange resin has a crosslinking degree of 2 to 10,
The method according to claim (1) or (2), characterized in that the method has a specific surface area of 0.1 to 5 m27t 1 and a porosity of less than 1O capacity board. (41 The method according to claim i11, (2) and f31, characterized in that the alcohol is 2-ethylhexyl alcohol. 151 The alcohol used for reflux is supplied to the esterification reaction. Claims il+, (2), (3) characterized in that the amount of alcohol is at least 10.
) or the method described in (4).