Scalable Preparation of O-(Diphenylphosphinyl) hydroxylamine (DPPH)

Abstract

A. tert-Butyl (diphenylphosphoryl)oxycarbamate. Into a clean and dry 1-L 3-necked flask containing a magnetic stir bar (1.25 in egg-shaped) tert-butyl-N-hydroxycarbamate (30.9 g, 232 mmol, 1.10 equiv) is added in one portion along with dichloromethane (200 mL) (Note 2) in one portion. Once the charging is completed, the middle neck of the flask is fitted with a 125-mL addition funnel and a nitrogen inlet, followed by placing a temperature probe on the second neck and a septum on the third neck of the flask. After connecting the setup to a nitrogen inlet, stirring of 200 rpm is initiated, and