Use of Sacrificial Anodes in the Transformation of Organic Halides, Residuals from Industry

Abstract

Cyclic voltammograms (CV) (DMF/TBAP 0.1M, Hg) of 2,2-dichloroethanol (DCOH) and 1,1,2-trichloroethane (TCE) showed irreversible cathodic waves related to the cleavage of C-Cl from the gem-dichlorinated group. DCOH worked as a probase, in electrolysis using aluminum sacrificial anode. In the presence of 2-butanone, dimeric alkenes, products from aldolic condensation, were obtained in large amounts. Coelectrolysis of TCE and benzophenone, in aluminum, furnished reduction products from benzophenone, without any evidence of chlorinated alcohol. CV of 2,2dichloroethylethylfumarate (DCEF) revealed the presence, at low scan rates, of two well defined reduction peaks (Epc₁, Epc₂) and a third one (Epc₃) close to the supporting electrolyte discharge. As the scan rate increases, the first wave turns into a reversible one and a new wave, intermediate between Epc₁ and Epc₂ (Epc_i) appears. Its height (Ipc_i) increases as Ipc₂ decreases. Epc₁ dependence with scan rate suggests an EC process, related to the reduction of the olefin, followed by dimerization. The remaining cathodic waves showed to be irreversible and the last one is related to C-Cl cleavage. Electrohydrodimerization is the main process in electrolyses of DCEF.