Phosphorus–nitrogen compounds. Part XLIII. Reactions of NN-dialkylanilines with phosphorus(V) chlorides; examples of ambident nucleophilic behaviour

Abstract

The reactions of hexachlorocyclotriphosphazatriene (N₃P₃Cl₆) with dialkylanilines (PhNR₂) yield ‘carbon’-[N₃P₃Cl₅(C₆H₄·NR₂)] and ‘nitrogen-substituted,’[N₃P₃Cl₅(NRPh)] derivatives, whereas the analogous reactions of octachlorocyclotetraphosphazatetraene (N₄P₄Cl₈) yield only ‘nitrogen-substituted’ derivatives [N₄P₄Cl₇(NRPh) and N₄P₄Cl₆(NRPh)₂(R = Me)]. The behaviour of phosphoryl chloride with NN-dialkylanilines is much more complex, but ‘carbon-substitution’ predominates. Products include (R₂N·C₆H₄)₂P(O)R′, (R₂N·C₆H₄)₃P(O), (PhNR)P(O)R′₂, and PhNHR (R = Me or Et; R′= Cl, OH, or OEt) and (R₂N·C₆H₄)₂P(O)NRPh, (PhNR)₃P(O), (PhNR)₂P(O)(NHPh), (R₂N·C₆H₄)₂CH₂, and (R₂N·C₆H₄)₃CH (R = Me). From the analogous reactions of thiophosphoryl chloride only (Me₂N·C₆H₄)P(S)(OEt)₂ and (Et₂N·C₆H₄)₃P(S) were isolated. The behaviour of phosphoryl and thiophosphoryl chlorides with N-methylaniline was briefly investigated. Possible mechanisms for the reactions of phosphorus(V) chlorides with NN-dialkylanilines are briefly discussed. The ambident behaviour of the latter with the former and with cyanuric chloride is compared. S₀ Values are deduced from the ¹H n.m.r. spectra of the ‘carbon-substituted’ compounds.