JP3890387B2 - Method for producing dihydroxydiphenylsulfone - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing both high purity 2,4'-dihydroxydiphenylsulfone and 4,4'-dihydroxydiphenylsulfone.
[0002]
[Prior art and problems to be solved by the invention]
2,4'-dihydroxydiphenylsulfone (hereinafter, also referred to as 2,4'-form) is extremely useful as a color developer for thermal paper among various phenolic compounds and has recently attracted attention. For example, in a heat-sensitive recording material containing a leuco dye as a color developing substance and a 2,4 ′ isomer as a color developing substance as a main component, deterioration due to a plasticizer or light due to a plasticizer can be prevented. Has the effect of developing color at a sufficient density.
[0003]
As a method for producing the 2,4 ′ isomer, a method is known in which phenol and sulfuric acid are subjected to a dehydration reaction using phosphonic acid or phosphinic acid as a catalyst (JP-A-6-107622).
[0004]
However, in this method, although the reaction is carried out using a catalyst to increase the selectivity of 2,4 ′ isomer, 2,4 ′ isomer, 4,4 ′ isomer (4,4 isomer) is obtained from the obtained isomer mixture. In order to isolate '-dihydroxydiphenylsulfone), more complicated separation and purification steps are required (Japanese Patent Laid-Open No. 6-107623).
[0005]
It is an object of the present invention to easily isolate 2,4′-form and 4,4′-form without using a catalyst and without requiring complicated separation / purification steps. , 4 'body and 4,4' body are provided in an industrially advantageous manner.
[0006]
[Means for Solving the Problems]
In the present invention, when dihydroxydiphenylsulfone is produced by dehydration reaction of a sulfonating agent and phenol, 2.0 to 4.0 moles of phenol per mole of sulfonating agent is 2 of the theoretical yield of dihydroxydiphenylsulfone. The reaction is carried out in a solvent of 0 to 6.5 times the weight of o-dichlorobenzene, and at the end of the reaction, the ratio of unreacted phenol to the total amount of unreacted phenol and o-dichlorobenzene in the reaction solution is 2 to 20 weight. %, The total amount of unreacted phenol and o-dichlorobenzene was 2.0 to 7.0 times the theoretical yield of dihydroxydiphenylsulfone, and 4,4′- at 80 to 160 ° C. from this reaction solution. Dihydroxydiphenylsulfone is precipitated and separated, and then 2,4'-dihydroxydiphenylsulfone is isolated from the filtrate. It is a manufacturing method of dihydroxydiphenyl sulfone, wherein.
[0007]
According to the production method of the present invention, the production ratio of the 2,4 ′ body and the 4,4 ′ body can be increased to nearly 50:50 by weight, and the 2,4 ′ body and the 4,4 ′ body. Can be easily isolated.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the sulfonating agent used in the present invention include concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid and the like. A preferred sulfonating agent is concentrated sulfuric acid.
[0009]
The proportion of the sulfonating agent and phenol used is 2.0 to 4.0 mol, preferably 2.1 to 2.7 mol, of phenol with respect to 1 mol of the sulfonating agent. If the proportion of phenol used is less than 2.0 moles per mole of sulfonating agent, the 4,4 ′ isomers and sulfonic acids increase, and if it exceeds 4.0 moles, the yield decreases. The body and 2,4 'body cannot be separated efficiently.
[0010]
The amount of o-dichlorobenzene used is 2.0 to 6.5 times the weight of the theoretical yield of dihydroxydiphenylsulfone, preferably 2.5 to 4.0 times the weight. If the amount of o-dichlorobenzene used is less than 2.0 times the theoretical yield of dihydroxydiphenylsulfone, the 4,4 ′ and 2,4 ′ isomers cannot be efficiently separated, and the 6.5 times weight is reduced. If it exceeds, the capacity increases, which is not preferable from the viewpoint of economy.
[0011]
If the use ratio of sulfonating agent and phenol and the use amount of o-dichlorobenzene are within the above ranges, the production ratio of 2,4 ′ form and 4,4 ′ form is close to 50:50 by weight. Can be increased up to.
[0012]
Although reaction temperature is not specifically limited, It is preferable to set it as 150-185 degreeC. The reaction time is not particularly limited, but is preferably 3 to 20 hours. Water is distilled out of the reaction system to allow the dehydration reaction to proceed, and the reaction is terminated when the water no longer distilled off even when heated.
