JP2004339203A - METHOD FOR PRODUCING alpha,beta-UNSATURATED CARBOXYLIC ACID - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an industrially advantageous method for producing an α,β-unsaturated carboxylic acid (e.g. acrylic acid, methacrylic acid). <P>SOLUTION: This method for producing the α,β-unsaturated carboxylic acid expressed by formula (2) (wherein, R is H, an alkyl, an aryl, an aralkyl, an alkenyl or an alkynyl) comprises performing the reaction of a carboxylic acid expressed by formula (1) (wherein, R is the same as above) with formaldehyde or a formaldehyde precursor in the presence of a metal sulfate salt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method for producing an α, β-unsaturated carboxylic acid by reacting a carboxylic acid with formaldehyde or a formaldehyde precursor. Among the α, β-unsaturated carboxylic acids obtained, acrylic acid and methacrylic acid are important compounds as raw materials for acrylate resin monomers.

  Methacrylic acid, which is particularly important among α, β-unsaturated carboxylic acids, has conventionally been produced widely by reacting acetone and hydrocyanic acid and passing through acetone cyanohydrin. However, this production method uses a very toxic hydrocyanic acid and has a problem that a large amount of waste such as ammonium sulfate is by-produced. It is also produced by a method of obtaining methacrolein by oxidizing isobutene and further oxidizing it. However, there is a problem that a multi-tube type very large reactor is required.

  On the other hand, a method has been proposed in which a carboxylic acid is reacted with formaldehyde or a formaldehyde precursor to produce an α, β-unsaturated carboxylic acid. For example, a method for producing an α, β-unsaturated carboxylic acid or an ester thereof by contacting formaldehyde or a formaldehyde precursor with a carboxylic acid, a carboxylic acid ester, or a carboxylic anhydride by using a catalyst containing an oxide of niobium is disclosed. (See Patent Document 1). However, in this method, preparation of the catalyst was complicated, for example, using niobium fluoride which is easily absorbed and difficult to handle. Also, the niobium fluoride used is expensive and is not practical in terms of cost.

  On the other hand, a method for producing acrylic acid or methacrylic acid using a catalyst in which a sulfur oxide is present in a solid catalyst having an acid point with an acid strength of pKa ≦ −3.0 has also been proposed (see Patent Document 2). However, there is no description about metal sulfate, and preparation of the catalyst was complicated.

  In addition, for example, a method using a porous high surface area silica containing an alkali metal and a regulator element such as zirconium (see Patent Document 3) as a catalyst or a composite oxide of silica-cesium-tungsten and a metal such as silver is used. Although a method of using the compound (see Patent Document 4) has been proposed, the preparation of the catalyst is complicated, and it is hardly a practical method.

JP 2001-507697 A JP-A-62-221651 JP 2002-511336 A JP-A-5-331098

  An object of the present invention is to provide a method for efficiently producing an α, β-unsaturated carboxylic acid by reacting a carboxylic acid with formaldehyde or a formaldehyde precursor using a catalyst that can be easily prepared.

（式中、Ｒは水素原子、アルキル基、アリール基、アラルキル基、アルケニル基またはアルキニル基を表す。）
で示されるカルボン酸とホルムアルデヒドまたはホルムアルデヒド前駆体とを金属硫酸塩の存在下に反応させることを特徴とする式（２）

（式中、Ｒは前記と同じ意味を表す。）
で示されるα，β−不飽和カルボン酸の製造方法を提供するものである。 Therefore, the present inventors have conducted intensive studies on a method of producing an α, β-unsaturated carboxylic acid by reacting a carboxylic acid with formaldehyde or a formaldehyde precursor, and as a result, using a metal sulfate which can be easily prepared as a catalyst. As a result, the present inventors have found that the reaction proceeds efficiently, leading to the present invention.
That is, the present invention relates to formula (1)

(In the formula, R represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or an alkynyl group.)
Wherein a carboxylic acid represented by the formula (1) is reacted with formaldehyde or a formaldehyde precursor in the presence of a metal sulfate.

(In the formula, R represents the same meaning as described above.)
The present invention provides a method for producing an α, β-unsaturated carboxylic acid represented by the formula:

  According to the present invention, in a method for producing an α, β-unsaturated carboxylic acid from a carboxylic acid and formaldehyde or a formaldehyde precursor, a catalyst which can be easily prepared from a metal sulfate which is relatively easily available is efficiently used. It can be implemented and its industrial value is great.

Hereinafter, the present invention will be described in detail.
In the carboxylic acid represented by the formula (1) used in the present invention (hereinafter, referred to as carboxylic acid (1)), when R is a hydrogen atom, the corresponding carboxylic acid is acetic acid.

