JPH0616585A - Method for producing dipentaerythritol - Google Patents

Abstract

(57) [Summary] [Structure] In the presence of an acid catalyst, pentaerythritol is subjected to a condensation reaction in a liquid phase to synthesize dipentaerythritol, and by-products such as formal present in the reaction solution are hydrolyzed to give pentaerythritol. Collect as. [Effect] Since pentaerythritol, which is a raw material for producing dipentaerythritol, can be recovered from the by-product, the production cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing dipentaerythritol, more specifically, dipentaerythritol (hereinafter abbreviated as D-PE) is synthesized by a dehydration condensation reaction of pentaerythritol using an acid catalyst. It is about the method.

[0002]

2. Description of the Related Art D-PE is a by-product during the synthetic reaction of pentaerythritol (hereinafter abbreviated as PE), that is, when PE is produced by reacting formaldehyde with acetaldehyde in the presence of an alkali. It is a general industrial production method that is obtained by separating and purifying.
In order to increase the by-product ratio of D-PE in this reaction, (1) the molar ratio of formaldehyde to acetaldehyde charged to the reaction system is made smaller than the theoretical molar ratio of 4. (2) The reaction is carried out by increasing the concentrations of formaldehyde, acetaldehyde and alkaline agent. (3) PE is added to the aqueous formaldehyde solution to carry out the reaction. And other methods have been proposed. However, the methods (1) and (2) have a poor total yield of PE and D-PE, and the quality of the main product, PE, is poor. , A part of acetaldehyde is charged in advance, and formaldehyde,
A method (Japanese Patent Publication No. 1-44689) has been proposed in which alkali and acetaldehyde are kept at a theoretical molar ratio or higher and the reaction temperature is kept at 50 ° C. or lower to simultaneously drop them to react.

However, the above-mentioned method for producing D-PE by the reaction of acetaldehyde and formaldehyde still has the following problems. (A) PE and D-PE must be separated and recovered from impurities such as by-product sodium formate, bispentaerythritol monoformal, excess formaldehyde or self-condensate of acetaldehyde / formaldehyde, and the purification process is extremely complicated. Becomes (B) The amount of D-PE that can be produced depends on the amount of PE produced.
The limit is ~ 15%, which cannot meet the recent increase in demand.

On the other hand, a method for synthesizing a polypentaerythritol mixture using PE with phosphoric acid, sulfuric acid, etc. is also known, but a means for selectively synthesizing D-PE has not been described (USP 2462047). According to the knowledge of the present inventors, when PE is dehydrated and condensed using an acid catalyst, D-PE is produced.
PE is changed to tripentaerythritol (hereinafter abbreviated as T-PE) to high molecular weight polypentaerythritol, or an intramolecular condensate is generated, so it is difficult to put it to practical use as it is. .

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the D-PE production method by the condensation reaction of PE in the presence of the above-mentioned acid catalyst, the present inventors changed the product D-PE to polypentaerythritol sequentially. Therefore, we considered that it is possible to selectively synthesize D-PE by lowering the PE conversion. As a result, D-PE can be synthesized as a main product by lowering the conversion of PE. In this reaction solution, formal such as pentaerythritol monocyclic formal (hereinafter abbreviated as MCF) is started, It was found to contain other by-products. PE and D-PE are separated and obtained as crystals from this reaction solution, but since the solution after acquisition contains a large amount of unreacted PE, it must be recycled to the reaction system again. When this solution is actually recycled to the reaction system and the reaction is repeated, by-products accumulate and it is necessary to purge part of the reaction solution, and PE and D-PE are obtained as crystals from the reaction solution. In addition to the deterioration of crystallinity, it was found that there are problems that by-products are generated and the PE unit consumption is deteriorated due to purging of by-products.

[0006]

Means for Solving the Problems The present inventors have made extensive studies in order to solve the above problems. As a result, when the reaction solution containing by-products such as formal compounds is hydrolyzed under specific conditions, MCF decomposes and can be recovered as PE.
Surprisingly, we found that high boiling by-products other than MCF can also be decomposed and recovered as PE. Therefore, even if the reaction solution after decomposition is recycled to the reaction system and the reaction is repeated, the amount of by-products accumulated is reduced and the amount of purge of the reaction solution can be reduced. Does not deteriorate when it is obtained as crystals.
Since PE can be recovered, the basic unit of PE can be improved, and the present invention was completed.

That is, the method for producing dipentaerythritol according to the present invention comprises a reaction solution A prepared by subjecting PE to a condensation reaction in the liquid phase in the presence of an acid catalyst to synthesize D-PE, or a reaction solution A.
Solution B after separating some or all of PE and D-PE
Hydrolyze by-products such as formal present in the inside,
A method for producing D-PE, which is characterized in that it is recovered as PE. Hereinafter, the present invention will be described in more detail.

