JPH0742279B2 - Method for purifying γ-butyrolactone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a method for purifying γ-butyrolactone.

γ-Butyrolactone is used in various solvents and improvers because it has physical properties such as excellent solubility in various monomers and polymers and is easy to handle. Further, γ-butyrolactone has a high chemical reactivity and leads to γ-butyrolactone derivatives such as hydrolysis reaction products, oxidation reaction products and reduction reaction products in addition to reaction products with ammonia, amine and sulfur compounds, and is used as an extraction solvent. It is used as a raw material for pharmaceutical intermediates, agricultural chemical intermediates, and special plasticizers.

[Prior Art] Conventionally, γ-butyrolactone is industrially produced by a hydrogenation reaction of maleic anhydride or a partial hydride thereof, such as succinic anhydride and succinic acid. Is an intermediate product, succinic anhydride, succinic acid and reaction by-products, propionic acid, butyric acid,
Organic acids such as enanthate, alcohols such as propanol and butanol, and esters thereof are included.

However, depending on the application, high-purity γ-butyrolactone is required, and in particular, there are problems that the acid content in the impurities has a bad odor and affects the production of the γ-butyrolactone derivative. Conventionally, the purification of such γ-butyrolactone has been carried out by a treatment exclusively by distillation, but even if the distillation is carried out very precisely, a satisfactory purification effect cannot be obtained. Is difficult to remove.

For this reason, a method has been proposed in which crude γ-butyrolactone is treated with a mineral acid, and then an alkali such as an alkali metal hydroxide or carbonate is added thereto for neutralization, followed by distillation (Japanese Patent Publication No. No. 8662).

[Problems to be solved by the invention]

However, in the above method, γ-butyrolactone causes a side reaction with an alkali, and an alkali salt of γ-oxybutyric acid or 4,4′-oxynibutyric acid is produced,
There was a problem that the acid content in γ-butyrolactone was not substantially removed, and the recovery rate was lowered due to the loss of γ-butyrolactone. That is, an object of the present invention is to industrially advantageously remove the acid component in γ-butyrolactone to obtain high-purity γ-butyrolactone.

[Means for solving problems]

As a result of diligent studies by the present inventors to achieve such an object, when the crude γ-butyrolactone is treated with a hydroxide or oxide of an alkaline earth metal and then distilled, the side reaction of γ-butyrolactone is suppressed. , Significantly less acid content γ
The present invention has been completed by finding that butyrolactone can be obtained.

That is, the gist of the present invention is that the low boiling point substance was previously removed γ
-Adding at least one compound selected from alkaline earth metal oxides or hydroxides to butyrolactone,
A method for purifying γ-butyrolactone is characterized in that it is heat-treated and then distilled.

Hereinafter, the present invention will be described in more detail.

The γ-butyrolactone applicable to the present invention is a gas phase or liquid phase catalytic hydrogenation method of maleic anhydride or a partial hydride thereof, a cyclization dehydrogenation method of 1,4-butanediol, γ-hydroxybutyraldehyde, γ-butyrolactone. It is produced by various methods such as cyclization of hydroxybutyric acid, and in particular γ-butyrolactone having a relatively high boiling point acid content obtained by a catalytic hydrogenation reaction of maleic anhydride or a partial hydride thereof is obtained. It is suitable to apply. Examples of the partially hydrogenated maleic anhydride include succinic anhydride and succinic acid, and these raw materials may be used alone or as a mixture. As the catalyst used in the hydrogenation reaction, any catalyst having a desired hydrogenation activity can be used, and nickel catalysts, cobalt catalysts, palladium catalysts, copper catalysts and the like improved with various promoters are known. There is. Hydrogenation reaction is 1 to 150 kg / cm ²
The reaction pressure is 100 ° C. to 350 ° C. and the reaction temperature is 100 to 350 ° C. In the reaction product obtained by the reaction, in addition to γ-butyrolactone, tetrahydrofuran, succinic anhydride and succinic acid intermediate products and alcohols such as propanol and butanol as reaction by-products, propionic acid, butyric acid, It contains organic acids such as enanthate and esters thereof, high-boiling substances, produced water and the like. In the present invention, it is necessary to previously remove a substance having a lower boiling point than γ-butyrolactone from such crude γ-butyrolactone. As a general distillation treatment method, a two-column type distillation column is used, the first column is distilled under normal pressure or under pressure to distill off a substance having a lower boiling point than γ-butyrolactone, and then the second column is vacuum distilled. To obtain the product γ-butyrolactone by distilling, or using a one-column distillation column to distill the low boiling point product and at the same time obtain the product γ-butyrolactone in the side cut and separate the high boiling point product. Etc. are adopted. By such a general method, 99% or more, and further 99.5% or more of highly pure γ-butyrolactone can be obtained. However, even such high-purity γ-butyrolactone generally contains an acid content of 500 ppm or more.

That is, in the method of the present invention, by adding an oxide or hydroxide of an alkaline earth metal to γ-butyrolactone obtained by the above-mentioned purification method, heat-treating it at a temperature of 120 ° C. or higher, and then distilling it. The acid content in γ-butyrolactone can be 500 ppm or less, and if the conditions are selected, it can be 100 ppm or less.

