C thermal reactions

FIGURE 1. Gas-phase vibrational circular dichroism (VCD) spectra for (2S, 3S)-1-l3C-l, 2,3,-dj-cyclopropane (more intense spectrum) and for a 360 min, 407 °C thermal reaction product mixture of l3C, d3-cyclopropanes (less intense spectrum)165166... 

The use of high-temperature (200 °C) thermal reactions for the synthesis of dibenzoboroles from 2-biphenyldialk-ylboranes was first realized by Kbster and Benedikt <1963AG419>. It was later shown that the pyridine adduct of 2-biphenylborane could also be converted by thermolysis to the corresponding pyridine adduct of dibenzoborole <1973JOM33>. In the recent literature, there have been no reports on the use of thermal and photochemical methods to prepare borole derivatives. 

Dautzenberg and de Deken [11] have suggested that such processes could be important in hydroprocessing. They viewed the overall process as a competition between thermal and catalytic reactions. Over ca 430°C, thermal reactions were suggested to predominate and the removal/inter-conversion of oils, resins and asphaltenes proceeded at about the same rate. At somewhat lower temperatures, preferential removal of oils and resins was suggested via a catalytic reaction. The consequent removal of asphaltene solvent then led to precipitation of the asphaltenes and to coking. Similar arguments can be used to explain the results of Mochida et al [12] and of Nakata et al [13]. 

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