JPH06145102A - Production of carboxylic aryl ester - Google Patents

Abstract

PURPOSE:To economically obtain a high-purity, low-colored carboxylic aryl ester in high yield. CONSTITUTION:The objective carboxylic aryl ester is produced by esterification between a carboxylic acid and a phenolic compound in the presence of an esterification catalyst, a mixture of (A) an alkali or alkaline earth metal sulfate, (B) sulfuric acid or sulfamic acid and (C) hypophosphorous acid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a process for producing a carboxylic acid aryl ester.

[0002]

2. Description of the Related Art Many studies have been conducted and various methods have been proposed for producing a carboxylic acid aryl ester by esterifying a carboxylic acid with a phenol in the presence of a catalyst. Typical examples are (1) a method using sulfuric acid and boric acid as a catalyst, (2) a method using polyphosphoric acid, and (3) a method using polyphosphoric acid ester (for example, a new experimental chemistry course). , Volume 14 (2), P1004, Maruzen).

[0003]

However, by any of the conventional methods, the coloration of the reaction product was remarkable, and it was not possible to economically obtain a highly pure carboxylic acid aryl ester in a high yield.

[0004]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that a combination of three specific types of catalysts, that is, an alkali metal or alkaline earth metal sulfate (a). It was found that a carboxylic acid aryl ester with little coloration can be produced economically, in high purity and in high yield by using a catalyst comprising a mixture of carboxylic acid, sulfuric acid or sulfamic acid (b) and hypophosphorous acid (c). Reached That is, the present invention provides a method for producing a carboxylic acid aryl ester in which a carboxylic acid (A) and a phenol (B) are subjected to an esterification reaction in the presence of a catalyst (C), wherein (C) is an alkali metal or alkaline earth metal. Is a mixture of the metal sulfate (a) with sulfuric acid or sulfamic acid (b) and hypophosphorous acid (c).

In the present invention, as the carboxylic acid (A), aliphatic monocarboxylic acids such as acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid and pivalic acid; benzoic acid and toluyl. Acids, aromatic monocarboxylic acids such as dimethylbenzoic acid and naphthoic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, methylmalonic acid, ethylmalonic acid, methylsuccinic acid, α-methylglutaric acid Examples thereof include acids, aliphatic dicarboxylic acids such as α-methyladipic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid.

In the present invention, specific examples of the phenols (B) include phenol; naphthol; alkyl groups (methyl, ethyl, n-propyl, t-butyl, hexyl,
Octyl, nonyl, decyl group, etc.), alkenyl group (isopropenyl, allyl group, etc.), aryl group (phenyl, tolyl, xylyl, biphenyl, naphthyl, cumyl group, etc.), cycloalkyl group (cyclohexyl group, etc.), alkoxy group ( Methoxy, ethoxy group, etc.), aryloxy group (phenoxy group, etc.), alkylthio group (methylthio group, ethylthio group, etc.), arylthio group (phenylthio group, etc.), halogen group (fluoro, chloro, bromo group, etc.), cyano group or Examples thereof include a substituted phenol in which a hydrogen atom directly bonded to an aromatic ring is substituted with a nitro group; and a substituted naphthol substituted with a similar group.

In the present invention, the catalyst (C) is a combination of an alkali metal or alkaline earth metal sulfate (a) and sulfuric acid or sulfamic acid (b) and hypophosphorous acid (c), and if necessary. You may use together methanesulfonic acid, benzenesulfonic acid, a sulfone type ion exchange resin, p-toluenesulfonic acid, etc. Specific examples of (a) include sodium sulfate, magnesium sulfate, potassium sulfate, calcium sulfate and the like, and sodium sulfate and magnesium sulfate are preferable.

In the catalyst (C), the weight ratio of alkali metal or alkaline earth metal sulfate (a) to sulfuric acid or sulfamic acid (b) and hypophosphorous acid (c) is usually (a) :( b). ) :( c) = 1: (0.01 to 5):
(0.1-5), preferably 1: (0.05-
1): (0.3 to 3). When the ratio of sulfuric acid or sulfamic acid (b) exceeds 5, the speed of the side reaction is accelerated and the coloring becomes remarkable. If it is less than 0.01, the reaction takes a long time, which is uneconomical. When the ratio of hypophosphorous acid is less than 0.1, there is no effect of suppressing the coloring, and when it exceeds 5, the generation of sulfur due to the reduction of sulfuric acid becomes intense and the coloring becomes remarkable.

