Continuous-pressure-changing rectification method and device for preparing medicine-level sulfoxide chloride

Abstract

The invention relates to a continuous-pressure-changing rectification method and a device for preparing medicine-level sulfoxide chloride. With the adoption of the pressure-changing rectification method, an indirect sequence of carrying out heavy component removal and then carrying out light component removal is adopted as a rectification sequence, so that the decomposition of sulfoxide chloride at high temperature is reduced; sulfur is coarsely mixed with raw materials, sulfur is mixed with tower top gas of a heavy component removal tower, and a low-boiling-point substance, namely sulfur dichloride which is hard to remove, is fundamentally converted into a high-boiling-point substance, namely sulfur monochloride which is easy to remove, due to multistep sulfur adding; and a catalyst is added, so that the dissolution rate and reaction rate of the sulfur are accelerated. The heavy component removal tower is subjected to normal-pressure operation; and a light component removal tower is subjected to depressurized operation. The energy consumption of operation is reduced, and the decomposition reaction of the sulfoxide chloride hardly carries out under depressurized conditions, so that the probability that the color and luster of products are polluted by sulfur dichloride is greatly reduced, high-purity and colorless sulfoxide chloride products are produced from tower bottoms, and the content is over 99.9%.

Description

technical field [0001] The invention belongs to the technical field of chemical production, and in particular relates to a continuous pressure swing rectification method and device for producing pharmaceutical grade thionyl chloride. Background technique [0002] Thionyl chloride is a colorless or pale yellow liquid with a pungent odor at normal temperature and pressure. It will decompose in a small amount above the boiling point (78.8°C). The decomposition rate is faster at 140°C. The products are sulfur dioxide, chlorine, sulfur dichloride and sulfur monochloride. Because of its strong chlorination and acyl chloride ability, it is an important chemical intermediate and widely used in traditional industries such as agriculture, medicine and dyes. . In addition, the scope of application of thionyl chloride is also expanding, and the downstream fields are gradually increasing. It has been used in food additive industries such as the preparation of sucralose and new energy in...

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Problems solved by technology

The liquid phase solvent method removes excess impurities by adding an organic solvent and reacting with impurities in thionyl chloride, but this method forms by-products that are difficult to recycle, and thionyl chloride is dissolved in the solvent and is difficult to recover , resulting in a lower product yield; at present, rectification and purification methods are often used at home and abroad. The difficulty of this method is that thionyl chloride will decompose in a small amount above the boiling point, and the decomposed product sulfur dichloride will seriously affect the color of the product. Even if the product contains 0.1% (mass fraction) of sulfur dichloride, it will make the product appear obviously yellow, so it is difficult to obtain colorless and high-purity thionyl chloride product

For this problem, some invention patents have been proposed at home and abroad, such as U.S. patents US3155457, US3592593, US4337235 and US4388290, Chinese patents CN101284650A, CN101920938, the above patents are all one-stage or intermittent atmospheric distillation methods, and have not effectively solved the problem of chlorination. The problem that sulfone will be decomposed into sulfur dichloride, an impurity that is difficult to remove above the boiling point, and the energy and material consumption are relatively large, so it is impossible to obtain high-purity pharmaceutical-grade thionyl chloride

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