Process for the preparation of highly concentrated aqueous solutions of pure monochloroacetaldehyde

摘要

The invention relates to an improved process for the preparation of highly concentrated aqueous solutions of pure monochloroacetaldehyde by reacting chlorine with vinyl acetate in water. In this process, liquid chlorine, vinyl acetate and water in a molar ratio from 1 : 0.99 to 0.999 : 6 to 10 are continuously reacted at temperatures from -10 to +20 DEG C and an average product residence time from 5 to 500 minutes, the reaction mixture produced is treated at temperatures from 0 to 35 DEG C with, for example, sodium carbonate in a sufficient quantity to maintain a pH between 1 and 2 in the reaction mixture, and said mixture is subsequently distilled under a pressure from 20 to 60 kPa, using a column of average separation efficiency. The distillate obtained is in the form of aqueous solutions containing from 70 to 88% by weight of monochloroacetaldehyde, with only small amounts of acetic acid (< 0.5% by weight) and other organic by-products (< 1.0% by weight in total). <IMAGE>