RESUMO
Ozonolysis is used for oxidation of a model cyclic molecule-decalin, which may be considered as an analog of saturated cyclic molecules present in heavy oil. The conversion of decalin exceeds 50% with the highest yield of formation of acids about 15-17%. Carboxylic acids, ketones/aldehydes, and alcohols are produced as intermediate products. The methods of UV-visible, transmission IR, attenuated total reflection IR-spectroscopy, NMR and mass-spectrometry were used to identify reaction products and unravel a possible reaction mechanism. The key stage of the process is undoubtedly the activation of the first C-H bond and the formation of peroxide radicals.
RESUMO
A new approach for the determination of ozone concentration in solutions in organic liquids based on spectrophotometric absorbance measurements in the visible region was proposed and substantiated. The molar absorption coefficient of ozone in the absorption maximum at ~600nm is 8.0mol-1 L cm-1 for hydrocarbons (hexane, heptane, isooctane), CHCl3 and CCl4, and 5.3mol-1 L cm-1 for methanol and 4.5mol-1 L cm-1 for water (±10%). The coefficient monotonically decreases with increasing dielectric constant of the liquid. The low molar absorption coefficient allows the use of spectrophotometric measurements for determination of high ozone concentrations ranging from approximately 1·10-2mol L-1 up to 1.0mol L-1.
RESUMO
The chemical species formed from nitric acid in aqueous solutions of sulfuric acid (up to 18.0molL-1) were studied by optical spectroscopy method. The concentration region of nitronium ion formation was identified and NO2+ ion absorption spectrum was measured (λmax≤190nm and ε190=1040±50mol-1Lcm-1).