Carboxylic acid (A) used in the method of the present invention:
The equivalent ratio of phenols (B) is usually 1: (0.5-1
0), and preferably 1: (1.1 to 4).
If (B) is less than 0.5, a large amount of unreacted carboxyl groups remain, making purification difficult, which is not preferable. If (B) exceeds 10, it takes time to remove unreacted (B), which is uneconomical.

Carboxylic acid (A) used in the method of the present invention:
The weight ratio of the catalyst (C) is usually 1: (0.001-0.
3), preferably 1: (0.005-0.1)
Is. When (C) is less than 0.001, the catalyst (C)
Effect is hardly exhibited, and if it exceeds 0.3, it is uneconomical.

In the production method of the present invention, the esterification reaction may be carried out without solvent or in a solvent.
The temperature of the esterification reaction is usually 40 to 300 ° C, preferably 80 to 230 ° C. If the temperature exceeds 300 ° C, coloring becomes remarkable, which is not preferable, and if the temperature is less than 40 ° C, the reaction takes a long time, which is uneconomical.

When carried out in a solvent, the boiling point of the organic solvent used is usually 40 to 220 ° C. Specific examples of this organic solvent include aromatic hydrocarbon solvents (benzene, xylene,
Examples thereof include ethylbenzene and toluene), aliphatic hydrocarbon solvents (hexane, pentane, etc.), halogenated hydrocarbon solvents (chloroform, ethylene dichloride, etc.), ether solvents (tetrahydrofuran, dioxane, etc.), and the like. You may use these 2 or more types together. Of these, preferred is one or more selected from benzene, toluene, xylene and ethylbenzene.

As a method for removing water by-produced by the esterification reaction during the reaction, a method of continuously removing it with a dehydrator or the like, and a dehydrating agent (for example, dicyclohexylcarbodiimide, trifluoroacetic anhydride, etc.) are allowed to coexist. Method etc. are mentioned. Examples of the dehydrating device include a Dean-Stark type dehydrating device, a device in which a desiccant [Molecular Sieve (Molecular Sieve 5A, etc.)] is placed in a Soxhlet extractor, and the like.

When the method of purifying and isolating the carboxylic acid aryl ester from the product after the completion of the esterification reaction is exemplified, this product is washed with weak alkaline water to obtain the catalyst (C).
After removing unreacted components and byproducts, the carboxylic acid aryl ester can be isolated by removing the solvent when a solvent is used. If necessary, further purification by distillation or recrystallization using various solvents may be performed for purification.

[0015]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

Example 1 500 ml of 4 equipped with a Dean-Stark type dehydrator
Xylene 229g, adipic acid 51g,
99 g of phenol, 1.0 g of anhydrous sodium sulfate, 0.3 g of sulfuric acid and 1.0 g of hypophosphorous acid were added, and the temperature was raised to the reflux temperature of xylene of 144 ° C. After removing 12 g of produced water while refluxing for about 8 hours, the reaction mixture, which was almost transparent, was mixed with 50 g of water.
Cooled to ° C. The mixture was washed with an aqueous solution of sodium hydroxide and then with water to remove unreacted substances and catalyst residues. Further, 150 g of xylene was removed under reduced pressure and cooled with ice. The mixture was filtered off to obtain 95 g of white crystalline adipic acid diphenyl ester (yield 91%, melting point 107-108 °).
C) got. A 50% acetone solution of adipic acid diphenyl ester separated by filtration was prepared, and the hue of this solution was adjusted to A
It was 20 when measured by the PHA method.

Example 2 93 g of white crystalline adipic acid diphenyl ester was prepared in the same manner as in Example 1 except that 1.0 g of anhydrous sodium sulfate in Example 1 was replaced with 1.0 g of anhydrous magnesium sulfate.
(Yield 89%) was obtained. Similarly, the hue as an acetone solution was 20.

Example 3 99 g of the phenol of Example 1 was added to 120 g of p-cresol.
In the same manner as in Example 1 except that the above was used, 100 g (yield 88%) of white crystalline adipic acid crescyl ester was obtained. Similarly, the hue as an acetone solution was 30.

Example 4 White crystalline pivalic acid α-naphthyl ester was prepared in the same manner as in Example 1 except that 51 g of adipic acid in Example 1 was replaced with 71 g of pivalic acid and 99 g of phenol was replaced with 150 g of α-naphthol. 135 g (yield 85%, melting point 6
5 to 67 ° C) was obtained. Similarly, the hue as an acetone solution was 40.

Example 5 In the same manner as in Example 1 except that 51 g of adipic acid in Example 1 was replaced with 85 g of benzoic acid, 120 g of phenyl benzoic acid phenyl ester (yield 87%, melting point 68 to 70) was obtained.
C) was obtained. Similarly, the hue as an acetone solution was 20.

Example 6 White crystalline diphenyl terephthalate was prepared in the same manner as in Example 1 except that 51 g of adipic acid in Example 1 was replaced with 58 g of terephthalic acid and 0.3 g of sulfuric acid was replaced with 0.3 g of sulfamic acid. Ester 100 g (yield 90%, melting point 74-
75 ° C) was obtained. Similarly, the hue as an acetone solution is 3
It was 0.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that anhydrous sodium sulfate was not used. The reaction system was black. The mixture was washed with an aqueous sodium hydroxide solution and then with water. Further, xylene was removed under reduced pressure and cooled with ice. The mixture is filtered off,
Black product 6 with adipic acid diphenyl ester as the main component
0 g (58% yield, melting point 100-106 ° C) were obtained. A 50% acetone solution of this black material was prepared, and the hue of this solution was 300 as measured by the APHA method. Furthermore, this black product was recrystallized using 200 g of ethanol, but could not be decolorized.

Comparative Example 2 The reaction was carried out in the same manner as in Example 1 except that hypophosphorous acid was not used. The reaction system was black. The mixture was washed with an aqueous sodium hydroxide solution and then with water. Further, xylene was removed under reduced pressure and cooled with ice. The mixture was separated by filtration to obtain 45 g of a black product containing adipic acid diphenyl ester as a main component (yield 43%, melting point 100 to 106 ° C). Similarly, the hue of the acetone solution was 400, and the color could not be decolorized even by recrystallization.

Comparative Example 3 The reaction was carried out in the same manner as in Example 1 except that anhydrous sodium sulfate and hypophosphorous acid were not used. The reaction system was black.
The mixture was washed with an aqueous sodium hydroxide solution and then with water. Further, xylene was removed under reduced pressure and cooled with ice. The mixture was separated by filtration to obtain 30 g of a black product containing adipic acid diphenyl ester as a main component (yield 29%, melting point 98 to 106 ° C). Similarly, the hue of the acetone solution was 500, and the color could not be decolorized even by recrystallization.

Comparative Example 4 A reaction was carried out in the same manner as in Example 1 except that sulfuric acid, anhydrous sodium sulfate and hypophosphorous acid were not used, and 0.5 g of polyphosphoric acid was used instead. The reaction system was black. The mixture was washed with an aqueous sodium hydroxide solution and then with water. Further, xylene was removed under reduced pressure and cooled with ice. The mixture is filtered to obtain a black product 30 containing adipic acid diphenyl ester as a main component.
g (yield 29%, melting point 99-107 ° C.) was obtained. Similarly, the hue of the acetone solution was 500, and the color could not be decolorized even by recrystallization.

[0026]

Industrial Applicability According to the production method of the present invention, a high-purity carboxylic acid aryl ester can be obtained in high yield without coloring. In particular, the dicarboxylic acid diaryl ester obtained by this production method is useful as a polyester raw material,
It is also useful as a sensitizer for heat-sensitive recording paper and other various synthetic intermediates.

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Claims (2)

[Claims] 1. A carboxylic acid (A) and a phenol (B)
In the process for producing a carboxylic acid aryl ester in which an esterification reaction is carried out in the presence of an esterification catalyst (C), the catalyst (C) comprises a sulfate (a) of an alkali metal or an alkaline earth metal and sulfuric acid or sulfamic acid. A process for producing a carboxylic acid aryl ester, which comprises using a mixture of (b) and hypophosphorous acid (c). 2. In the catalyst (C), the weight ratio is (a) :( b) :( c) = 1: (0.01 to 5):
(0.1-5) The method for producing a carboxylic acid aryl ester according to claim 1.