Synthesis
Quickly weigh 10.2g of anhydrous AlCl3 (finely ground), added to a dry four-necked flask, and immediately add 114mL of m-dichlorobenzene (dried), the middle mouth mounted electric stirrer, the side of the mouth, respectively, thermometer, constant-pressure dropping funnel (containing a certain amount of purified acetic anhydride, the upper part of the spherical condenser tube is connected to a drying tube equipped with anhydrous CaCl2 and the absorption of toxic gases and the absorption device (absorbent solution for the), under uniform stirring, slowly dripping from the constant-pressure dropping funnel, adjust the drop acceleration, so that the reaction temperature is controlled below 60 , and adjust the drop acceleration, so that the reaction temperature is controlled below 60 . 5% NaOH solution), under uniform stirring, from the constant pressure dropping funnel slowly drop acetic anhydride, adjust the drop acceleration, so that the reaction temperature is controlled below 60 , the temperature rises in the drop process, a large number of white gases escaping, the solution color deepens, the drop is completed, the solution is a mauve 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 reactants were transferred to a partition funnel, the organic layer was separated, the aqueous layer was extracted with toluene in two stages, and finally the toluene layer was combined, the toluene layer was washed with 5% NaOH solution, distilled water, respectively, until the aqueous layer was pH=7.
Toluene as well as a small amount of water mixture was removed by rotary evaporation and recovered, and the residue was subjected to decompression distillation for collection of fractions at 125~126C under 25 mm Hg (under atmospheric pressure, 2,4&# 39;-dichloroacetophenone has a boiling point of 245~247C), which is a brown oily liquid. The product was placed in a refrigerator to cure the crystallization. In this experiment, ethanol was used as the solvent for recrystallization, and the product obtained from curing was recrystallized and dried to obtain the final product 2,4'-dichloroacetophenone.
