JPS62153248A - Purification of ethyl acetate - Google Patents

Abstract

PURPOSE:To obtain the titled high-purity compound useful for applications, e.g. urethane resin, silver salt photographic films, etc., by bringing ethyl acetate containing a very small amount of diethyl acetal into contact with a specific strong acidic cation ion exchange resin in the presence of a given amount of water and distilling the resultant product. CONSTITUTION:Ethyl acetate containing a very small amount of diethyl acetal (ethyl acetate of >=99.0 purity produced for industrial use is used. When the amount of the diethyl acetal contained as an impurity is >=500ppm, the ethyl acetate is distilled to reduce the amount to <=500ppm) is brought into contact with a strong acidic cation exchange resin having 2-30%, preferably 5-15%, based on the exchange groups, H type groups in the presence of water in a molar amount of 2-10 times based on the diethyl acetal. The resultant product is then distilled to purify the aimed compound. An apparatus in which the exchange resin is filled in a fixed bed and liquid is continuously passed therethrough is practical for industrial use as an apparatus filled with the exchange resin.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for purifying ethyl acetate. Ethyl acetate purified to a high degree of purity is particularly used for applications such as urethane resins, reagents, and silver salt photographic films.

Conventional technology Conventionally, as an industrial method for producing ethyl acetate, crude ethyl acetate is produced by performing a Tiscienko reaction using acetaldehyde as a raw material using a catalyst mainly composed of aluminum alcoholade, and then unreacted acetaldehyde, by-product ethanol, and diethyl acetal are produced. It is generally manufactured by removing such as
3 pages, first published in 1963 (Kagaku Kogyosha). The impurities that still remain in ethyl acetate after normal distillation include very small amounts of acetaldehyde, ethyl vinyl ether, ethanol, diethylacetanopecrotonaldehyde, and others, and may be used in small amounts depending on the purpose of urethane resin, reagents, silver salt photographic film, etc. Impurities such as unsaturated compounds, aldehydes, acetals, and alcohols may also cause problems.・As a method for removing trace amounts of impurities in ethyl acetate, ethyl acetate containing trace amounts of impurities is brought into contact with acid clay, activated clay, bentonite, silica alumina, or zeolite, and then subjected to low-boiling separation distillation. There is a known method for purifying the
Publication No. 436).

Problems to be Solved by the Invention In the conventional methods, the removal of diethyl acetal contained as an impurity in ethyl acetate is not yet satisfactory.

Means for Solving the Problems According to the method of the present invention, ethyl acetate containing a trace amount of diethyl acetal is added to the exchange group of a strongly acidic cation exchange resin in the presence of water in an amount 2 to 10 times the molar amount of diethyl acetal. By bringing it into contact with a strongly acidic cation exchange resin in which 2 to 30% of the product is in the H type, and then distilling it, it is possible to obtain highly pure (99.99% or more) ethyl acetate that contains almost no diethyl acetal. .

Ethyl acetate, which is a raw material for the method of the present invention, is manufactured for industrial use and has a purity of 99.0% or more. and 50
It is desirable to keep it below 0 ppm.

Strongly acidic cation exchange resins include Na type resins such as commercially available Amberlis 15 (MR type; Rohm and
(manufactured by Haas Corporation), Diaion HPK-25 (high porous type; manufactured by Mitsubishi Kasei Corporation), Duolite C-26 (porous type; manufactured by Duolite International Company), etc., and preferably 2 to 30% of the Na type. The one in which 5 to 15% of the exchange groups are partially regenerated into the H type is used.

In the case of a strongly acidic cation exchange resin that is only in the Na type and has not been partially regenerated into the H type, the reaction will hardly proceed;
If 30% or more is partially regenerated, the hydrolysis of ethyl acetate will proceed, resulting in loss, which is not preferable. As the type of the ion exchange resin, gel, porous, high porous, etc. are used. Although the type of device for filling the ion exchange resin is not limited, it is industrially practical to use a device that fills the resin in a fixed bed and continuously passes the liquid through it. The tower passage condition is LH8■
(liquid flow rate L/H/catalyst filling amount L) is 1.0 to 3.0,
The temperature of the column liquid at that time is 10 to 50°C, preferably 20 to 35°C. If the temperature is low, the reaction will be slow, and
When the temperature exceeds 50°C, the hydrolysis of ethyl acetate cannot be ignored.

