JPH0480894B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing in high yield a halogen-containing aromatic dicarboxylic acid or an ester thereof, in which two or four chlorine or bromine atoms are bonded to fixed positions on a benzene nucleus. α,ω-Bis(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid or its ester is useful as a raw material for high modulus polyester, such as tire cords, conveyor belts, power transmission belts, and hoses. Can be used as a rubber reinforcement material. α,ω-bis(2-chlorophenoxy)alkane-4,4′-dicarboxylic acid or α,ω-bis(2,6-dichlorophenoxy)alkane-
Polyesters formed by condensing 4,4'-dicarboxylic acid or its derivatives with alkylene glycol are known (for example, Japanese Patent Publications No. 49-1795, No. 49-1328, Japanese Patent Publication No. 49-13235, and Japanese Patent Publication No. 49-13235, 49-13236). (However, X is hydrogen or chlorine atom, R is hydrogen or lower alkyl group, n is 2, 4 or 6
(an integer of ) Also, α,ω-bis(2-bromnoenoxy)
Alkane-4,4'-dicarboxylic acid or α,ω-
Bis(2,6-dibromophenoxy)alkane-
Polyesters formed by condensing 4,4'-dicarboxylic acid or its derivatives with alkylene glycol are also known (for example, JP-A-49-52292 and JP-B-Sho 57-22935). (In the formula, X is hydrogen or a bromine atom, R is a hydrogen atom or a lower alkyl group, and n is an integer of 2, 4 or 6) Conventionally, methods for producing the above halogen-containing dicarboxylic acid or its ester include: A method is known in which p-hydroxybenzoic acid or its ester is chlorinated or brominated and then reacted with α,ω-dihalogenated polymethylene (Japanese Patent Publication No. 11899/1989 or 102639/1989). There is. (However, X in the formula is a chlorine, bromine, or hydrogen atom, and at least one of the two Xs bonded to the benzene nucleus represents a chlorine or bromine atom.) However, during the etherification reaction in this conventional method, When α,ω-dibromopolymethylene is used as a raw material, the yield is 60-75% (Tokuko Showa
50-11899), however, the NaBr produced as a by-product during the reaction severely corrodes the metal, making it impossible to use a normal stainless steel reactor, and α, ω
-There were problems such as dibromopolymethylene being expensive as a raw material. On the other hand, when α,ω-dichloropolymethylene is used as a raw material, the yield is only 40% at most (see comparative examples of the present invention), and the total yield of the chlorination reaction and etherification reaction is even lower. Therefore, it was disadvantageous for industrial use. Therefore, the present inventors conducted studies with the aim of economically producing a color-free, highly pure halogen-containing aromatic dicarboxylic acid or its ester in high yield. As a result, an etherification reaction was carried out by heating p-oxybenzoic acid or its lower alkyl ester with alkylene dichloride, and α,ω-bis(phenoxy)alkane-
The above objective can be achieved by obtaining 4,4'-dicarboxylic acid or its lower alkyl ester and reacting it with chlorine or bromine in the presence of a specific solvent to carry out a chlorination or bromination reaction. We have found that this can be achieved effectively. (However, X in the formula is a chlorine, bromine or hydrogen atom, and at least one of the two Xs bonded to the benzene nucleus represents a chlorine or bromine atom.) In other words, the present invention is directed to α,ω-bis(phenoxy)
Alkane-4,4'-dicarboxylic acid or its lower alkyl ester is treated with chlorine in the presence of at least one selected from halogenated hydrocarbons having 1 to 8 carbon atoms and halogenated carbons having 1 to 2 carbon atoms. Alternatively, it provides a method for producing a halogen-containing aromatic dicarboxylic acid represented by the following general formula or a lower alkyl ester thereof, which is characterized by reacting with bromine. (In the formula, X is chlorine, bromine or hydrogen atom,
At least one of the two Xs bonded to the benzene nucleus
) represents a chlorine or bromine atom, R represents hydrogen or a lower alkyl group, and n represents an integer of 2, 4 or 6) Usually, when complex compounds with large molecular weights are chlorinated, they are chlorinated. Since there are many types of sites, there will be many by-products, resulting in a decrease in the purity and yield of the obtained target product. Therefore, as in conventional methods, chlorination is usually performed first on compounds with small molecular weights. It is common to do so. However, the present inventors found that α, ω− under specific conditions.
By selectively halogenating only the position ortho to the adjacent oxygen atom of the benzene ring of bis(phenoxy)alkane-4,4'-dicarboxylic acid or its ester, halogen-containing aromatic dicarboxylic acid or its ester can be produced. It was discovered that it is possible to produce The present invention will be explained in detail below. The α,ω-bis(phenoxy)alkane-4,4'-dicarboxylic acid or its lower alkyl ester used as the contributing substance may be prepared by various methods, or may be p-hydroxybenzoic acid or its lower alkyl ester. Preferably, those obtained by the reaction of an alkyl ester and an alkylene dichloride are used. The p-hydroxybenzoic acid or its lower alkyl ester used here is:
For example, specifically p-hydroxybenzoic acid, p-
Methyl hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate,
Examples include butyl p-hydroxybenzoate.
Preferably p-hydroxybenzoic acid or its methyl ester is used. Further, as the alkylene dichloride, a linear alkylene dichloride having 2, 4 or 6 carbon atoms is used, and specific examples thereof include ethylene dichloride, butylene dichloride, hexamethylene dichloride and the like. Preferably ethylene dichloride is used. The amount of alkylene dichloride used is 0.5 to 1.5 per mole of p-hydroxybenzoic acid or its lower alkyl ester.