[0013]
The reaction solution at the end of the reaction is a mixed solution of 2,4′-form, 4,4′-form, tri-form (trihydroxytriphenyldisulfone), sulfonic acids, unreacted phenol and o-dichlorobenzene. Utilizes the difference in solubility at the crystallization temperature to isolate the 2,4 ′ and 4,4 ′ isomers from this mixture. At that time, the ratio of the unreacted phenol to the total amount of the unreacted phenol and o-dichlorobenzene in the reaction solution at the end of the reaction is 2 to 20% by weight, and the unreacted phenol and o-dichlorobenzene The total amount is 2.0 to 7.0 times the theoretical yield of dihydroxydiphenylsulfone. Preferably, the ratio of unreacted phenol to the total amount of unreacted phenol and o-dichlorobenzene is 2 to 10% by weight, and the total amount of unreacted phenol and o-dichlorobenzene is the theoretical yield of dihydroxydiphenylsulfone. 2.5 to 4.5 times the weight.
[0014]
The ratio of unreacted phenol to the total amount of unreacted phenol and o-dichlorobenzene in the reaction solution at the end of the reaction, and the ratio of the total amount of unreacted phenol and o-dichlorobenzene to the theoretical yield of dihydroxydiphenylsulfone are as described above. If it is in the range of 2,4 'body and 4,4' body can be easily isolated.
[0015]
That is, after completion of the reaction, the reaction solution is cooled to 80 to 160 ° C. to precipitate 4,4 ′ body and separated by filtration or the like, and then 2,4 ′ body can be isolated from the filtrate. To isolate the 2,4 'form from the filtrate, (1) further cool the filtrate to precipitate the 2,4' form and filter, or (2) add water and a basic alkali metal compound to the filtrate. Either dissolve the 2,4 'isomer in the aqueous phase and separate it from the organic phase, then add acid to the aqueous phase to precipitate the 2,4' isomer and filter, or (3) evaporate the filtrate to dryness To obtain 2,4 'body.
[0016]
【Example】
Example 1
A mixture of 216.4 g (2.3 mol) of phenol and 975 g of o-dichlorobenzene (o-DCB) (3.9 times the theoretical yield of dihydroxydiphenylsulfone) under stirring was mixed with 100.0 g (1. 0 mol) was added dropwise and the temperature was raised. The reaction liquid began to boil around 150 ° C., and reaction product water started to distill together with o-DCB. The distillate was condensed in a condenser and separated into two phases by a trap, and the lower o-DCB phase was continuously returned to the reaction system. About 5 hours after the temperature increase, the temperature of the reaction system reached 180 ° C., the generation of water stopped, and the amount of water in the trap was fixed at 38 ml. When the reaction solution is analyzed by gas chromatography at this time, the ratio of unreacted phenol to the total amount of unreacted phenol and o-DCB in the reaction solution is 4.8% by weight, and unreacted phenol and o-DCB. The total amount was 4.1 times the theoretical yield of dihydroxydiphenylsulfone.
[0017]
Moreover, as a result of analyzing the reaction solution by high performance liquid chromatography at this point, the composition of the reaction product was 2,4 ′ form: 4,4 ′ form: tri form = 47.3: 49.3: 3 by weight ratio. .4.
[0018]
Next, the reaction solution was cooled to 120 ° C. and stirred at the same temperature for 30 minutes, and then the precipitated crystals were separated by filtration to obtain 122.0 g of a wet cake (A). Furthermore, after cooling a filtrate to 25 degreeC, the precipitated crystal | crystallization was separated by filtration and 234.8g of wet cake (B) was obtained. The analysis result (excluding o-DCB) of the wet cake (A) by high-performance liquid chromatography is as follows: 2,4 ′ form: 4,4 ′ form: tri form = 4.8: 94.3: 0 The yield based on the sulfuric acid used (calculated as a dry product) was 42.4%. Moreover, the analysis result (except for o-DCB) of the wet cake (B) by high performance liquid chromatography is 2,4 ′ form: 4,4 ′ form: tri form = 85.8: 8.6 in weight ratio. : 5.6, and the yield based on sulfuric acid used (calculated as a dry product) was 46.9%. The yield of wet cakes (A) and (B) based on the sulfuric acid used (calculated as a dry product) was 89.3%.
[0019]
Example 2
After reacting in the same manner as in Example 1, the reaction solution was cooled to 120 ° C., and the precipitated crystals were separated by filtration to obtain 122.0 g of a wet cake (A). To this filtrate, 350 ml of water and 78.0 g of 48% NaOH aqueous solution were added, and after completely dissolving at 50 ° C., the mixture was allowed to stand and liquid-separated to remove the lower organic phase. Next, 70.0 g of 65% sulfuric acid was added to the aqueous phase, and the precipitated crystals were filtered off at 25 ° C., then washed with water and dried to obtain 119 g of a dried product (C). The analysis result (excluding o-DCB) of the wet cake (A) by high-performance liquid chromatography is as follows: 2,4 ′ form: 4,4 ′ form: tri form = 4.8: 94.3: 0 The yield based on the sulfuric acid used (calculated as a dry product) was 42.4%. In addition, the analysis result of the dried product (C) by high performance liquid chromatography is 2,4 ′ form: 4,4 ′ form: tri form = 86.0: 8.5: 5.5 in weight ratio, The yield based on the sulfuric acid used was 47.1%. The yield of wet cake (A) and dry product (C) based on the sulfuric acid used (calculated as dry product) was 89.5%.
[0020]
Comparative Example 1
After adding 100.0 g (1.0 mol) of 98% sulfuric acid dropwise to a mixture of 282.3 g (3.0 mol) of phenol and 250 g of o-DCB (1.0 times the theoretical yield of dihydroxydiphenylsulfone) with stirring. The temperature rose. The reaction liquid began to boil around 150 ° C., and reaction product water started to distill together with o-DCB. The distillate was condensed in a condenser and separated into two phases by a trap, and the lower o-DCB phase was continuously returned to the reaction system. About 5 hours after the temperature increase, the temperature of the reaction system reached 180 ° C., the generation of water stopped, and the amount of water in the trap was fixed at 37 ml. When the reaction solution is analyzed by gas chromatography at this time, the ratio of unreacted phenol to the total amount of unreacted phenol and o-DCB in the reaction solution is 29.3% by weight. The total amount was 1.6 times the weight of the theoretical yield of dihydroxydiphenylsulfone.
[0021]
Moreover, as a result of analyzing the reaction solution by high performance liquid chromatography at this time, the composition of the reaction product was 2,4 ′ form: 4,4 ′ form: tri form = 30.9: 68.4: 0 in weight ratio. .7.
[0022]
Next, the reaction solution was cooled to 120 ° C. and stirred at the same temperature for 30 minutes, and then the precipitated crystals were separated by filtration to obtain 153.9 g of a wet cake (A). Furthermore, after cooling a filtrate to 25 degreeC, the precipitated crystal | crystallization was separated by filtration and 132.7g of wet cake (B) was obtained. The analysis result (excluding o-DCB) of the wet cake (A) by high-performance liquid chromatography was 2,4 ′ form: 4,4 ′ form: tri form = 11.7: 88.1: 0 in weight ratio. 2 and the yield based on the sulfuric acid used (calculated as a dry product) was 53.5%. Moreover, the analysis result (except for o-DCB) of the wet cake (B) by high-performance liquid chromatography is 2,4 ′ form: 4,4 ′ form: tri form = 62.2: 36.4 in weight ratio. : 1.4, and the yield based on sulfuric acid used (calculated as a dry product) was 31.8%. The yield of wet cakes (A) and (B) based on the sulfuric acid used (calculated as a dry product) was 85.3%.
[0023]
【The invention's effect】
According to the production method of the present invention, the production ratio of the 2,4 ′ body and the 4,4 ′ body can be increased to nearly 50:50 by weight, and the 2,4 ′ body and the 4,4 ′ body. Can be easily isolated, so that the high purity 2,4 ′ form and 4,4 ′ form can be industrially advantageously co-produced.

Claims (1)

The sulfonating agent and phenol by dehydration reaction in manufacturing a dihydroxydiphenyl sulfone, phenol 2.1 to 2.7 moles relative to the sulfonating agent 1 mole, the theoretical yield of dihydroxydiphenyl sulfone 2.5-4 The reaction is carried out in a 0- fold weight of o-dichlorobenzene solvent, and at the end of the reaction, the ratio of unreacted phenol to the total amount of unreacted phenol and o-dichlorobenzene in the reaction solution is set to 2 to 10 % by weight. The total amount of unreacted phenol and o-dichlorobenzene was 2.5 to 4.5 times the theoretical yield of dihydroxydiphenylsulfone, and 4,4′-dihydroxydiphenylsulfone was added from this reaction solution at 80 to 160 ° C. It is characterized by separating out and then isolating 2,4'-dihydroxydiphenylsulfone from the filtrate. A process for producing dihydroxydiphenyl sulfone.