2024-82-0Relevant articles and documents
Nitration of moderately deactivated arenes with nitrogen dioxide and molecular oxygen under neutral conditions. Zeolite-induced enhancement of regioselectivity and reversal of isomer ratios
Peng, Xinhua,Fukui, Naoyuki,Mizuta, Masayuki,Suzuki, Hitomi
, p. 2326 - 2335 (2003)
In the presence of zeolites, moderately deactivated arenes such as 1-nitronaphthalene, naphthonitriles, and methylated benzonitriles can be smoothly nitrated at room temperature by the combined action of nitrogen dioxide and molecular oxygen. The regioselectivity is considerably improved as compared with the conventional nitration methodology based on nitric and sulfuric acids. In some cases, the minor isomer became favoured to a significant extent, resulting in the reversal of ordinary isomer ratios of nitration products.
13C NMR investigation of electronic interactions in 5-substituted 1-naphthonitriles
Schuster, Ingeborg I.
, p. 301 - 310 (2007/10/03)
Carbon-13 NMR chemical shifts of 5-Z-substituted 1-naphthonitriles (1; Z = H, F, Cl, Br, NH2, NMe2, CN, NO2, OMe, CHO, CO2Me) in deuteriochloroform and in neat trifluoroacetic acid (TFA) are reported. The CN carbon shifts are found to correlate well with the dual substituent parameters (DSPs). Negative values of the transmission coefficients in the DSP correlation give evidence of a reverse substituent electronic effect, which is associated with variations in π polarization of the CN multiple bond, due primarily to differences in the through-space field effects of the various Z. The effect diminishes for 1 in neat TFA because of the greater contribution of dipolar ArC+=N- to the resonance hybrid. Deviations of the aromatic carbon shifts from substituent chemical shift additivities are small, yet show distinct patterns for many of the carbon resonances. The deviations of the C-1 - CN ipso carbon shifts of 1 in neutral solvents and in TFA correlate roughly with the DSPs. They are attributable to changes in charge density at C-1 that arise as a consequence of substituent-induced changes in the polarity of the CN bond. The greater than expected shielding that is observed for the C-6 and C-8 resonances accords with reduced electron withdrawal by +R substituents and increased mesomeric activity by electron-donating groups, Z, in response to the CN-induced charge depletion within the adjacent aromatic ring. From the location of data for 5-methoxy-1-naphthonitrile (1; Z = OMe) in the chemical shift correlations of 1 in neat TFA, one can conclude that the methoxy group of this compound, unlike that of 1-methoxynaphthalene itself, is not significantly hydrogen-bonded by TFA.
