CN101786973B - Synthesizing process of 4-methyl sodium benzene sulphinate - Google Patents

Abstract

A kind of synthesis technique of sodium 4-methylbenzenesulfinate, its steps are: (1) 4-methylbenzenesulfonyl chloride is dissolved in methylene chloride; (2) the 4-methylbenzene of last step gained The dichloromethane solution of sulfonyl chloride is added dropwise in the aqueous solution of sodium sulfite, and 10% sodium hydroxide solution is added dropwise at the same time, and the control system becomes alkaline; (3) the solvent dichloromethane in the reaction solution obtained in the second step is recovered by distillation , to obtain an aqueous solution of sodium 4-methylbenzenesulfinate; (4) cooling the aqueous solution of sodium 4-methylbenzenesulfinate, suction filtering, washing with water, and drying to obtain sodium 4-methylbenzenesulfinate. In this method, the dichloromethane solution containing 4-methylbenzenesulfonyl chloride is directly added dropwise into the aqueous solution of sodium sulfite, which prevents the hydrolysis of 4-methylbenzenesulfonyl chloride; It balances the alkali adjustment and improves the recovery rate of the solvent, making the production environment cleaner and avoiding gas emissions.

Description

Synthetic process of sodium 4-methylbenzenesulfinate

technical field

The invention relates to a new synthesis process of sodium 4-methylbenzenesulfinate.

Background technique

Sodium 4-methylbenzenesulfinate is obtained by reducing 4-methylbenzenesulfonyl chloride under the action of reducing agent sodium sulfite. The raw material 4-methylbenzenesulfonyl chloride is insoluble in water, but is easily hydrolyzed in water; while the reducing agent sodium sulfite is insoluble in any organic solvent, only soluble in water. Therefore, the commonly used process generally adopts water phase reaction, and 4-methylbenzenesulfonyl chloride solid is added in the aqueous solution of sodium sulfite in batches. The hydrogen chloride produced in the reaction process increases the acidity of the system, so a weak base sodium bicarbonate is also added in the reaction process as an acid-binding agent to control the pH value. In this process, since the solid 4-methylbenzenesulfonyl chloride needs to be fed in batches, part of the 4-methylbenzenesulfonyl chloride is hydrolyzed in water, which reduces the yield, and the general yield is about 80%.

Contents of the invention

The present invention aims to propose a new synthesis process of sodium 4-methylbenzenesulfinate, which can improve the yield of sodium 4-methylbenzenesulfinate.

The steps of the synthetic technique of this 4-methylbenzenesulfinate sodium are: (1) 4-methylbenzenesulfonyl chloride is dissolved in methylene chloride; (2) the 4-methylbenzenesulfonate obtained in the previous step is The dichloromethane solution of acyl chloride is added dropwise in the aqueous solution of sodium sulfite, and 10% sodium hydroxide solution is added dropwise in the aqueous solution of sodium sulfite simultaneously, and control system becomes alkaline; (3) solvent two in the 2nd step gained reaction solution Chloromethane is distilled and recovered to obtain an aqueous solution of 4-methylbenzenesulfinic acid sodium; (4) the aqueous solution of 4-methylbenzenesulfinic acid sodium is cooled, suction filtered, washed with water, and dried to obtain 4-methylbenzenesulfinic acid Sodium acid.

This method has changed the feeding mode, and the dichloromethane solution containing 4-methylbenzenesulfonyl chloride is directly added dropwise in the sodium sulfite aqueous solution, has prevented the hydrolysis of 4-methylbenzenesulfonyl chloride, can improve the yield, and the product yield can be improved. Up to 85-89%; the acid-binding agent is changed to sodium hydroxide, and the buffer pair composed of the reducing agent is adjusted to balance the alkali, and the recovery rate of the solvent is improved, the production environment is cleaner, and gas emission is also avoided.

Description of drawings

Fig. 1 is the flow chart of the synthetic technique of 4-sodium methylbenzene sulfinate;

Figure 2 is a schematic diagram of the production device.

