JPS63162682A - Purification of glycidol - Google Patents

Abstract

PURPOSE:To improve the stability of the titled substance useful as intermediate raw material for various chemicals, by reacting allyl alcohol with hydrogen peroxide to obtain glycidol containing glycidoaldehyde as a by-produced impurity and treating the glycidoaldehyde in glycidol with a reducing agent. CONSTITUTION:Glycidol is produced by reacting allyl alcohol with hydrogen peroxide in the presence of preferably 3,000-7,000ppm of a catalyst (e.g. tungstic acid, etc.). In the above process, glycidoaldehyde existing in glycidol as a by- produced impurity is treated with preferably 500-1,000ppm of a reducing agent (e.g. sodium borohydride).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for purifying glycidol obtained by epoxidation reaction of allyl alcohol.

More specifically, the present invention relates to a method for purifying glycidol obtained by reacting allyl alcohol with hydrogen peroxide in the presence of a catalyst.

[Prior Art] Glycidol is an extremely reactive compound that simultaneously has an epoxy group and an alcoholic hydroxyl group in its molecule, and is a useful compound as an intermediate raw material for various chemical products.
．． It is called 3-epoxy-1-propatool.

Various methods are known for producing glycidol by epoxidation reaction of allyl alcohol.
In No. 55512, allyl alcohol is epoxidized with hydrogen peroxide using a tungsten compound as a catalyst at 110 to 220°C.

A method of fractionation into glycidol, water and high boiling point by-products using a thin film evaporator under conditions of 5-5 Q Torr.

Japanese Patent Publication No. 57-52341 discloses a method in which epoxidation is performed using a peracetic acid solution using a low-boiling solvent with a boiling point lower than that of acetic acid, and the bottom liquid formed into two layers is divided into a layer rich in glycidol and a layer containing less glycidol. , and furthermore, the special public official
No. 38273 discloses an alkyl vanadate catalyst used in a method of epoxidation with an organic hydroperoxide.

When producing glycidol using an epoxidizing agent by these various methods, the purification method for glycidol differs depending on the type of epoxidizing agent.When allyl alcohol is epoxidized with hydrogen peroxide, the reaction mixture produced contains In addition to glycidol, excess allyl alcohol, water,
This includes the catalyst and by-product glycidaldehyde.

Removal of glycidol from the reaction mixture has conventionally been carried out as follows.

That is, excess allyl alcohol was recovered in the form of an aqueous solution using a black surface under reduced pressure of about 130 Torr.

Furthermore, high boiling substances such as the catalyst are separated from the mixture containing water, glycidol, catalyst, etc., and glycidol (product name) is further separated and purified from the mixture whose main components are water and glycidol using a thin film evaporator etc. .

Most of the glycidaldehyde produced at this time is distilled out from the top of the product column along with water, but a portion is entrained in the product glycidol as an impurity.

[Problems to be Solved by the Invention] When a derivative is produced using glycidol containing glycidaldehyde, not only does the appearance of the derivative deteriorate due to polymerization of glycidaldehyde, which is an impurity.
The problem is that glycidaldehyde, which is an impurity, adversely affects the stability of glycidol.

In order to solve the above-mentioned problems, the inventors of the present invention have completed two inventions as a result of intensive studies on methods for purifying glycidol.

C Structure of the Invention] That is, 2 the present invention is ``a method for producing glycidol by reacting allyl alcohol and hydrogen peroxide in the presence of a catalyst, in which glycidaldehyde, a by-product impurity in glycidol, is treated with a reducing agent. A method for purifying glycidol characterized by the following.

Glycidol of improved quality is obtained by the purification method of the present invention.

The purification method of the present invention will be explained in detail below.

First, the synthesis reaction of glycidol is carried out as follows.

The reaction is carried out in dilute aqueous medium at pH 3~8 and 30~
It is carried out in the presence of excess allyl alcohol at a temperature of 70°C.

When the pH is less than 3, glycidol reacts with water and becomes glycerin, reducing the yield; on the other hand, when the Pll is 8 or more,
(This is not preferable because 202 decomposes.

If the temperature is less than 30°C, the reaction rate will be low.

Yield will be low.

On the other hand, when the two temperatures are 60°C or higher, the reaction rate increases, but
+(,02 decomposition increases, so this is not preferable.

The appropriate molar amount of allyl alcohol to be added is 1 to 4 times the molar amount.

The reason why the reaction is carried out with an excess of allyl alcohol is that the produced glycidol is further oxidized and decomposed, and on the other hand, if it is too much, more alcohol will be recovered.

This is because collection costs will increase.

The specific method for adjusting the pH to 3 to 8 is to add H at the time of catalyst preparation.
Add NaOH to 2WO4 to make Na2WO4 or Na
This is carried out by adding 2WO4 as a catalyst during the reaction.

The appropriate m of the catalyst to be added is 3000 to O11t)m, and if it is less than 3000 ppm, the reaction rate will be slow;
If the amount exceeds 7,000 ppm, the reaction rate will not become faster, but the amount used will increase, and tungstic acid is especially expensive, so it is not economical.