Moles are preferred. The reaction temperature of P-hydroxybenzoic acid or its lower alkyl ester and alkylene dichloride is preferably 80 to 200°C. The reaction can be carried out either under normal pressure or under increased pressure. Preferably it is carried out under pressure. The thus obtained α,ω-bis(phenoxy)alkane-4,4'-dicarboxylic acid or its ester can be obtained by, for example, filtering the precipitated crystals after cooling the reaction mixture and washing with lower alcohol and water. Can be isolated and purified. Specific examples of α,ω-bis(phenoxy)alkane-4,4'-dicarboxylic acid or its lower alkyl ester used as a starting material in the present invention include 1,2-bis(phenoxy)ethane-4,4'-
dicarboxylic acid, 1,4-bis(phenoxy)butane-4,4'-dicarboxylic acid, 1,6-bis(phenoxy)hexane-4,4'-dicarboxylic acid and their dimethyl esters, diethyl esters,
Examples include dipropyl ester and dibutyl ester. Preferably 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid dimethyl, diethyl, dipropyl, and dibutyl esters,
1,4-bis(phenoxy)butane-4,4'-dicarboxylic acid methyl, diethyl, dipropyl, dibutyl esters, 1,6-bis(phenoxy)
Hexane-4,4'-dicarboxylic acid dimethyl, diethyl, dipropyl, and dibutyl esters are used. Particularly preferred is dimethyl 1,2-bis(phenoxy)ethane-4,4'-dicarboxylate. Examples of the halogenated carbon hydrogen and halogenated carbon used as solvents include chlorobenzene, bromobenzene, chlorotoluene, bromotoluene, chloroxylene, bromoxylene, dichlorobenzene, dibromobenzene, dichlorotoluene, dibromotoluene, trichlorobenzene, Tribromobenzene, trichlorotoluene, tribromotoluene, carbon tetrachloride, carbon tetrabromide, chloroform,
Examples include bromoform, dichloroethane, dibromoethane, dichloroethane, dibromoethane, trichloroethane, tribromoethane, tetrachloroethane, tetrabromoethane, etc. Two or more of these can be used in combination, but among them, chlorobenzene, dichlorobenzene, tetrachloroethane are preferred, and in particular dichlorobenzene (especially orthodichlorobenzene) or tetrachloroethane are most preferably used. Molar ratio of chlorine or bromine to the dicarboxylic acid or ester thereof when reacting the α,ω-bis(phenoxy)alkane-4,4′-dicarboxylic acid or ester thereof with chlorine or bromine in the presence of the solvent. is preferably 2 or more and less than 4, particularly preferably 2 to 3.5, when replacing one chlorine or bromine to the benzene nucleus. Furthermore, when two chlorine or bromine atoms are substituted for the benzene nucleus, the number is preferably 4 or more, and particularly preferably 4 to 8. The reaction is carried out by first dissolving the dicarboxylic acid or its ester in the above solvent and blowing chlorine or bromine gas into it, but the reaction temperature is below the boiling point, especially when dichlorobenzene or tetrachlorobenzene, which is preferably used in the present invention, is used. When used as a solvent, a temperature range of 95 to 140°C is particularly suitable. The amount of solvent used must be sufficient to dissolve the dicarboxylic acid or its ester; for example, 1,2-
When using dimethyl bis(phenoxy)ethane-4,4'-dicarboxylate as a starting material, about twice as much or more preferably 2 to 15 times the amount of orthodichlorobenzene, or more than 1 times the amount, preferably 1 Preferably, ~9 times the amount of tetrachloroethane is used. In addition, in the above reaction, the yield may be further improved by adding a Lewis acid, particularly boron trifluoride, iodine, sulfuric acid, more preferably iodine, as a catalyst. Although the reaction can be carried out under normal pressure, increased pressure, or reduced pressure, normal pressure or slightly increased pressure is preferred industrially. Further, the reaction can be carried out in any manner such as batchwise, continuous or semi-continuous. After the reaction with chlorine or bromine is completed, the desired halogen-containing aromatic compound is obtained by cooling and filtering the product, or by pouring the reaction product into a large amount of water and filtering the precipitate, washing and drying. Dicarboxylic acids or their esters can be obtained efficiently in high yields.
Further, the crystals of the halogen-containing aromatic dicarboxylic acid or its ester obtained by the method of the present invention were white. The crystals of the halogen-containing aromatic dicarboxylic acid or its ester obtained by the conventional method are colored yellow due to coloring trace impurities,
Moreover, this coloration cannot be removed by ordinary purification methods (for example, if this product undergoes a polycondensation reaction with alkylene glycol, it becomes a black-colored polymer). However, according to the present invention, it has become possible to obtain white crystals that are not colored yellow. The present invention will be explained in further detail by giving examples below. Note that the numbers in the examples indicate parts by weight. In addition, the b value is a unit that expresses the yellowness of the color tone (the higher the b value, the more yellow it is), and is manufactured by Suga Test Instruments Co., Ltd.
Measured using an SM color computer. Example 1 1,2-bis(phenoxy)ethane-4,4'-
50 g (0.15 mol) of dimethyl dicarboxylate, 100 parts of orthodichlorobenzene, and 0.2 g of iodine were charged into a reactor equipped with a reflux device, and the temperature was raised to 130° C. while stirring. 1,2-bis(phenoxy)ethane-4,4'-
After dimethyl dicarboxylate was completely dissolved, 27 g (0.38 mol) of chlorine gas was blown into the solution at the same temperature for 2 hours to cause a reaction. After cooling the reaction, separate the white precipitate,
Dry. The yield of this white precipitate is 70%,
Purified by recrystallization from toluene (recrystallization yield 91
%) The melting point of the recrystallized product is 200-203℃, and the color tone (b
value) was 2.2, which was good. This purified product was confirmed to be the desired dimethyl 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate from the elemental analysis values shown in Table 1.