Detailed ways

As shown in Figure 1, the step of the synthetic technique of this 4-methylbenzenesulfinate sodium is: (1) 4-methylbenzenesulfonyl chloride is dissolved in methylene chloride; The dichloromethane solution of 4-methylbenzenesulfonyl chloride is added dropwise in the aqueous solution of sodium sulfite, and 10% sodium hydroxide solution is added dropwise in the aqueous solution of sodium sulfite simultaneously, and the control system becomes alkaline; (3) the reaction obtained in the second step The solvent dichloromethane in the liquid is distilled and recovered to obtain an aqueous solution of 4-sodium methylbenzenesulfinate; (4) the aqueous solution of 4-methylbenzenesulfinate is cooled, suction filtered, washed with water, and dried to obtain 4- Sodium toluene sulfinate.

The synthesis process of this sodium 4-methylbenzenesulfinate is to add the dichloromethane solution of 4-methylbenzenesulfonyl chloride dropwise in the aqueous solution of sodium sulfite, and use sodium hydroxide as an acid-binding agent, through controlling the amount, to reach Sodium sulfite and sodium bisulfite buffer to adjust the pH. After the solvent dichloromethane enters the system, it leaves the system quickly and is recovered by evaporation. The reaction solution was cooled to room temperature, filtered with suction, washed with a small amount of water to remove inorganic salts, and dried to obtain a pure product. Due to the subtle difference in the ultraviolet absorption of sodium 4-methylbenzenesulfinate and sodium 4-methylbenzenesulfonate in the water phase, a suitable wavelength can be selected for tracking analysis with a UV spectrophotometer to obtain the ratio of the main product to the by-product , to determine the reduction yield.

The reaction formula that 4-methylbenzenesulfonyl chloride is reduced into sodium 4-methylbenzenesulfinate is as follows:

The following describes the embodiment

Example 1:

(1) Add 13.74g (0.109mol) of anhydrous sodium sulfite and 300ml of deionized water into a four-necked bottle equipped with a ZNY2000 intelligent chemical reaction control device for pH, temperature and stirring.

(2) After the sodium sulfite is completely dissolved, add dropwise a solution of 20.07g (0.1mol) 4-methylbenzenesulfonyl chloride dissolved in 50ml of dichloromethane. The temperature is controlled at 55-60°C. Sodium solution, control system pH=8.

(3) After the raw material was added dropwise, the dropwise addition of alkali was stopped and the temperature was raised to 85° C. for 1.3 hours. The reduction yield was 89% through ultraviolet spectrophotometric tracking analysis.

(4) Solvent methylene chloride is recovered by distillation at this reaction temperature.

(5) The reaction mixture is cooled and crystallized, and 4-methylbenzenesulfinate sodium and inorganic salt crystals are separated out, and the crude product is recrystallized to obtain 4-methylbenzenesulfinate sodium crystals, and the quality after drying is 16.0 grams .

Example 2:

(1) Add 13.74g (0.109mol) of anhydrous sodium sulfite and 300ml of deionized water into a four-necked bottle equipped with a ZNY2000 intelligent chemical reaction control device for pH, temperature and stirring.

(2) After the sodium sulfite is completely dissolved, add dropwise a solution of 20.07g (0.1mol) 4-methylbenzenesulfonyl chloride dissolved in 50ml of dichloromethane, the temperature is controlled at 55-60°C, and at the same time add dropwise 10% sodium hydroxide solution Control system pH=7.6.

(3) After the dropwise addition of the raw materials is completed, the dropwise addition of alkali is stopped and the temperature is raised to 85° C. for 1 hour. After ultraviolet spectrophotometric tracking analysis, the reduction yield was 89%.

(4) Solvent methylene chloride is recovered by distillation at this reaction temperature.

(5) The reaction mixture was cooled and crystallized, and 4-methylbenzenesulfinic acid sodium and inorganic salt crystals were separated out, and the crude product was recrystallized to obtain 4-methylbenzenesulfinic acid sodium crystals, and the quality after drying was 15.9 grams .

Example 3:

(1) Add 13.74g (0.109mol) of anhydrous sodium sulfite and 250ml of deionized water into a four-necked bottle equipped with a ZNY2000 intelligent chemical reaction control device for pH, temperature and stirring.

