Preparation of benzene sulfonyl chloride_Kain Industrial Additive

Background and Overview^[1]

Benzenesulfonyl chloride is a white flake crystal with a melting point of 69-71°C. It is an important organic synthesis drug intermediate and is mainly used in the synthesis of chloramphenicol, chloramphenicol, thiamphenicol and other drugs.

The existing production process of benzene sulfonyl chloride is produced by the reaction between benzene and chlorosulfonic acid. Since the hydrogen chloride gas produced by the reaction is input into the planar absorption equipment at a slight positive pressure, the water in the absorption equipment absorbs the hydrogen chloride and releases heat to keep the temperature constant. As the hydrogen chloride gas rises, the absorption effect becomes worse and worse. Due to the action of high-temperature hydrochloric acid, the equipment and contacts of the absorption system are easily corroded and damaged, resulting in a large amount of hydrogen chloride gas leakage that cannot be absorbed. The exhaust gas is sprayed and absorbed by the ceramic absorption tower. Discharged into sewers, seriously polluting the surrounding environment. At the same time, after the sulfonation reaction, the sulfonation liquid is slowly added to a large amount of ice water for hydrolysis and dilution, thus producing waste sulfuric acid with a concentration of about 20%. Due to the low acid concentration, it is difficult to process and is discharged in large quantities, which seriously pollutes the environment. Increased management costs.

benzenesulfonyl chloride

Apply^[3]

Benzenesulfonyl chloride is a widely used chemical intermediate for the preparation of sulfonamides and the identification of various amines.

Preparation^[2]

The synthesis of industrial benzene sulfonyl chloride uses benzene and chlorosulfonic acid as raw materials and is purified through sulfonation. The current synthesis method of benzene sulfonyl chloride is to use excess sulfonyl chloride and benzene for sulfonation reaction. After the reaction, the excess sulfonyl chloride is destroyed by washing with water, and then neutralized by alkali washing. This process has the following problems: 1. Due to chlorosulfonic acid It is a strong acid that will immediately decompose and release a large amount of gas and heat when meeting water, which is prone to accidents; 2. The sulfonation reaction temperature is high and the content of by-products such as phenyl sulfone is high, resulting in a low yield of benzenesulfonyl chloride, only 40~ 50%.

Specific method:

Method 1:

(1) Sulfonation reaction: Using chlorosulfonic acid and pure benzene with a molar ratio of 3.8:1 as raw materials, first add chlorosulfonic acid into a reaction kettle with a heating and stirring function, and stir at a stirring rate of 100r/min. Under stirring, use a constant pressure dropping funnel to add pure benzene dropwise at a dropping rate of 1 ml/min, and keep the reaction at 20°C for 2 hours until the reaction is complete. The generated hydrogen chloride gas is condensed and absorbed by secondary falling film to produce mass. The concentration is 38% hydrochloric acid solution;

(2) Add sodium chloride: Add 10g of dry sodium chloride to the mixture with sufficient sulfonation reaction in step (1), and continue to stir at a temperature of 20°C at a stirring rate of 300r/min. After reacting at a constant temperature for 30 minutes, the generated hydrogen chloride gas is condensed and secondary falling film absorption is made into a hydrochloric acid solution with a mass concentration of 38%; sodium chloride will react with some by-products to generate benzenesulfonyl chloride, which not only reduces the by-products generated, and also improved the yield;

(3) Pickling: Add waste acid solution with a mass concentration of 60% to the reacted solution in step (2), stir and pickle at a constant temperature below 30°C at a rate of 200r/min for 20min, and then Let stand and layer;

(4) Water washing: Take the upper solution after pickling and standing in step (3), add an appropriate amount of distilled water to wash, and let stand; the middle solution and the lower solution are collected and placed in the by-product tank and the sulfuric acid solution tank respectively, where , the sulfuric acid solution in the sulfuric acid solution tank can be used as the acid solution for pickling to achieve recycling;

(5) Distillation: Take the lower layer of the water-washed solution in step (4) and place it into a rectification kettle, perform distillation under reduced pressure at a temperature of 250°C, and collect the fraction at 150°C/-0.098MPa, which is Benzenesulfonyl chloride pure product.

Method 2: Industrial production process

When producing, put 1120kg chlorosulfonic acid (HSO3Cl) into the sulfonation reaction kettle according to the feed ratio, start stirring and control the stirring speed to 50 rpm, and drop 300kg benzene into the sulfonation reaction kettle for sulfonation. chemical reaction, the benzene dropwise addition reaction time is 3.5 hours, and the reaction temperature is controlled at 25°C; the sulfonation liquid generated by the sulfonation reaction is sent to the hydrolysis dilution kettle, and a calculated amount of 588kg hydrochloric acid with a concentration of 30% is dropped into the sulfonation liquid. The dripping speed is first Slow and then fast. The dripping amount per hour is 50-200kg. Control the reaction temperature to be less than 50°C. The hydrolysis and dilution time is 3.5 hours. Then the material is left to stand and stratified. The hydrogen chloride gas produced by the sulfonation reaction and hydrolysis dilution is absorbed by the falling film absorption tower. , the water spray volume is 5m3/hour. The sulfonation reaction, hydrolysis dilution reaction and hydrogen chloride gas absorption system are always in a slightly negative pressure state through the water ejector. A small amount of hydrogen chloride tail gas is absorbed by the water ejector and then supplied to the falling film absorption tower. Absorb water, and the vacuum degree of the entire absorption system is 0.01MPa; the 60% sulfuric acid separated from the liquid phase after the material is left to stand and stratified is sent to the sulfuric acid storage tank. At the same time, the crude benzene sulfonyl chloride is sent to the bleaching kettle for rinsing. After rinsing, the material is sent to the reducer. Pressure distillation kettle; after distillation in the distillation kettle, control the vacuum degree ≥ 0.096MPa, the distillation temperature 160-180°C, and the distillation speed 130-160kg/hour. During the distillation process, the head and tail materials are returned to the bleaching kettle to continue washing, clear and transparent The concentrate is the finished product of benzene sulfonyl chloride. The quality indicators of the finished product of benzene sulfonyl chloride are as follows: 1. Content 99.52%, 2. Free acid (calculated as HCL) ≤ 0.1%, 3. Diphenyl sulfone ≤ 0.09%, 4. Chroma (Heizen) ≤ 25.

Main reference materials

[1] Li Ying, Li Chengkun, Zhang Jianlin, Mou Qingping, Wu Wenlei, & Yao Gang et al. A preparation method of substituted benzenesulfonyl chloride.

[2] Yang Zhixiang. (2004). Research on the synthesis process of m-methoxybenzenesulfonyl chloride. (Doctoral dissertation, Zhejiang University).

[3] Li Xin, Shen Min��, Yang Qian, & Cai Tianming. (2012). %determination of piperazine in water using pre-column derivatization with p-tosyl chloride. Analytical Laboratory, 31( 12), 48-52.