  When R is an alkyl group, the alkyl group has 1 to 10 carbon atoms. Examples of the carboxylic acid (1) include propionic acid, butyric acid, valeric acid, 3-methylbutanoic acid, caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid and the like.

  When R is an aryl group, the aryl group has 6 to 10 carbon atoms. Examples of the carboxylic acid (1) include phenylacetic acid, p-toluylacetic acid, and naphthylacetic acid.

  When R is an aralkyl group, the aralkyl group has 7 to 10 carbon atoms. Examples of the carboxylic acid (1) include 3-phenylpropionic acid.

  When R is an alkenyl group, the alkenyl group has 2 to 10 carbon atoms. Examples of the carboxylic acid (1) include vinyl acetic acid, 4-pentenoic acid, and 10-undecenoic acid.

  When R is an alkynyl group, the alkynyl group has 2 to 10 carbon atoms. Examples of the carboxylic acid (1) include 3-butyric acid, 3-pentynic acid, and 3-hexynic acid.

  As the carboxylic acid (1), acetic acid and propionic acid are preferable, and propionic acid is more preferable.

  The formaldehyde used in the present invention can be used in various forms. Although it can be supplied with an aqueous solution such as formalin or with 100% formaldehyde, when it is difficult to supply with 100% formaldehyde, a formaldehyde precursor can be used. The formaldehyde precursor is not particularly limited as long as it is a compound which easily decomposes in the reaction system to give formaldehyde. Specific examples of the formaldehyde precursor include trioxane and paraformaldehyde, and trioxane is preferred. These can be used after being diluted with an organic or inorganic medium.

  The supply amount of formaldehyde or formaldehyde precursor is usually 0.01 to 10 moles, in terms of formaldehyde, based on the carboxylic acid used. It is preferably 0.03 to 3 times by mole, and more preferably about 0.1 to 1 times by mole.

  The α, β-unsaturated carboxylic acid produced by reacting the carboxylic acid (1) with formaldehyde or a formaldehyde precursor is represented by the formula (2). When R is a hydrogen atom, that is, when the starting carboxylic acid is acetic acid, the resulting α, β-unsaturated carboxylic acid represented by the formula (2) (hereinafter referred to as α, β-unsaturated carboxylic acid (2)) ) Is acrylic acid, and when R is a methyl group, that is, when the starting carboxylic acid is propionic acid, the α, β-unsaturated carboxylic acid (2) is methacrylic acid.

In the present invention, the metal sulfate acts as a catalyst.
The metal sulfate used in the present invention is not particularly limited as long as it contains a metal and sulfate ions, and also includes an oxymetal sulfate such as vanadyl sulfate. Specific examples of metal sulfates include, for example, cobalt sulfate such as nickel sulfate, cobalt (II) sulfate and cobalt (III) sulfate, iron sulfate such as iron (II) sulfate and iron (III) sulfate, aluminum sulfate, and sulfuric acid. Vanadyl, copper sulfate such as copper (I) sulfate and copper (II) sulfate, chromium sulfate such as chromium (II) sulfate and chromium (III) sulfate, manganese sulfate such as manganese (II) sulfate and manganese (III) sulfate, Zirconium sulfate, zinc sulfate, silver sulfate, palladium sulfate, indium sulfate, nickel ammonium sulfate and the like. Among these, nickel sulfate, cobalt sulfate, aluminum sulfate, iron sulfate, and vanadyl sulfate are preferred, and nickel sulfate is more preferred. These may be used alone, in a mixture or in a complex, and may contain water of crystallization. Moreover, it is also possible to use it by supporting it on a carrier such as silica or alumina.

  Although the method for preparing the catalyst is not particularly limited, it may be prepared by a simple method such as calcination. Since the metal sulfate is generally easily available in the form of a hydrate, a preparation method in which the hydrate is calcined is preferred.

The calcination temperature when preparing the catalyst by calcination is generally in the range of 50 ° C to 1000 ° C, preferably in the range of 100 ° C to 500 ° C, more preferably in the range of 150 ° C to 450 ° C, further preferably It is in the range of about 200 ° C to 400 ° C.

  This reaction can be carried out by a continuous system or a batch system, but the continuous system is industrially preferable.

  When the reaction is carried out in a continuous manner, the feed amount of the starting carboxylic acid is generally in the range of 0.1 g / hr to 100 g / hr, preferably in the range of about 0.3 g / hr to 20 g / hr, per 1 g of the catalyst. .

  In this reaction, an inert gas can be supplied in addition to the carboxylic acid (1) and formaldehyde or a formaldehyde precursor. Examples of the inert gas include nitrogen, helium, argon and the like, and nitrogen is usually used in terms of cost.