The raw material liquid to be subjected to hydrolysis in the method of the present invention is D-PE obtained by subjecting PE to a condensation reaction in the liquid phase in the presence of an acid catalyst, a molten state or a polar solvent.
Reaction solution A synthesized from PE or PE and D-PE from reaction solution A
Is a solution B after separating a part or all of the above. In the reaction solution A or solution B, for example, when phosphoric acid is used as an acid catalyst, in addition to unreacted PE, D-PE, T-PE, MCF,
Pentaerythritol dicyclic formal (below
DCF), bispentaerythritol monoformal (hereinafter abbreviated as BPEMF), PE monoester phosphate, phosphate diester, phosphate triester, formaldehyde, and other by-products.

The method of hydrolysis in the method of the present invention is
It is important that the reaction solution A or solution B is heated in a water solvent in the presence of an acid catalyst to extract water vapor.

When water is used as a solvent in the D-PE synthesis reaction (reaction in a molten state) or as a polar solvent, water for hydrolysis may be added to the reaction solution A or solution B. On the other hand, when the D-PE synthesis reaction was performed using a polar solvent other than water, water for hydrolysis was added after distilling off the polar solvent, or water was added without distilling off the polar solvent. Alternatively, the decomposition reaction may be carried out in a mixed solvent system of a polar solvent and water. The amount of water added as a solvent is in the range of 0.1 to 100, preferably 0.5 to 20, in weight ratio with respect to PE used as a raw material in the D-PE synthesis reaction. If the amount of water is less than this range, the effect of hydrolysis is small, and if it is more than this range, the volume of the hydrolysis tank becomes large, which is not economical.

In the method of the present invention, hydrolysis is carried out in the presence of an acid catalyst. The raw material liquid to be subjected to hydrolysis in the present invention is
Since the reaction solution is a reaction solution prepared by synthesizing D-PE from PE in the presence of an acid catalyst, the reaction solution A or solution B contains an acid catalyst.
Therefore, it is possible to carry out the decomposition reaction without newly adding an acid catalyst during the hydrolysis reaction. Further, when the amount of the acid catalyst decreases during the separation of PE or D-PE, the reduction reaction may be added to carry out the decomposition reaction. On the other hand, it is also possible to carry out the D-PE synthesis reaction using a homogeneous acid catalyst such as phosphoric acid and the decomposition reaction using a solid acid catalyst such as zeolite. In this case, the reaction liquid A or the solution B can be introduced into the decomposition tank filled with the solid acid catalyst to carry out the decomposition reaction. Furthermore, both the D-PE synthesis reaction and the decomposition reaction can be carried out using a solid acid catalyst.

As the acid catalyst used in the present invention, as described above, the catalyst for synthesizing D-PE from PE can be used as it is in the decomposition reaction, so that a substance usually used as a catalyst for dehydration condensation reaction of alcohol can be used. As an example, the catalyst course, Vol. 8, page 278, is shown in Table 13.3. For example, mineral acids such as phosphoric acid and sulfuric acid, organic acids such as paratoluene sulfonic acid, inorganic acids such as metal sulfates and metal phosphates, clay minerals such as montmorillonite, solid acid catalysts such as silica / alumina, zeolites, etc. Is.

The optimum amount of the catalyst varies depending on the kind of the catalyst, but for example, in the case of phosphoric acid, it is 0.01 to 4%, preferably 0.1 to 3% with respect to the reaction solution. When the amount of the catalyst is small, the reaction rate is low, and when it is large, the by-product of impurities increases.

In the method of the present invention, formalin is produced by hydrolyzing formals such as MCF and other by-products. Therefore, if the formalin produced is removed outside the system, the hydrolysis can be efficiently performed. At this time, formalin may be removed from the system by separating formalin and water with a condenser installed in the decomposition tank, or formalin may be removed from the system by being accompanied by steam. In the latter case, the decomposition reaction may be carried out while continuously supplying water or steam equal to the amount of steam extracted, or the water charged in the decomposition tank is extracted as steam without supplying water or steam. You can just do it.

The reaction temperature in the method of the present invention is 100 to 30.
The temperature is 0 ° C, preferably 150 to 250 ° C. When the reaction temperature is low, the reaction rate is low, and when it is high, the by-product of impurities increases.
The reaction pressure may be a pressure that can maintain a predetermined reaction temperature. Usually, it is 1 to 50 kg / cm ² .

The method of the present invention can be carried out by any of a batch method, a semi-batch method and a continuous method. For example, in the case of the batch method, a raw material solution for decomposition, water,
Also, the reaction proceeds by charging an acid catalyst as necessary and extracting steam while heating. Further, in the case of the continuous method, the raw material liquid for decomposition, water and, if necessary, the acid catalyst are continuously supplied to one of the reactors, the reaction mixture is continuously extracted from the other, and the other is extracted. The reaction is carried out by extracting water vapor from the soup mouth.