[Table] Comparative Example 1 93 parts (0.5 mol) of methyl 3-chloro-4-oxybenzoate and 27 g (0.5 mol) of sodium methylate were dissolved in 600 g of methanol. Add 25g (0.25mol) of ethylene dichloride to this and
The mixture was reacted in an autoclave at 150° C. for 6 hours with stirring. The crude yield of dimethyl 1,2-bis(2-chlorophenoxyethane)-4,4'-dicarboxylate obtained by pouring the reaction product into a large amount of water, separating the generated white precipitate, and drying it is as follows: It was extremely low at 31%. Moreover, the color tone (b value) was 8.6, which was poor. Example 2 1,4-bis(phenoxy)butane-4,4'-
54 g (0.15 mol) of dimethyl dicarboxylate, 100 g of orthodichlorobenzene, and 0.2 g of iodine were charged into a reactor equipped with a reflux device, and the temperature was raised to 130° C. while stirring. After that, 27g of chlorine gas was added as in Example 1.
(0.38 mol) was blown into the solution and reacted. After cooling the reaction mixture, the white precipitate was separated and dried. The yield of this white precipitate was 80%, and the recrystallized product purified by recrystallization from ethyl acetate (recrystallization yield 84%) had a melting point of 174-176°C and a good color tone (b value) of 2.7. It was hot. From the elemental analysis values in Table 2, the desired 1,4-bis(2-chlorophenoxy)butane-
It was confirmed that it was dimethyl 4,4'-dicarboxylate.