  If the reaction temperature is too low, the reaction rate is slow, and if it is too high, side reactions are likely to occur. Therefore, it is preferable to carry out the reaction in the range of 150 ° C to 500 ° C. The temperature is more preferably in the range of 200 ° C to 400 ° C, and still more preferably in the range of about 250 ° C to 350 ° C.

  The reaction pressure is not particularly limited. However, if the reaction pressure is too high, the equipment cost becomes high. Therefore, the reaction is usually carried out at a gauge pressure of 0 MPa (0 MPa means atmospheric pressure) to 10 MPa. More preferably, it is in the range of about 0.05 MPa to 1 MPa.

  The reaction mixture after completion of the reaction may contain α, β-unsaturated carboxylic acid (2), unreacted raw materials, and other impurities. From the reaction mixture, the α, β-unsaturated carboxylic acid may be purified to a purity required for each application, and the method is not particularly limited, and a general method such as distillation and extraction can be applied.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1
30 g of nickel sulfate hexahydrate (NiSO4.6H2O, manufactured by Nacalai Tesque, special grade) placed on an evaporating dish was charged into a muffle furnace heated to 350 ° C, and kept at 350 ° C for 5 hours. The obtained yellow solid was molded, and one having a size of 12 to 24 mesh was sieved and taken out.
5 g of the molded product was placed in a reaction tube made of a SUS tube having an inner diameter of 1/2 inch. In addition, a vaporization tube arranged upstream of the reaction tube was filled with quartz grains (manufactured by Wako Pure Chemical Industries, 20 to 28 mesh).
A mixed solution of propionic acid (Kanto Chemical, special grade) and trioxane (Kanto Chemical, special grade) (20 g of trioxane dissolved in 230 g of propionic acid was used) was placed in a vaporizing tube and a reaction tube heated to 300 ° C. Nitrogen was introduced at a flow rate of 82 ml / min at a flow rate of 0.1 ml / min. The internal pressure of the reaction tube was maintained at a gauge pressure of 2 kg / cm 2 (corresponding to 0.2 MPa) by a back pressure valve provided downstream of the reaction tube.
The reaction liquid collected 2 to 4 hours after the start of the liquid feeding was quantitatively analyzed by gas chromatography. The yield of methacrylic acid with respect to propionic acid was 11%, and the yield of methacrylic acid with respect to trioxane (production The value obtained by dividing the number of moles of methacrylic acid by the number of moles of the introduced trioxane in terms of formaldehyde, the same applies hereinafter) was 47%.

Example 2
A reaction was carried out in the same manner as in Example 1 except that nickel sulfate hexahydrate was placed in a muffle furnace at room temperature and then heated to 350 ° C. and held for 5 hours during catalyst preparation. As a result, methacrylic acid was converted to propionic acid. The yield was 9%, and the yield of methacrylic acid based on trioxane was 40%.

Example 3
The reaction was carried out in the same manner as in Example 2 except that the temperature of the muffle furnace was raised to 300 ° C. during the preparation of the catalyst, and as a result, the yield of methacrylic acid relative to propionic acid was 11%, and the yield of methacrylic acid relative to trioxane was 11%. The rate was 49%.

Example 4
The reaction was carried out in the same manner as in Example 1 except that nickel sulfate hexahydrate was placed in a muffle furnace at room temperature during the preparation of the catalyst, and then heated and maintained at 400 ° C. As a result, the yield of methacrylic acid relative to propionic acid was 8%. %, And the yield of methacrylic acid based on trioxane was 37%.

Example 5
After dissolving 15 g of nickel sulfate hexahydrate and 1.8 g of cobalt sulfate heptahydrate (CoSO4.7H2O) in 200 g of ion-exchanged water, the mixture was evaporated to dryness at 50 ° C. under reduced pressure using an evaporator. The obtained solid was put into a muffle furnace heated to 350 ° C., and kept at 350 ° C. for 5 hours. The obtained solid was molded, and one having a size of 12 to 24 mesh was sieved and taken out.
The reaction was conducted in the same manner as in Example 1 except that the catalyst prepared above was used. As a result, the yield of methacrylic acid with respect to propionic acid was 7%, and the yield of methacrylic acid with respect to trioxane was 32%.

