JPH02338B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new method for producing 4,4'-dihydroxybenzophenone, which is useful as a dye intermediate, a synthetic raw material for synthetic resins, etc.

As for the production of 4,4'-dihydroxybenzophenone, Soviet Patent No. 529149 describes a method for alkaline hydrolysis of 4,4'-dichlorobenzophenone. However, this method requires equipment costs due to the high temperature reaction, making it difficult to supply inexpensive industrial products.

Furthermore, US Pat. No. 3,366,691 describes a method for synthesizing 4,4'-bis(phenoxy)benzophenone by reacting diphenyl ether and phosgene in the presence of an AlCl ₃ catalyst, and then alkaline hydrolysis of this. be. However, the use of harmful phosgene gas and the need for hydrolysis at high temperatures similar to the above method pose major obstacles to industrialization.

In view of the above problems, the present inventors have conducted intensive studies to overcome the drawbacks of the conventional methods and to develop a method for industrially producing 4,4'-dihydroxybenzophenone in an easy and efficient manner. As a result, they discovered a new method for manufacturing from a biscarbonate compound and phenol, and completed the present invention.

That is, the present invention involves reacting bis(4-trichloromethylphenyl) carbonate and phenol in an organic solvent in the presence of a Lewis acid catalyst to obtain bis[4(4'-hydroxybenzoyl)phenyl]carbonate. This is a method for producing 4,4'-dihydroxybenzophenone, which is characterized in that the compound is then subjected to alkaline hydrolysis.

The method of the present invention consists of two steps and is represented by the following reaction formula.

The starting material bis(4-trichloromethylphenyl) carbonate () is obtained by side chain chlorination of bis(4-methylphenyl) carbonate obtained by reacting 4-methylphenol with phosgene or trichloromethyl chloroformate. , can be produced almost quantitatively.

Phenol can be added dropwise in a molten state, but since it is solid at room temperature, it is preferable to dilute it with an organic solvent before adding it dropwise. There is no particular restriction on the dilution ratio, and an amount that facilitates the dropwise addition of phenol is sufficient.

The amount of phenol used is a molar ratio of 2.0 to 3.0 times the theoretically calculated amount to the raw material carbonate (),
Preferably the molar ratio is 2.0 to 2.2 times.

The catalyst used in the method of the present invention is
Known Lewis acid catalysts such as AlCl ₃ , FeCl ₃ , SbCl ₅ and the like are used.

Although the catalyst can be added in portions, it is preferable to add it all at once. The amount of catalyst is ()
The amount is 1.8 to 4.0 times by mole, preferably 2.0 to 3.0 times by mole.

Examples of the organic solvent used in step (1) of the method of the present invention include carbon disulfide, dichloromethane, dichloroethane, and tetrachloroethane.

The amount of solvent used varies depending on the solubility of bis(4-trichloromethylphenyl) carbonate (). An appropriate compound that facilitates reaction control and decomposes the complex with the Lewis acid produced in the reaction to facilitate the removal of bis[4(4'-hydroxybenzoyl)phenyl]carbonate (), which is the intermediate of the present invention. The amount is 2 to 20 times the weight of (),
Preferably it is 5 to 10 times.

The reaction temperature in step (1) is carried out at 50°C or lower, preferably -5 to 15°C.

The reaction time depends on the scale and capacity of the reactor. Further, the dropping rate of phenol can be freely controlled, and is selected within the range of 1 to 10 hours.

In the alkaline hydrolysis step (second step) of the present invention, it is important to dissolve the intermediate () and improve contact with the alkali. For this purpose, it is better to use a water-soluble organic solvent to react in a homogeneous system than to react in an aqueous system. However, sufficient reaction can be achieved even in a suspended state, which is not necessarily a homogeneous system.

Examples of water-soluble solvents include methanol, ethanol, dioxane, and tetrahydrofuran.

Further, as a solvent insoluble in water, toluene, monochlorobenzene, dichloroethane, etc. can be used.

