Electrolytic Reactions of Heterocyclic Systems

In the electrolytic formation of heterocyclic systems the role of the current is to bring one or both of the reaction centers to a suitable oxidation state. These reactions may be classified in different ways here they are treated according to the type of bond formed. 

Section III contains a discussion of the electrolytic reactions in which a heterocyclic system is formed the reactions will be treated under the following headings ring formation reactions, ring contractions, and ring expansions. 

Electrolytic formation of carbon bonds during formation of heterocyclic compounds occurs in the reduction of ketones to pinacols, in the hydrodimerization reaction, in some radical coupling reactions, and in the oxidative coupling of activated aromatic systems. 

Stability. Another major facet in the overall performance of electrochromic materials is the stability of the system. Many potential issues, such as degradation of the active redox couple due to irreversible oxidation or reduction at extreme potentials, iR loss of the electrode or the electrolyte, detrimental side reactions due to the presence of water or oxygen in the cell or heat release due to the resistive parts in the system, can result in the eventual loss of electrochromic contrast and function [7]. One effective approach towards the improvement of electrochemical cycling stability is the use of boron fluoride ethyl ether (REEF.) during the electrochemical synthesis of some heterocyclic compounds (including thiophene and bithiophene) [20]. For example, Camurlu et al. have shown reasonable stability and a switching speed of less than 1.5 s for the homopolymer of hexanedioic acid bis (2-thiophen-3-ylethyl) ester (HABTE) [21],... 

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