Example 6
30 g of nickel sulfate hexahydrate put on the evaporating dish was put into a muffle furnace heated to 300 ° C., and kept at 300 ° C. for 5 hours. The obtained yellow solid was molded, and one having a size of 12 to 24 mesh was sieved and taken out.
5 g of the molded product was placed in a reaction tube made of a SUS tube having an inner diameter of 3/4 inch. No vaporization tube was placed upstream of the reaction tube.
A mixture of propionic acid and trioxane (using 20 g of trioxane dissolved in 230 g of propionic acid) was introduced into the reaction tube heated to 300 ° C. at a flow rate of 0.2 ml / min, and nitrogen was introduced at a flow rate of 123 ml / min. did. The internal pressure of the reaction tube was maintained at a gauge pressure of 2 kg / cm 2 (corresponding to 0.2 MPa) by a back pressure valve provided downstream of the reaction tube.
After 1 hour to 3 hours from the start of the liquid feeding, the collected reaction solution was quantitatively analyzed by gas chromatography. The yield of methacrylic acid with respect to propionic acid was 12%, and the yield of methacrylic acid with respect to trioxane was 54%. %Met.

Example 7
At the time of catalyst preparation, 30 g of nickel sulfate hexahydrate was put into a muffle furnace heated to 250 ° C., and the reaction was carried out in the same manner as in Example 6 except that the temperature was kept at 250 ° C. for 5 hours. As a result, the yield of methacrylic acid relative to propionic acid was determined. The yield was 12%, and the yield of methacrylic acid based on trioxane was 54%.

Example 8
30 g of nickel sulfate hexahydrate placed on the evaporating dish was put into a muffle furnace heated to 350 ° C., and kept at 350 ° C. for 5 hours. The obtained yellow solid was molded, and one having a size of 12 to 24 mesh was sieved and taken out.
5 g of the molded product was placed in a reaction tube made of a SUS tube having an inner diameter of 3/4 inch. No vaporization tube was placed upstream of the reaction tube.
A mixture of propionic acid and trioxane (using 20 g of trioxane dissolved in 230 g of propionic acid) is introduced into the reaction tube heated to 330 ° C. at a flow rate of 0.2 ml / min, and nitrogen is introduced at a flow rate of 82 ml / min. did. The internal pressure of the reaction tube was maintained at a gauge pressure of 2 kg / cm 2 (corresponding to 0.2 MPa) by a back pressure valve provided downstream of the reaction tube.
After 1 hour to 3 hours from the start of the liquid feeding, the collected reaction solution was quantitatively analyzed by gas chromatography. The yield of methacrylic acid with respect to propionic acid was 8%, and the yield of methacrylic acid with respect to trioxane was 35%. %Met.

Comparative Example 12.1 g of niobium fluoride (manufactured by Aldrich) was gradually added to 38.2 g of colloidal silica (manufactured by Nissan Chemical Co., containing 40 wt% -SiO2), and the mixture was aged by stirring at room temperature for 1 hour. The white solid obtained by evaporating water to dryness was calcined at 300 ° C. for 4 hours and at 450 ° C. for 6 hours. The obtained white solid was molded, and the one having a size of 12 to 24 mesh was sieved and taken out.
5 g of the molded product was put into a reaction tube made of a SUS tube having an inner diameter of 3/4 inch, and after holding the catalyst with quartz wool, 40 g of quartz grains were introduced. In addition, a vaporization tube arranged upstream of the reaction tube was filled with quartz grains. A mixed solution of propionic acid (Kanto Chemical, special grade) and trioxane (Kanto Chemical, special grade) (20 g of trioxane dissolved in 230 g of propionic acid was used) was placed in a vaporizing tube and a reaction tube heated to 300 ° C. Nitrogen was introduced at a flow rate of 82 ml / min at a flow rate of 0.1 ml / min. The internal pressure of the reaction tube was maintained at a gauge pressure of 2 kg / cm 2 (corresponding to 0.2 MPa) by a back pressure valve provided downstream of the reaction tube.
The reaction liquid collected 2 hours to 4 hours after the start of the liquid sending was quantitatively analyzed by gas chromatography. The yield of methacrylic acid with respect to propionic acid was 6%, and the yield of methacrylic acid with respect to trioxane was 27%. %Met.

Claims (5)

Equation (1)

(In the formula, R represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or an alkynyl group.)
Wherein a carboxylic acid represented by the formula (1) is reacted with formaldehyde or a formaldehyde precursor in the presence of a metal sulfate.

(In the formula, R represents the same meaning as described above.)
A method for producing an α, β-unsaturated carboxylic acid represented by the formula: The method for producing an α, β-unsaturated carboxylic acid according to claim 1, wherein the metal sulfate is nickel sulfate, cobalt sulfate, aluminum sulfate, iron sulfate or vanadyl sulfate. The method for producing an α, β-unsaturated carboxylic acid according to claim 1, wherein the metal sulfate is nickel sulfate. The method for producing an α, β-unsaturated carboxylic acid according to any one of claims 1 to 3, wherein the carboxylic acid is acetic acid or propionic acid. The method for producing an α, β-unsaturated carboxylic acid according to any one of claims 1 to 4, wherein the formaldehyde precursor is trioxane.