Method for preparing 4, 4 '-difluorobenzophenone by tubular diazotization oxidation method

The invention discloses a method for preparing 4, 4 '-difluorobenzophenone by a tubular diazotization oxidation method, which comprises the following steps: S1, dissolving 4, 4'-diaminodiphenylmethane in a solvent, and reacting to obtain 4, 4 '-diaminodiphenylmethane hydrochloride slurry; s2, preparing a sodium nitrite solution; s3, carrying out diazotization oxidation reaction on the slurry and a sodium nitrite solution in a tubular reactor to obtain a 4, 4 '-diaminodiphenylmethane dichloro diazonium salt solution; s4, cooling and centrifuging the diazonium salt solution; s5, taking the centrifugal mother liquor to react with a fluoboric acid aqueous solution, washing and drying to obtain a 4, 4 '-diaminodiphenylmethane difluoboric acid diazonium salt solid; the preparation method comprises the following steps of S1, preparing a diazonium salt solid, S2, preparing a diazonium salt solution, S6, cracking and distilling the diazonium salt solid to obtain 4, 4 '-difluorodiphenylmethane, S7, preparing a nitric a