Phosgene method for synthesizing chloroformic acid-2-chloroethyl ester

Abstract

The invention discloses a phosgene method for synthesizing chloroformic acid-2-chloroethyl ester. The phosgene method comprises the following steps: step 1, adding Ag2-chloroethanol into a reaction device at the bottom, and cooling the materials in the reaction device to a set temperature of -5 to -15 DEG C; step 2, after the temperature of the materials in the reaction device is reduced to the set temperature, and introducing phosgene through a flow meter; wherein the cumulative introduction amount of phosgene is Bg; step 3, when the phosgene flow is accumulated to Bg, stopping introducing phosgene, heating the materials in the reaction device to 20-25 DEG C, and keeping the temperature for 2 hours; step 4, after heat preservation is completed, introducing nitrogen to remove excessive phosgene and hydrogen chloride to obtain a chloroformic acid-2-chloroethyl ester product. By reducing the reaction temperature in the early stage, the side reactions are inhibited, the concentration of 2-chloroethanol gradually decreases in the later stage, the possibility of generation of side reactions is reduced, the temperature is gradually increased then, the complete reaction of 2-chloroethanolis promoted, the generation of side reactions is reduced, and the product yield is increased.

Description

Technical field [0001] The invention belongs to the field of chemistry, and particularly relates to a method for synthesizing 2-chloroethyl chloroformate by a phosgene method. Background technique [0002] 2-Chloroethyl chloroformate is a chemical with a molecular formula of C3H4Cl2O2. It is mainly used as a reagent for organic synthesis and is a raw material for many drugs. The existing preparation method is to add chloroethanol into the phosgene reactor, start stirring, and then pass phosgene through a phosgene flow meter. The phosgene temperature is 40~50℃, and the phosgene is continuously vented for 20-24 hours. When the end point is reached, the phosgene is sampled and analyzed. After reaching the standard, the phosgene is stopped, and then the phosgene and hydrogen chloride are driven away by nitrogen to obtain the product. However, our company found that in the above-mentioned production method, since the starting temperature and the ending temperature are consistent, at ...

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Problems solved by technology

However, the research of our company has found that in the above production method, since the starting temperature and the ending temperature are consistent, at the beginning, 2-chloroethanol will react with the product 2-chloroethyl chloroformate to generate carbonic acid diester: