JPH0580263B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a highly active solid catalyst used for esterification reactions and transesterification reactions, particularly a method for producing a polytitanium oxygen solid catalyst. [Prior art and its problems] Conventionally, in esterification and transesterification reactions, organic acids such as para-toluenesulfonic acid,
Catalysts such as inorganic acids such as sulfuric acid and hydrochloric acid, alkalis, and tetraalkoxytitanium are used. For example, useful plasticizers for plastics such as dioctyl phthalate (hereinafter abbreviated as DOP) and dioctyl adipate (hereinafter abbreviated as DOA) are industrially produced through esterification reactions, but they suffer from the following problems. There is. Catalysts used in these industrial esterification reactions naturally require high practical activity, but it is extremely difficult to achieve nearly 100% reaction between acid and alcohol. It is. When using a large amount of these catalysts for the purpose of increasing the reaction rate, the larger the amount of catalyst used, the more problematic the removal of catalyst residue becomes. In particular, in order to remove unreacted and residual acids, the standard requires an acid value of 0.1, or even lower, in order to improve the electrical properties and thermal stability of plastic compositions containing plasticizers. Therefore, a highly active catalyst that is highly active at low concentration is desired. In the case of para-toluenesulfonic acid catalysts, the catalytic activity is sufficiently rapid at low temperatures, but there are difficulties in removing catalyst residues, and in the case of alkoxy titanium catalysts, as with acid catalysts, it is difficult to remove catalyst residues (catalyst decomposition and removal). If the acid value cannot be sufficiently lowered by (including the following), a neutralization and water washing step is essential. At this time, the remaining acid becomes a salt and acts as a surfactant, posing a new problem of poor separation between the ester layer and the aqueous layer. In particular, the more complex the acid, the more difficult it is to remove it, and the lower the acid value of the esterification reaction product. Recently, a method using a chelating agent as a method for removing catalyst residue from a titanium catalyst (US Pat. No. 4,506,091)
Also, research is being conducted on heterogeneous solid catalysts in which the catalyst components do not dissolve in the reaction system as much as possible. For example, an esterification reaction catalyst supported on a carrier has been proposed [CA131919h (1984)]. In addition, as a heterogeneous titanium catalyst that can be used in trace amounts and minimizes the loss of catalyst dissolution in the esterification reaction, a tetraalkoxytitanate polymer is hydrolytically treated with peroxide in the presence of an alkali. Next, the treated product is diluted with monoalcohol (n-butyl alcohol, heptanol, etc.).
A method in which reflux treatment is carried out in esterification (hydric alcohol) has been proposed (Japanese Patent Application Laid-open No. 53-94296), but the preparation process of the catalyst is complicated, and it is difficult to design the optimal catalyst characteristics for various esterification reactions. It is difficult and sometimes difficult. [Problems to be Solved by the Invention] The present invention improves the drawbacks of the conventional esterification and transesterification catalysts described above.
The aim is to provide a novel, highly active titanium-based solid catalyst. [Specific means for solving the problem] ●<Background of the invention> The present inventor has developed a titanium-based solid prepared by first reacting alkoxy titanium with a polyol and then highly crosslinking the resulting reaction product. We discovered that the product (polyol polytitanate) and its hydrated product (polyol polytitanate) are extremely useful as catalysts for esterification reactions and transesterification reactions, and filed a patent application (patent application 60-219140). Regarding the polyol polytitanate ester and polyol polytitanate catalyst, the present inventors
After further investigation, we came up with the idea that water could be considered as a bifunctional diol as a polyol component to be reacted with alkoxytitanium.
As a result of investigating the reaction between alkoxytitanium and water, the inventors discovered that a useful titanium-based solid catalyst could be obtained, and the present invention was achieved. That is, the present inventors obtained solid catalysts for polyol polytitanate and polyol polytitanate useful in the reaction of alkoxytitaniums and polyfunctional polyols as described above, and then added water instead of the polyol component. The research proceeded with the expectation that a useful substance with catalytic activity could also be obtained by reacting with . However, in contrast to the reaction between alkoxytitaniums and polyfunctional polyols, water does not necessarily act divalently; for example, when alkoxytitanium is reacted with an excess amount of water, that is, 4 moles of water, water becomes 1
As a result, an insoluble hydroxide corresponding to Ti(OH) ₄ is produced. Even if an attempt is made to produce a high molecular weight product by divalently acting water on alkoxytitaniums, it is not always easy to control the molecular weight since trivalent or tetravalent titanium compounds are used. In particular, during the process of increasing the molecular weight of the reaction product, oligomers are always generated based on the molecular weight distribution, but when this oligomer is hydrolyzed by adding excess water in the activation treatment described below, the hydrolysis becomes excessive and Ti
It was discovered that (OH) ₄ or something that dissolves in the esterification reaction solution that is the target of the catalytic action is generated, and the acid value of the esterification reaction product does not decrease because of this. In view of the above, the present inventors have pursued a synthesis method that minimizes the formation of oligomer components in the reaction of alkoxytitaniums with water, thereby achieving sufficient catalytic activity in the esterification reaction and It was thought that an esterification reaction product with a low acid value could be obtained at the final stage of the process. This way of thinking can be schematically explained using the following equation. <Polytitanium oxidation reaction>

[ka]

[Chemical formula] As shown in the previous formula, 1 mole of alkoxytitanium is equivalent to 4 alkoxytitanium, and when it is reacted with 2 moles of water, that is, 40H equivalent (alkoxytitanium equivalent to OH equivalent = 1:1). , first a compound with structure [A] is produced, and this reaction product [A] is further subjected to a dealcoholization reaction to produce polytitanic acid having a partially ester structure having structure [B]. . For convenience, this reaction will hereinafter be referred to as polytitanium oxidation reaction. This polytitanium oxidation reaction proceeds by a dealcoholization reaction, and the reaction can be promoted by heating in a solid state, a solvent, or the alcohol produced. In particular, by heating while removing the alcohol produced under reduced pressure, [B] produced by the polytitanium oxidation reaction can be polymerized and crosslinked. For the reasons mentioned above, in the polytitanium oxidation reaction, it is extremely important to polymerize the product [B] while minimizing the formation of oligomers, and the higher the polymerization, the more difficult it is to generate oligomers. If a method in which alkoxytitaniums are reacted with a large amount of water in one step is adopted, a large amount of monomolecules represented by Ti(OH) ₄ or hydrates of oligomers soluble in the solution of the esterification reaction are produced, which is undesirable. . That is, when producing a titanium-based solid catalyst by polytitanium oxidation reaction, if polytitanic acid [B] which is polymerized by reacting alkoxytitaniums with water cannot be uniformly produced,
Many monomolecular or oligomer hydrates are produced as by-products, and as a result, the acid value of the esterification reaction product is not lowered. Therefore, in the polytitanium oxidation reaction, how to polymerize polytitanic acid [above [B]
[Compound]] is an important point, and the present invention overcomes this problem. ●<Specific structure of the invention> To summarize the present invention, it is an invention relating to a method for producing polytitanic acid used as a catalyst for esterification reaction and transesterification reaction, and the polytitanic acid is an alkoxy titanium hydroxide. It is manufactured by reacting, polymerizing, and highly crosslinking. The present invention also relates to a method for producing polytitanic acid, which is used as a catalyst for esterification reactions and transesterification reactions, by activating the polytitanic acid partially having an ester structure prepared as described above by water treatment. It is. Hereinafter, the configuration of the present invention will be explained in detail. In producing the [A] compound in the polytitanium oxidation reaction described above, the reaction of the titanium compound simultaneously proceeds between titanium molecules, resulting in dimerization and further multimerization of titanium alkoxide as shown in the following formula. Reactions also occur, and these reactions proceed simultaneously with the production of [A].

