JP2003261504A - Method for producing (meth) acrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a target (meth) compound by subjecting a (meth) acrylate ester and an alcohol to a transesterification reaction.
An object of the present invention is to provide an economical and environmentally friendly production method that can reduce the amount of an alkoxytitanium compound newly used as a catalyst when producing an acrylate ester. SOLUTION: In a method of producing a target (meth) acrylate by subjecting a starting alkyl (meth) acrylate and a starting alcohol to a transesterification reaction in the presence of a titanium compound catalyst, an unreacted starting material is obtained from a reaction solution. The residual liquid containing the catalyst obtained by distilling and recovering the alkyl (meth) acrylate, the raw material alcohols and the target (meth) acrylate is brought into contact with the alcohol for regeneration, and the alkoxytitanium compound is regenerated and recovered by an alcohol exchange reaction. A method for producing a (meth) acrylic ester, which is reused as at least a part of a transesterification catalyst.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a (meth) acrylic acid ester, and more particularly to a (meth) acrylic acid ester which is easily and economically and industrially regenerated and recovered for reuse. The present invention relates to a manufacturing method.

[0002]

BACKGROUND OF THE INVENTION Tetraalkoxytitanium has extremely high reaction activity and selectivity and is widely used as a catalyst for transesterification or direct esterification reaction. For example, British Patent No. 962928 discloses a method for producing a (meth) acrylic acid ester using tetraalkoxy titanium as a catalyst and hydroquinone or methylene blue as a polymerization inhibitor. In addition, JP-A-49-
Japanese Patent No. 26223 discloses a method of transesterifying an unsaturated ester using tetraisopropoxy titanium as a catalyst and an amino compound containing a benzene nucleus or a naphthalene nucleus as a polymerization inhibitor.

The tetraalkoxytitanium catalyst is usually treated as a waste after the raw material or the target substance is distilled out from the reaction solution after the transesterification reaction, concentrated as a high boiling point substance, and then treated. However, the disposable use of the catalyst not only increases the production cost, but also has a problem that the load on the environment is large.

[0004]

In order to address this problem, a method of recycling the high boiling point concentrate containing the catalyst component as it is to the reaction system is carried out. However, in this case, the catalyst may be partially deactivated and the activity may be lower than that of the new catalyst. Further, in the case where the target product is an unsaturated carboxylic acid ester as in the present invention, there is a possibility that the polymerization may easily occur by recycling.

The present invention has been made in view of the above-mentioned conventional problems, and produces a desired (meth) acrylic acid ester by transesterifying an alkyl (meth) acrylic acid ester with an alcohol. In this case, it is an object of the present invention to provide an economical and environmentally friendly production method capable of reducing the amount of alkoxytitanium compound newly used as a catalyst.

[0006]

The object of the present invention is to carry out a transesterification reaction between a starting material (meth) acrylic acid alkyl ester and a starting material alcohol in the presence of an alkoxytitanium compound as a transesterification reaction catalyst. In the method for producing an ester, a residual liquid containing a catalyst after distilling and collecting unreacted starting material (meth) acrylic acid alkyl ester, starting material alcohols and target (meth) acrylic acid ester from a reaction solution is used as a regeneration alcohol. The present invention relates to a method for producing a (meth) acrylic acid ester, which comprises contacting with an alcoholic titanium compound, regenerating and recovering an alkoxytitanium compound by an alcohol exchange reaction, and reusing this as at least a part of a transesterification reaction catalyst.

In the present invention, when the residual liquid containing the catalyst is brought into contact with the regenerating alcohol, the catalytic titanium compound can be recovered in the form of an alkoxy titanium compound having catalytic activity. Therefore, this can be reused for the transesterification reaction catalyst. can do. As a result, the amount of the newly used alkoxytitanium compound can be reduced, which is economical, and the load on the environment can be reduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The starting material (meth) acrylic acid alkyl ester used in the present invention is preferably, for example, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate or butyl methacrylate. Here, "(meth) acrylic" means
As commonly used, it means "acrylic" and "methacrylic".

Examples of the raw material alcohols used in the present invention include alkanols, alkoxyalkanols, alkenoxyalkanols, alkenols, phenoxyalkanols, cycloalkanols, alkylcycloalkanols, cycloalkylalkanols and phenyl. Examples thereof include alkanols, alkylphenylalkanols, haloalkanols, cyanoalkanols, aminoalkanols and the like. Particularly, those having 2 or more and 20 or less carbon atoms are preferable.

Among such alcohols, alkanols, alkenols and aminoalkenols are preferable, and alkanols are particularly preferable.

Specifically, n-propanol, isopropanol, n-butanol, isobutanol, tertiary butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-ethylhexanol, lauryl alcohol, Stearyl alcohol, tridecanol, dimethylaminoethanol, diethylaminoethanol, cyclohexanol, 3,
3,5-trimethylcyclohexanol, 4-tert-butylcyclohexanol, benzyl alcohol,
Examples thereof include 1-phenylethyl alcohol, 2-phenylethyl alcohol, phenoxyethanol, methoxyethanol, ethoxyethanol, butoxyethanol, allyl alcohol and methallyl alcohol, but are not limited thereto.

The charge mixing ratio of the raw material (meth) acrylic acid alkyl ester and the raw material alcohols can be set arbitrarily, but from the viewpoint of the productivity of the target compound, 1 mole of the raw material alcohols is used. Usually, the starting material (meth) acrylic acid alkyl ester is 0.1 to 10 mol, preferably 0.3 to 4 mol.

The titanium compound catalyst used as the transesterification reaction catalyst in the present invention is generally used as a transesterification catalyst represented by tetraalkoxytitanium. For example, when represented by TiR ¹ R ² R ³ R ⁴ , ¹ ,
R ² , R ³ and R ⁴ are each independently a hydroxyl group (O
H), an alkoxy group having up to 18 carbon atoms, an alkenyloxy group, an aryloxy group, an alkylcarbonyloxy group, an alkyl or alkoxyamino group. It may also be a group that forms a chelate, such as an acetylacetonate group. At this time, the alkyl group may be linear or branched, may be substituted with a halogen, a cyano group or an alkylamino group, and the aryl group may be one in which a hydrogen atom is substituted with an alkyl group. Among these, an alkoxytitanium compound in which at least one alkoxy group is bonded to Ti is preferable, and a tetraalkoxytitanium in which four alkoxy groups are bonded is particularly preferable.

Specific examples of titanium compound catalysts include:
Tetramethoxy titanium, tetraethoxy titanium, tetra-i-propoxy titanium, tetra-n-butoxy titanium, tetra (2-ethylhexyloxy) titanium, tetrastearyloxy titanium, di-i-propoxybis (acetylacetonato) titanium, di Examples include -n-butoxybis (triethanolaminato) titanium, tri-n-butoxytitanium stearate, and isopropoxytitanium tristearate.

The titanium compound catalyst may be used alone or in any mixture of two or more kinds. The amount of titanium compound catalyst used in the transesterification reaction is
0.01 to the mol of the raw material alcohol used
It is 30 mol%, preferably 0.03 to 10 mol%.
If the amount of the catalyst used is too small, there are drawbacks such as a decrease in the yield of the target (meth) acrylic acid ester, an increase in the amount of unreacted substances recovered, and a long reaction time, which lowers the productivity. Also, if the amount is too large, the yield of the target (meth) acrylic acid ester, the reaction time, etc. do not change significantly, and it merely causes an increase in the amount of catalyst used.

The catalyst may be added to the reaction solution by adding these catalysts to the reaction vessel together with the raw material (meth) acrylic acid alkyl ester, the raw material alcohols and the polymerization inhibitor. As a result, the activity decreases, so it is preferable to add a catalyst to the raw material whose water content has been reduced by performing a dehydration operation in advance. If necessary, they may be added in portions during the reaction.

The transesterification reaction can be carried out under any of reduced pressure, normal pressure and increased pressure. The reaction temperature is not particularly limited and can be freely set by the boiling temperature of the reaction solution at a set pressure, but a higher temperature is preferable from the viewpoint of reaction kinetics. However, from the viewpoint of preventing polymerization, 15
It is preferably 0 ° C or lower.