[Table] Example 3 1,2-bis(phenoxy)ethane-4,4'-
50 g (0.15 mol) of dimethyl dicarboxylate and 100 g of orthodichlorobenzene were placed in a reactor equipped with a reflux vessel, and the temperature was raised to 130° C. with stirring. 1,2-bis(phenoxy)ethane-4,4'-
After dimethyl dicarboxylate was completely dissolved, 85 g (1.20 mol) of chlorine gas was blown into the solution for 2 hours to cause a reaction. After distilling off the orthodichlorobenzene in the reaction product, the white precipitate was separated and dried. The crude yield of this white precipitate was 96%, and it was purified by recrystallization from ethanol (recrystallization yield 80%).
The melting point of the recrystallized product is 198-200℃, and the color tone (b value) is
It was good at 1.9. From the elemental analysis values shown in Table 3, it was confirmed that the product was the desired dimethyl 1,2-bis(2,6-dichlorophenoxy)ethane-4,4'-dicarboxylate.

[Table] Comparative Example 2 Methyl 3,5-dichloro-4-oxybenzoate
111g (0.5 mole), 27g sodium methylate
(0.5 mol) was dissolved in 600 g of methanol. Add 25 g (0.25 mol) of ethylene dichloride to this and place it in an autoclave under stirring at 150℃ for 6 hours.
I let it react over time. Pour the reactants into a large amount of water,
The generated white precipitate was separated and dried to obtain 1,2-
Bis(2,6-dichlorophenoxy)ethane-
The crude yield of dimethyl 4,4'-dicarboxylate was extremely low at 31%, and the color tone (b value) was poor at 6.7. Example 4 1,2-bis(phenoxy)ethane-4,4'-
50 g (0.15 mol) of dimethyl dicarboxylate and 100 g of tetrachloroethane were placed in a reactor equipped with a reflux device, and the temperature was raised to 110° C. with stirring. 1,2-bis(phenoxy)ethane-4,4'-
After dimethyl dicarboxylate was completely dissolved, 36 g (0.45 mol) of bromine gas was blown into the solution over 2 hours to cause a reaction. After cooling the reaction, separate the white precipitate,
Dry. The crude yield of this white precipitate was 71%, and the recrystallized product was purified by recrystallization from toluene (recrystallization yield 82%). The melting point of the recrystallized product was 215-216°C, and the color tone (b value) was 2.5.
It was good. From the elemental analysis values in Table 4, the desired 1,2-bis(2-bromophenoxy)ethane-
It was confirmed that it was dimethyl 4,4'-dicarboxylate.

[Table] Comparative Example 3 Methyl 3-bromo-4-oxybenzoate 116g
(0.5 mol) and 27 g (0.5 mol) of sodium methylate were dissolved in 600 g of methanol. Add 25g (0.25mol) of ethylene dichloride to this and
The mixture was reacted in an autoclave at 150° C. for 6 hours with stirring. The reaction product was poured into a large amount of water, the white precipitate formed was separated and dried, and the crude yield of dimethyl 1,2-bis(2bromophenoxy)ethane-4,4'-dicarboxylate was extremely high at 35%. The color tone (b value) was poor at 7.3. Example 5 1,2-bis(phenoxy)ethane-4,4'-
50 g (0.15 mol) of dimethyl dicarboxylate, 150 g of tetrachloroethane, and 0.2 g of iodine were charged into a reactor equipped with a reflux vessel, and the temperature was raised to 110° C. with stirring. 1,2-bis(phenoxy)ethane-4,4'-
After dimethyl dicarboxylate was completely dissolved, 27 g (0.38 mol) of chlorine gas was blown into the solution for 2 hours to cause a reaction. After cooling the reaction, separate the white precipitate,
Dry. The crude yield of this white precipitate was 91%, and the recrystallized product was purified by recrystallization from toluene (recrystallization yield 90%).The melting point of the recrystallized product was 204-205℃, and the color tone (b value) was
It was good at 2.2. From the elemental analysis values shown in Table 5, it was confirmed that this was the desired dimethyl 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate.

