JP2636367B2 - Method for producing biphenyl-4,4'-diol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to biphenyl-4,4'-diol (hereinafter, referred to as 4,4'-diol).
4′-BPDO).

4,4'-BPDO is a compound useful as a monomer for engineering plastics and as an antioxidant for polymer materials.

(Prior art) 4,4'-dialkoxybiphenyl (hereinafter 4,4'-DABP
Abbreviated. ) Can be dealkylated to produce 4,4'-BPDO, according to ML Watts et al.
It has only been reported that 4'-dimethoxybiphenyl was reacted with boron tribromide in methylene chloride to give 4,4'-BPDO in 86% yield [Chemistry and Industry (London) (Chem. .Ind. (London), 19
63, (41), 1658)].

In addition, generally reported examples of similar allyl ether cleavage reaction include hydrogen bromide, hydrogen iodide, trifluoroacetic acid,
Cleavage reactions with acids such as concentrated hydrochloric acid, aluminum chloride and aluminum bromide, and reactions with bases such as potassium hydroxide and Grignard reagents or organometallic reagents are known.

(Problems to be Solved by the Invention) In order to develop a method for producing 4,4'-BPDO from 4,4'-DABP, the present inventors converted 4,4'-DABP into halogen in an acetic acid solvent. The method of dealkylation with hydrogen chloride was studied diligently, but the reaction conversion of 4,4'-DABP was high, but the acetoxylation of 4-hydroxy-4'-acetoxybiphenyl, 4,4'-diacetoxybiphenyl, etc. Many by-products were produced, and the selectivity and yield of 4,4'-BPDO were low.

(Means for Solving the Problems) In view of the above-mentioned current situation, the present inventors have proposed 4,4'-DAB
As a result of further intensive studies on a method for producing 4,4′-BPDO by dealkylating P with hydrogen halide, when the reaction was carried out in an aliphatic carboxylic acid solvent containing a certain amount of water, 4,4′-BPDO was obtained. DABP
It has been found that the reaction conversion rate does not change, side reactions such as acetoxylation are remarkably suppressed, and 4,4′-BPDO can be obtained with high selectivity and yield, and the present invention has been completed.

That is, the present invention relates to 4,4'-DABP represented by the general formula (1). (Where R and R 'are aliphatic hydrocarbon groups having 1 to 15 carbon atoms, and R and R' represent the same or different groups) in an aliphatic carboxylic acid solvent containing 1 to 50% by weight of water. And the general formula HX (2) (wherein, X represents any one of chlorine, bromine and iodine.)
And a process for producing 4,4'-BPDO, characterized by reacting with a hydrogen halide represented by the formula:

 Hereinafter, the present invention will be described in detail.

The dealkylation of 4,4'-DABP according to the present invention is achieved by reacting with a hydrogen halide containing any of chlorine, bromine and iodine in an aliphatic carboxylic acid solvent containing water.

The reason why side reactions such as acetoxylation are suppressed by the method of the present invention is not necessarily clear, but by adding water to the solvent, the equilibrium of the esterification reaction between the generated 4,4′-BPDO and acetic acid is improved. It is considered that this has been achieved to shift to the original system.

The alkyl group in the alkoxyl of 4,4′-DABP described in the present invention is an aliphatic hydrocarbon group having 1 to 15 carbon atoms, specifically, a methyl group, an ethyl group, a normal propyl group, an isopropyl group, Examples include a normal butyl group, an isobutyl group, and a tertiary butyl group, and the two alkyl groups may be the same or different. More specifically, 4,
Examples of 4'-DABP include 4,4'-dimethoxybiphenyl, 4
-Ethoxy-4'-methoxybiphenyl, 4,4'-diethoxybiphenyl and the like. The hydrogen halide used in the present invention is hydrochloric acid, hydrobromic acid, and hydroiodic acid. Among them, hydrochloric acid and hydrobromic acid are particularly preferred in terms of ease of handling, reactivity, and economy. Is most preferred. Hydrofluoric acid is a super-strong acid and adversely affects the reaction, which is not preferable. The amount of hydrogen halide used is preferably 2 to 60 moles per mole of 4,4'-DABP, and if it is less than 2 moles, a high conversion cannot be expected. Not economic. The aliphatic carboxylic acid solvent in the present invention is an aliphatic carboxylic acid having 10 or less carbon atoms, specifically, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid,
Valeric acid, isovaleric acid, caproic acid, 2-ethylbutyric acid, 2
-Ethylhexanoic acid and the like. Among them, acetic acid and propionic acid, which are easily available and inexpensive, are most preferable. The amount of water characterizing the present invention is based on the total weight of the solvent.
It is 1 to 50% by weight, more preferably 1 to 20% by weight. The reason is that it is difficult to suppress the acetoxylation of 4,4'-BPDO when the amount of water is less than 1% by weight, and the amount of water is less than 50%.
If the content is more than 10% by weight, the reaction rate of the dealkylation is significantly reduced. The 4,4'-DABP concentration is determined based on the amount of hydrogen halide dissolved in the solvent, and is usually about 0.1 to 5 mol / mol in terms of economy and reactivity. The reaction temperature is low, it is difficult to react, and at high temperatures, side reactions and decomposition of products are observed.
200 ° C. The reaction pressure may be normal pressure or pressurization, and the time may vary depending on the reaction temperature and the like, but it can be generally carried out for 0.5 to 50 hours. Separation and recovery method uses 4,4'-BPDO
And a method of completely removing the solvent by crystallization by adding a poor solvent, and a method of completely distilling off the solvent. In this way, the purity is substantially 99.9%.
4,4′-BPDO can be obtained almost quantitatively.