As the reaction proceeds, the alcohol by-produced from the starting material (meth) acrylic acid alkyl ester can be taken out of the reaction system as an azeotropic mixture with the starting material (meth) acrylic acid alkyl ester or a suitable solvent. .

The polymerization inhibitor used in the transesterification reaction is not particularly limited, but examples thereof include hydroquinone, hydroquinone monomethyl ether, phenothiazine and N-.
An oxyl compound or the like can be used.

It is presumed that a part or all of the titanium compound catalyst has been changed to a compound different from the original catalyst after the transesterification reaction. Although not clear what specific changes, for example if the original catalyst is ^{TiR 1 R 2 R 3 R 4} , part or all of ^{R 1, R 2, R 3} , R 4 is a raw alcohol It is presumed that the compound derived from the alkoxy group derived from the hydroxyl group or the hydroxyl group or the ester group is contained.

The transesterification reaction may be carried out batchwise or continuously, but batchwise is preferred.
In either case of the present invention, in the present invention, the titanium compound is recovered from the reaction mixture after the transesterification reaction and the residue liquid after the raw materials and the desired product are distilled. Usually, the residual liquid contains 1 to 30% by weight of titanium compound as titanium atoms. When the residual liquid contains solids such as polymers, it is preferable to filter the solids.

In the present invention, the titanium compound catalyst used in the transesterification reaction is recovered in the alcohol exchange reaction as an alkoxytitanium compound that can be used again as a catalyst. The alcohol exchange reaction is performed, for example, by Brad.
ley, dc, Wardlaw, W., J. Chem. Soc. 1952 , 2773 ~ 27
78 and Emelyanova, I. Suvorov, AL, Pozdeev,
AA, Ir. Inst. Khi., Akad. Nauk SSSR, Ural. Fil
ial 1968 , No. 15, 53 to 7, and in the present invention, an alkoxytitanium compound can be recovered by using such an alcohol exchange reaction. An alcohol exchange reaction is carried out by mixing and contacting the residual liquid and the alcohol for regeneration in a liquid phase at an appropriate reaction temperature using an appropriate device. The reaction temperature is preferably 20 to 100 ° C,
The reaction time can be appropriately selected, but is usually about 1 to 3 hours.

The regeneration alcohol used for regeneration and recovery is preferably one in which the recovered alkoxytitanium compound is obtained as a solid. Specific examples of such regeneration alcohol include methanol, tertiary butanol and stearyl alcohol. , Cyclohexanol and the like. Of these, methanol is preferable.

As described above, since tetraalkoxy titanium reacts rapidly with water to form an oxide which is an inactive substance, the alcohol for regeneration used in the alcohol exchange reaction should be as low as possible in water content, and should be recycled. In the process, it is preferable that the water content is reduced as much as possible before handling. The water concentration of the regenerating alcohol is preferably 500 p
pm or less, more preferably 200 ppm or less.

The molar ratio of the regenerating alcohol used is preferably 8 to 60 with respect to 1 mol of titanium contained in the treatment liquid.
It is a mole.

When the reaction solution after the alcohol exchange reaction is kept at 30 ° C. or lower, the alkoxytitanium compound is deposited.
The alkoxytitanium compound in the reaction solution is separated and recovered by solid-liquid separation means such as filtration and centrifugation. The regenerated and recovered alkoxytitanium compound has an alkoxy group derived from the regenerating alcohol. It is preferred that the alkoxytitanium compound contains a high proportion of tetraalkoxytitanium, that is, most of the catalyst is recovered in the form of tetraalkoxytitanium. Further, a high-purity product can be obtained by washing the solid with the alcohol for regeneration used as necessary and further drying.

[0027]

EXAMPLES The present invention will be described below with reference to examples and comparative examples. The components in the reaction solution were analyzed by gas chromatography. The definitions of conversion rate and selectivity used in the present specification are as follows. Conversion rate (%) = (moles of raw material alcohol reacted / moles of raw material alcohol fed) × 100 Selectivity (%) = (generated (meth) acrylic acid ester / moles of raw material alcohol reacted) × 100 Example 1] 20 equipped with a 20-stage Oldershaw distillation column
103.1 kg of methyl methacrylate in a 0 L reactor
(1030 mol), n-butanol 44.5 kg (60
0 mol), tetra-n-butoxy titanium 102.0 g
(0.3 mol) and 17.1 g of phenothiazine were charged, the mixture was stirred under an air stream and the transesterification reaction was carried out under reflux for 3.5 hours. When the reaction solution was analyzed by gas chromatography, the conversion rate of n-butanol was 9
8.2%, n-butyl methacrylate selectivity is 100%
Met. During this period, methanol produced by the reaction was removed from the system by azeotropic distillation with methyl methacrylate. At this time, the temperature of the reaction liquid rose from 102 ° C to 133 ° C. Then, unreacted methyl methacrylate, n-butanol, and n-butyl methacrylate produced were distilled off under reduced pressure to obtain 260 g of a concentrated residue liquid. Further, the concentrated residue liquid is filtered with a pressure filter (the filter paper is No. 2 manufactured by TOYO) to 200
The solid content was separated by filtration under a nitrogen pressure of kPa. The amount of the concentrated residue liquid obtained by filtering off the solid content was 258 g, and the composition was 43% of organic titanium compound (0.3 mol as Ti), n-
Butyl methacrylate was 55% and the polymerization inhibitor was 2%.

192.2 g (6 mol) of methanol was charged into a reactor equipped with a stirrer, a cooler, a thermometer and a dropping funnel, and the methanol was refluxed. 258 g of a concentrated residue liquid containing an organotitanium compound whose solid content is filtered off under a nitrogen atmosphere
Was added dropwise over 1 hour. After completion of dropping, the mixture was aged under reflux of methanol for 2 hours and cooled to 30 ° C. 1 of this liquid
Filtration was performed under a nitrogen pressure of 00 kPa, and 65.3 g of solid tetramethoxytitanium (purity 70%) was obtained as the filtration residue.

2 L equipped with a 20-stage Oldershaw distillation column
Methyl methacrylate 10 in a four-necked flask with side tube
31 g (10.3 mol), n-butanol 445 g (6
Mol), 0.74 g (0.003 mol) of tetramethoxytitanium obtained by the above method and 0.17 g of phenothiazine were charged, and transesterification was carried out under reflux for 2.5 hours. The conversion of n-butanol was 97.4% and the selectivity of n-butyl methacrylate was 100%.

[0030]

INDUSTRIAL APPLICABILITY According to the present invention, when the target (meth) acrylic acid ester is produced by the transesterification reaction, the transesterification catalyst can be regenerated and recovered and reused. It is possible to reduce the amount of the alkoxytitanium compound used, and to provide an economical and environmentally friendly manufacturing method.

Continued front page    F-term (reference) 4H006 AA02 AC48 BA10 BA32 BC40                       BD36 BD52 KA03                 4H039 CA66 CD90 CE10

Claims (5)

[Claims] 1. A method for producing a target (meth) acrylic acid ester by subjecting a raw material (meth) acrylic acid alkyl ester and a raw material alcohol to transesterification in the presence of a titanium compound catalyst as a transesterification reaction catalyst, The residual liquid containing the catalyst after distilling and recovering the unreacted starting material (meth) acrylic acid alkyl ester, starting material alcohols and target (meth) acrylic acid ester from the reaction solution is contacted with the regenerating alcohol to carry out the alcohol exchange reaction. A method for producing a (meth) acrylic acid ester, characterized in that the alkoxytitanium compound is regenerated and recovered by means of and is reused as at least a part of a transesterification reaction catalyst. 2. A filtrate obtained by filtering the residual liquid and the regenerating alcohol are brought into contact with each other to cause an alcohol exchange reaction, and an alkoxytitanium compound is precipitated as a solid to be regenerated and recovered. Method for producing (meth) acrylic acid ester. 3. The method for producing a (meth) acrylic acid ester according to claim 1, wherein the regenerating alcohol used in the alcohol exchange reaction is methanol. 4. The method for producing a (meth) acrylic acid ester according to claim 1, wherein the water content in the regenerating alcohol used in the alcohol exchange reaction is 500 ppm or less. 5. The method for producing a (meth) acrylic acid ester according to claim 1, wherein the regenerated and recovered alkoxytitanium compound contains tetraalkoxytitanium.