[0017]

EXAMPLES The present invention will now be described in more detail with reference to examples.

In the examples, the reaction results (D-PE and T-PE selectivities) are shown in mol% corrected for D-PE and T-PE contained in the raw materials. The pressure display is indicated by gauge pressure.

Example 1 (Synthesis of raw material liquid for hydrolysis) Internal volume 1 made of stainless steel
A reactor equipped with a liter, a thermometer, a pressure gauge, a heating and stirring device, and a stainless steel 5 μm mesh filter and a liquid outlet at the bottom, PE 341.2 g as raw material, D-PE
10.9g, T-PE 0.9g, BPEMF 2.7g, MCF 2.0g, PE phosphates 0.6g, other by-products 10.1g, water 41.5g
Also, a recycle solution containing 3.4 g of 85% phosphoric acid was charged.
After replacing the inside of the reactor with nitrogen, the temperature was raised to 220 ° C. and then the reaction was performed for 140 minutes. During this time, the pressure was 12 kg / cm ² .

After the reaction, a part of the reaction solution was taken out and analyzed. PE 301.0 g, D-PE 32.9 g and T-PE were found in the reaction solution.
There were 5.1 g, MCF 4.6 g, PE phosphates 2.6 g, and other by-products 21.8 g. From this, the results of this reaction are PE conversion 12.5%, D-PE selectivity 55.1%, T-
The PE selectivity was 10.6% (hereinafter referred to as reaction solution a).

Then, 316 g of water was fed into the reactor for 30 minutes by using a pump, and the liquid temperature was adjusted to 60 ° C. to crystallize a part of unreacted PE, and a liquid phase portion was passed through a filter at the bottom. As a result of extraction, PE 118.9g, D-PE 31.0g, T-PE 3.2g
, MCF 4.3 g, PE phosphoric acid esters 2.3 g, and other by-products 18.5 g were obtained (307 g) (hereinafter, referred to as solution b).

Next, the above solution b was kept at 45 ° C. to crystallize D-PE, and then the liquid phase part was centrifuged. As a result, PE 57.8 g, D-
396.1 g of a solution containing PE 6.5 g, T-PE 0.2 g, MCF 4.3 g, PE phosphoric acid ester 1.8 g, other by-products 17.0 g, and water 305.5 g was obtained (hereinafter referred to as solution c). Referred to).

(Hydrolysis reaction) A hydrolysis reaction was carried out using the above solution c.

Into a reactor made of stainless steel having an internal volume of 1 liter, a thermometer, a pressure gauge, a heating and stirring device, and a water inlet and a steam outlet, 392.6 g of the above solution c and 7
Charged 0g. After replacing the inside of the reactor with nitrogen, the temperature was raised,
180 minutes after reaching 200 ° C, the decomposition reaction was carried out while extracting steam from the steam outlet. When the extracted steam was condensed, 298 g of water was recovered. During this time, the pressure was 15 kg / cm ² .

After the completion of the reaction, liquid analysis was carried out.
It contained 4.9g, D-PE 6.9g, T-PE 0.4g, MCF 3.2g, PE phosphoric acid ester 0.5g, and other by-product 4.5g. From this, the MCF conversion rate in the decomposition reaction was 26.3%, MCF
The standard PE selectivity was 736.6%. In addition, the results of the synthetic reaction from PE including the recovered PE to the D-PE were 10.4% conversion and D-PE.
PE selectivity was 67.2% and T-PE selectivity was 12.8%.

Example 2 (Synthesis of raw material liquid for hydrolysis) PE 326.2 g, D-PE 11.3 g, T-PE 0.1 g, and B were used as raw materials in the reactor used in Example 1.
PEMF 12.3g, other by-products 0.4g, water 88.6g and 85
% Phosphoric acid 2.2 g was charged. After replacing the inside of the reactor with nitrogen, the temperature was raised to 220 ° C. and then the reaction was performed for 140 minutes.

PE 308.2 g, D-PE 28.4 g, T-
There were 2.9 g of PE, 5.4 g of MCF, 0.9 g of phosphoric acid esters of PE, and 4.1 g of other by-products. From this, the results of this reaction are PE conversion 8.8%, D-PE selectivity 61.6%, T-
The PE selectivity was 10.4% (hereinafter referred to as reaction solution a ').

Next, 263 g of water was fed into the reactor for 30 minutes by using a pump, the liquid temperature was adjusted to 60 ° C. to crystallize a part of unreacted PE, and the liquid phase portion was passed through a filter at the bottom. As a result of extraction, PE 93.0g, D-PE 25.9g, T-PE 1.5g,
410 g of a solution containing 4.9 g of MCF, 0.9 g of PE phosphates and 1.7 g of other by-products was obtained. (Hereinafter, this is referred to as solution b ').

