22737-37-7

Clear colorless liquid

bp 137–139°C, 78–80°C/100 mmHg; d 0.830 g cm?3; flash point 28°C.

N,O-Bis(trimethylsilyl)hydroxylamine is a protected, lipophilic form of hydroxylamine. It reacts with a variety of electrophiles predominantly by attack on the nitrogen nucleophilic center. Reaction with acid chlorides (1 equiv) in the presence of triethylamine gives N,O-bis(trimethylsilyl)- hydroxamic acids by N-acylation.A related reagent, tris(trimethylsilyl) hydroxylamine, gives the same product in high yields, also by N-acylation.Hydrolysis gives the free hydroxamic acids, whereas thermal fragmentation affords isocyanates (eq 1).

N,O-Bis(trimethylsilyl)hydroxylamine can be prepared in 69% yield by treating dry hydroxylamine with equiv chlorotrimethylsilane and equiv triethylamine.A safer preparation, which avoids the use of the explosive solid, hydroxylamine, uses the reaction of hydroxylamine hydrochloride with excess hexamethyldisilazane (71–75% yield).Alternatively, neutralization of hydroxylamine hydrochloride with ethylenediamine followed by addition of chlorotrimethylsilane can be used.