Abstract: The relation between the reaction temperature and orientation of fluorine substitution in 2,4-difluoronitrobenzene by lithium phenoxides XC6H4OLi (X = p-OMe, p-Me, m-Me, N, p-F) in liquid ammonia suggests the enthalpy control of the competing reactions at the ortho and para positions with respect to the nitro group in the temperature range from -55 to -33°C. Increase in the electron-donor power of the substituent in the nucleophile in the series p-F ≈ H < m-Me < p-Me < p-OMe favors preferential substitution of the ortho-fluorine atom for enthalpy considerations. PM3, AM1, and MNDO semiempirical calculations of the relative heats of formation of anionic intermediates in the phenoxydefluorination of 2,4-difluoronitrobenzene indicate higher stability of a complexes corresponding to nucleophile addition at the para position of the aromatic substrate.

Cite: Politanskaya L.V. , Malykhin E.V. , Shteingarts V.D.
Reactions of Aromatic Compounds with Nucleophilic Reagents in Liquid Ammonia. XVI. Thermodynamic Aspects of Orientation in Reactions of 2,4-Difluoronitrobenzene with Substituted Lithium Phenoxides
Russian Journal of Organic Chemistry. 1997. V.33. N5. P.644-651. Scopus РИНЦ

ArticleLinkType.TRANSLATED_TO_ORIGINAL: Politanskaya L.V. , Malykhin E.V. , Shteingarts V.D.
Interaction of aromatic compounds with nucleophilic reagents in liquid ammonia .16. Thermodynamic aspects of orientation in 2,4-difluoronitrobenzene reactions with lithium substituted phenolates
Журнал органической химии (RUSS J ORG CHEM+). 1997. V.33. N5. P.703-710. WOS

Identifiers:

Scopus	2-s2.0-0031315843
Elibrary	13250954