Naphthalene, anodic processes

Anodic substitution reactions of aromatic hydrocarbons have been known since around 1900 [29, 30]. The course of these processes was established primarily by a study of the reaction between naphthalene and acetate ions. Oxidation of naphthalene in the presence of acetate gives 1-acetoxynaphthalene and this was at first taken to indicate trapping of the acetyl radical formed during Kolbe electrolysis of... 

The electrochemical oxidation at BDD as final treatment in a combined two-step biological/electrochemical process was investigated by Panizza et al. (2006) for the removal of naphthalene sulfonates contained in infiltration water of an industrial site. Mono and disulfonate naphthalenes were easily removed in the biological step, whereas bio-refractory compounds with complex molecules were oxidised by electrolysis at BDD anodes. With this combination the energy demand was significantly lowered with respect to mat required in a single electrochemical step. 

Aluminum is used as the anode and nichrome as the cathode. There is also available in the cell a catalytic amount of titanium for fixation purposes, in addition to naphthalene, which serves a purpose again in the reduction stage. The electrolyte is tetrabutylammonium chloride. Aluminum isopropoxide increases the over-all efliciency and turns this process into a catalytic one. This system starts with titanium tetraiso-propoxide. Reduction takes place, presumably again to the titanium (II) level. We have evidence from electrochemical experiments that titanium (II) is produced and involved in the fixation. Titanium (II), once formed, picks up N2 from the atmosphere and forms the complex, which then is available for reduction by sodium naphthalenide. Naphthalene is present in a catalytic amount and is reduced at the cathode to the radical anion. In this experiment, one can actually see it as a greenish color at the cathode. Naphthalenide reduces the No compound, producing the nitride. Normally, the reaction would stop at this point. We believe that in the electrochemical process, aluminum (III) abstracts nitride from titanium and forms aluminum nitride. This nitride transfer also can be observed in nonelectrolytic reactions. Thus, aluminum nitride is stored and ammonia is available at any time, merely by protonation. Both titanium and naphthalene are catalytic and permit operation of an over-all catalytic process. 

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