At this time, the reaction proceeds as follows.

CH=CH-CH20H+H202 (allyl alcohol) (hydrogen peroxide) (glycidol) H (acrolein) The above reaction is carried out for 5 to 7 hours in the case of a batch system, and for 8 to 10 hours in the case of a continuous system.

The entire amount of glycidaldehyde produced as a by-product in the above reaction is introduced into the product column together with the product glycidol.

Most of it is distilled out from the top of the tower along with water, but some of it gets mixed into the product glycidol.

As mentioned above, polymerization of this by-product glycidaldehyde not only deteriorates the appearance of the derivative, but also has the problem of adversely affecting the stability of glycidol due to the glycidaldehyde impurity. are doing.

If this by-produced glycidaldehyde is attempted to be completely removed, the amount of glycidol lost from the top of the column will increase, the yield of glycidol will decrease, and this will be economically disadvantageous.

By treating the glycidaldehyde mixed in the product glycidol with a reducing agent, it is possible to obtain glycidol of excellent quality without impairing the yield.

As the reducing agent, sodium borohydride NaBH, aluminum borohydride AJI [3)-14, etc. can be used.

A specific treatment method is to pass the glycidol product through a tower filled with tablets of a reducing agent, or to add powder of the reducing agent to the glycidol product.

In the method of the present invention, when sodium borohydride Na8H4 is used as the reducing agent, the reaction proceeds according to the following reaction formula.

(Glycidaldehyde) The concentration of glycidaldehyde produced as a by-product in glycidol is 700ppIm~1l100pp, so in the case of the addition method, the amount of reducing agent added is 500~1000ppm+
is preferred.

This is because if the amount of reducing agent added is less than 50 pp-, the effect of removing glycidaldehyde will be low, and conversely, adding more than 1000 pp- will be wasteful.

Sodium borohydride and aluminum borohydride are preferable because they can be reduced at room temperature and pressure, and selectively reduce aldehydes.

The hydrogen peroxide used for epoxidation is preferably 30 to 60% C degree.

If the hydrogen peroxide concentration is lower than 30%, the reaction rate of the epoxidation reaction will be slow, whereas if it is higher than 60%, a large amount of high boiling point products will be produced, which is not preferable.

After the hydrogen peroxide has completely reacted, the excess alcohol is recovered in the form of an aqueous solution using a black surface, and the mixture containing water, glycidol, the high-boiling products produced by the reaction of glycidol, and the catalyst is transferred to a thin film evaporator. Alternatively, the catalyst is separated by filtration using another evaporator with a suitable structure for a short residence time, and then the evaporated liquid containing water and glycidol is fractionated again under reduced pressure to obtain high-purity glycidol. obtain.

In the product column, water is obtained from the top of the column, and glycidol is obtained in the gas phase from the bottom of the column.

Next, the present invention will be explained in detail by way of examples.

[Reference example 1 Using acid salt of tungstic acid as catalyst.

Allyl alcohol is epoxidized with hydrogen peroxide, unreacted allyl alcohol is recovered from the black surface, and the catalyst is separated using a thin film evaporator.

Distilled glycidol and water are blackfaced with the product name.

Water is distilled off from the top of the tower, and glycidol is obtained in the gas phase from the bottom of the tower.

[Example 11 From the product name, the glycidaldehyde content in the product obtained by adding 1000 pu of sodium borohydride to the distilled glycidol was not detected by gas chromatography analysis, and the glycidol obtained in this way was not detected. The appearance of glycerin monoacrylate synthesized from acrylic acid was 100 in terms of APHA value.

[Example 21 From the product name, the glycidaldehyde content in the product obtained by adding 500 pu of sodium borohydride to the distilled glycidol was 0 as a result of gas chromatography analysis.
．． The appearance of the glycerin monoacrylate synthesized from glycidol and acrylic acid thus obtained was 150 in terms of A P 11 A value.

[Actual MVA-3] 1000 parts of glycidol distilled from the product name was treated in a column filled with 1 part of sodium borohydride tablets.

The glycidaldehyde content in ffi[a was determined to be 0.01% by gas chromatography analysis.

The appearance of glycerin monoacrylate synthesized from glycidol and acrylic acid obtained in this way is that of API.
The IA value was 130 [Comparative Example-11 From the product name, glycerin synthesized from acrylic acid using glycidol containing 0.01% glycidol dezide, which was not treated with a reducing agent as distilled. The appearance of the monoacrylate was 800 in terms of APHA value.

[Comparative Example-2] According to the product name, the glycidaldehyde content m in the product was 0.08%, which was obtained by adding 100 ppI of sodium phosphorus hydride to the distilled glycidol.

Glycerin monoacrylate synthesized from this material and acrylic acid had an appearance of 700 in terms of APHA value.

Claims (1)

[Claims] A method for purifying glycidol, which comprises treating glycidaldehyde, a by-product impurity in glycidol, with a reducing agent, in a method for producing glycidol by reacting allyl alcohol and hydrogen peroxide in the presence of a catalyst.