JP3089760B2 - Method for producing 4-benzyloxy-4'-hydroxydiphenyl sulfone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing 4-benzyloxy-4'-hydroxydiphenylsulfone, which is a useful raw material used as an image stabilizer for heat-sensitive recording materials.

[0002]

2. Description of the Related Art The reaction between a phenolic hydroxyl group and an aralkyl halide, which is a unit reaction for producing an aralkyloxy compound, is generally well known. However, when there are two phenolic hydroxyl groups as in the present invention, both hydroxyl groups are aralkylated, and it is difficult to selectively obtain only one of them in high yield. A method for producing the same compound as that of the present invention is disclosed in JP-A-59-225157, and an improvement is provided by benzylating only one of the two hydroxyl groups as described above. That is, 1 mol of 4,4′-dihydroxydiphenyl sulfone (hereinafter referred to as “BPS”) is mixed with 0.8 mol of an alkaline substance.
Dissolved in water containing 水 1.2 mol, at a temperature of 40-80 ° C.
With 0.8 to 1.2 moles of benzyl chloride,
The proportion of these used is important. When the amount of benzyl chloride is 0.8 mol or less with respect to 1 mol of BPS of the raw material, the residual ratio of the raw material is increased, and when the amount is 1.2 mol or more, by-product 4,4 is produced. It is stated that the amount of 4'-dibenzyldiphenylsulfone tends to be large, and that the same tendency also exists in the use ratio of an alkaline substance.

[0003]

However, in the above production method, when the amount of benzyl chloride used is increased in order to increase the conversion rate of the starting BPS to the target compound, the by-product 4,4 is reduced.
4′-Dibenzyloxydiphenyl sulfone (hereinafter referred to as “di-form”) is produced, and when the amount used is reduced, BP of the raw material is reduced.
This was not sufficient, for example, a large amount of S remained and the yield decreased, and in some cases a purification step was required.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, in order to increase the conversion rate of the starting BPS to the target compound, the amount of benzyl chloride to be used is at least 1 to 1 relative to BPS. In order to prevent the formation of the di-isomer at this time, only one of the two hydroxyl groups of BPS is included in the reaction system, including the time of dissolution of BPS in water, in the reaction system. It has been found that it is important to make it exist as a salt. That is, in the present invention, 1.0 mol of 4,4'-dihydroxydiphenylsulfone is dissolved in water containing 0.8 to 1.0 mol of an alkaline substance, and 1.2 to 1.4 mol of benzyl chloride is reacted. A process for producing 4-benzyloxy-4'-hydroxydiphenylsulfone, wherein the reaction solution is reacted at a pH of 7.5 to 8.5. Add the substance and adjust the pH to 8.0-9.0,
A process for producing 4-benzyloxy-4'-hydroxydiphenylsulfone, which comprises separating 4-benzyloxy-4'-hydroxydiphenylsulfone at -70 ° C.

[0005] In the present invention, the amount of the alkaline substance used is extremely important. That is, when dissolving the raw material BPS in water, if the amount of the alkaline substance used is 1.0 mol or more with respect to 1.0 mol of the BPS, the formation of the di-form is increased. And proceeding the reaction by adding benzyl chloride into the reaction system, p
It is important that the amount of the alkaline substance used for the adjustment of H7.5 to 8.5 is necessary and minimum. At that time, the total amount of the alkaline substance used for dissolving the BPS and adjusting the pH is preferably 1.2 to 1.5 mol. In general, benzyl chloride reacts to generate chlorine ions, and the pH tends to shift to the acidic side during the reaction. Therefore, it is very rarely necessary to adjust the pH with an acidic substance. The specific amount of the alkaline substance used for pH adjustment is preferably 0.2 to 0.7 mol based on 1 mol of BPS as a raw material. When the pH is 7.5 or less, the formation of the di-isomer can be suppressed, but the progress of the reaction is slowed down, and a large amount of raw material remains.
When the ratio is 5 or more, the reaction proceeds rapidly, but two hydroxyl groups of BPS easily form a salt, and the formation of a di-form increases.
Here, examples of the alkaline substance used include, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, potassium carbonate, and the like. These include sodium hydroxide and sodium carbonate.

Next, the proportion of BPS and benzyl chloride used as raw materials is also important. In order to improve the yield in particular, the former is 1.0 mol and the latter is 1.2 to 1.4 mol. It is necessary. It was supposed that the amount of benzyl chloride used in the monobenzylation reaction was much higher than that generally used, and that the formation of the di-form was naturally increased. However, by adjusting the pH in the reaction system as described above, it is possible to suppress the formation of the di-isomer and to obtain the target compound in high yield. Here, when the amount of benzyl chloride used does not reach 1.2 mol, the residual amount of BPS as a raw material increases and the yield decreases, and when it exceeds 1.4 mol, the formation of di-form increases.