The amount of these organic solvents to be used is at least 10 times that of the intermediate (). The amount of water to be used in combination is at least twice the theoretical amount by molar ratio to the intermediate ().
When reacting in an aqueous system, use an amount that makes the alkali concentration 30% or less.

Examples of the alkali used in step (2) of the present invention include aqueous ammonia, hydroxides and carbonates of alkali metals and alkaline earth metals.

As alkali metal hydroxides and carbonates,
Examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, and the like.

Examples of alkaline earth metal hydroxides and carbonates include magnesium hydroxide, calcium hydroxide, barium hydroxide, magnesium carbonate, and barium carbonate. Generally, it is preferable in the present invention to select an alkali that is easily soluble in water or a water-soluble solvent.

The amount of alkali used is between 2 and 8 of the intermediate ().
The molar ratio is preferably 3 to 5.5 times.

The reaction temperature is usually below 50℃, preferably 10-30℃
It is.

To carry out the method of the invention, bis(4-trichloromethylphenyl) carbonate () is dissolved or suspended in the organic solvent and then a Lewis acid catalyst is added. Phenol diluted with a portion of the organic solvent is added dropwise to this mixture to carry out the reaction in step (1).

After the reaction is completed, the reaction contents are poured into ice water, the reaction complex with the Lewis acid and the unreacted Lewis acid are hydrolyzed, and the precipitated intermediate () is separated.

This intermediate () is then dissolved in an organic solvent,
Hydrolyze by adding aqueous alkaline solution. The reaction solution is distilled to recover the organic solvent and recycled. Add water and mineral acid to the distillation residue to neutralize excess alkali and dissolve the formed inorganic salts. The precipitated 4,4'-dihydroxybenzophenone can be separated in high yield.

The present invention will be specifically explained below using examples.

Example 1 449 parts of bis(4-trichloromethylphenyl) carbonate were dissolved in 2 parts of dichloromethane, and 347 parts of AlCl ₃ were added with stirring.

Next, a solution prepared by dissolving 188 parts of phenol in 1 part of dichloromethane was added dropwise into the solution over 1 hour. After the dropwise addition was completed, the temperature was gradually raised to room temperature, and the reaction was completed by stirring for 1 hour.

This reaction solution was poured into ice water to decompose the generated reaction complex and unreacted AlCl ₃ , and the precipitated crystals were separated, washed with water, and dried to form bis[4(4'-hydroxy) Benzoyl) phenyl] carbonate (), 423 parts (yield 93 based on theoretical yield)
%) was obtained.

Next, this was dissolved in 3.5 parts of ethanol, 625 parts of 28% aqueous ammonia was added, and the mixture was stirred at room temperature for 6 hours.
The reaction solution was distilled to remove the solvent, then 100 parts of water was added, neutralized with 1% by weight hydrochloric acid, cooled, filtered, washed with cold water and dried to give 4,4'-dihydroxy with a melting point of 211-215°C. 390 parts of benzophenone (yield 98% based on ()) was obtained.

Example 2 423 parts of bis[4(4'-hydroxybenzoyl)phenyl]carbonate () obtained in the same manner as in Example 1 was dissolved in 3.5 ml of ethanol to give a solution of 30%
976 parts of NaOH aqueous solution was added, and the mixture was stirred at room temperature for 4 hours. After distilling the reaction solution to remove the solvent, add 100 parts of water, neutralize with 1% by weight hydrochloric acid, cool, filter,
After washing with cold water and drying, it becomes 4,4′- with a melting point of 210-214℃.
390 parts of dihydroxybenzophenone was obtained in a yield of 98%.

Claims (1)

[Claims] 1. Bis(4-trichloromethylphenyl) carbonate and phenol are reacted in an organic solvent in the presence of a Lewis acid catalyst to obtain bis[4(4'-hydroxybenzoyl)phenyl]carbonate. A method for producing 4,4'-dihydroxybenzophenone, characterized in that the compound is then subjected to alkaline hydrolysis.