Next, the solution b ′ was kept at 45 ° C. to crystallize D-PE, and then the liquid phase part was centrifuged to obtain PE 48.1 g, D-
PE 5.0g, T-PE 0g, MCF 4.9g, PE phosphates
340.7 g of a liquid containing 0.9 g, 2.1 g of other by-products, and 276.1 g of water was obtained. (Hereinafter, this is referred to as solution c ').

(Hydrolysis reaction) The decomposition reaction reactor used in Example 1 was charged with 3.3 g of this solution c'33, and after nitrogen substitution, the temperature was raised and 848 g of water was pumped in 180 minutes after reaching 200 ° C. Was used for the decomposition reaction, and at the same time, the decomposition reaction was carried out while extracting steam equivalent to the amount of water sent from the steam extraction port. During this time, the pressure was 15 kg / cm ² .

After completion of the reaction, liquid analysis was carried out to find PE 5
It contained 2.7g, D-PE 5.1g, T-PE 0.01, MCF 2.32g, PE phosphoric acid ester 0.1g and other by-products 1.85g. From this, the MCF conversion rate in the decomposition reaction was 51.7%, and the MCF
The standard PE selectivity was 244.0%. In addition, the results of the synthetic reaction from PE including the recovered PE were 7.5% conversion and D-PE.
The selectivity was 73.4% for T-PE and 12.2% for T-PE.

Example 3 (Synthesis of raw material liquid for hydrolysis) PE 329.5 g, D-PE 5.5 g, T-PE 0.1 g and B were used as raw materials in the reactor used in Example 1.
14.7 g of PEMF, 19.3 g of water and 6.3 g of 85% phosphoric acid were charged. After purging the inside of the reactor with nitrogen, the temperature was raised to 200 ° C. and then the reaction was carried out for 140 minutes.

PE 276.9 g, D-PE 35.1 g, T-
There were 5.9 g PE, 5.5 g MCF, 8.5 g PE phosphates, and 11.0 g other by-products. From this, the net result of this reaction is PE conversion of 19.4% and D-PE selectivity of 47.
The selectivity was 6% and T-PE was 9.5% (hereinafter referred to as reaction solution a ").

Reaction liquid a "(PE 270.8 g, D-PE 34.3 g, T-
PE 6.1 g, MCF 5.4 g, PE phosphoric acid ester 8.3 g, and other by-products 10.7 g) are added to water to make 518.8 g, 45
After crystallizing D-PE kept at ℃, the result of centrifugation of the liquid phase part, PE 86.0g, D-PE 10.5g, T-PE 0.6g, MCF 5.6g,
628.8 g of a solution containing 6.9 g of PE phosphoric acid esters and 517.9 of water was obtained. (Hereinafter, this is referred to as solution b ″).

(Hydrolysis reaction) Using 625.4 g of this solution b ", the inside of the reactor was replaced with nitrogen in the same manner as in Example 2, and then 1740 g of water was pumped in 180 minutes after the temperature was raised to 200 ° C. Then, the decomposition reaction was carried out while simultaneously extracting steam equivalent to the amount of water sent from the steam outlet, while the pressure was 15 kg / cm ² .

After completion of the reaction, liquid analysis was carried out.
It contained 4.8 g, D-PE 11.1 g, T-PE 0.6, MCF 1.7 g, PE phosphoric acid esters 0.3 g, and other by-products 5.2 g.
From this, the MCF conversion rate in the decomposition reaction is 68.%, which is based on the MCF standard.
PE selectivity was 264.3%. PE including collected PE
Thus, the results of the synthetic reaction of D-PE were: conversion 16.5%, D-PE selectivity 57.4%, T-PE selectivity 11.%.

[0037]

EFFECTS OF THE INVENTION According to the method of the present invention, when a reaction solution containing by-products such as formals is hydrolyzed, MCF and other by-products are also decomposed and can be recovered as PE, thereby improving the PE basic unit. In addition, even if the reaction solution after decomposition is recycled to the reaction system and the reaction is repeated, the amount of by-products accumulated is reduced, and the crystallinity when PE and D-PE are obtained as crystals from this reaction solution is also reduced. It does not deteriorate and becomes extremely advantageous industrially.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshihiko Kambara 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Kagaku Co., Ltd. (72) Eiji Koga 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Kagaku Co., Ltd.

Claims (1)

[Claims] 1. A reaction solution A in which pentaerythritol is subjected to a condensation reaction in a liquid phase in the presence of an acid catalyst to synthesize dipentaerythritol, or pentaerythritol and part or all of dipentaerythritol are separated from the reaction solution A. A method for producing dipentaerythritol, which comprises hydrolyzing by-products such as formal compounds present in the solution B to be recovered and then recovering them as pentaerythritol.