2-chloro-1-(3,4-difluorophenyl)ethanone preparation steps are as follows: quickly weigh 10.2g anhydrous aluminum trichloride, (finely ground), added to a dry four-necked flask, and immediately add 11.4mL of o-difluorobenzene (dried), the middle of the mouth mounted electric stirrer, the side of the mouth, respectively, the installation of thermometers, constant-pressure dropping funnel (containing a certain amount of purified acetic anhydride, the top of the spherical condensing tube Connected to a dry tube equipped with anhydrous calcium chloride and toxic gas absorption device (absorption solution for 5% NaOH solution), under uniform stirring, from the constant pressure dropping funnel slowly dripping acetic anhydride, adjust the drop acceleration, so that the reaction temperature is controlled at 60 ?? below the temperature rise in the process of dropping, there are a large number of white gas escapes, the solution color deepens, dropping is completed, the solution is lavender viscous. Heating reflux reaction with an oil bath until no HCl gas escapes, the solution becomes light brown. Remove the gas absorption device, after cooling, the four-necked flask in a cold water bath, add a certain amount of ice-water mixture under stirring, the solids are all dissolved (if not dissolved, add a small amount of concentrated hydrochloric acid dropwise). The reaction is transferred to a partition funnel, the organic layer is separated, the aqueous layer is extracted with toluene in two batches, and finally the toluene layer is combined, the toluene layer is washed with 5% NaOH solution, distilled water, respectively, until the aqueous layer is pH=7. The toluene as well as a small amount of the water mixture is removed by rotary evaporation and recovered, and the residue is subjected to decompression distillation for the collection of 25 .
The fraction at 125-126??C at mmHg (boiling point of 2-chloro-1-(3,4-difluorophenyl)ethanone is 245-247??C at atmospheric pressure) was a brown oily liquid.