〔Example〕

Example 1 34 g (0.1 mol, 0.4 molar equivalent) of tetrabutoxytitanium was dissolved in 70 g of butanol, and while stirring, 70 g containing 3.6 g (0.2 mol, 0.4 molar equivalent) of water was dissolved.
butanol mixture was mixed dropwise at room temperature. The liquid becomes cloudy upon the first drop, but when the drop is stopped, it mixes and dissolves. The addition takes 1 hour and eventually an oil precipitates out. When the temperature is raised to reflux while stirring, a portion of the solid precipitates out after 4 hours. The butanol is then distilled to a mostly solid precipitate. By carefully reducing the pressure while heating while preventing bumping, butanol distills out, and finally 180
After heating for 3 hours at ~190℃/20mmHg, confirm that no butanol comes out, and further heat for 1mm.
Heating under reduced pressure with Hg was performed for 15 minutes. Next, 3.6 g of water dissolved in 20 g of butanol was added, heated for 1 hour, and the precipitate was collected by filtration.
8.4g after washing with butanol and drying under reduced pressure
A polytitanic acid solid catalyst was obtained. 0.5030 g of the polytitanic acid solid catalyst prepared above was added to a mixture of 146 g (1 mol) of adipic acid and 325 g (2.5 mol) of 2-ethylhexanol, and the dehydration and esterification reaction was carried out at 180-200°C with a small amount of toluene. It was done in the presence of After 30 minutes, half of the calculated amount of water had distilled out, and after 80 minutes, almost all of the water had been distilled out. The acid value after 120 minutes is 0.13, and the acid value after 240 minutes is 0.02.
It was hot. Control Example 3.4 g of tetrabutoxytitanium was dissolved in 5 g of butanol and added to a mixture of 20 ml of water and 50 ml of butanol under reflux. A colorless precipitate was deposited, 6
After a period of time, the precipitate was collected by filtration, washed, and left to dry overnight at 80° C. in a vacuum dryer. reaction product
Calculated as Ti(OH) ₄ , 0.7005 g was used as an amount corresponding to 0.5 g of polytitanic acid in Example 1, and added to a mixture of 146 g (1 mol) of adipic acid and 325 g (2.5 mol) of 2-ethylhexanol. A dehydration esterification reaction was performed. The water in the dehydration esterification reaction was quickly distilled off, with half the amount distilled out after 45 minutes, and approximately the calculated amount distilled out after 90 minutes. However, the measured acid value of the dehydrated esterification reaction product was 6.6 ml/g after 3 hours.
4.1 after 7 hours, 2.2 after 15 hours, 1 even after long heating.
It didn't go below that. The rate at which water is produced by the dehydration esterification reaction appears to be better when the surface of the solid catalyst is hydrated, but on the other hand, the acid value of the esterification reaction product does not decrease. Example 2 A solution of 9.7 g of tetrabutoxytitanium tetramer (product of Tokyo Kasei Co., Ltd.) in 20 g of butanol was added with 1.35 g of water.
g was dissolved in 20 g of butanol, the solution was mixed under heating, and the reaction was carried out in the same manner as in Example 1. Tetrabutoxytitanium tetramer corresponds to 0.01 mole 10 equivalents, and the final reaction product is

〔Effect of the invention〕

The catalyst for esterification and transesterification reactions comprising solid highly crosslinked polytitanic acid according to the present invention can make the acid value of the reaction product extremely low. The industrial significance of this is extremely large; the catalyst residue (solid) can be removed by simple filtration, and the reaction products of esterification and transesterification produced in the presence of the catalyst of the present invention have extremely high acid values. Since the reaction product is low, the step of washing the reaction product can be omitted.

Claims (1)

[Scope of Claims] 1 (i) A step of reacting alkoxytitanium with water to obtain a reaction product; (ii) Next, the reaction product is subjected to a dealcoholization treatment to polymerize and highly crosslink polytitanium. A method for producing a solid catalyst for esterification and transesterification reactions, comprising the steps of: obtaining an acid solid. 2 For the alkoxy equivalent of alkoxy titanium,
2. The method for producing a solid catalyst for esterification and transesterification reactions according to claim 1, wherein both components are reacted in a ratio of 1:1 to 2 equivalents, calculated as a divalent equivalent of water. 3. Esterification reaction according to claim 1 or 2, characterized in that alkoxytitanium and water are reacted in the presence of a carrier such as silica, alumina, zeolite, diatomaceous earth, molecular sieve, activated carbon, etc. and a method for producing a solid catalyst for transesterification. 4. As alkoxytitanium, lower alcohol alkoxytitanium is reacted with higher alcohol,
Claim 1, characterized in that an alkoxytitanium of higher alcohol is used;
A method for producing a solid catalyst for esterification reactions and transesterification reactions according to item 2 or 3. 5. Esterification reaction according to claim 1, 2, 3, or 4, characterized in that a polymerized and highly crosslinked polytitanic acid solid is made into a hydrate by water treatment. and a method for producing a solid catalyst for transesterification.