. Can. J. Chem. 53,3761 (1975). 1,3,5-Trinitrobenzene reacts with potassium phenoxide in dimethyl sulfoxide solution to yield a o-complex in which bonding has occurred between the para carbon of the phenoxy moiety and an unsubstituted carbon of the nitroaromatic substrate. A minor proportion of ortho adduct is also obtained. When the reaction is performed in v/v) one obtains initially the methoxide adduct of TNB which is then smoothly transformed into the phenoxide adduct. The latter is stable to dilute mineral acid, unlike the former; formation of a o-complex involving bonding between the phenoxy oxygen and a carbon of TNB is thereby excluded. The reaction represents the first instance of phenoxide ion acting as an ambident nucleophile towards aromatic carbon. The implication of this finding on the course of related SNAr reactions is discussed on the basis of kinetic and thermodynamic control of product formation. Chem. 53, 3761 (1975). Le trinitro-1,3,5 bendne (TNB) reagit avec le phenolate de potassium dans le DMSO pour conduire a un complexe-o dans lequel un lien s'ktablit entre la position-para d'un phenolate et un carbone non substitue du substrat nitroaromatique. On obtient aussi des quantites plus faibles d'adduit ortho. Quand on effectue la reaction dans le DMSO-MeOH (80:20 v/v) on obtient au dtbut le produit d'addition du methylate sur le TNB qui se transforme par la suite en adduit du phenolate. Ce dernier est stable en milieu acide dilue ce qui n'est pas le cas du premier; la formation d'un complexe-o impliquant un lien entre I'oxygene du phenolate et un carbone du TNB est exclue sur cette base. La rtaction correspond au premier cas oh I'ion phenolate agit comme nucleophile ambident vis-a-vis un carbone aromatique. On discute de I'implication de ce rkultat sur I'orientation des reactions SNAr; cette discussion est faite en se basant sur le contrble cinttique et thermodynamique de la formation du produit.[Traduit par le journal]Whereas alkoxide ion o-complexes of nitroaromatic compounds have been extensively investigated ( 1 4 ) and their structures fully established (e.g. 1) (5, 6), corresponding aryloxide ion complexes have so far received only scant attention (7-10). Moreover, little agreement exists at present concerning the structures of such aryloxide complexes. Bond formation between the phenoxy oxygen and the nitrogen center of a nitro group was proposed by Tronov and co-workers (7, 8), on the basis of colorimetric studies, for the reaction of phenoxide ion with dinitrobenzene. A more conventional structure, 2, involving bonding between phenoxy oxygen and an unsubstituted carbon of the nitroaromatic was advanced by Shein and Byval'kevich 'Presented in part at the 58th Annual Canadian Chemical Conference of the Chemical Institute of Canada, Toronto, Ontario, May, 1975. ZPermanent address: Institute of Organic Chemistry and Technology, Politechnika, Warsaw, Poland.(9), on the basis of n.m.r. and u.v.-visible spectroscopy, for the phenoxide ion reaction with 1,3,5-trinitrobenzene (TNB). In c...