[Table] Example 6 1,2-bis(phenoxy)ethane-4,4'-
54 g (0.15 mol) of diethyl dicarboxylate, 216 g of tetrachloroethane, and 0.2 g of iodine were charged into a reactor equipped with a reflux device, and the temperature was raised to 105 to 115° C. while stirring. Thereafter, in the same manner as in Example 1, 27 g (0.38 mol) of chlorine gas was blown into the reactor to cause a reaction. After cooling the reaction mixture, the white precipitate was separated and dried. The yield of this white precipitate was 86%, and the recrystallized product purified by recrystallization from xylene (recrystallization yield 91%) had a melting point of 149-153°C and a good color tone (b value) of 2.0. It was hot. From the elemental analysis values in Table 6, the desired 1,2-bis(2-chlorophenoxy)ethane-
It was confirmed that it was diethyl 4,4'-dicarboxylate.

[Table] Example 7 1,6-bis(phenoxy)hexane-4,
58 g (0.15 mol) of dimethyl 4'-dicarboxylate, 2000 g of carbon tetrachloride, and 0.2 g of iodine were charged into a reactor equipped with a reflux device, and the temperature was raised to 60° C. while stirring. Thereafter, in the same manner as in Example 1, 27 g (0.38 mol) of chlorine gas was blown into the reactor to cause a reaction. After cooling the reaction mixture, the white precipitate was separated and dried. The yield of this white precipitate was 72%, and it was purified by recrystallization from ethanol. The recrystallized product has a melting point of 82~
At 84°C, the color tone (b value) was 2.6, which was good. 7th
From the elemental analysis values shown in the table, it was confirmed that the product was the desired dimethyl 1,6-bis(2-chlorophenoxy)hexane-4,4'-dicarboxylate.

[Table] Example 8 1,2-bis(phenoxy)ethane-4,4'-
54 g (0.15 mol) of dimethyl dicarboxylate, 216 g of chlorobenzene, and 0.2 g of iodine were charged into a reactor equipped with a reflux device, and the temperature was raised to 120 to 125° C. while stirring. Thereafter, in the same manner as in Example 1, 27 g (0.38 mol) of chlorine gas was blown into the reactor to cause a reaction. After cooling the reaction mixture, the white precipitate was separated and dried. The yield of this white precipitate was 90%, and the recrystallized product purified by recrystallization from xylene (recrystallization yield 92%) had a melting point of 201-205°C and a good color tone (b value) of 2.1. It was hot. From the elemental analysis values in Table 8, the desired 1,2-bis(2-chlorophenoxy)ethane-
It was confirmed that it was dimethyl 4,4'-dicarboxylate.

【table】

Claims (1)

[Claims] 1 α,ω-bis(phenoxy)alkane-4,
Reacting 4'-dicarboxylic acid or its lower alkyl ester with chlorine or bromine in the presence of at least one selected from halogenated hydrocarbons having 1 to 8 carbon atoms and halogenated carbons having 1 to 2 carbon atoms. 1. A method for producing a halogen-containing aromatic dicarboxylic acid or a lower alkyl ester thereof represented by the following general formula. (However, X in the formula is a chlorine, bromine or hydrogen atom, and at least one of the two Xs bonded to the benzene nucleus is a chlorine or bromine atom.R is a hydrogen atom or a lower alkyl group, and n is a (Indicates an integer of 2, 4 or 6.)