As for the distillation conditions, for example, two distillation columns are used, the number of plates in the first column is 20 to 40, the reflux ratio is 5 to 1O, and the proportion of low boiling point fraction is 5 to 10%; the number of plates in the second column is 20 to 40 reflux. Ratio 0.5~
1.5 and the proportion of high-boiling fractions is 5-15%.

Through such distillation, ethyl acetate with a purity of 99.99% or more can be obtained.

Examples and reference examples are shown below.

Example 1 Strongly acidic cation exchange resin AND-LIST 15 (MR type;
Rohm and Haas) partially regenerated into 10% SO, H type with hydrochloric acid and filled into a reactor (16 times), and 0.0% water was added at room temperature.
3 g / 8 drops of ethyl acetate (commercially available: general industrial use)
was passed through the reactor at a rate of 1800 g/H to obtain a liquid (this liquid is referred to as the reactor outlet liquid). This reactor outlet liquid is subjected to continuous distillation in two columns as it is, and in the first column, 170 g of low boiling point fraction is obtained at a reflux ratio of 10.
/H separation, and a product of 1400 g/H was obtained at a reflux ratio of 1.0 in the second column. Table 1 shows the results of various tests on the product.

The peroxide test was also passed even when the product was left in a brown glass bottle at room temperature for 15 days.

Table 1 EtOH; E-Nol AcTL
; Diethylacetal Cr)10; Crotonaldehyde HAc; Acetic acid ND
; Not detected TR: Trace, IPPM Below analysis method This test method is a partially revised version of JIS-8361.

(1) Peroxide sample 2 Qml → Transfer to a stoppered test tube → 2.5ml of potassium iodide solution + 2.5ml of water → Shake → Leave for 1 hour...
Does not yellow. (Passed) (2) Aldehyde sample IQml → Transfer to a stoppered test tube → Nessler solution IQm
l → Shake vigorously for 10 seconds → Leave for 1 minute...The aquarium will not become cloudy or discolored.

(Passed) (3) Sulfuric acid colored substance (according to the method of JP-A-57-81436) Sample 5+++l → Cool to below 10°C → Add 5 ml of sulfuric acid dropwise over 10 minutes while stirring without exceeding 30°C → Keep at 50°C ± 1°C for 1 hour in a hot water bath → Determine the hue after cooling (4) Among the analysis of each component, moisture is analyzed by the Karl Fischer method, acetic acid by neutralization titration, and others by gas chromatography.

(The units, abbreviations, and analytical methods are the same in the following tables.) Example 2 In Example 1, the ion exchange resin used was the strongly acidic cation exchange resin Diaion HP K-23 (high porous type: manufactured by Mitsubishi Chemical Corporation). A product was obtained in the same manner as in Example I, except that a product partially regenerated into 5% SO, H type was used. The analysis results of the product are shown in Table 2.

Table 2 Example 3 In Example 1, the ion exchange resin used was a strongly acidic cation exchange resin Duolite C-26 (porous type; manufactured by Duolite International) partially regenerated into 8% 5O3H type. A product was obtained in the same manner as in Example 1 except for this.

The analysis results of the product are shown in Table 3.

Table 3 Reference Example 1 Strongly acidic cation exchange resin Amberlyst 15 was added to 5o3N
As a result of filling the reactor as type A and performing liquid passage and distillation in the same manner as in Example 1, the product immediately after distillation passed the peroxide test, but the product after leaving it in a brown glass bottle at room temperature for 10 days did not pass the peroxide test. The oxide test failed. The results are shown in Table 4.

Table 4 Rejection after zero days Reference example 2 Strongly acidic cation exchange resin Amberlyst 15 was dissolved in hydrochloric acid.
As a result of filling the reactor with 00% SO, H type and passing the liquid in the same manner as in Example 1, the HAc of the reactor outlet liquid was 3600.
It was ppm.

Effects of the Invention By the method of the present invention, highly pure ethyl acetate containing almost no diethyl acetal can be obtained.

Claims (1)

[Claims] Ethyl acetate containing a trace amount of diethyl acetal is added to a strongly acidic cation exchange resin in which 2 to 30% of the exchange groups are H type in the presence of water in an amount 2 to 10 times the molar amount of diethyl acetal. A method for purifying ethyl acetate, which comprises bringing it into contact with an exchange resin and then distilling it.