JPH07157450A - Production of dipentaerythritol - Google Patents

Abstract

PURPOSE:To provide a new method for producing dipentaerythritol in which the dipentaerythritol can efficiently and economically be produced from raw materials industrially and readily available at a low cost. CONSTITUTION:This method for producing dipentaerythritol is to react pentaerythritol with carbonic acid esters in the absence or presence of an alkaline catalyst.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for producing dipentaerythritol. Dipentaerythritol is useful as a raw material for polyester, polyether, polyurethane, alkyd resin, lubricating oil and the like.

[0002]

BACKGROUND OF THE INVENTION Dipentaerythritol is a by-product in the synthetic reaction of pentaerythritol, that is, in the reaction of formaldehyde with acetaldehyde in the presence of alkali to produce pentaerythritol.
A general industrial production method is obtained by separating and purifying this (JP-A-57-139028). Further, as a method for improving the yield of dipentaerythritol and the quality of pentaerythritol which is a main product, formaldehyde, alkali and a part of acetaldehyde are charged in advance, and formaldehyde, alkali and acetaldehyde are added to each theoretical molar ratio. A method has also been proposed in which the above is maintained and the reaction temperature is kept at 50 ° C. or lower and the reaction is carried out by dropping simultaneously (Japanese Patent Publication No. 1-44689).

On the other hand, a method of synthesizing a polypentaerythritol mixture from pentaerythritol using phosphoric acid, sulfuric acid, etc. is also known, but a means for selectively synthesizing dipentaerythritol has not been described (USP-246204).
7).

[0004]

However, the above-mentioned method for producing dipentaerythritol by the reaction of acetaldehyde and formaldehyde still has the following problems. (1) Pentaerythritol and dipentaerythritol must be separated and recovered from impurities such as by-produced sodium formate, bispentaerythritol monoformal, excess formaldehyde or acetaldehyde-formaldehyde self-condensate, and the purification process is complicated. Becomes (2) The production amount of dipentaerythritol depends on the production amount of pentaerythritol.
The limit is 10 to 15%, which cannot meet the recent increase in demand.

On the other hand, the method of dehydration condensation of pentaerythritol using an acid catalyst can obtain dipentaerythritol according to the knowledge of the present inventors, but the produced dipentaerythritol is tripentacyclic. Erythritol is converted to high-molecular-weight polypentaerythritol, or an intramolecular condensate is produced, so that it is difficult to put it to practical use as it is. Therefore, an object of the present invention is to propose a novel method for producing dipentaerythritol, which solves the problems of the prior art.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems. As a result, they have found that dipentaerythritol is efficiently produced when a carbonic acid ester is reacted with pentaerythritol in the absence of a catalyst or in the presence of an alkali catalyst, and the present invention has been completed. So far, no method for producing dipentaerythritol from carbonic acid esters and pentaerythritol has been reported, and the present invention is a novel method for producing dipentaerythritol. Although the reaction mechanism in the method of the present invention is not clear, the presence of 3,3-bis (hydroxymethyl) oxetane in the reaction solution is recognized, and therefore it can be presumed that oxetane is passed through as a reaction intermediate.
Hereinafter, the present invention will be described in more detail.

The pentaerythritol used as a raw material in the method of the present invention can be industrially produced by reacting formaldehyde and acetaldehyde in the presence of an alkali, and can be used as a raw material without further purification. . Further, examples of the carbonates as the other raw material include dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, dibenzyl carbonate, diphenyl carbonate, ethylene carbonate and the like.

The amount of carbonic acid ester and pentaerythritol used in the method of the present invention is not particularly limited, but 0.1 to 20 mol, preferably 0.5 to 10 mol of pentaerythritol is used per 1 mol of carbonic acid ester. . If it is less than this range, the amount of dipentaerythritol produced is small and the amount of polypentaerythritol produced as a by-product increases, and if it is large, the amount of unreacted pentaerythritol recovered increases, which is economically disadvantageous.

In the method of the present invention, the reaction proceeds without using a catalyst when the carbonic acid ester and pentaerythritol are reacted, but the reaction proceeds more efficiently when the reaction is carried out in the presence of an alkali catalyst. Examples of the alkali catalyst used include alkali metal hydroxides, alkaline earth metal hydroxides, alkoxides, carbonates, and carboxylates. For example, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, lithium methoxide, lithium ethoxide, lithium isopropoxide, sodium methoxide, sodium ethoxide, sodium isopropoxide, lithium carbonate. , Sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, lithium acetate, sodium acetate, potassium acetate, magnesium acetate, calcium acetate, lithium propionate, sodium oxalate, potassium laurate, magnesium formate and the like. Of these alkali catalysts, alkali metal hydroxides, alkaline earth metal hydroxides, and alkoxides are preferable.

In the present invention, the carbonate ester and pentaerythritol can be reacted in a molten state without using a solvent, but a solvent may be used if necessary. Examples of preferred solvents include benzene, xylene, decalin, hydrocarbons such as tetralin, dioxane, tetrahydrofuran, ethyl ether, anisole, phenyl ether, diglyme, tetraglyme, ethers such as 18-crown-6, methyl acetate, Esters such as ethyl butyrate, methyl benzoate, γ-butyrolactone, ketones such as acetone, acetophenone, benzophenone, N-methylpyrrolidin-2-one, N, N-dimethylacetamide, N-methylpiperidone, hexamethylphosphoric triton N-substituted amides such as amides, tertiary amines such as N, N-diethylaniline, N-methylmorpholine, pyridine and quinoline, sulfones such as sulfolane, sulfoxides such as dimethyl sulfoxide, 1,3- Urea derivatives such as dimethyl-2-imidazolidinone, trib Silicone oil, water, etc. can be exemplified in addition to the phosphine oxide such as Le phosphine oxide.

