دانلود مقاله با موضوع تخریب حرارتی رنگهای آزوبنزن
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موضوع به انگلیسی:Thermal degradation of azobenzene dyes
بخشی از متن:Ten azobenzene dyes were tested for their thermal degradation products from ambient temperature to 800 °C
using a thermogravimetric technique. Degradation products were analyzed at each 100 °C increment using gas
chromatography‐mass spectrometry. Products were identified based on their mass spectral data and their retention
times. Thermal degradation from all dyes resulted in loss of the azo group as nitrogen gas and aromatic
free radicals. Electron withdrawing groups enhance the dissociation of the phenyl nitrogen bond at the benzene
moiety carrying the electron withdrawing group. On the other hand, electron donating groups inhibited the
dissociation of the phenyl‐N bond of the benzene moiety carrying the electron donating groups. The loss of
nitrogen molecule from the dyes appeared to be taken place in a two‐step rather than a one‐step reaction in
which the phenyl nitrogen bond of the phenyl group carrying the electron withdrawing group splits to form
phenyl and azo phenyl radicals following by the loss of a nitrogen molecule and a new phenyl radical. This
was also supported by calculating degradation reaction enthalpies and bond dissociation energies using density
functional theory quantum mechanics
