JPH04364151A - Production of benzyl-4,4'-dicarboxylic acid and its ester - Google Patents

Abstract

PURPOSE:To obtain the subject compound by reacting a formylbenzoic acid ester readily available at a low cost in the presence of a solvent and a prussiate, providing a benzoyl-4,4'-dicarboxylic acid ester and then oxidizing the resultant ester or once hydrolyzing the ester and further oxidizing the prepared hydrolyzate. CONSTITUTION:For example, a p-formylbenzoic acid ester, expressed by the formula (R is 1-3C alkyl or 6-10C aryl) and formed as a by-product in oxidizing p-xylene and synthesizing terephthalic acid or its ester is placed in a solvent such as a mixed solvent of ethanol and water and a prussiate such as sodium prussiate is subsequently added and reacted while stirring the mixture to afford a benzoyl-4,4'-dicarboxylic acid ester, which is then subjected to oxidation treatment or the ester group is hydrolyzed and further subjected to oxidation treatment. Thereby, benzyl-4,4'-dicarboxylic acid and its ester are obtained. Thus, the objective compound can be obtained by using the inexpensive raw material and simple reaction operation according to the aforementioned method. The above-mentioned objective compound is extremely useful as a raw material for new polymers and an intermediate for synthetic products.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The present invention relates to a process for producing benzyl-4,4'-dicarboxylic acid and its ester. More specifically, the present invention relates to a novel manufacturing method that provides extremely easily and inexpensively benzyl-4,4'-dicarboxylic acid and its ester, which are useful as polymer raw materials, synthetic intermediates, and the like.

0002

BACKGROUND OF THE INVENTION Benzyl-4,4'-dicarboxylic acid and its esters are well known and are used as raw materials for various polymers, synthetic intermediates, and the like. For example, the Journal of the Chemical Society of Japan, 1977 (4) 556 reports on a polyamide composed of benzyl-4,4'-dicarboxylic acid dichloride and an aromatic diamine, and a quinoxaline-containing polyamide derived therefrom.

[0003] Makromol. Chem. 188
1253 (1987), diethyl-4,4'-(2-
A polyamide synthesized from phenyl-4,5-imidazole dibenzoate and using this as an acid component has been reported. Benzyl-4,4'-
The copolymerization of dicarboxylic acids into polyesters has been described. Furthermore, in JP-A-62-256831, 5,6-bis(4-ethoxycarboxyphenyl)-3-substituted-as-triazine is produced by reacting benzyl-4,4'-dicarboxylic acid diethyl ester with amidrazone. A polyamide synthesized using the same is described.

[0004] The benzyl-4,4'-dicarboxylic acid derivatives described in these known documents are obtained by, for example, reacting toluene and oxalyl chloride in the presence of anhydrous aluminum chloride to obtain 4,4'-dimethylbenzyl. , a method of oxidizing this to carboxylic acid (German patent 91389)
1), a method of oxidizing 4,4'-dimethylbenzoin,
Method of reacting diaryliodonium salt with carbon monoxide in the presence of a transition metal catalyst and a reducing metal
-175447), but all of them involved complicated reactions, low yields, and were difficult to produce on an industrial scale.

[0005]

[Object of the invention] Therefore, the object of the present invention is to
The object of the present invention is to provide a new method for producing 4'-dicarboxylic acid and its ester at low cost using a simple method.

[0006]

[Structure of the Invention] The object of the present invention is to provide the following formula (I)

000
7]

[Formula, R is an alkyl group having 1 to 3 carbon atoms, 6 to 1 carbon atoms]
0 aryl group. p-formylbenzoic acid ester represented by ] is reacted in the presence of a solvent and a cyanide salt,
Benzyl-4,4, which is a benzoin-4,4'-dicarboxylic acid ester, which is subjected to oxidation treatment or after hydrolysis of the ester group, oxidation treatment is performed.
This can be achieved by a method for producing '-dicarboxylic acid and its ester.

The p-formylbenzoic acid ester used as a raw material in the present invention is a compound represented by the above formula (I). In formula (I), R represents an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms, specifically,
Examples include methyl, ethyl, phenyl, and tolyl. Among these, R is preferably methyl, that is, p-formylbenzoic acid methyl ester.

[0009] p-formylbenzoic acid ester is, for example,
It is a compound produced as a by-product when synthesizing terephthalic acid and/or its ester, which is a raw material for polyesters such as polyethylene terephthalate and polytetramethylene terephthalate, by oxidizing it from p-xylene.
It can be used as an inexpensive raw material.

In the method of the present invention, benzoin-4,4'-dicarboxylic acid ester is first produced by reacting p-formylbenzoic acid ester in the presence of a solvent and a cyanide salt. The solvent to be used is not particularly limited, but preferably includes water, methanol, ethanol, propanol, and the like. It is also preferable to use a mixture of these depending on the case. It is particularly preferable to use a mixed solvent of water and an alcoholic solvent as the solvent. There is no particular restriction on the amount of solvent used, and the amount of solvent used is
4'-dicarbonate is dissolved or dispersed,
Any amount that can form a slurry and maintain uniform fluidity is sufficient, but approximately 3 to 3
This is about 50 times the amount.

[0011] Specific examples of cyanide include sodium cyanide and potassium cyanide. Among these, sodium cyanide is preferred as the cyanide. Hydrocyanate acts as a catalyst in this reaction. The amount of cyanide used is preferably about 0.1 to 20 equivalent %, more preferably about 0.5 to 10 equivalent %, based on p-formylbenzoic acid. There are no particular restrictions on the reaction conditions, and the target benzoin-4
, 4'-dicarboxylic acid ester can be produced.Although these conditions vary depending on the type and amount of the solvent and cyanide, the reaction temperature is approximately 0 to 0.
The temperature is 100°C, preferably about 10 to 80°C, and the reaction time is about 5 minutes to 10 hours, preferably about 10 minutes to 5 hours.

