The invention discloses a preparation method for a
photoinitiator bis(2,4,6-trimethylbenzoyl)
phenylphosphine oxide. The preparation method comprises the synthesis steps: under the protection of
inert gas, carrying out a reaction of
aluminium trichloride or
tin tetrachloride and
trimethylsilane in the temperature range of 0-100 DEG C to obtain
aluminium dichloride ions, and rapidly acting with dichlorophenyl
phosphine in the
reaction system, to obtain a bis(
aluminium trichloride or
tin tetrachloride)
phosphine salt intermediate; then carrying out a reaction of the intermediate and 2,4,6-trimethyl
benzoyl chloride, to obtain bis(2,4,6-trimethylbenzoyl)phenyl
phosphine; and under the condition of the temperature of 20-50 DEG C, oxidizing by
nitrogen dioxide, to obtain the target product. The method avoids use of a dangerous active
metal potassium or
sodium, and adopts aluminium trichloride or
tin tetrachloride with relatively low price and
trimethylsilane for on-site generation of the active intermediate to achieve the reaction. The method has the characteristics of low preparation cost, simple and
safe operation process, easy control of the reaction process, high product yield, good purity, easy realization of
mass production and the like.