As the alkaline earth metal oxide or hydroxide used in the method of the present invention, magnesium, calcium,
Examples thereof include oxides or hydroxides of alkaline earth metals such as barium and strontium, and specifically, magnesium oxide, calcium oxide, barium oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide and the like are preferable. These compounds may be used either alone or as a mixture thereof. The addition amount of the oxide or hydroxide of the alkaline earth metal may be very small, and for example, it is usually 1 with respect to 1 equivalent of the acid content (value converted as succinic acid) contained in γ-butyrolactone. A range of 1 equivalent or more, preferably 1 to 20 equivalents is suitable. As a method of adding the additive, the powder of the additive may be added directly to the treatment kettle, but it is preferable to continuously supply the additive in a slurry state in which the additive is suspended in γ-butyrolactone to the treatment kettle. desirable.

In the present invention, after the above additives are added to γ-butyrolactone, heat treatment is performed at a temperature of 100 to 250 ° C., preferably 120 to 250 ° C. for a residence time of several minutes or longer, preferably 10 minutes to 3 hours, and then distilled. To obtain the product γ-butyrolactone. Distillation can be carried out under reduced pressure or atmospheric pressure by batch or continuous distillation. When the above heat treatment is carried out in a distillation column, γ-butyrolactone and the above additives may be supplied to a kettle and distillation may be carried out while heat treating at a treatment temperature of 120 ° C to 250 ° C. The additive added to the above kettle is γ-
It reacts with the organic acid in butyrolactone to form an organic acid salt, which becomes a liquid state and stays at the bottom of the pot. Therefore, γ−
When butyrolactone and the above additive are continuously supplied, the additive salt produced by continuously reacting with the organic acid in γ-butyrolactone can be withdrawn from the bottom.
However, if the treatment temperature is 120 ° C. or lower, the viscosity of the produced salt becomes so high that the salt cannot be extracted.

〔Example〕

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 A reaction product containing γ-butyrolactone obtained by the catalytic hydrogenation reaction of maleic anhydride was subjected to a light boiling separation column (the actual number of stages).
Low-boiling substances are distilled off from the top of the column under 20 stages and the column bottom temperature is 212 ° C and the column bottom pressure is 765 mmHg. On the other hand, the column bottom extraction liquid is a high boiling separation column (20 actual stages, column top pressure is 252 mmHg, column). Top temperature 169.5 ℃
Γ-butyrolactone was extracted from the top of the column under the conditions (1). The obtained γ-butyrolactone had a purity of 99.15% and an acid content of 8
The content was 10 ppm and the water content was 6500 ppm.

A 500 ml three-necked flask equipped with a simple distillation apparatus was charged with 200 parts by weight of γ-butyrolactone described above, and 0.36 parts by weight of calcium oxide powder was added thereto (this is the acid content in γ-butyrolactone (converted to succinic anhydride). (Corresponding to 4 times equivalent to the value) that was heated) with stirring. The dispersed calcium oxide became liquid in the boiling state and remained at the bottom of the flask. After heat treatment at a boiling point of 206 ° C. for 5 minutes, γ-butyrolactone was removed by simple distillation. The acid content of the distillate was 78 ppm for the fraction with a distillation rate of 15%, and 31 ppm for the subsequent distillates (distillates with a distillation rate of 15% to 80%).

Example 2 Purification was carried out by the same method as in Example 1 except that calcium hydroxide was used instead of calcium oxide as the additive. The acid content in the distillate components is 15%
Distillate up to 72ppm, distillate from 15% to 80% distillate is 28ppm
It was.

Comparative Example 200 parts by weight of γ-butyrolactone used in Example 1 was charged, and 0.26 parts by weight of sodium hydroxide was added thereto (4 times equivalent to the acid content in γ-butyrolactone (value converted to succinic anhydride)). (Corresponding) was added and the temperature was raised with stirring. The liquid in the kettle was colored orange in the boiling state. The acid content in the distillate component was 760 ppm for the fraction with a distillation rate of 15% and 680 ppm for the fraction with a distillation rate of 15% to 75%, and the liquid in the kettle after cooling was gelled.

〔The invention's effect〕

According to the present invention, the acid component in γ-butyrolactone can be industrially advantageously removed to obtain high-purity γ-butyrolactone.

Claims (3)

[Claims] 1. A .gamma.-characterized in that at least one compound selected from oxides or hydroxides of alkaline earth metals is added to .gamma.-butyrolactone from which low-boiling substances have been removed in advance, heat treated and then distilled. Butyrolactone distillation purification method 2. A high boiling point substance is also removed from .gamma.-butyrolactone before adding an oxide or hydroxide of an alkaline earth metal. Butyrolactone distillation purification method 3. A .gamma.-butyrolactone obtained by separating and removing a low-boiling substance and a high-boiling substance by subjecting a reaction product produced by catalytic hydrogenation of maleic anhydride or its partial hydride to a low-boiling substance and a high-boiling substance. -Butyrolactone-distillation purification method of γ-butyrolactone according to claim 1, characterized in that