A novel rearrangement in ESI-MSn of spirocyclic pentaerythritol di(phosphate monoamides)

Several spirocyclic pentaerythritol di(phosphate monoamides) as intumescent flame retardants were synthesized and analyzed by electrospray ionization multistage tandem mass spectrometry. A novel amino group migration from the phosphoryl group to the two methylenes was observed. This migration is believed to be a general pathway for ions with the small size and electronic donating alkyl groups of spirocyclic pentaerythritol di(phosphate monoamides), which is assisted by twice nucleophilic substitutions. Steric and electronic effects of alkyl groups might be a key factor responsible for this migration.