JPH0687794A - Production of ester - Google Patents

Abstract

PURPOSE:To provide a production method of ester intended to substantially improving workability by adding glycol compound(s) to an esterification liquid prior to neutralizing the liquide with an alkali metal (bi)carbonate to effectively suppress the foaming due to the CO2 generated by the neutralization. CONSTITUTION:Firstly, an esterification is made between (A) a carboxylic acid and/or carboxilic anhydride [pref. acetic acid (anhydride)] and (B) a 2- phenoxyethyl alcohol of formula I (X is carbamoyl, nitro, or cyano) [e.g. 4-(2- hydroxyethoxy)benzamide] in the presence of an acid catalyst (normally, p- toluenesulfonic acid). Then, a glycol compound(s) of formula II (R<1> and R<2> are each H or 1-10C alkyl; R<3> is H or 1-4C alkyl; n is 1-3) (e.g. ethylene glycol) is added to the resultant reaction liquide followed by neutralizing the acidic compound(s) in the reaction product containing the objective carboxylic ester using an aqueous solution of an alkali metal carbonate and/or alkali metal bicarbonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ester, and more particularly to the production of an ester obtained by the esterification reaction of carboxylic acid and / or carboxylic anhydride with 2-phenoxyethyl alcohol in the presence of an acid catalyst. At
The present invention relates to a method for neutralizing an acidic substance present in a reaction solution.

The product ester obtained according to the invention is
It has high boiling point and high melting point physical properties and is used as a special solvent.

[0003]

2. Description of the Related Art In a reaction solution obtained by an esterification reaction of a carboxylic acid and / or a carboxylic anhydride with an alcohol in the presence of an acid catalyst, an unreacted carboxylic acid and an acid catalyst coexist as acidic substances. ing.

In order to remove the acidic impurities, a neutralization treatment is usually carried out with an aqueous solution of an alkali metal carbonate and / or bicarbonate in which the pH of the wastewater is easily adjusted, and then the ester layer and the water layer are separated. After liquid separation, the ester layer is washed again with water. In this case, the carbon dioxide generated by the neutralization reaction foams violently, so that the neutralization operation becomes extremely complicated, which is a serious problem particularly in the case of large-scale industrial production.

As a method for solving these problems, JP-A-59-127692 discloses that an alkali metal carbonate or bicarbonate such as sodium carbonate or sodium bicarbonate should be treated with 0.01
A method is described in which a low-foaming neutralizing agent added with a defoaming agent such as a silicon-based or mineral oil-based anti-foaming agent in an amount of at least wt% is used for neutralizing an acidic waste liquid.

[0006]

However, if the above-mentioned method is applied to the method for neutralizing and removing an acidic substance in the production of the carboxylic acid ester of 2-phenoxyethyl alcohol of the present invention, the elimination of these Since the foaming agent is hardly dissolved in water, the above-mentioned defoaming agent is mixed in the organic layer containing the ester, and as a result, it remains in the product ester to cause a decrease in the purity and a decrease in the function of the product.

Under these circumstances, the acidic substance present in the reaction solution obtained by the above-mentioned esterification reaction is neutralized and the purity of the desired carboxylic acid ester is lowered by an industrially easy method. It was a problem to prevent.

[0008]

In order to solve the above problems, the inventors of the present invention have diligently studied a method of neutralizing a reaction solution containing a carboxylic acid ester when producing the carboxylic acid ester. The present invention has been completed by discovering that the amount of foaming is significantly reduced by neutralizing with an aqueous solution of an alkali metal carbonate and / or an alkali metal bicarbonate after adding a glycol compound.

That is, the present invention provides an ester obtained by an esterification reaction of a carboxylic acid and / or a carboxylic anhydride with a 2-phenoxyethyl alcohol represented by the following general formula [1] in the presence of an acid catalyst. Before neutralizing the acidic substance in the reaction product containing the above with an aqueous solution of an alkali metal carbonate and / or an alkali metal bicarbonate, a glycol compound represented by the following general formula [2] is added to the reaction solution. It is a method for producing a carboxylic acid ester, which is characterized in that it is added alone or as a mixture.

[0010]

[Chemical 3] (In the formula, X is a carbamoyl group, a nitro group or a cyano group.)

[0011]

[Chemical 4] (However, in the formula, R ¹ and R ² are independently hydrogen or carbon number.
1 to 10 alkyl group, R ³ is hydrogen or 1 to 4 carbon atoms
And an n is an integer of 1 to 3. )

[0012]

DETAILED DESCRIPTION OF THE INVENTION As the carboxylic acid, any one of acetic acid, acetic anhydride, propionic acid, propionic anhydride, butyric acid and butyric anhydride is used.

Alcohol has the general formula [1]

[Chemical 5] (Wherein X represents any one of a carbamoyl group, a nitro group, and a cyano group), and is 4- (2-hydroxyethoxy) benzamide, 2- (2- Hydroxyethoxy) benzonitrile,
2- (4-nitrophenoxy) ethanol and the like can be exemplified.

The acid catalyst is an organic sulfonic acid such as p-toluenesulfonic acid, ethanesulfonic acid and benzenesulfonic acid, but generally p-toluenesulfonic acid is used.

The reaction method may be a conventional method, such as carboxylic acid and / or
Alternatively, the carboxylic acid anhydride and the alcohol are reacted in the presence of a solvent. Here, the reaction solvent may be benzene, toluene, or the like used in a general esterification reaction.