In the present invention, when dissolving BPS in an aqueous solution of an alkaline substance, it is preferable to heat the mixture to a temperature of 40 ° C. to a reaction temperature or lower. Further, the temperature at the time of adding benzyl chloride to the BPS aqueous solution for the reaction is preferably from 50 to 80 ° C. If the temperature is lower than 50 ° C, the progress of the reaction is slowed, and the economic efficiency is reduced. In some cases, the by-product di-body tends to be produced more often.

The reaction solution thus obtained is in the form of a suspension in which 4-benzyloxy-4'-hydroxydiphenylsulfone, which is the object of the present invention, is precipitated. Can be taken out. However, since a small amount of BPS as a raw material remains, the pH of the reaction solution is adjusted to pH 8.0 to 9.0 with an alkaline substance and the pH is adjusted to 40 to
It is preferable that the raw material BPS is dissolved at a temperature of 70 ° C. and then separated from the aqueous solution. According to the production method of the present invention, since the formation of the di-form which is not dissolved in the alkaline aqueous solution is small, a high-purity product can be easily obtained as described above,
This is an extremely useful method in industry. Needless to say, recrystallization or dissolving in an aqueous alkali solution, followed by purification treatment, such as acidification, may be performed to obtain an extremely high purity.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. Example 1 250.3 g (1.0 mol) of BPS was added to sodium hydroxide 4
60 liters in 3.0 liters of water containing 0.0 g (1.0 mole)
Benzyl chloride at the same temperature.
(1.3 mol) was added dropwise over 2 hours. Further, the reaction was carried out at the same temperature for 7 hours. During the reaction, 120 g of a 10% aqueous solution of caustic soda was maintained so as to maintain a pH of 7.6 to 7.8.
The reaction was performed while adding (0.3 mol). After the completion of the reaction, a part of the reaction solution was sampled and the product composition was measured by liquid chromatography.
%, BPS was 1.0%, and di-form was 0.5%, which contained other impurities. Further, the reaction solution was adjusted to pH 8.5 by adding a 10% aqueous sodium hydroxide solution, cooled to 50 ° C, filtered and dried to obtain 332 g of 4-benzyloxy-4′-hydroxydiphenylsulfone, melting point 171 to 173 ° C. . At this time, the yield (vs. BPS) was 97.6%. As determined by liquid chromatography, the purity was 98.2%, the di-form was 0.5%, and the BPS was below the detection limit. Comparative Example 1 In Example 1, 250.3 g (1.0 mol) of BPS
Was dissolved in 3.0 l of water containing 52.0 g (1.3 mol) of caustic soda at 60 ° C. and reacted in the same manner without adjusting the pH. An aliquot of the reaction solution was taken, and the product composition was measured by liquid chromatography. The target compound was 91.7%, BPS was 1.5%, and the di-form was 3.8.
% And other impurities, and particularly the formation of di-form was increased. Comparative Example 2 The amount of benzyl chloride used in Example 1 was
The reaction was carried out in the same manner, except that 6.6 (1.0 mol) was used. After completion of the reaction, a part of the reaction solution was taken, and the product composition was measured by liquid chromatography.
%, BPS was 18.0%, and the di-form was 0.5%, containing other impurities, and a large amount of unreacted raw material BPS remained.

[0010]

According to the production method of the present invention, the raw material BP
High purity 4 with extremely low content of S and by-products
-Benzyloxy-4'-hydroxydiphenyl sulfone can be obtained in high yield.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 317/00 C07C 315/00 CA (STN) REGISTRY (STN)

Claims (5)

(57) [Claims] 1. A solution of 1.0 mol of 4,4'-dihydroxydiphenylsulfone in water containing 0.8 to 1.0 mol of an alkaline substance, and 1.2 to 1.4 mol of benzyl chloride.
(Excluding 1.2) , wherein the reaction solution is reacted at a pH of 7.5 to 8.5. A process for producing 4-benzyloxy-4'-hydroxydiphenylsulfone. 2. The method according to claim 1, wherein the alkaline substance is sodium hydroxide or sodium carbonate. 3. The process according to claim 1, wherein the pH of the reaction solution is adjusted by adding an alkaline substance in the reaction at a pH of 7.5 to 8.5. 4. The method according to claim 1, wherein the reaction temperature is 50 to 80 ° C. 5. After completion of the reaction, the reaction solution is adjusted to pH 8.0 to 9.0.
2. The process according to claim 1, wherein the pH is adjusted by adding an alkaline substance to 0, and 4-benzyloxy-4'-hydroxydiphenylsulfone is separated at 40 to 70 ° C.