After the completion of the above reaction, the produced benzoin-4
, 4'-dicarboxylic acid ester can be isolated by filtration. In some cases, it is also preferable to partially concentrate the solvent and then filter it. At this time, the obtained filtrate contains cyanide as a catalyst, and by adding p-formylbenzoic acid ester as a raw material again to this, the above-mentioned reaction can be repeated.

In the present invention, the obtained benzoin-4
, 4'-dicarboxylic acid ester is then oxidized. The method of oxidation treatment is not particularly limited, and conventionally known reactions capable of converting benzoin to benzyl can be used as they are; examples include a method using nitric acid, a method using copper sulfate and pyridine, and the like. The reaction is preferably carried out under conventionally known conditions; for example, in the case of a method using copper sulfate and pyridine, benzoin-4,4'-dicarboxylic acid is added to the reaction solution consisting of copper sulfate, pyridine, and water. Add ester and heat at a temperature of about 70 to 90℃ for 1 to 5 minutes.
By reacting for about an hour, the desired benzyl-4,4'-dicarboxylic acid ester can be obtained almost quantitatively. In order to obtain benzyl-4,4'-dicarboxylic acid, the benzyl-4,4'-dicarboxylic acid ester thus obtained may be hydrolyzed, but for example, in the case of alkaline hydrolysis, the benzyl skeleton itself is Since there are problems such as benzylic acid transfer, it is preferable to hydrolyze the ester group to a carboxylic acid at the benzoin stage and then perform the above-mentioned oxidation treatment.

Hydrolysis of benzoin-4,4'-dicarboxylic acid ester can be carried out by conventionally known methods, such as a method using an acid catalyst or a method using an equivalent amount of alkali.

[0015]

According to the present invention, as mentioned above, benzyl-4,4'
- Dicarboxylic acids and their esters can be obtained. The obtained benzyl-4,4'-dicarboxylic acid and its ester are extremely useful as new polymer raw materials and intermediates for synthetic products, and the present invention has great industrial significance.

[0016]

[Examples] The present invention will be explained in detail with reference to Examples, in which "parts" means "parts by weight".

[0017]

[Example 1] p-formylbenzoic acid methyl ester 16
4 parts of ethanol, 500 parts of ethanol, and 300 parts of water were placed in a reaction vessel equipped with a stirring device, and the mixture was stirred and dissolved at room temperature of about 15°C. 5 g of sodium cyanide was added to this solution with stirring. After about 5 minutes, benzoin-4,4'-dicarboxylic acid dimethyl ester began to precipitate, and after 15 minutes, it became difficult to stir the reaction system due to the precipitated crystals. Then, 200 parts of ethanol and 100 parts of water were added, and the mixture was further stirred at room temperature for 1 hour, and then gradually heated to react at 60° C. for 30 minutes. The reaction mixture was cooled, and the precipitated crystals were filtered, washed with water and ethanol, and then vacuum dried at 80° C. for 4 hours to obtain 148 g of pale yellow crystals. This was then recrystallized from ethanol to give benzoin-4,4
116 g of '-dicarboxylic acid dimethyl ester was obtained.

Melting point 130-133°C, elemental analysis [theoretical values in parentheses] C65.79% (65.85%), H4.99
% (4.91%).

[0019]

Example 2 200 parts of copper sulfate pentahydrate, 200 parts of pyridine and 100 parts of water were placed in a reaction vessel equipped with a stirrer and heated in a water bath to dissolve the copper sulfate. 40 parts of benzoin-4,4'-dicarboxylic acid dimethyl ester obtained in Example 1 was added to this solution, and the mixture was reacted on a water bath at 80 to 90°C for 2 hours. During this reaction, crystals precipitate in the reaction system,
Since stirring became difficult, 100 parts of pyridine and 50 parts of water were added. After the reaction was completed, the reaction mixture was cooled, and the precipitated crystals were filtered and further washed with water to remove copper sulfate. The obtained yellow crystals were vacuum dried at 80°C for 4 hours to obtain 38.5 parts of benzyl-4,4'-dicarboxylic acid dimethyl ester.

Melting point 205-206°C, elemental analysis [theoretical value in parentheses] C66.31% (66.26%), H4.21
% (4.32%).

[0021]

[Example 3] 32.8 parts of benzoin-4,4'-dicarboxylic acid dimethyl ester obtained in Example 1, 10 parts of sodium hydroxide, and 400 parts of water were placed in a reactor equipped with a stirrer and a reflux condenser. The mixture was heated under reflux for 2 hours. The reaction solution turned light brown and transparent. After cooling this solution, dilute hydrochloric acid was added to precipitate the reaction solution, and the precipitated pale yellow precipitate was filtered, further washed well with water, and dried under vacuum at 80°C for 4 hours.
28.5 parts of '-dicarboxylic acid were obtained. The benzoin-4,4'-dicarboxylic acid thus obtained was oxidized in exactly the same manner as in Example 2 to obtain benzyl-4,4'-dicarboxylic acid. Melting point 300℃ or higher, elemental analysis [theoretical values in parentheses] C64.51% (64.43%), H3.36% (
3.38%).

Claims (1)

[Claims] [Claim 1] The following formula (I) [Formula, R is an alkyl group having 1 to 3 carbon atoms, 6 to 1 carbon atoms]
0 aryl group. p-formylbenzoic acid ester represented by ] is reacted in the presence of a solvent and a cyanide salt,
Benzyl-4,4, which is a benzoin-4,4'-dicarboxylic acid ester, which is subjected to oxidation treatment or after hydrolysis of the ester group, oxidation treatment is performed.
'-dicarboxylic acid and its ester production method.