Autoredox reaction

This is known as an autoredox reaction. S(1V) is thus not thermodynamically stable at all and need not be considered further in this problem. Instead of considering reactions 1 and 2, we consider the direction reduction of S(V1) to S(0),... 

It can be seen from this figure that the steady state production of nitrosobenzene is preceded by an induction period, in which aniline is the main product. Further, small amounts of azobenzene and azoxybenzene are formed throughout the reaction. The existence of an autoredox reaction implies that a selectivity of 100% from nitrobenzene to nitrosobenzene is impossible. After the induction period the selectivity of nitrobenzene to nitrosobenzene becomes above 90% of the reduction products. The extent of conversion of nitrobenzene is also time dependent. In the steady state situation about 20% of the nitrobenzene is converted, after an initial conversion of 65%. 

Another alternative is the autoredox reaction. D-Gluconic acid and D-glucitol were obtained concurrently in 90% yield by paired electrolysis of glucose with a lead sheet cathode and a dimensionally stable anode in a press-filtration diaphragm cell.20... 

The first special case to be dealt with is the crossing of curves 1 and 2 at about pH 8. Consider the relative positions of curves 1 and 2 for pH > 8. This indicates that S(s) is not stable in this region and will undergo a spontaneous autoredox reaction, S(s) - S04 + HS (not balanced). The consequence is that S(s) is not stable for pH > 8 and the relevant redox couple will be that for SOj /HS" ... 

This work shows that oxygen-free sulfite in lime/limestone slurries, exposed to sulfur dioxide, slowly decomposes under process conditions. In fact, auto-redox reactions of sulfur oxyacids can occur in all coal desulfurization systems, including coal-gasification systems and impurities present in commercial flue gas systems are capable of catalyzing the reaction under process conditions. Our experiments indicate that any large-scale coal utilization will depend on appropriate control of the autoredox reactions of sulfur species. 

Reaction (2) requires oxygen vacancies in the oxide surface, which can be created by using a redactor like CO or CH. In the experiments described here nitrobenzene is reduced selectively to nitrosobenzene and some molecules of nitrobenzene are oxidised to CO, COj, H O and so on. The latter reaction is required to create oxygen vacancies, needed for the reduction reaction (autoredox-reaction [2,6]). 

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