JPH0511098B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method 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 Teitsienko reaction using acetaldehyde as a raw material using a catalyst mainly composed of aluminum alcoholate, and then unreacted acetaldehyde, secondary ethanol, diethyl acetal, etc. It is generally manufactured by removing it by distillation.
First edition in 1943 (Kagaku Kogyosha). Impurities that still remain in ethyl acetate after normal distillation include very small amounts of acetaldehyde, ethyl vinyl ether, ethitanol, diethyl acetal, crotonaldehyde, and others. Even small amounts of impurities such as unsaturated compounds, aldehydes, acetals, and alcohols can 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 ethyl acetate is removed by low-boiling separation distillation. A purification method is known (Japanese Unexamined Patent Publication No. 81436/1983). 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 groups of an acetic acid cation exchange resin in the presence of water in an amount of 2 to 10 times the molar amount of diethyl acetal. High purity (99.99% or more) ethyl acetate containing almost no diethyl acetal can be obtained 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. Ethyl acetate, which is a raw material for the method of the present invention, is as follows:
A product manufactured for industrial use with a purity of 99.0% or more is used, but if the amount of diethyl acetal contained as an impurity is 500 ppm or more, it is desirable to reduce it to 500 ppm or less by distillation in advance. Strongly acidic cation exchange resins include Na-type ones, such as commercially available Amberlyst 15 (MR type; manufactured by Rohm and Haas), Diaion HPK-
25 (high porous type; made by Mitsubishi Kasei Corporation), Duolite C-26 (porous type; made by Duolite International Co., Ltd.), etc., and 2 to 30% of the Na type,
Preferably, 5 to 15% of the exchange groups are partially regenerated into H type. In the case of a strongly acidic cation exchange resin with only Na type that has not been partially regenerated to H type, the reaction will hardly proceed, and if more than 30% is partially regenerated, hydrolysis of ethyl acetate will proceed and loss will occur. This is undesirable. Examples of the ion exchange resin type include gel,
Porous, high porous types, etc. are used. Although the type of equipment for filling the ion exchange resin is not limited, it is industrially practical to use equipment that packs the ion exchange resin into a fixed bed and allows it to stay overnight continuously. As for the tower passage conditions,
LHSV (liquid flow rate L/H/catalyst filling amount L) is 1.0~
3.0, the temperature of the flowing liquid at that time is 10 to 50℃,
Preferably it is 20-35°C. If the temperature is low, the reaction is slow, and if the temperature exceeds 50°C, the hydrolysis of ethyl acetate cannot be ignored. As for the distillation conditions, for example, using two distillation towers,
The number of plates in the first column is 20 to 40, the reflux ratio is 5 to 10, and the proportion of low boiling point fraction is 5 to 10%; the number of plates in the second column is 20 to 40, and the reflux ratio is 5 to 10.
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 Acidic cation exchange resin Andorist 15
(MR type; manufactured by Rohm and Haas) with hydrochloric acid for 10 minutes.
%SO ₃ H-form partially regenerated into a reactor, 0.3 g/H of water was added dropwise at room temperature, and ethyl acetate (commercially available: general industrial use) was charged overnight at 1800 g/H. (referred to as outlet liquid). This reactor outlet liquid was subjected to continuous distillation in two columns as it was, and in the first column, a low boiling point fraction was separated at a reflux ratio of 10 to 170 g/H, and in the second column, a product of 1400 g/H was obtained at a reflux ratio of 1.0. Table 1 shows various tests for the product. The product also passed the peroxide test even after being left in a brown glass bottle at room temperature for 15 days.

[Table] Analysis method This test method is a partially revised version of JIS-K-8361. (1) Oxide sample 20ml → Transfer to a stoppered test tube → Potassium iodide solution 2.5ml + water 2.5ml → Shake → Place for 1 hour...
Does not yellow. (Passed) (2) Aldehyde sample 10ml → Transfer to a stoppered test tube → Nessler solution
10ml → Shake vigorously for 10 seconds → Leave for 1 minute...The aquarium will not become cloudy or discolored. (Passed) (3) 5 ml sample of sulfur colored substance (according to the method of JP-A-57-81436) → Cool to below 10°C → Stir while dropping 5 ml of sulfuric acid over 10 minutes without exceeding 30°C → Keep at 50℃±1℃ for 1 hour in hot water → Determine the hue after cooling (4) For each component analysis, water content is determined by Karl Fischer method, vinegar powder is determined by neutralization titration method, and other components are determined by gas chromatography. (Units, abbreviations, and analytical methods are the same in the tables below.) Example 2 In Example 1, the ion exchange resin used was the strongly acidic cation exchange resin Diaion HPK-25.
(high porous type; manufactured by Mitsubishi Kasei Corporation) in 5% SO ₃ H
A product was obtained in the same manner as in Example 1 except that a partially recycled mold was used. Table 2 shows the analysis results of the parts.

[Table] Example 3 In Example 1, the strongly acidic cation exchange resin Duolite C-26 (porous type; manufactured by Duolite International) was partially regenerated into 8% SO ₃ H type. A product was obtained in the same manner as in Example 1, except that the same material was used. The analysis results of the product are shown in Table 3.

【table】

[Table] Reference example 1 Strongly acidic cation exchange resin Amberlyst 15
As a result of filling the SO ₃ Na form into the reactor and carrying out the overnight wake and distillation in the same manner as in Example 1, the product immediately after distillation passed the peroxide test, but it was stored in a brown glass bottle.
The peroxide test after standing at room temperature for 10 days failed. The results are shown in Table 4.

[Table] Reference Example 2 Strongly acidic cation exchange resin Amberlyst 15 was made into 100% SO ₃ H form with hydrochloric acid and filled into a reactor and left overnight in the same manner as in Example 1. As a result, the reactor outlet liquid was
HAc was 3600ppm. 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] 1. 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 ion exchange resin and then distilling it.