Of these solvents, hydrocarbons, N-substituted amides, sulfones, urea derivatives, water and the like are preferable.
These solvents can be used alone or as a mixed solvent. When used as a mixed solvent, the other solvent is preferably an alcohol forming an ester with carbonic acid. For example, methanol is used when using dimethyl carbonate and ethanol is used when using diethyl carbonate.

In the method of the present invention, carbonic acid esters and pentaerythritol undergo transesterification to first produce carbonic acid ester of pentaerythritol. In this step, the reaction is carried out while refluxing the carbonic acid ester. The reaction temperature is usually 50 to 200 ° C. Then, the alcohol liberated from the carbonic acid ester is distilled off, and the reaction temperature is further raised to carry out the reaction. The reaction temperature in this step is 100 to 250 ° C, preferably 120 to 220 ° C. If the reaction temperature is less than 100 ° C, the reaction rate is extremely slow, and if it exceeds 250 ° C, by-products of impurities increase.

The reaction pressure may be a pressure that can maintain a predetermined reaction temperature. Normally 1 to 50 kg / cm ² (gauge pressure)
Is. If necessary, the reaction pressure may be increased with an inert gas such as argon, helium or nitrogen. The reaction time varies depending on the reaction temperature, the type of catalyst, etc., but is usually 0.05 to 10
It is used for 0 hours, preferably 0.1 to 80 hours.

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, carbonic acid esters, pentaerythritol, a solvent and a catalyst are charged into a reactor, and the reaction proceeds while heating. In the case of the continuous method, the reaction is carried out by continuously supplying the carbonic acid ester, pentaerythritol, the solvent and the catalyst to one of the reactors and continuously withdrawing the reaction mixture from the other.

[0015]

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

Example 1 Internal volume of 500 m equipped with a thermometer, condenser and stirring device
136 g of pentaerythritol (1.
0mol), diethyl carbonate 59g (0.5mol), ethanol 15.6g as solvent and 85% potassium hydroxide 0.66g as catalyst
(0.01 mol) was charged, the reactor was heated in an oil bath and refluxed at a reaction temperature of 85 to 100 ° C. for 4 hours. Then, the condenser was removed, a distillation apparatus equipped with a rectification column was attached to the reactor, and ethanol was distilled off at 85 to 150 ° C for 2 hours. Next, the distillation apparatus was removed, the temperature was raised to 190 ° C in 1 hour, and then the reaction was continued at 190 ° C for 5 hours.

After the reaction, the reaction solution was analyzed by gas chromatography. As a result, the yield of dipentaerythritol was 20.0% with respect to the pentaerythritol used as the starting material.
Tripentaerythritol was produced at a yield of 10.8%,
In addition, 3,3-bis (hydroxymethyl) oxetane was produced in a yield of 1.5%.

Example 2 In Example 1, the amount of potassium hydroxide used was 0.33 g (0.0
The reaction was carried out in the same manner as in Example 1 except that the distillation apparatus was removed, the temperature was raised to 190 ° C. in 1 hour, and the reaction was terminated. After the reaction, the reaction solution was analyzed by gas chromatography to find that the yield of dipentaerythritol was 13.13 based on pentaerythritol used as a raw material.
2%, tripentaerythritol yield 5.4%, and 3,3-bis (hydroxymethyl) oxetane yield
It was generating 9.0%.

Example 3 In Example 2, the distillation apparatus was removed and 190 ° C. was added for 1 hour.
The reaction was performed in the same manner as in Example 2 except that the temperature was raised to 190 ° C and the reaction was continued at 190 ° C for 3.5 hours.

After the reaction, the reaction solution was analyzed by gas chromatography. As a result, the yield of dipentaerythritol was 20.2% with respect to pentaerythritol used as a raw material.
The yield of tripentaerythritol was 11.1%, and the yield of 3,3-bis (hydroxymethyl) oxetane was 3.2%.
Was being generated.

Example 4 In Example 1, the amount of potassium hydroxide used was 0.40 g (0.0
06mol), using 66g of tetralin as a solvent,
The reaction was performed in the same manner as in Example 1 except that the reaction was continued at 190 ° C for 3 hours. After the reaction, the reaction solution was analyzed by gas chromatography to find that the yield of dipentaerythritol was 21.5% and the yield of tripentaerythritol was 11.8% with respect to pentaerythritol used as a raw material. Bis (hydroxymethyl) oxetane was produced in a yield of 3.3%.

[0022]

Industrial Applicability According to the method of the present invention, dipentaerythritol can be produced efficiently and industrially and economically from carbonic acid esters and pentaerythritol which are industrially available at a low cost, and therefore, it is industrially advantageous. It is a big advantage.

Claims (2)

[Claims] 1. A method for producing dipentaerythritol, which comprises reacting pentaerythritol with carbonic acid esters. 2. The method for producing dipentaerythritol according to claim 1, wherein the reaction is carried out in the presence of an alkali catalyst.