In the reaction solution obtained by the esterification reaction,
In addition to the target ester, when the acid catalyst and the carboxylic acid and / or carboxylic acid anhydride are used in excess equivalent numbers (here, equivalents refer to acid-base equivalents, the same applies hereinafter) to the alcohol, unreacted Carboxylic acid is also included. To remove the acidic substances present in the reaction solution, after adding a glycol compound to the reaction solution, a neutralization treatment is carried out with an aqueous solution containing a basic neutralizing agent, and the produced neutralized salt is dissolved in the aqueous layer. Separated from the organic layer containing the desired ester.

The neutralization temperature is not particularly limited, but is preferably 80 ° C. or lower, and at 80 ° C. or higher, boiling of the solvent begins to occur.

The basic neutralizing agent is an alkali metal carbonate and / or an alkali metal bicarbonate. Examples of the alkali metal carbonate include sodium carbonate and potassium carbonate, and examples of the alkali metal bicarbonate include Examples thereof include sodium hydrogen carbonate and potassium hydrogen carbonate.

The amount of the basic neutralizing agent added is preferably in the range of 1 to 3 times the equivalent of the acid in the reaction solution. Here, if the amount of the neutralizing agent is too small, the acidic substance in the reaction solution cannot be sufficiently neutralized and is mixed as an impurity in the product ester. If the amount of the neutralizing agent exceeds the above range, the alkali metal remains in the organic layer after neutralization, and it becomes necessary to increase the number of times of washing with water after neutralization, which prolongs the process time.

The concentration of the aqueous solution of the basic neutralizing agent is not particularly limited, but is preferably 5 to 20% by weight. If the concentration is too high, neutralized salts will precipitate in the system, and if the concentration is too low, the amount of wastewater will increase significantly.

In the present invention, the glycol-based compound added in the above neutralization is represented by the general formula [2]

[Formula 6] (In the formula, R1 and R2 each have a hydrogen or carbon number of 1 to
10 represents an alkyl group, and R3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms. n represents an integer of 1 to 3), and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and propylene glycol diethyl ether.

The amount of these glycol compounds added to the reaction solution is preferably 0.1 to 5.0% by weight based on the reaction solvent. If the addition amount is too small, a large amount of foaming due to carbon dioxide generated by the neutralization reaction cannot be avoided, and if the addition amount is excessive, it becomes difficult to separate the aqueous layer and the organic layer containing the ester after the neutralization treatment. .

[0023]

EXAMPLES Next, examples will be shown in order to describe the present invention more specifically, but the present invention is not necessarily limited to the examples.

Example 1 4- (2-hydroxyethoxy) benzamide 45 g (0.25 equivalent), p-toluenesulfonic acid 9.5 g (0.05 equivalent), propionic acid 22.2 g (0.3 equivalent) and toluene 250 g were charged at the same time and refluxed with toluene. The reaction was carried out for 5 hours (reaction temperature 110 ° C). After that, the reaction solution was transferred to a 500 ml graduated test tube, the additives shown in Table 1 were added, and the mixture was neutralized with an aqueous solution prepared by dissolving 10.6 g (0.2 equivalents) of sodium carbonate in 90 g of water while stirring at 70 ° C. Was performed and the amount of foaming at that time was measured. The results are shown in Table 1.

[0025]

[Table 1]

Example 2 26.4 g (0.3 equivalents) of butyric acid was used in place of propionic acid in Example 1, and the reaction was carried out under reflux of toluene for 4 hours (reaction temperature
110 ° C). After that, the reaction solution was transferred to a 500-ml graduated test tube, the additives shown in Table 1 were added, and the mixture was kept at 70 ° C with stirring, but neutralized with an aqueous solution of 13.8 g (0.2 equivalent) of potassium carbonate dissolved in 80 g of water. The treatment was performed and the foaming amount at that time was measured. The results are shown in Table 2.

[0027]

[Table 2]

[0028]

INDUSTRIAL APPLICABILITY When a carboxylic acid ester is produced by an esterification reaction from an aliphatic carboxylic acid and / or an aliphatic carboxylic acid anhydride and an alcohol in the presence of an acid catalyst, a reaction solution containing the ester compound is reacted. By neutralizing the acidic substance in the liquid with an alkali metal carbonate and / or an alkali metal bicarbonate, a small amount of a glycol-based compound is added to the reaction liquid, whereby foaming due to generation of carbon dioxide generated by the neutralization reaction occurs. It is effectively suppressed and the workability in the neutralization step is greatly improved.

[Chemical 6]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C07C 235/60 7106-4H 253/30 255/54 9357-4H // C07B 61/00 300

Claims (1)

[Claims] 1. A reaction product containing an ester obtained by an esterification reaction of a carboxylic acid and / or a carboxylic anhydride with a 2-phenoxyethyl alcohol represented by the following general formula [1] in the presence of an acid catalyst: Before neutralizing the acidic substance in the product with an aqueous solution of an alkali metal carbonate and / or an alkali metal bicarbonate, a glycol compound represented by the following general formula [2] may be used alone or in a mixture in the reaction solution. A method for producing a carboxylic acid ester, which comprises adding the carboxylic acid ester. [Chemical 1] (However, X in the formula is a carbamoyl group, a nitro group, or a cyano group.) (However, in the formula, R ¹ and R ² are independently hydrogen or carbon number.
1 to 10 alkyl group, R ³ is hydrogen or 1 to 4 carbon atoms
And an n is an integer of 1 to 3. )