No abstract

By using cyclopropyl bromide as precursor, the allyl cation C3H 5+ can be generated at low temperature in an SbF5 matrix and observed by IR spectroscopy; the experimental IR spectrum agrees well with that computed by ab initio methods. Characterization by 13C NMR spectroscopy failed, but the 13C NMR chemical shifts of this and other allyl cations could be predicted accurately for the first time by the GIAO/MP‐2 method.

Thermal dimerization of nitroso compounds in the solid state was investigated by using para-substituted nitrosobenzenes as model compounds. A mechanism that includes the interplay of topochemical reaction trajectories and phase transfer was proposed on the basis of FT-IR spectroscopic kinetics, time-resolved powder diffraction, and low-temperature X-ray structure determination. From shapes of the kinetic curves analyzed on the basis of the Avrami model, it was found that phase transfer could be triggered by a dimerization reaction of para-substituted nitrosobenzene to azodioxide, which, in turn, can be caused by different packing factors such as disorder in the starting nitroso monomer crystals. Since the represented model can be extended to a broad series of compounds, we propose it as a general method for investigations of solid-state reaction mechanisms.

No abstract

This investigation is a case study about the nature of the adiabatic organic solid-state reactions by kinetic measurements of the processes that occur during the dimerization of aromatic nitroso compounds under three different topochemical environments in crystals.