Under nitrogen, a 50 L extractor was charged with dichloromethane (20 L), triethylamine (7.1 L, 50.9 mol), and hydroxylamine hydrochloride (1769 g, 25.5 mol). The mixture was stirred for 45 minutes then tert-butylchlorodiphenylsilane (7 kg, 25.5 mol) was added in seven 1 kg portions over 40 minutes. Additional dichloromethane (10 L) was added, filling the vessel to capacity. The joints were stoppered and the mixture stirred at 20° C. for 5 days. The resulting thick white suspension was filtered to remove the precipitate (mostly triethylamine hydrochloride). The filtrate was concentrated to a thick paste by rotary evaporation on two separate evaporators. Ethyl acetate (4 L) was added to each portion and evaporation continued until 2 L of solvent were condensed. The suspension from each half was combined in the 50-L reactor, ethyl acetate (28 L) was added, and the mixture was stirred for 15 minutes. The mixture was filtered (removing the remaining triethylamine hydrochloride) and the solvent evaporated (again using two rotary evaporators). When most of the solvent was removed, hexane (4 L) was added to each portion and evaporation continued until 2 L of solvent were condensed. The two halves were combined in the 50-L reactor, hexane (20 L) was added, and the mixture was stirred for 15 minutes. The resulting white solid was collected by filtration, washed with hexanes, and dried in a vacuum oven at 40° C., giving 4780 g (69% yield) of O-(tert-butyldiphenylsilyl)-hydroxylamine.
