EPR and ENDOR spectroscopic study of the reactions of aromatic azides with gallium trichloride
作者:Giorgio Bencivenni、Riccardo Cesari、Daniele Nanni、Hassane El Mkami、John C. Walton
DOI:10.1039/c0ob00084a
日期:——
The reactions of gallium trichloride with phenyl and deuterio-phenyl azides, as well as with 4-methoxyphenyl azide and deuterium isotopomers, were examined by product analysis, CW EPR spectroscopy and pulsed ENDOR spectroscopy. The products included the corresponding anilines together with 4-aminodiphenylamine type dimers, and polyanilines. Complex CW EPR spectra of the radical cations of the dimers
的反应 三氯化镓 与苯基和氘代叠氮化物,以及 4-甲氧基苯基叠氮化物通过产物分析,连续波EPR光谱和脉冲ENDOR光谱检查了氘和氘的同位素异构体。产品包括相应的苯胺以及4-氨基二苯胺型二聚体和聚苯胺。二聚体[ArNHC 6 H 4 NH 2 ] + ˙和三聚体[ArNHC 6 H 4 NHC 6 H 4 NH 2 ] +的自由基阳离子的复杂CW EPR光谱获得。借助氘取代类似物的数据以及脉冲Davies ENDOR光谱对这些EPR光谱进行了分析。自由基阳离子的DFT计算提供了确凿的证据,并表明未成对的电子被容纳在广泛的π-离域轨道中。提出了一种机制来解释芳族叠氮化物还原转化为相应的苯胺并因此还原为二聚体和三聚体的机理。
Effect of molecular motion and solvent interactions on nitrogen-15 relaxation in anilines
作者:Joseph B. Lambert、Daniel Stec
DOI:10.1002/mrc.1270220506
日期:1984.5
AbstractDipolar relaxation of 15N in anilines and anilinium ions is influenced by overall motion of the molecule, by rotation about the aryl–‐nitrogen bond, by inversion of the aniline nitrogen and by interactions of the NH2 or NH3+ group with the solvent. These factors are assessed by comparison of the 13C and 15N dipolar relaxation times as a function of para‐substitution on the aryl ring. In the anilines (solvent CDCl3), electron withdrawal brings about faster relative motion of the amine side‐chain, contrary to expectation from consideration of CN rotation but in agreement with the effects from nitrogen inversion. The 15N dipolar relaxation time correlates with the Hammett σp. For the anilinium ions (solvent Me2SO‐d6), there is no correlation with σp and no qualitative relationship with either CN rotation or N inversion. Nitrogen‐15 relaxation, corrected for overall motion as judged by ring 13C relaxation, correlates with the inductive parameter σI. Electron withdrawal through induction reduces hydrogen bonding and increases side‐chain mobility. For most of the anilines and for all of the anilinium ions, solvent interactions cause the nitrogen side‐chain to be less mobile than the aryl ring. Under these circumstances, the Woessner approach cannot be used to calculate barriers. The hydrogen bond donor properties of the anilines are reduced in the absence of electron‐donating substituents, and the first barriers to NH2 rotation/inversion were calculated by this procedure: aniline in CDCl3 3.5 kcal/mol, p‐chloroaniline in CDCl3 3.4 kcal/mol and p‐nitroaniline in acetone 3.8 kcal/mol.
Becker, Heinz G. O.; Pfeifer, Dietmar; Radeglia, Reiner, Zeitschrift fur Naturforschung, Teil B: Anorganische Chemie, Organische Chemie, 1983, vol. 38, # 12, p. 1591 - 1597
作者:Becker, Heinz G. O.、Pfeifer, Dietmar、Radeglia, Reiner
DOI:——
日期:——
A Ceric Ammonium Nitrate N-Dearylation of <i>N</i>-<i>p</i>-Anisylazoles Applied to Pyrazole, Triazole, Tetrazole, and Pentazole Rings: Release of Parent Azoles. Generation of Unstable Pentazole, HN<sub>5</sub>/N<sub>5</sub><sup>-</sup>, in Solution
作者:Richard N. Butler、John M. Hanniffy、John C. Stephens、Luke A. Burke
DOI:10.1021/jo702423z
日期:2008.2.1
pentazole ring. The unstable HN5/N5- produced at −40 °C did not build up in the solution but degraded to azide ion and nitrogen gas with a short lifetime. The 15N-labeling of the N3- ion obtained from all samples proved unequivocally that it came from the degradation of HN5 (tautomeric forms) and/or its anion N5- in the solution.