(Effects of the Invention) As is clear from the above description, according to the present invention,
4,4'-BPDO can be produced from 4'-DABP with extremely high selectivity and yield. 4,4'-B obtained by the present invention
PDO is much higher in purity than 4,4'-BPDO obtained by other methods and does not require special purification.

Therefore, by implementing the present invention, excellent quality
4,4'-BPDO can be produced industrially advantageously.

(Examples) Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 214 mg (1.0 mmol) of 4,4'-dimethoxybiphenyl (hereinafter abbreviated as 4,4'-DMBP) in a 50 ml glass container,
5.2 g of acetic acid, 485 mg (6.0 mmol) of HBr, and 551 mg of water were charged, and after sealing, the reaction was carried out at 180 ° C. for 8 hours. After the reaction, the reaction solvent was distilled off, and the residue was dissolved in methyl isobutyl ketone and washed with water. Gas chromatographic analysis of this methyl isobutyl ketone solution showed that 4,4'-BPDO185.6
The production of 0.2 mg of an intermediate 4-hydroxy-4'-methoxybiphenyl (hereinafter abbreviated as 4,4'-HMBP) in which only one methyl group of 4,4'-DMBP was dealkylated was recognized. Was.

This is because the reaction conversion of 4,4'-DMBP is 100% and 4,4'-B
The yield of PDO corresponds to 99.9%.

 No acetoxy-substituted product was found.

Examples 2 to 12 The reaction was carried out in the same manner as in Example 1 under the conditions shown in Table 1. In Examples 6 to 8, the reaction was carried out at normal pressure without sealing the glass container. Table 2 shows the obtained results. In any of the examples, formation of acetoxy-substituted product was not observed at all.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1, except that water was not contained in the solvent. This corresponds to a water content of acetic acid of 0%. After the reaction, the reaction solvent was distilled off, and the residue was dissolved in methyl isobutyl ketone and washed with water. Gas chromatographic analysis of this methyl isobutyl ketone solution revealed that 74.5 mg of 4,4'-BPDO, 85.6 m of 4-hydroxy-4'-acetoxybiphenyl (hereinafter abbreviated as 4,4'-HAcBP).
g, 4,4'-diacetoxybiphenyl (hereinafter 4,4'-DAc
(Abbreviated as BP) 21.5 mg and 34.8 mg of other unknown components were produced.

This is because the reaction conversion of 4,4'-DMBP is 100% and 4,4'-B
The yield of PDO was 40.0%, the yield of 4,4'-HAcBP was 37.2%,
The yield of 4'-DAcBP corresponds to 7.9%.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1 except that the charged amount of water was 6.74 g. This corresponds to a water content of acetic acid of 56.5%. After the reaction, the solvent was distilled off, and the residue was dissolved in methyl isobutyl ketone and washed with water. Gas chromatographic analysis of this methyl isobutyl ketone solution showed that 29.8 mg of 4,4'-BPDO and 88.8 mg of 4,4'-HMBP were formed.

This is because the reaction conversion of 4,4'-DMBP is 60.9% and 4,4'-DMBP.
The yield of BPDO was 16.1%, which corresponds to 44.8% of 4,4'-HMBP. Although no acetoxy-substituted product was formed, the reaction conversion of 4,4'-DMBP was extremely low. there were.

Claims (1)

(57) [Claims] 1. A 4,4'-dialkoxybiphenyl represented by the general formula (1) (Where R and R 'are aliphatic hydrocarbon groups having 1 to 15 carbon atoms, and R and R' represent the same or different groups) in an aliphatic carboxylic acid solvent containing 1 to 50% by weight of water. And the general formula HX (2) (wherein, X represents any one of chlorine, bromine and iodine.)
A process for producing biphenyl-4,4'-diol, characterized by reacting with hydrogen halide represented by the formula: