Hydrogen Peroxide → (2,4,6-Trimethylbenzoyl)bis(o-tolyl)phosphine oxide

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Under argon and with exclusion of moisture, 4.6 g of chopped sodium (0.20 mol) are placed at room temperature in 100 ml of tetrahydrofuran. Stirring slowly, 24.9 g (0.10 mol) of ditolyl phosphine chloride (isomeric mixture of di-ortho, di-para and ortho-para) are added dropwise at 20-25° C. After stirring for 12 h, the red solution is filtered via a glass frit (G2 porosity) into a sulfonation flask with exclusion of moisture and using argon as protective gas. With stirring and cooling, 19.0 g (0.105 mol; 5% excess) of 2,4,6-trimethylbenzoyl chloride are added dropwise over 30 minutes at room temperature. After stirring for another 2 hours, the brownish-red reaction suspension is poured on water and extracted with toluene. The organic phase is dried over magnesium sulfate, filtered and concentrated by evaporation in a rotary evaporator (Rotavap). The resulting phosphine has a 23.24 ppm shift in the 31P-NMR spectrum. The residue is taken up in 100 ml of toluene and charged with 11.5 g (0.10 mol) of hydrogen peroxide (30%). The reaction is complete after stirring for 2 hours at a temperature from 50-60° C. The reaction emulsion is poured on water and washed with an aqueous saturated sodium hydrogencarbonate solution and then dried over magnesium sulfate and filtered. The filtrate is concentrated by evaporation in a Rotavap. The residue is purified over silica gel and dried under high vacuum, yielding 33.8 g (90% of theory) of the title compound in the form of a yellow viscous oil. The 31P-NMR shift is 14.54 ppm.

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