The general procedure for the synthesis of N,O-di-BOC-hydroxylamine from di-tert-butyl dicarbonate was as follows: first, hydroxylamine hydrochloride (550.0 g, 7.9 mol) was dissolved in a solvent mixture of water (5.5 L) and heptane/MTBE (5:1, 5.5 L), and the mixture was cooled to -5 °C. Subsequently, a solution of di-tert-butyl dicarbonate (3.55 Kg, 16.3 mol) and triethylamine (1.67 Kg, 16.5 mol) in heptane/MTBE (5:1, 1.1 L), which was pre-cooled to -5°C, was slowly added dropwise to the above mixture, and the dropwise process lasted for more than 2 hours. The reaction mixture was continued to be stirred at -5°C for 1 hour, then gradually warmed up to room temperature and stirred overnight. Upon completion of the reaction, the organic layer and the aqueous layer were separated, and the organic layer was washed twice with saturated aqueous ammonium chloride solution (2 L) and saturated aqueous sodium chloride solution (1 L) sequentially, then dried with anhydrous sodium sulfate, filtered and concentrated to obtain an oily product, which was converted to a white solid by crystallization. Finally, the resulting solid was stirred with heptane (1 L) in an ice-water bath and filtered to afford the target product N,O-dibOC-hydroxylamine (1360.2 g, 73% yield). The structure of the product was confirmed by 1H NMR (d6-DMSO) with characteristic peaks located at δ 10.7 (broad single peak, 1H), 1.44 (single peak, 9H), 1.40 (single peak, 9H).
