6407-12-1Relevant articles and documents
15N NUCLEAR POLARISATION IN NITRATION AND RELATED REACTIONS. PART 2. p-NITROPHENOL
Clemens, Anthony H.,Ridd, John H.,Sandall, John P. B.
, p. 1667 - 1672 (1984)
The nitrous acid-catalysed nitration of p-nitrophenol by H(15)NO3 in aqueous trifluoroacetic acid gives a strong emission signal during reaction for the 2-(15)NO2 group in the 15N n.m.r. spectrum of the 2,4-dinitrophenol formed: the enhancement is by a factor of up to 600.The reaction is accompanied by 11percent migration of the original 4-nitro group to the 2-position and substitution by the labelled nitro group at the 4-position.The 15N n.m.r. spectrum during the related reaction using 15N labelled p-nitrophenol and unlabelled nitric acid shows that the migration of the 4-(15)NO2 group to the 2-position causes a strongly enhanced absorption signal for the 2-(15)NO2 group in the 2,4-dinitrophenol formed.A strongly enhanced absorption signal for this group is also found for the reaction of p-nitrophenol with H(15)NO3 in the presence of sodium azide.The complete set of results is interpreted in terms of nuclear polarisation deriving from the reactions of the radical pair ArO.NO2. when formed either by diffusion or from a singlet precursor.The reaction between hydrazoic acid and nitric acid is catalysed by p-nitrophenol.
