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• 446-35-5 2,4-Difluoronitrobenzene 
• 1121-69-3 lithium 4-methylphenoxide 
• 106-44-5 p-cresol 

Relevant academic research and scientific papers

The influence of nucleophile substituents on the orientation in the reaction between 2,4-difluoronitrobenzene and lithium phenoxides in liquid ammonia

The dependence of the orientation of aryloxydefluorination of 2,4-difluoronitrobenzene (1) (o/p ratio) by the action of X-substituted lithium phenoxides 2 (X = p-OMe, p-Me, p-Et, p-iPr, p-tBu, m-Me, H, p-F) in liquid ammonia in the temperature range from -55 to -35 °C has been investigated. The enthalpic preference for ortho-fluorine substitution decreases with weakening substituent electron-donating capability in the order: p-OMe > p-Me ≈ p-Et > m-Me > H ≥ p-F. The predominant fluorine substitution at the ortho position for X = p-Me, p-Et turns into a preference for substitution at the para position when X = p-iPr, and this increases further on going to X = p-tBu, PM3, AM1 and MNDO MO calculations showed greater stability of the intermediate anionic σ-complexes formed on nucleophile addition at the para position, thus suggesting that the predominant ortho substitution manifested for X = p-OMe, m-Me, H, p-F and p-Alk = Me, Et is due to control over orientation by the charge distribution in the substrate. The substrate electronic structure, as a controlling factor, is probably changed by the relative stability of intermediate anionic σ-complexes on going to p-Alk = iPr, tBu, as a consequence of an enhancement of the substituent's electron-withdrawing nature with the increase in alkyl group polarizability in the order: p-Me ≈ p-Et p-iPr p-tBu.

Reactions of aromatic compounds with nucleophilic reagents in liquid ammonia: XVII. Effect of ionic association on the orientation in aryloxydefluorination of 2,4-difluoronitrobenzene

The analysis of dependence of fluorine replacement orientation in 2,4-difluoronitrobenzene effected by nucleophiles Y-C6H4OM (Y = p-OMe, p-Me, m-Me, H, p-F, p-Cl, m-F, m-Cl; M = Li, Na, K, Et4N, Bu4N) in liquid

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

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.

Reaction of Aromatic Compounds with Nucleophilic Reagents in Liquid Ammonia. XIV. Effect of Liquid Ammonia as Solvent on the Orientation of Phenoxydefluorination of 2,4-Difluoronitrobenzene by Substituents in the Nucleophile

A relation is revealed between the orientation of fluorine substitution in 2,4-dinitrofluorobenzene (ortho/para ratio) by phenoxy group under the action of X-substituted lithium phenoxides (X = H, p-Me, m-Me, p-OMe, p-F, p-Cl, m-Cl, m-F) in liquid ammonia at -35 to -33°C and the nature of substituent X. Comparison of log (ortho/para) with values of -δΔG0 = ΔG0H - ΔG1X, which characterize the effect of substituent X on the Gibbs energies of protonation of substituted phenoxides in the gas phase and aqueous and DMSO solutions, together with the data on the relative contributions of various components of substituent effect in the title reaction, shows that liquid ammonia behaves like aprotic dipolar solvent.