To a solution of 1- (biphenyl-4-yl) -2-methyl-2-chloropropane-1-one synthesized in Step 3) was added 62.2 g of morpholine and 114 g of a saturated sodium carbonate solution, The reaction was carried out. After the completion of the reaction, the aqueous phase was separated and the aqueous phase was separated. After the organic phase was washed with an equal volume of water, the solvent was recovered under reduced pressure to give 1_ (biphenyl-4-yl) -2-morpholinylpropan-1-one. The recovered solvent was allowed to be applied directly to the next batch. The crude product was recrystallized from absolute ethanol, filtered and dried to give a white powder Solid 182.5 grams, the yield of 91%, 99.4% purity, the filtrate can be applied to the next batch of crude crystal 1~2 times.