(2) After the sodium sulfite is completely dissolved, add dropwise a solution of 20.07g (0.1mol) 4-methylbenzenesulfonyl chloride dissolved in 50ml of dichloromethane, the temperature is controlled at 55-60°C, and at the same time add dropwise 10% sodium hydroxide solution Control system pH = 7.6.

(3) After the raw material is added dropwise, stop adding alkali and raise the temperature to 85° C. for 50 minutes. After ultraviolet spectrophotometric tracking analysis, the reduction yield was 86%.

(4) Solvent methylene chloride is recovered by distillation at this reaction temperature.

(5) The reaction mixture is cooled and crystallized, and 4-methylbenzenesulfinic acid sodium and inorganic salt crystals are separated out, and the crude product is recrystallized to obtain 4-methylbenzenesulfinic acid sodium crystals, and the quality after drying is 15.3 grams .

Example 4:

(1) Add 13.74g (0.109mol) of anhydrous sodium sulfite and 200ml of deionized water into a four-necked bottle equipped with a ZNY2000 intelligent chemical reaction control device for pH, temperature and stirring.

(2) After the sodium sulfite is completely dissolved, add dropwise a solution of 20.07g (0.1mol) 4-methylbenzenesulfonyl chloride dissolved in 50ml of dichloromethane, the temperature is controlled at 55-60°C, and at the same time add dropwise 10% sodium hydroxide solution Control system pH=7.6.

(3) After the dropwise addition of the raw materials is completed, the dropwise addition of alkali is stopped and the temperature is raised to 85° C. for 1.2 hours. After ultraviolet spectrophotometric tracking analysis, the reduction yield was 89%.

(4) Solvent methylene chloride is recovered by distillation at this reaction temperature.

(5) The reaction mixture is cooled and crystallized, and 4-methylbenzenesulfinate sodium and inorganic salt crystals are separated out, and the crude product is recrystallized to obtain 4-methylbenzenesulfinate sodium crystals, and the quality after drying is 16.0 grams .

The present invention is a new process for synthesizing sodium 4-methylbenzenesulfinate. The raw material 4-methylbenzenesulfonyl chloride of the process is dissolved in dichloromethane and the flow rate is controlled for feeding. After the solvent sends the raw material into the reaction kettle, it is recovered by evaporation. Recycling, reducing environmental pollution, and easy industrial production. The designed production device is shown in Figure 2. Among the figure 1 is the elevated storage tank of the solution of 4-methylbenzenesulfonyl chloride dissolved in dichloromethane, 2 is the lye storage tank, 3 is the reactor, 4 is the condenser, 5 is the dichloromethane storage tank, and 6 is the Pump. The reaction process is: put the reducing agent sodium sulfite and water into the reactor 3, heat it to 80°C under stirring, then add the dichloromethane solution of 4-methylbenzenesulfonyl chloride dropwise from the high-level storage tank 1 into the reactor, and simultaneously from The lye storage tank 2 drips lye into the reaction kettle, the heat in the reaction process evaporates the solvent and enters the condenser 4, and the condenser condenses the methylene chloride into a liquid, enters the methylene chloride storage tank 5, and then uses the pump 6 Put it into the high level storage tank 1 for the dissolution of 4-methylbenzenesulfonyl chloride solid. After the raw materials were added dropwise, the temperature was kept for 1 hour, the discharged material was cooled, crystallized, and the crude product was obtained by suction filtration.

Claims (1)

1. the synthesis technique of a 4-methyl sodium benzene sulphinate is characterized in that the steps include: that (1) is dissolved in the 4-toluene sulfonyl chloride in the methylene dichloride; (2) dichloromethane solution with the 4-toluene sulfonyl chloride of gained of upper step is added drop-wise in the aqueous solution of S-WAT, drips 10% sodium hydroxide solution simultaneously in the aqueous solution of S-WAT, and hierarchy of control alkalize; (3) with the methylene chloride Distillation recovery in the 2nd step gained reaction solution, obtain the aqueous solution of 4-methyl sodium benzene sulphinate; (4) aqueous solution cooling, suction filtration, washing, the oven dry with the 4-methyl sodium benzene sulphinate obtains the 4-methyl sodium benzene sulphinate.

Images