The invention relates to a synthesis method of 2, 2'-dihydroxy-4, 4'-dimethoxybenzophenone. The method comprises the following steps: 1) enabling m-dimethoxybenzene and
oxalyl chloride to react in the presence of a catalyst at the temperature of 70-80 DEG C for getting an
intermediate product 2, 2', 4, 4'-tetramethoxy
benzophenone, wherein the weight ratio of the m-dimethoxybenzene to the
oxalyl chloride is 1:1-20, the used catalyst is azo isobutyronitrile or
benzoyl peroxide, and the using quantity of the catalyst is 0.5%-2% of the weight of the m-dimethoxybenzene; and 2) enabling the obtained
intermediate product and Lewis acid to react under the condition of taking an organic
reagent as a
solvent, wherein the
reaction temperature is 50 DEG C and the reaction time is 2-3 hours; and stopping the reaction, adding water for
hydrolysis, skimming, performing rotary
evaporation and recrystallizing to get the 2, 2'-dihydroxy-4, 4'-dimethoxybenzophenone. The Lewis acid is one of AlCl3, ZnCl2, BF3 and polyphosphoric acid; and the organic
reagent is one of
dichloroethane,
toluene,
xylene,
nitrobenzene and
chlorobenzene. According to the method, the
reaction temperature is appropriate, the catalyst is simple and easy to get, the using quantity of the catalyst is low, the environmental
pollution is small, and the method is closest to the requirements of
green chemistry.