Preparation method for photoinitiator bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide

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.