Method for preparing 4.4-dichlorodiphenyl sulfone by using sulfur trioxide

Abstract

The invention discloses a method for preparing 4.4-dichlorodiphenyl sulfone by using sulfur trioxide, which comprises the following steps: dripping sulfur trioxide into chlorobenzene to perform a sulfonation reaction; after the sulfonation reaction is finished, adding dimethyl sulfoxide serving as a catalyst, heating, introducing nitrogen, dripping thionyl chloride to perform an acid halogenation reaction and absorbing sulfur dioxide and hydrogen chloride generated in an acid halogenation reaction process by using alkaline liquor; and after acid halogenation reaction is finished, adding antimony pentachloride serving as a catalyst, introducing nitrogen, and dripping chlorobenzene at room temperature to perform a Friedel-Crafts reaction to produce coarse 4.4-dichlorodiphenyl sulfone. Therefore, the method can effectively lower reaction temperature and reaction time, thereby saving production cost; in addition, nitrogen is introduced into the reaction solution in the whole reaction process, so the production of byproducts is reduced effectively. The 4.4-dichlorodiphenyl sulfone yield of the method may reach 98 percent.

Description

technical field [0001] The invention relates to a preparation method of 4.4-dichlorodiphenyl sulfone, in particular to an improved preparation method of 4.4-dichlorodiphenyl sulfone after sulfur trioxide is used for sulfonation of chlorobenzene. Background technique [0002] 4.4-Dichlorodiphenylsulfone, referred to as DDS, is a white crystal, sublimable, easily soluble in benzene, chlorobenzene, DMF and other organic solvents; slightly soluble in ethanol and methanol; insoluble in water. Its flash point is 233°C and its boiling point is 397°C. [0003] 4.4-Dichlorodiphenyl sulfone is widely used in the field of engineering plastics and fine chemicals. It is the main raw material for the preparation of engineering plastics such as polysulfone and polyethersulfone, and is also an intermediate for medicine, dyes, and pesticides. [0004] At present, the sulfur trioxide method for preparing 4.4-dichlorodiphenyl sulfone has the advantages of good product quality, high yield, mil...

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Problems solved by technology

[0004] At present, the sulfur trioxide method for preparing 4.4-dichlorodiphenyl sulfone has the advantages of good product quality, high yield, mild reaction conditions, and low waste. However, its entire process route is long, and the Fockers reaction is due to the use of FeCl3 or AlCl3 As a catalyst, the reaction temperature is between 150-160°C, the reaction temperature is high, and the reaction time is as long as 8 hours. At the same time, the refining process route is complicated and the equipment investment is large. Therefore, the process is limited to a certain extent.