Ambident nucleophiles. II. Nitrogen-bonded and carbon-bonded σ-complex formation in the reaction of pyrrolide anions with 1,3,5-trinitrobenzene
- 1 August 1982
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 60 (15) , 1988-1995
- https://doi.org/10.1139/v82-280
Abstract
Reaction of 1,3,5-trinitrobenzene (TNB) with pyrrole, 2,5-dimethyl pyrrole, and 2,4-dimethyl-3-ethyl pyrrole in the presence of a strong base (CH3O−) yields nitrogen- and/or carbon-bonded 1:1 σ-complexes in dimethylsulphoxide (DMSO). Depending on the stoichiometry of the reagents, 1:2 and 2:1 pyrrole–TNB diadducts are also formed. Identification of all complexes was effected by nmr. The reactive species are shown to be the pyrrolide ions and the results emphasize the ambident character of these anions towards an aromatic electrophile. Some of the complexes have been isolated as crystalline potassium salts when experiments are performed in acetonitrile. Among the isolable complexes, the kineticallybutnotthermodynamicallyfavored nitrogen adduct of pyrrole (5a) is remarkably unreactive. The second-order rate constant kH+ for is H+-catalyzed decomposition in aqueous solution is only 1 L mol−1 s−1 (t = 25 °C).Keywords
This publication has 0 references indexed in Scilit: