Sodium Hydroxide → Bis(4-methoxyphenyl)phosphine

Participants

Reaction Steps

A solution-suspension of 1.4 g (5.34 mmol) of bis(4-methoxyphenyl)phosphine-oxide in 18 mL of toluene was treated under argon with 3.35 g (2.5 mL, 25 mmol) of trichlorosilane in one portion. This resulted in moderate heat and gas evolution and led to complete solution of the phosphine oxide. The mixture was heated at 90° for 5 h, whereupon the clear colorless solution was cooled to 0°. With vigorous stirring, 8.0 mL of 2 N aqueous sodium hydroxide solution (16 mmol) was added slowly while cooling the mixture in an ice-bath to moderate the vigorous reaction. When all the sodium hydroxide had been added, the mixture was allowed to warm to room temperature and stirred vigorously until all solid dissolved (30-90 min), leaving two clear, colorless liquid phases. The layers were allowed to separate and the toluene layer was drawn off under argon via a cannula. The aqueous layer was extracted with 2×20 mL of toluene. The combined toluene extracts were dried (deoxygenated brine and sodium sulfate), filtered, and stripped of solvent on the rotary evaporator at 80°/5 mm Hg to give 1.11 g (84.5%) of crude product. The thick oil was distilled by bulb to bulb distillation at 115°-135°/0.02 mm Hg for 1 h to give 0.747 g (57%) of bis-(4-methoxyphenyl)phosphine as a colorless thick oil which shortly crystallized to colorless, slightly greasy crystals.

Provenance & Evidence